[PATCH v10 00/19] KVM RISC-V Support

[PATCH v10 00/19] KVM RISC-V Support

[Anup Patel]

This series adds initial KVM RISC-V support. Currently, we are able to boot
RISC-V 64bit Linux Guests with multiple VCPUs.

Few key aspects of KVM RISC-V added by this series are:
1. Minimal possible KVM world-switch which touches only GPRs and few CSRs.
2. Full Guest/VM switch is done via vcpu_get/vcpu_put infrastructure.
3. KVM ONE_REG interface for VCPU register access from user-space.
4. PLIC emulation is done in user-space.
5. Timer and IPI emuation is done in-kernel.
6. MMU notifiers supported.
7. FP lazy save/restore supported.
8. SBI v0.1 emulation for KVM Guest available.
9. Forward unhandled SBI calls to KVM userspace.
10. Hugepage support for Guest/VM

Here's a brief TODO list which we will work upon after this series:
1. SBI v0.2 emulation in-kernel
2. SBI v0.2 hart state management emulation in-kernel
3. In-kernel PLIC emulation
4. ..... and more .....

This series can be found in riscv_kvm_v10 branch at:
https//github.com/avpatel/linux.git

Our work-in-progress KVMTOOL RISC-V port can be found in riscv_v1 branch
at: https//github.com/avpatel/kvmtool.git

The QEMU RISC-V hypervisor emulation is done by Alistair and is available
in mainline/alistair/riscv-hyp-ext-v0.5.1 branch at:
https://github.com/kvm-riscv/qemu.git

To play around with KVM RISC-V, refer KVM RISC-V wiki at:
https://github.com/kvm-riscv/howto/wiki
https://github.com/kvm-riscv/howto/wiki/KVM-RISCV64-on-QEMU

Changes since v9:
 - Squash PATCH19 and PATCH20 into PATCH5
 - Squash PATCH18 into PATCH11
 - Squash PATCH17 into PATCH16
 - Added ONE_REG interface for VCPU timer in PATCH13
 - Use HTIMEDELTA for VCPU timer in PATCH13
 - Updated KVM RISC-V mailing list in MAINTAINERS entry
 - Update KVM kconfig option to depend on RISCV_SBI and MMU
 - Check for SBI v0.2 and SBI v0.2 RFENCE extension at boot-time
 - Use SBI v0.2 RFENCE extension in VMID implementation
 - Use SBI v0.2 RFENCE extension in Stage2 MMU implementation
 - Use SBI v0.2 RFENCE extension in SBI implementation
 - Moved to RISC-V Hypervisor v0.5 draft spec
 - Updated Documentation/virt/kvm/api.txt for timer ONE_REG interface
 - Rebased patches on Linux-5.5-rc3

Changes since v8:
 - Rebased series on Linux-5.4-rc3 and Atish's SBI v0.2 patches
 - Use HRTIMER_MODE_REL instead of HRTIMER_MODE_ABS in timer emulation
 - Fixed kvm_riscv_stage2_map() to handle hugepages
 - Added patch to forward unhandled SBI calls to user-space
 - Added patch for iterative/recursive stage2 page table programming
 - Added patch to remove per-CPU vsip_shadow variable
 - Added patch to fix race-condition in kvm_riscv_vcpu_sync_interrupts()

Changes since v7:
- Rebased series on Linux-5.4-rc1 and Atish's SBI v0.2 patches
- Removed PATCH1, PATCH3, and PATCH20 because these already merged
- Use kernel doc style comments for ISA bitmap functions
- Don't parse X, Y, and Z extension in riscv_fill_hwcap() because it will
  be added in-future
- Mark KVM RISC-V kconfig option as EXPERIMENTAL
- Typo fix in commit description of PATCH6 of v7 series
- Use separate structs for CORE and CSR registers of ONE_REG interface
- Explicitly include asm/sbi.h in kvm/vcpu_sbi.c
- Removed implicit switch-case fall-through in kvm_riscv_vcpu_exit()
- No need to set VSSTATUS.MXR bit in kvm_riscv_vcpu_unpriv_read()
- Removed register for instruction length in kvm_riscv_vcpu_unpriv_read()
- Added defines for checking/decoding instruction length
- Added separate patch to forward unhandled SBI calls to userspace tool

Changes since v6:
- Rebased patches on Linux-5.3-rc7
- Added "return_handled" in struct kvm_mmio_decode to ensure that
  kvm_riscv_vcpu_mmio_return() updates SEPC only once
- Removed trap_stval parameter from kvm_riscv_vcpu_unpriv_read()
- Updated git repo URL in MAINTAINERS entry

Changes since v5:
- Renamed KVM_REG_RISCV_CONFIG_TIMEBASE register to
  KVM_REG_RISCV_CONFIG_TBFREQ register in ONE_REG interface
- Update SPEC in kvm_riscv_vcpu_mmio_return() for MMIO exits
- Use switch case instead of illegal instruction opcode table for simplicity
- Improve comments in stage2_remote_tlb_flush() for a potential remote TLB
  flush optimization
- Handle all unsupported SBI calls in default case of
  kvm_riscv_vcpu_sbi_ecall() function
- Fixed kvm_riscv_vcpu_sync_interrupts() for software interrupts
- Improved unprivilege reads to handle traps due to Guest stage1 page table
- Added separate patch to document RISC-V specific things in
  Documentation/virt/kvm/api.txt

Changes since v4:
- Rebased patches on Linux-5.3-rc5
- Added Paolo's Acked-by and Reviewed-by
- Updated mailing list in MAINTAINERS entry

Changes since v3:
- Moved patch for ISA bitmap from KVM prep series to this series
- Make vsip_shadow as run-time percpu variable instead of compile-time
- Flush Guest TLBs on all Host CPUs whenever we run-out of VMIDs

Changes since v2:
- Removed references of KVM_REQ_IRQ_PENDING from all patches
- Use kvm->srcu within in-kernel KVM run loop
- Added percpu vsip_shadow to track last value programmed in VSIP CSR
- Added comments about irqs_pending and irqs_pending_mask
- Used kvm_arch_vcpu_runnable() in-place-of kvm_riscv_vcpu_has_interrupt()
  in system_opcode_insn()
- Removed unwanted smp_wmb() in kvm_riscv_stage2_vmid_update()
- Use kvm_flush_remote_tlbs() in kvm_riscv_stage2_vmid_update()
- Use READ_ONCE() in kvm_riscv_stage2_update_hgatp() for vmid

Changes since v1:
- Fixed compile errors in building KVM RISC-V as module
- Removed unused kvm_riscv_halt_guest() and kvm_riscv_resume_guest()
- Set KVM_CAP_SYNC_MMU capability only after MMU notifiers are implemented
- Made vmid_version as unsigned long instead of atomic
- Renamed KVM_REQ_UPDATE_PGTBL to KVM_REQ_UPDATE_HGATP
- Renamed kvm_riscv_stage2_update_pgtbl() to kvm_riscv_stage2_update_hgatp()
- Configure HIDELEG and HEDELEG in kvm_arch_hardware_enable()
- Updated ONE_REG interface for CSR access to user-space
- Removed irqs_pending_lock and use atomic bitops instead
- Added separate patch for FP ONE_REG interface
- Added separate patch for updating MAINTAINERS file

Anup Patel (15):
  RISC-V: Export riscv_cpuid_to_hartid_mask() API
  RISC-V: Add bitmap reprensenting ISA features common across CPUs
  RISC-V: Add hypervisor extension related CSR defines
  RISC-V: Add initial skeletal KVM support
  RISC-V: KVM: Implement VCPU create, init and destroy functions
  RISC-V: KVM: Implement VCPU interrupts and requests handling
  RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls
  RISC-V: KVM: Implement VCPU world-switch
  RISC-V: KVM: Handle MMIO exits for VCPU
  RISC-V: KVM: Handle WFI exits for VCPU
  RISC-V: KVM: Implement VMID allocator
  RISC-V: KVM: Implement stage2 page table programming
  RISC-V: KVM: Implement MMU notifiers
  RISC-V: KVM: Document RISC-V specific parts of KVM API.
  RISC-V: KVM: Add MAINTAINERS entry

Atish Patra (4):
  RISC-V: KVM: Add timer functionality
  RISC-V: KVM: FP lazy save/restore
  RISC-V: KVM: Implement ONE REG interface for FP registers
  RISC-V: KVM: Add SBI v0.1 support

 Documentation/virt/kvm/api.txt          |  169 +++-
 MAINTAINERS                             |   11 +
 arch/riscv/Kconfig                      |    2 +
 arch/riscv/Makefile                     |    2 +
 arch/riscv/include/asm/csr.h            |   78 +-
 arch/riscv/include/asm/hwcap.h          |   22 +
 arch/riscv/include/asm/kvm_host.h       |  264 ++++++
 arch/riscv/include/asm/kvm_vcpu_timer.h |   44 +
 arch/riscv/include/asm/pgtable-bits.h   |    1 +
 arch/riscv/include/uapi/asm/kvm.h       |  127 +++
 arch/riscv/kernel/asm-offsets.c         |  148 ++++
 arch/riscv/kernel/cpufeature.c          |   83 +-
 arch/riscv/kernel/smp.c                 |    2 +
 arch/riscv/kvm/Kconfig                  |   34 +
 arch/riscv/kvm/Makefile                 |   14 +
 arch/riscv/kvm/main.c                   |   97 +++
 arch/riscv/kvm/mmu.c                    |  762 +++++++++++++++++
 arch/riscv/kvm/tlb.S                    |   43 +
 arch/riscv/kvm/vcpu.c                   | 1013 +++++++++++++++++++++++
 arch/riscv/kvm/vcpu_exit.c              |  639 ++++++++++++++
 arch/riscv/kvm/vcpu_sbi.c               |  171 ++++
 arch/riscv/kvm/vcpu_switch.S            |  382 +++++++++
 arch/riscv/kvm/vcpu_timer.c             |  225 +++++
 arch/riscv/kvm/vm.c                     |   86 ++
 arch/riscv/kvm/vmid.c                   |  120 +++
 drivers/clocksource/timer-riscv.c       |    8 +
 include/clocksource/timer-riscv.h       |   16 +
 include/uapi/linux/kvm.h                |    8 +
 28 files changed, 4558 insertions(+), 13 deletions(-)
 create mode 100644 arch/riscv/include/asm/kvm_host.h
 create mode 100644 arch/riscv/include/asm/kvm_vcpu_timer.h
 create mode 100644 arch/riscv/include/uapi/asm/kvm.h
 create mode 100644 arch/riscv/kvm/Kconfig
 create mode 100644 arch/riscv/kvm/Makefile
 create mode 100644 arch/riscv/kvm/main.c
 create mode 100644 arch/riscv/kvm/mmu.c
 create mode 100644 arch/riscv/kvm/tlb.S
 create mode 100644 arch/riscv/kvm/vcpu.c
 create mode 100644 arch/riscv/kvm/vcpu_exit.c
 create mode 100644 arch/riscv/kvm/vcpu_sbi.c
 create mode 100644 arch/riscv/kvm/vcpu_switch.S
 create mode 100644 arch/riscv/kvm/vcpu_timer.c
 create mode 100644 arch/riscv/kvm/vm.c
 create mode 100644 arch/riscv/kvm/vmid.c
 create mode 100644 include/clocksource/timer-riscv.h

-- 
2.17.1

[PATCH v10 01/19] RISC-V: Export riscv_cpuid_to_hartid_mask() API

[Anup Patel]

The riscv_cpuid_to_hartid_mask() API should be exported to allow
building KVM RISC-V as loadable module.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
 arch/riscv/kernel/smp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index eb878abcaaf8..6fc7828d41e4 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -10,6 +10,7 @@
 
 #include <linux/cpu.h>
 #include <linux/interrupt.h>
+#include <linux/module.h>
 #include <linux/profile.h>
 #include <linux/smp.h>
 #include <linux/sched.h>
@@ -63,6 +64,7 @@ void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out)
 	for_each_cpu(cpu, in)
 		cpumask_set_cpu(cpuid_to_hartid_map(cpu), out);
 }
+EXPORT_SYMBOL_GPL(riscv_cpuid_to_hartid_mask);
 
 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 {
-- 
2.17.1

[PATCH v10 02/19] RISC-V: Add bitmap reprensenting ISA features common across CPUs

[Anup Patel]

This patch adds riscv_isa bitmap which represents Host ISA features
common across all Host CPUs. The riscv_isa is not same as elf_hwcap
because elf_hwcap will only have ISA features relevant for user-space
apps whereas riscv_isa will have ISA features relevant to both kernel
and user-space apps.

One of the use-case for riscv_isa bitmap is in KVM hypervisor where
we will use it to do following operations:

1. Check whether hypervisor extension is available
2. Find ISA features that need to be virtualized (e.g. floating
   point support, vector extension, etc.)

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 arch/riscv/include/asm/hwcap.h | 22 +++++++++
 arch/riscv/kernel/cpufeature.c | 83 ++++++++++++++++++++++++++++++++--
 2 files changed, 102 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 1bb0cd04aec3..5589c012e004 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -8,6 +8,7 @@
 #ifndef _ASM_RISCV_HWCAP_H
 #define _ASM_RISCV_HWCAP_H
 
+#include <linux/bits.h>
 #include <uapi/asm/hwcap.h>
 
 #ifndef __ASSEMBLY__
@@ -22,6 +23,27 @@ enum {
 };
 
 extern unsigned long elf_hwcap;
+
+#define RISCV_ISA_EXT_a		('a' - 'a')
+#define RISCV_ISA_EXT_c		('c' - 'a')
+#define RISCV_ISA_EXT_d		('d' - 'a')
+#define RISCV_ISA_EXT_f		('f' - 'a')
+#define RISCV_ISA_EXT_h		('h' - 'a')
+#define RISCV_ISA_EXT_i		('i' - 'a')
+#define RISCV_ISA_EXT_m		('m' - 'a')
+#define RISCV_ISA_EXT_s		('s' - 'a')
+#define RISCV_ISA_EXT_u		('u' - 'a')
+
+#define RISCV_ISA_EXT_MAX	256
+
+unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap);
+
+#define riscv_isa_extension_mask(ext) BIT_MASK(RISCV_ISA_EXT_##ext)
+
+bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit);
+#define riscv_isa_extension_available(isa_bitmap, ext)	\
+	__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_##ext)
+
 #endif
 
 #endif /* _ASM_RISCV_HWCAP_H */
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 0b40705567b7..e172a2322b34 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -6,6 +6,7 @@
  * Copyright (C) 2017 SiFive
  */
 
+#include <linux/bitmap.h>
 #include <linux/of.h>
 #include <asm/processor.h>
 #include <asm/hwcap.h>
@@ -13,15 +14,57 @@
 #include <asm/switch_to.h>
 
 unsigned long elf_hwcap __read_mostly;
+
+/* Host ISA bitmap */
+static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
+
 #ifdef CONFIG_FPU
 bool has_fpu __read_mostly;
 #endif
 
+/**
+ * riscv_isa_extension_base() - Get base extension word
+ *
+ * @isa_bitmap: ISA bitmap to use
+ * Return: base extension word as unsigned long value
+ *
+ * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
+ */
+unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap)
+{
+	if (!isa_bitmap)
+		return riscv_isa[0];
+	return isa_bitmap[0];
+}
+EXPORT_SYMBOL_GPL(riscv_isa_extension_base);
+
+/**
+ * __riscv_isa_extension_available() - Check whether given extension
+ * is available or not
+ *
+ * @isa_bitmap: ISA bitmap to use
+ * @bit: bit position of the desired extension
+ * Return: true or false
+ *
+ * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
+ */
+bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
+{
+	const unsigned long *bmap = (isa_bitmap) ? isa_bitmap : riscv_isa;
+
+	if (bit >= RISCV_ISA_EXT_MAX)
+		return false;
+
+	return test_bit(bit, bmap) ? true : false;
+}
+EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
+
 void riscv_fill_hwcap(void)
 {
 	struct device_node *node;
 	const char *isa;
-	size_t i;
+	char print_str[BITS_PER_LONG + 1];
+	size_t i, j, isa_len;
 	static unsigned long isa2hwcap[256] = {0};
 
 	isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
@@ -33,8 +76,11 @@ void riscv_fill_hwcap(void)
 
 	elf_hwcap = 0;
 
+	bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
+
 	for_each_of_cpu_node(node) {
 		unsigned long this_hwcap = 0;
+		unsigned long this_isa = 0;
 
 		if (riscv_of_processor_hartid(node) < 0)
 			continue;
@@ -42,8 +88,24 @@ void riscv_fill_hwcap(void)
 		if (riscv_read_check_isa(node, &isa) < 0)
 			continue;
 
-		for (i = 0; i < strlen(isa); ++i)
+		i = 0;
+		isa_len = strlen(isa);
+#if IS_ENABLED(CONFIG_32BIT)
+		if (!strncmp(isa, "rv32", 4))
+			i += 4;
+#elif IS_ENABLED(CONFIG_64BIT)
+		if (!strncmp(isa, "rv64", 4))
+			i += 4;
+#endif
+		for (; i < isa_len; ++i) {
 			this_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
+			/*
+			 * TODO: X, Y and Z extension parsing for Host ISA
+			 * bitmap will be added in-future.
+			 */
+			if ('a' <= isa[i] && isa[i] < 'x')
+				this_isa |= (1UL << (isa[i] - 'a'));
+		}
 
 		/*
 		 * All "okay" hart should have same isa. Set HWCAP based on
@@ -54,6 +116,11 @@ void riscv_fill_hwcap(void)
 			elf_hwcap &= this_hwcap;
 		else
 			elf_hwcap = this_hwcap;
+
+		if (riscv_isa[0])
+			riscv_isa[0] &= this_isa;
+		else
+			riscv_isa[0] = this_isa;
 	}
 
 	/* We don't support systems with F but without D, so mask those out
@@ -63,7 +130,17 @@ void riscv_fill_hwcap(void)
 		elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
 	}
 
-	pr_info("elf_hwcap is 0x%lx\n", elf_hwcap);
+	memset(print_str, 0, sizeof(print_str));
+	for (i = 0, j = 0; i < BITS_PER_LONG; i++)
+		if (riscv_isa[0] & BIT_MASK(i))
+			print_str[j++] = (char)('a' + i);
+	pr_info("riscv: ISA extensions %s\n", print_str);
+
+	memset(print_str, 0, sizeof(print_str));
+	for (i = 0, j = 0; i < BITS_PER_LONG; i++)
+		if (elf_hwcap & BIT_MASK(i))
+			print_str[j++] = (char)('a' + i);
+	pr_info("riscv: ELF capabilities %s\n", print_str);
 
 #ifdef CONFIG_FPU
 	if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
-- 
2.17.1

[PATCH v10 03/19] RISC-V: Add hypervisor extension related CSR defines

[Anup Patel]

This patch extends asm/csr.h by adding RISC-V hypervisor extension
related defines.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 arch/riscv/include/asm/csr.h | 78 ++++++++++++++++++++++++++++++++++--
 1 file changed, 75 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 0a62d2d68455..afb6733475c2 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -30,6 +30,8 @@
 #define SR_XS_CLEAN	_AC(0x00010000, UL)
 #define SR_XS_DIRTY	_AC(0x00018000, UL)
 
+#define SR_MXR		_AC(0x00080000, UL)
+
 #ifndef CONFIG_64BIT
 #define SR_SD		_AC(0x80000000, UL) /* FS/XS dirty */
 #else
@@ -51,26 +53,74 @@
 #define CAUSE_IRQ_FLAG		(_AC(1, UL) << (__riscv_xlen - 1))
 
 /* Interrupt causes (minus the high bit) */
-#define IRQ_U_SOFT		0
 #define IRQ_S_SOFT		1
+#define IRQ_VS_SOFT		2
 #define IRQ_M_SOFT		3
-#define IRQ_U_TIMER		4
 #define IRQ_S_TIMER		5
+#define IRQ_VS_TIMER		6
 #define IRQ_M_TIMER		7
-#define IRQ_U_EXT		8
 #define IRQ_S_EXT		9
+#define IRQ_VS_EXT		10
 #define IRQ_M_EXT		11
 
 /* Exception causes */
 #define EXC_INST_MISALIGNED	0
 #define EXC_INST_ACCESS		1
+#define EXC_INST_ILLEGAL	2
 #define EXC_BREAKPOINT		3
 #define EXC_LOAD_ACCESS		5
 #define EXC_STORE_ACCESS	7
 #define EXC_SYSCALL		8
+#define EXC_HYPERVISOR_SYSCALL	9
+#define EXC_SUPERVISOR_SYSCALL	10
 #define EXC_INST_PAGE_FAULT	12
 #define EXC_LOAD_PAGE_FAULT	13
 #define EXC_STORE_PAGE_FAULT	15
+#define EXC_INST_GUEST_PAGE_FAULT	20
+#define EXC_LOAD_GUEST_PAGE_FAULT	21
+#define EXC_STORE_GUEST_PAGE_FAULT	23
+
+/* HSTATUS flags */
+#define HSTATUS_VTSR		_AC(0x00400000, UL)
+#define HSTATUS_VTVM		_AC(0x00100000, UL)
+#define HSTATUS_SP2V		_AC(0x00000200, UL)
+#define HSTATUS_SP2P		_AC(0x00000100, UL)
+#define HSTATUS_SPV		_AC(0x00000080, UL)
+#define HSTATUS_SPRV		_AC(0x00000001, UL)
+
+/* HGATP flags */
+#define HGATP_MODE_OFF		_AC(0, UL)
+#define HGATP_MODE_SV32X4	_AC(1, UL)
+#define HGATP_MODE_SV39X4	_AC(8, UL)
+#define HGATP_MODE_SV48X4	_AC(9, UL)
+
+#define HGATP32_MODE_SHIFT	31
+#define HGATP32_VMID_SHIFT	22
+#define HGATP32_VMID_MASK	_AC(0x1FC00000, UL)
+#define HGATP32_PPN		_AC(0x003FFFFF, UL)
+
+#define HGATP64_MODE_SHIFT	60
+#define HGATP64_VMID_SHIFT	44
+#define HGATP64_VMID_MASK	_AC(0x03FFF00000000000, UL)
+#define HGATP64_PPN		_AC(0x00000FFFFFFFFFFF, UL)
+
+#ifdef CONFIG_64BIT
+#define HGATP_PPN		HGATP64_PPN
+#define HGATP_VMID_SHIFT	HGATP64_VMID_SHIFT
+#define HGATP_VMID_MASK		HGATP64_VMID_MASK
+#define HGATP_MODE		(HGATP_MODE_SV39X4 << HGATP64_MODE_SHIFT)
+#else
+#define HGATP_PPN		HGATP32_PPN
+#define HGATP_VMID_SHIFT	HGATP32_VMID_SHIFT
+#define HGATP_VMID_MASK		HGATP32_VMID_MASK
+#define HGATP_MODE		(HGATP_MODE_SV32X4 << HGATP32_MODE_SHIFT)
+#endif
+
+/* VSIP & HIP relation */
+#define VSIP_TO_HIP_SHIFT	(IRQ_VS_SOFT - IRQ_S_SOFT)
+#define VSIP_VALID_MASK		((_AC(1, UL) << IRQ_S_SOFT) | \
+				 (_AC(1, UL) << IRQ_S_TIMER) | \
+				 (_AC(1, UL) << IRQ_S_EXT))
 
 /* symbolic CSR names: */
 #define CSR_CYCLE		0xc00
@@ -91,6 +141,28 @@
 #define CSR_SIP			0x144
 #define CSR_SATP		0x180
 
+#define CSR_VSSTATUS		0x200
+#define CSR_VSIE		0x204
+#define CSR_VSTVEC		0x205
+#define CSR_VSSCRATCH		0x240
+#define CSR_VSEPC		0x241
+#define CSR_VSCAUSE		0x242
+#define CSR_VSTVAL		0x243
+#define CSR_VSIP		0x244
+#define CSR_VSATP		0x280
+
+#define CSR_HSTATUS		0x600
+#define CSR_HEDELEG		0x602
+#define CSR_HIDELEG		0x603
+#define CSR_HIE			0x604
+#define CSR_HTIMEDELTA		0x605
+#define CSR_HTIMEDELTAH		0x615
+#define CSR_HCOUNTERNEN		0x606
+#define CSR_HTVAL		0x643
+#define CSR_HIP			0x644
+#define CSR_HTINST		0x64a
+#define CSR_HGATP		0x680
+
 #define CSR_MSTATUS		0x300
 #define CSR_MISA		0x301
 #define CSR_MIE			0x304
-- 
2.17.1

[PATCH v10 04/19] RISC-V: Add initial skeletal KVM support

[Anup Patel]

This patch adds initial skeletal KVM RISC-V support which has:
1. A simple implementation of arch specific VM functions
   except kvm_vm_ioctl_get_dirty_log() which will implemeted
   in-future as part of stage2 page loging.
2. Stubs of required arch specific VCPU functions except
   kvm_arch_vcpu_ioctl_run() which is semi-complete and
   extended by subsequent patches.
3. Stubs for required arch specific stage2 MMU functions.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 arch/riscv/Kconfig                |   2 +
 arch/riscv/Makefile               |   2 +
 arch/riscv/include/asm/kvm_host.h |  82 ++++++++
 arch/riscv/include/uapi/asm/kvm.h |  47 +++++
 arch/riscv/kvm/Kconfig            |  33 ++++
 arch/riscv/kvm/Makefile           |  13 ++
 arch/riscv/kvm/main.c             |  93 +++++++++
 arch/riscv/kvm/mmu.c              |  83 ++++++++
 arch/riscv/kvm/vcpu.c             | 316 ++++++++++++++++++++++++++++++
 arch/riscv/kvm/vcpu_exit.c        |  36 ++++
 arch/riscv/kvm/vm.c               |  79 ++++++++
 11 files changed, 786 insertions(+)
 create mode 100644 arch/riscv/include/asm/kvm_host.h
 create mode 100644 arch/riscv/include/uapi/asm/kvm.h
 create mode 100644 arch/riscv/kvm/Kconfig
 create mode 100644 arch/riscv/kvm/Makefile
 create mode 100644 arch/riscv/kvm/main.c
 create mode 100644 arch/riscv/kvm/mmu.c
 create mode 100644 arch/riscv/kvm/vcpu.c
 create mode 100644 arch/riscv/kvm/vcpu_exit.c
 create mode 100644 arch/riscv/kvm/vm.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index baf0943c80d0..2e8551a9cd32 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -366,3 +366,5 @@ menu "Power management options"
 source "kernel/power/Kconfig"
 
 endmenu
+
+source "arch/riscv/kvm/Kconfig"
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index b9009a2fbaf5..65b58cec9abd 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -77,6 +77,8 @@ head-y := arch/riscv/kernel/head.o
 
 core-y += arch/riscv/
 
+core-$(CONFIG_KVM) += arch/riscv/kvm/
+
 libs-y += arch/riscv/lib/
 
 PHONY += vdso_install
diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
new file mode 100644
index 000000000000..e0b633f616a4
--- /dev/null
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Anup Patel <anup.patel@wdc.com>
+ */
+
+#ifndef __RISCV_KVM_HOST_H__
+#define __RISCV_KVM_HOST_H__
+
+#include <linux/types.h>
+#include <linux/kvm.h>
+#include <linux/kvm_types.h>
+
+#ifdef CONFIG_64BIT
+#define KVM_MAX_VCPUS			(1U << 16)
+#else
+#define KVM_MAX_VCPUS			(1U << 9)
+#endif
+
+#define KVM_USER_MEM_SLOTS		512
+#define KVM_HALT_POLL_NS_DEFAULT	500000
+
+#define KVM_VCPU_MAX_FEATURES		0
+
+#define KVM_REQ_SLEEP \
+	KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
+#define KVM_REQ_VCPU_RESET		KVM_ARCH_REQ(1)
+
+struct kvm_vm_stat {
+	ulong remote_tlb_flush;
+};
+
+struct kvm_vcpu_stat {
+	u64 halt_successful_poll;
+	u64 halt_attempted_poll;
+	u64 halt_poll_invalid;
+	u64 halt_wakeup;
+	u64 ecall_exit_stat;
+	u64 wfi_exit_stat;
+	u64 mmio_exit_user;
+	u64 mmio_exit_kernel;
+	u64 exits;
+};
+
+struct kvm_arch_memory_slot {
+};
+
+struct kvm_arch {
+	/* stage2 page table */
+	pgd_t *pgd;
+	phys_addr_t pgd_phys;
+};
+
+struct kvm_vcpu_arch {
+	/* Don't run the VCPU (blocked) */
+	bool pause;
+
+	/* SRCU lock index for in-kernel run loop */
+	int srcu_idx;
+};
+
+static inline void kvm_arch_hardware_unsetup(void) {}
+static inline void kvm_arch_sync_events(struct kvm *kvm) {}
+static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
+static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
+static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
+
+void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu);
+int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm);
+void kvm_riscv_stage2_free_pgd(struct kvm *kvm);
+void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu);
+
+int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
+int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
+			unsigned long scause, unsigned long stval,
+			unsigned long htval, unsigned long htinst);
+
+static inline void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch) {}
+
+#endif /* __RISCV_KVM_HOST_H__ */
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
new file mode 100644
index 000000000000..d15875818b6e
--- /dev/null
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Anup Patel <anup.patel@wdc.com>
+ */
+
+#ifndef __LINUX_KVM_RISCV_H
+#define __LINUX_KVM_RISCV_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <asm/ptrace.h>
+
+#define __KVM_HAVE_READONLY_MEM
+
+#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
+
+/* for KVM_GET_REGS and KVM_SET_REGS */
+struct kvm_regs {
+};
+
+/* for KVM_GET_FPU and KVM_SET_FPU */
+struct kvm_fpu {
+};
+
+/* KVM Debug exit structure */
+struct kvm_debug_exit_arch {
+};
+
+/* for KVM_SET_GUEST_DEBUG */
+struct kvm_guest_debug_arch {
+};
+
+/* definition of registers in kvm_run */
+struct kvm_sync_regs {
+};
+
+/* dummy definition */
+struct kvm_sregs {
+};
+
+#endif
+
+#endif /* __LINUX_KVM_RISCV_H */
diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
new file mode 100644
index 000000000000..88edd477b3a8
--- /dev/null
+++ b/arch/riscv/kvm/Kconfig
@@ -0,0 +1,33 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# KVM configuration
+#
+
+source "virt/kvm/Kconfig"
+
+menuconfig VIRTUALIZATION
+	bool "Virtualization"
+	help
+	  Say Y here to get to see options for using your Linux host to run
+	  other operating systems inside virtual machines (guests).
+	  This option alone does not add any kernel code.
+
+	  If you say N, all options in this submenu will be skipped and
+	  disabled.
+
+if VIRTUALIZATION
+
+config KVM
+	tristate "Kernel-based Virtual Machine (KVM) support (EXPERIMENTAL)"
+	depends on RISCV_SBI && MMU
+	select PREEMPT_NOTIFIERS
+	select ANON_INODES
+	select KVM_MMIO
+	select HAVE_KVM_VCPU_ASYNC_IOCTL
+	select SRCU
+	help
+	  Support hosting virtualized guest machines.
+
+	  If unsure, say N.
+
+endif # VIRTUALIZATION
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
new file mode 100644
index 000000000000..37b5a59d4f4f
--- /dev/null
+++ b/arch/riscv/kvm/Makefile
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for RISC-V KVM support
+#
+
+common-objs-y = $(addprefix ../../../virt/kvm/, kvm_main.o coalesced_mmio.o)
+
+ccflags-y := -Ivirt/kvm -Iarch/riscv/kvm
+
+kvm-objs := $(common-objs-y)
+
+kvm-objs += main.o vm.o mmu.o vcpu.o vcpu_exit.o
+
+obj-$(CONFIG_KVM)	+= kvm.o
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
new file mode 100644
index 000000000000..f29768c82fbe
--- /dev/null
+++ b/arch/riscv/kvm/main.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/kvm_host.h>
+#include <asm/csr.h>
+#include <asm/hwcap.h>
+#include <asm/sbi.h>
+
+long kvm_arch_dev_ioctl(struct file *filp,
+			unsigned int ioctl, unsigned long arg)
+{
+	return -EINVAL;
+}
+
+int kvm_arch_check_processor_compat(void)
+{
+	return 0;
+}
+
+int kvm_arch_hardware_setup(void)
+{
+	return 0;
+}
+
+int kvm_arch_hardware_enable(void)
+{
+	unsigned long hideleg, hedeleg;
+
+	hedeleg = 0;
+	hedeleg |= (1UL << EXC_INST_MISALIGNED);
+	hedeleg |= (1UL << EXC_BREAKPOINT);
+	hedeleg |= (1UL << EXC_SYSCALL);
+	hedeleg |= (1UL << EXC_INST_PAGE_FAULT);
+	hedeleg |= (1UL << EXC_LOAD_PAGE_FAULT);
+	hedeleg |= (1UL << EXC_STORE_PAGE_FAULT);
+	csr_write(CSR_HEDELEG, hedeleg);
+
+	hideleg = 0;
+	hideleg |= (1UL << IRQ_S_SOFT);
+	hideleg |= (1UL << IRQ_S_TIMER);
+	hideleg |= (1UL << IRQ_S_EXT);
+	csr_write(CSR_HIDELEG, hideleg);
+
+	csr_write(CSR_HIP, 0);
+
+	return 0;
+}
+
+void kvm_arch_hardware_disable(void)
+{
+	csr_write(CSR_HEDELEG, 0);
+	csr_write(CSR_HIDELEG, 0);
+}
+
+int kvm_arch_init(void *opaque)
+{
+	if (!riscv_isa_extension_available(NULL, h)) {
+		kvm_info("hypervisor extension not available\n");
+		return -ENODEV;
+	}
+
+	if (sbi_spec_is_0_1()) {
+		kvm_info("require SBI v0.2 or higher\n");
+		return -ENODEV;
+	}
+
+	if (sbi_probe_extension(SBI_EXT_RFENCE) <= 0) {
+		kvm_info("require SBI RFENCE extension\n");
+		return -ENODEV;
+	}
+
+	kvm_info("hypervisor extension available\n");
+
+	return 0;
+}
+
+void kvm_arch_exit(void)
+{
+}
+
+static int riscv_kvm_init(void)
+{
+	return kvm_init(NULL, sizeof(struct kvm_vcpu), 0, THIS_MODULE);
+}
+module_init(riscv_kvm_init);
diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
new file mode 100644
index 000000000000..04dd089b86ff
--- /dev/null
+++ b/arch/riscv/kvm/mmu.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/hugetlb.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+#include <linux/kvm_host.h>
+#include <linux/sched/signal.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+
+void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
+			   struct kvm_memory_slot *dont)
+{
+}
+
+int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
+			    unsigned long npages)
+{
+	return 0;
+}
+
+void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
+{
+}
+
+void kvm_arch_flush_shadow_all(struct kvm *kvm)
+{
+	/* TODO: */
+}
+
+void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
+				   struct kvm_memory_slot *slot)
+{
+}
+
+void kvm_arch_commit_memory_region(struct kvm *kvm,
+				const struct kvm_userspace_memory_region *mem,
+				const struct kvm_memory_slot *old,
+				const struct kvm_memory_slot *new,
+				enum kvm_mr_change change)
+{
+	/* TODO: */
+}
+
+int kvm_arch_prepare_memory_region(struct kvm *kvm,
+				struct kvm_memory_slot *memslot,
+				const struct kvm_userspace_memory_region *mem,
+				enum kvm_mr_change change)
+{
+	/* TODO: */
+	return 0;
+}
+
+void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu)
+{
+	/* TODO: */
+}
+
+int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm)
+{
+	/* TODO: */
+	return 0;
+}
+
+void kvm_riscv_stage2_free_pgd(struct kvm *kvm)
+{
+	/* TODO: */
+}
+
+void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu)
+{
+	/* TODO: */
+}
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
new file mode 100644
index 000000000000..bd7d6b154f61
--- /dev/null
+++ b/arch/riscv/kvm/vcpu.c
@@ -0,0 +1,316 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/kdebug.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+#include <linux/sched/signal.h>
+#include <linux/fs.h>
+#include <linux/kvm_host.h>
+#include <asm/csr.h>
+#include <asm/delay.h>
+#include <asm/hwcap.h>
+
+#define VCPU_STAT(x) { #x, offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU }
+
+struct kvm_stats_debugfs_item debugfs_entries[] = {
+	VCPU_STAT(ecall_exit_stat),
+	VCPU_STAT(wfi_exit_stat),
+	VCPU_STAT(mmio_exit_user),
+	VCPU_STAT(mmio_exit_kernel),
+	VCPU_STAT(exits),
+	{ NULL }
+};
+
+struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
+{
+	/* TODO: */
+	return NULL;
+}
+
+int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
+void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
+{
+}
+
+int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
+{
+	/* TODO: */
+	return 0;
+}
+
+void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
+{
+	/* TODO: */
+}
+
+int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
+{
+	/* TODO: */
+	return 0;
+}
+
+void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu)
+{
+}
+
+void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
+{
+}
+
+int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
+{
+	/* TODO: */
+	return 0;
+}
+
+int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
+{
+	/* TODO: */
+	return 0;
+}
+
+bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
+{
+	/* TODO: */
+	return false;
+}
+
+bool kvm_arch_has_vcpu_debugfs(void)
+{
+	return false;
+}
+
+int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
+vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
+{
+	return VM_FAULT_SIGBUS;
+}
+
+long kvm_arch_vcpu_async_ioctl(struct file *filp,
+			       unsigned int ioctl, unsigned long arg)
+{
+	/* TODO; */
+	return -ENOIOCTLCMD;
+}
+
+long kvm_arch_vcpu_ioctl(struct file *filp,
+			 unsigned int ioctl, unsigned long arg)
+{
+	/* TODO: */
+	return -EINVAL;
+}
+
+int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
+				  struct kvm_sregs *sregs)
+{
+	return -EINVAL;
+}
+
+int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
+				  struct kvm_sregs *sregs)
+{
+	return -EINVAL;
+}
+
+int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
+{
+	return -EINVAL;
+}
+
+int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
+{
+	return -EINVAL;
+}
+
+int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
+				  struct kvm_translation *tr)
+{
+	return -EINVAL;
+}
+
+int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
+{
+	return -EINVAL;
+}
+
+int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
+{
+	return -EINVAL;
+}
+
+int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
+				    struct kvm_mp_state *mp_state)
+{
+	/* TODO: */
+	return 0;
+}
+
+int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
+				    struct kvm_mp_state *mp_state)
+{
+	/* TODO: */
+	return 0;
+}
+
+int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
+					struct kvm_guest_debug *dbg)
+{
+	/* TODO; To be implemented later. */
+	return -EINVAL;
+}
+
+void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
+{
+	/* TODO: */
+
+	kvm_riscv_stage2_update_hgatp(vcpu);
+}
+
+void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
+{
+	/* TODO: */
+}
+
+static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
+{
+	/* TODO: */
+}
+
+int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+	int ret;
+	unsigned long scause, stval, htval, htinst;
+
+	vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+
+	/* Process MMIO value returned from user-space */
+	if (run->exit_reason == KVM_EXIT_MMIO) {
+		ret = kvm_riscv_vcpu_mmio_return(vcpu, vcpu->run);
+		if (ret) {
+			srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+			return ret;
+		}
+	}
+
+	if (run->immediate_exit) {
+		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+		return -EINTR;
+	}
+
+	vcpu_load(vcpu);
+
+	kvm_sigset_activate(vcpu);
+
+	ret = 1;
+	run->exit_reason = KVM_EXIT_UNKNOWN;
+	while (ret > 0) {
+		/* Check conditions before entering the guest */
+		cond_resched();
+
+		kvm_riscv_check_vcpu_requests(vcpu);
+
+		preempt_disable();
+
+		local_irq_disable();
+
+		/*
+		 * Exit if we have a signal pending so that we can deliver
+		 * the signal to user space.
+		 */
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			run->exit_reason = KVM_EXIT_INTR;
+		}
+
+		/*
+		 * Ensure we set mode to IN_GUEST_MODE after we disable
+		 * interrupts and before the final VCPU requests check.
+		 * See the comment in kvm_vcpu_exiting_guest_mode() and
+		 * Documentation/virtual/kvm/vcpu-requests.rst
+		 */
+		vcpu->mode = IN_GUEST_MODE;
+
+		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+		smp_mb__after_srcu_read_unlock();
+
+		if (ret <= 0 ||
+		    kvm_request_pending(vcpu)) {
+			vcpu->mode = OUTSIDE_GUEST_MODE;
+			local_irq_enable();
+			preempt_enable();
+			vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+			continue;
+		}
+
+		guest_enter_irqoff();
+
+		__kvm_riscv_switch_to(&vcpu->arch);
+
+		vcpu->mode = OUTSIDE_GUEST_MODE;
+		vcpu->stat.exits++;
+
+		/*
+		 * Save SCAUSE, STVAL, HTVAL, and HTINST because we might
+		 * get an interrupt between __kvm_riscv_switch_to() and
+		 * local_irq_enable() which can potentially change CSRs.
+		 */
+		scause = csr_read(CSR_SCAUSE);
+		stval = csr_read(CSR_STVAL);
+		htval = csr_read(CSR_HTVAL);
+		htinst = csr_read(CSR_HTINST);
+
+		/*
+		 * We may have taken a host interrupt in VS/VU-mode (i.e.
+		 * while executing the guest). This interrupt is still
+		 * pending, as we haven't serviced it yet!
+		 *
+		 * We're now back in HS-mode with interrupts disabled
+		 * so enabling the interrupts now will have the effect
+		 * of taking the interrupt again, in HS-mode this time.
+		 */
+		local_irq_enable();
+
+		/*
+		 * We do local_irq_enable() before calling guest_exit() so
+		 * that if a timer interrupt hits while running the guest
+		 * we account that tick as being spent in the guest. We
+		 * enable preemption after calling guest_exit() so that if
+		 * we get preempted we make sure ticks after that is not
+		 * counted as guest time.
+		 */
+		guest_exit();
+
+		preempt_enable();
+
+		vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+
+		ret = kvm_riscv_vcpu_exit(vcpu, run,
+					  scause, stval, htval, htinst);
+	}
+
+	kvm_sigset_deactivate(vcpu);
+
+	vcpu_put(vcpu);
+
+	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+
+	return ret;
+}
diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
new file mode 100644
index 000000000000..dcea9ce4e728
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/kvm_host.h>
+
+/**
+ * kvm_riscv_vcpu_mmio_return -- Handle MMIO loads after user space emulation
+ *			     or in-kernel IO emulation
+ *
+ * @vcpu: The VCPU pointer
+ * @run:  The VCPU run struct containing the mmio data
+ */
+int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+	/* TODO: */
+	return 0;
+}
+
+/*
+ * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
+ * proper exit to userspace.
+ */
+int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
+			unsigned long scause, unsigned long stval,
+			unsigned long htval, unsigned long htinst)
+{
+	/* TODO: */
+	return 0;
+}
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
new file mode 100644
index 000000000000..ac0211820521
--- /dev/null
+++ b/arch/riscv/kvm/vm.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/kvm_host.h>
+
+int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
+{
+	/* TODO: To be added later. */
+	return -ENOTSUPP;
+}
+
+int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
+{
+	int r;
+
+	r = kvm_riscv_stage2_alloc_pgd(kvm);
+	if (r)
+		return r;
+
+	return 0;
+}
+
+void kvm_arch_destroy_vm(struct kvm *kvm)
+{
+	int i;
+
+	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+		if (kvm->vcpus[i]) {
+			kvm_arch_vcpu_destroy(kvm->vcpus[i]);
+			kvm->vcpus[i] = NULL;
+		}
+	}
+}
+
+int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
+{
+	int r;
+
+	switch (ext) {
+	case KVM_CAP_DEVICE_CTRL:
+	case KVM_CAP_USER_MEMORY:
+	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
+	case KVM_CAP_ONE_REG:
+	case KVM_CAP_READONLY_MEM:
+	case KVM_CAP_MP_STATE:
+	case KVM_CAP_IMMEDIATE_EXIT:
+		r = 1;
+		break;
+	case KVM_CAP_NR_VCPUS:
+		r = num_online_cpus();
+		break;
+	case KVM_CAP_MAX_VCPUS:
+		r = KVM_MAX_VCPUS;
+		break;
+	case KVM_CAP_NR_MEMSLOTS:
+		r = KVM_USER_MEM_SLOTS;
+		break;
+	default:
+		r = 0;
+		break;
+	}
+
+	return r;
+}
+
+long kvm_arch_vm_ioctl(struct file *filp,
+		       unsigned int ioctl, unsigned long arg)
+{
+	return -EINVAL;
+}
-- 
2.17.1

[PATCH v10 05/19] RISC-V: KVM: Implement VCPU create, init and destroy functions

[Anup Patel]

This patch implements VCPU create, init and destroy functions
required by generic KVM module. We don't have much dynamic
resources in struct kvm_vcpu_arch so these functions are quite
simple for KVM RISC-V.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 arch/riscv/include/asm/kvm_host.h | 68 +++++++++++++++++++++++++++++++
 arch/riscv/kvm/vcpu.c             | 68 +++++++++++++++++++++++++++++--
 2 files changed, 132 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index e0b633f616a4..297431660be6 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -53,7 +53,75 @@ struct kvm_arch {
 	phys_addr_t pgd_phys;
 };
 
+struct kvm_cpu_context {
+	unsigned long zero;
+	unsigned long ra;
+	unsigned long sp;
+	unsigned long gp;
+	unsigned long tp;
+	unsigned long t0;
+	unsigned long t1;
+	unsigned long t2;
+	unsigned long s0;
+	unsigned long s1;
+	unsigned long a0;
+	unsigned long a1;
+	unsigned long a2;
+	unsigned long a3;
+	unsigned long a4;
+	unsigned long a5;
+	unsigned long a6;
+	unsigned long a7;
+	unsigned long s2;
+	unsigned long s3;
+	unsigned long s4;
+	unsigned long s5;
+	unsigned long s6;
+	unsigned long s7;
+	unsigned long s8;
+	unsigned long s9;
+	unsigned long s10;
+	unsigned long s11;
+	unsigned long t3;
+	unsigned long t4;
+	unsigned long t5;
+	unsigned long t6;
+	unsigned long sepc;
+	unsigned long sstatus;
+	unsigned long hstatus;
+};
+
+struct kvm_vcpu_csr {
+	unsigned long vsstatus;
+	unsigned long hie;
+	unsigned long vstvec;
+	unsigned long vsscratch;
+	unsigned long vsepc;
+	unsigned long vscause;
+	unsigned long vstval;
+	unsigned long hip;
+	unsigned long vsatp;
+};
+
 struct kvm_vcpu_arch {
+	/* VCPU ran atleast once */
+	bool ran_atleast_once;
+
+	/* ISA feature bits (similar to MISA) */
+	unsigned long isa;
+
+	/* CPU context of Guest VCPU */
+	struct kvm_cpu_context guest_context;
+
+	/* CPU CSR context of Guest VCPU */
+	struct kvm_vcpu_csr guest_csr;
+
+	/* CPU context upon Guest VCPU reset */
+	struct kvm_cpu_context guest_reset_context;
+
+	/* CPU CSR context upon Guest VCPU reset */
+	struct kvm_vcpu_csr guest_reset_csr;
+
 	/* Don't run the VCPU (blocked) */
 	bool pause;
 
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index bd7d6b154f61..cf8ca8d4a9ea 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -31,10 +31,48 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
 	{ NULL }
 };
 
+#define KVM_RISCV_ISA_ALLOWED	(riscv_isa_extension_mask(a) | \
+				 riscv_isa_extension_mask(c) | \
+				 riscv_isa_extension_mask(d) | \
+				 riscv_isa_extension_mask(f) | \
+				 riscv_isa_extension_mask(i) | \
+				 riscv_isa_extension_mask(m) | \
+				 riscv_isa_extension_mask(s) | \
+				 riscv_isa_extension_mask(u))
+
+static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+	struct kvm_vcpu_csr *reset_csr = &vcpu->arch.guest_reset_csr;
+	struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
+	struct kvm_cpu_context *reset_cntx = &vcpu->arch.guest_reset_context;
+
+	memcpy(csr, reset_csr, sizeof(*csr));
+
+	memcpy(cntx, reset_cntx, sizeof(*cntx));
+}
+
 struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
 {
-	/* TODO: */
-	return NULL;
+	int err;
+	struct kvm_vcpu *vcpu;
+
+	vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL);
+	if (!vcpu) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	err = kvm_vcpu_init(vcpu, kvm, id);
+	if (err)
+		goto free_vcpu;
+
+	return vcpu;
+
+free_vcpu:
+	kmem_cache_free(kvm_vcpu_cache, vcpu);
+out:
+	return ERR_PTR(err);
 }
 
 int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
@@ -48,13 +86,32 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
 
 int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
+	struct kvm_cpu_context *cntx;
+
+	/* Mark this VCPU never ran */
+	vcpu->arch.ran_atleast_once = false;
+
+	/* Setup ISA features available to VCPU */
+	vcpu->arch.isa = riscv_isa_extension_base(NULL) & KVM_RISCV_ISA_ALLOWED;
+
+	/* Setup reset state of shadow SSTATUS and HSTATUS CSRs */
+	cntx = &vcpu->arch.guest_reset_context;
+	cntx->sstatus = SR_SPP | SR_SPIE;
+	cntx->hstatus = 0;
+	cntx->hstatus |= HSTATUS_SP2V;
+	cntx->hstatus |= HSTATUS_SP2P;
+	cntx->hstatus |= HSTATUS_SPV;
+
+	/* Reset VCPU */
+	kvm_riscv_reset_vcpu(vcpu);
+
 	return 0;
 }
 
 void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
+	kvm_riscv_stage2_flush_cache(vcpu);
+	kmem_cache_free(kvm_vcpu_cache, vcpu);
 }
 
 int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
@@ -199,6 +256,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 	int ret;
 	unsigned long scause, stval, htval, htinst;
 
+	/* Mark this VCPU ran atleast once */
+	vcpu->arch.ran_atleast_once = true;
+
 	vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 
 	/* Process MMIO value returned from user-space */
-- 
2.17.1

[PATCH v10 06/19] RISC-V: KVM: Implement VCPU interrupts and requests handling

[Anup Patel]

This patch implements VCPU interrupts and requests which are both
asynchronous events.

The VCPU interrupts can be set/unset using KVM_INTERRUPT ioctl from
user-space. In future, the in-kernel IRQCHIP emulation will use
kvm_riscv_vcpu_set_interrupt() and kvm_riscv_vcpu_unset_interrupt()
functions to set/unset VCPU interrupts.

Important VCPU requests implemented by this patch are:
KVM_REQ_SLEEP       - set whenever VCPU itself goes to sleep state
KVM_REQ_VCPU_RESET  - set whenever VCPU reset is requested

The WFI trap-n-emulate (added later) will use KVM_REQ_SLEEP request
and kvm_riscv_vcpu_has_interrupt() function.

The KVM_REQ_VCPU_RESET request will be used by SBI emulation (added
later) to power-up a VCPU in power-off state. The user-space can use
the GET_MPSTATE/SET_MPSTATE ioctls to get/set power state of a VCPU.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 arch/riscv/include/asm/kvm_host.h |  23 ++++
 arch/riscv/include/uapi/asm/kvm.h |   3 +
 arch/riscv/kvm/vcpu.c             | 182 +++++++++++++++++++++++++++---
 3 files changed, 195 insertions(+), 13 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 297431660be6..94ae81220ac6 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -122,6 +122,21 @@ struct kvm_vcpu_arch {
 	/* CPU CSR context upon Guest VCPU reset */
 	struct kvm_vcpu_csr guest_reset_csr;
 
+	/*
+	 * VCPU interrupts
+	 *
+	 * We have a lockless approach for tracking pending VCPU interrupts
+	 * implemented using atomic bitops. The irqs_pending bitmap represent
+	 * pending interrupts whereas irqs_pending_mask represent bits changed
+	 * in irqs_pending. Our approach is modeled around multiple producer
+	 * and single consumer problem where the consumer is the VCPU itself.
+	 */
+	unsigned long irqs_pending;
+	unsigned long irqs_pending_mask;
+
+	/* VCPU power-off state */
+	bool power_off;
+
 	/* Don't run the VCPU (blocked) */
 	bool pause;
 
@@ -147,4 +162,12 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 
 static inline void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch) {}
 
+int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq);
+int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq);
+void kvm_riscv_vcpu_flush_interrupts(struct kvm_vcpu *vcpu);
+void kvm_riscv_vcpu_sync_interrupts(struct kvm_vcpu *vcpu);
+bool kvm_riscv_vcpu_has_interrupts(struct kvm_vcpu *vcpu, unsigned long mask);
+void kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu);
+void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
+
 #endif /* __RISCV_KVM_HOST_H__ */
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index d15875818b6e..6dbc056d58ba 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -18,6 +18,9 @@
 
 #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
 
+#define KVM_INTERRUPT_SET	-1U
+#define KVM_INTERRUPT_UNSET	-2U
+
 /* for KVM_GET_REGS and KVM_SET_REGS */
 struct kvm_regs {
 };
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index cf8ca8d4a9ea..989f2be83c19 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -11,6 +11,7 @@
 #include <linux/err.h>
 #include <linux/kdebug.h>
 #include <linux/module.h>
+#include <linux/percpu.h>
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
 #include <linux/sched/signal.h>
@@ -50,6 +51,9 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
 	memcpy(csr, reset_csr, sizeof(*csr));
 
 	memcpy(cntx, reset_cntx, sizeof(*cntx));
+
+	WRITE_ONCE(vcpu->arch.irqs_pending, 0);
+	WRITE_ONCE(vcpu->arch.irqs_pending_mask, 0);
 }
 
 struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
@@ -116,8 +120,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 
 int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
-	return 0;
+	return kvm_riscv_vcpu_has_interrupts(vcpu, 1UL << IRQ_VS_TIMER);
 }
 
 void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu)
@@ -130,20 +133,18 @@ void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
 
 int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
-	return 0;
+	return (kvm_riscv_vcpu_has_interrupts(vcpu, -1UL) &&
+		!vcpu->arch.power_off && !vcpu->arch.pause);
 }
 
 int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
-	return 0;
+	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
 }
 
 bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
-	return false;
+	return (vcpu->arch.guest_context.sstatus & SR_SPP) ? true : false;
 }
 
 bool kvm_arch_has_vcpu_debugfs(void)
@@ -164,7 +165,21 @@ vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
 long kvm_arch_vcpu_async_ioctl(struct file *filp,
 			       unsigned int ioctl, unsigned long arg)
 {
-	/* TODO; */
+	struct kvm_vcpu *vcpu = filp->private_data;
+	void __user *argp = (void __user *)arg;
+
+	if (ioctl == KVM_INTERRUPT) {
+		struct kvm_interrupt irq;
+
+		if (copy_from_user(&irq, argp, sizeof(irq)))
+			return -EFAULT;
+
+		if (irq.irq == KVM_INTERRUPT_SET)
+			return kvm_riscv_vcpu_set_interrupt(vcpu, IRQ_VS_EXT);
+		else
+			return kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_VS_EXT);
+	}
+
 	return -ENOIOCTLCMD;
 }
 
@@ -213,18 +228,121 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
 	return -EINVAL;
 }
 
+void kvm_riscv_vcpu_flush_interrupts(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+	unsigned long mask, val;
+
+	if (READ_ONCE(vcpu->arch.irqs_pending_mask)) {
+		mask = xchg_acquire(&vcpu->arch.irqs_pending_mask, 0);
+		val = READ_ONCE(vcpu->arch.irqs_pending) & mask;
+
+		csr->hip &= ~mask;
+		csr->hip |= val;
+	}
+}
+
+void kvm_riscv_vcpu_sync_interrupts(struct kvm_vcpu *vcpu)
+{
+	unsigned long hip;
+	struct kvm_vcpu_arch *v = &vcpu->arch;
+	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+	/* Read current HIP and HIE CSRs */
+	hip = csr_read(CSR_HIP);
+	csr->hie = csr_read(CSR_HIE);
+
+	/* Sync-up HIP.VSSIP bit changes does by Guest */
+	if ((csr->hip ^ hip) & (1UL << IRQ_VS_SOFT)) {
+		if (hip & (1UL << IRQ_VS_SOFT)) {
+			if (!test_and_set_bit(IRQ_VS_SOFT,
+					      &v->irqs_pending_mask))
+				set_bit(IRQ_VS_SOFT, &v->irqs_pending);
+		} else {
+			if (!test_and_set_bit(IRQ_VS_SOFT,
+					      &v->irqs_pending_mask))
+				clear_bit(IRQ_VS_SOFT, &v->irqs_pending);
+		}
+	}
+}
+
+int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq)
+{
+	if (irq != IRQ_VS_SOFT &&
+	    irq != IRQ_VS_TIMER &&
+	    irq != IRQ_VS_EXT)
+		return -EINVAL;
+
+	set_bit(irq, &vcpu->arch.irqs_pending);
+	smp_mb__before_atomic();
+	set_bit(irq, &vcpu->arch.irqs_pending_mask);
+
+	kvm_vcpu_kick(vcpu);
+
+	return 0;
+}
+
+int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq)
+{
+	if (irq != IRQ_VS_SOFT &&
+	    irq != IRQ_VS_TIMER &&
+	    irq != IRQ_VS_EXT)
+		return -EINVAL;
+
+	clear_bit(irq, &vcpu->arch.irqs_pending);
+	smp_mb__before_atomic();
+	set_bit(irq, &vcpu->arch.irqs_pending_mask);
+
+	return 0;
+}
+
+bool kvm_riscv_vcpu_has_interrupts(struct kvm_vcpu *vcpu, unsigned long mask)
+{
+	return (READ_ONCE(vcpu->arch.irqs_pending) &
+		vcpu->arch.guest_csr.hie & mask) ? true : false;
+}
+
+void kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu)
+{
+	vcpu->arch.power_off = true;
+	kvm_make_request(KVM_REQ_SLEEP, vcpu);
+	kvm_vcpu_kick(vcpu);
+}
+
+void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu)
+{
+	vcpu->arch.power_off = false;
+	kvm_vcpu_wake_up(vcpu);
+}
+
 int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
 				    struct kvm_mp_state *mp_state)
 {
-	/* TODO: */
+	if (vcpu->arch.power_off)
+		mp_state->mp_state = KVM_MP_STATE_STOPPED;
+	else
+		mp_state->mp_state = KVM_MP_STATE_RUNNABLE;
+
 	return 0;
 }
 
 int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
 				    struct kvm_mp_state *mp_state)
 {
-	/* TODO: */
-	return 0;
+	int ret = 0;
+
+	switch (mp_state->mp_state) {
+	case KVM_MP_STATE_RUNNABLE:
+		vcpu->arch.power_off = false;
+		break;
+	case KVM_MP_STATE_STOPPED:
+		kvm_riscv_vcpu_power_off(vcpu);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
 }
 
 int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
@@ -248,7 +366,33 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 
 static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
+	struct swait_queue_head *wq = kvm_arch_vcpu_wq(vcpu);
+
+	if (kvm_request_pending(vcpu)) {
+		if (kvm_check_request(KVM_REQ_SLEEP, vcpu)) {
+			swait_event_interruptible_exclusive(*wq,
+						((!vcpu->arch.power_off) &&
+						(!vcpu->arch.pause)));
+
+			if (vcpu->arch.power_off || vcpu->arch.pause) {
+				/*
+				 * Awaken to handle a signal, request to
+				 * sleep again later.
+				 */
+				kvm_make_request(KVM_REQ_SLEEP, vcpu);
+			}
+		}
+
+		if (kvm_check_request(KVM_REQ_VCPU_RESET, vcpu))
+			kvm_riscv_reset_vcpu(vcpu);
+	}
+}
+
+static void kvm_riscv_update_hip(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+	csr_write(CSR_HIP, csr->hip);
 }
 
 int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
@@ -311,6 +455,15 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
 		smp_mb__after_srcu_read_unlock();
 
+		/*
+		 * We might have got VCPU interrupts updated asynchronously
+		 * so update it in HW.
+		 */
+		kvm_riscv_vcpu_flush_interrupts(vcpu);
+
+		/* Update HIP CSR for current CPU */
+		kvm_riscv_update_hip(vcpu);
+
 		if (ret <= 0 ||
 		    kvm_request_pending(vcpu)) {
 			vcpu->mode = OUTSIDE_GUEST_MODE;
@@ -337,6 +490,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		htval = csr_read(CSR_HTVAL);
 		htinst = csr_read(CSR_HTINST);
 
+		/* Syncup interrupts state with HW */
+		kvm_riscv_vcpu_sync_interrupts(vcpu);
+
 		/*
 		 * We may have taken a host interrupt in VS/VU-mode (i.e.
 		 * while executing the guest). This interrupt is still
-- 
2.17.1

[PATCH v10 07/19] RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls

[Anup Patel]

For KVM RISC-V, we use KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls to access
VCPU config and registers from user-space.

We have three types of VCPU registers:
1. CONFIG - these are VCPU config and capabilities
2. CORE   - these are VCPU general purpose registers
3. CSR    - these are VCPU control and status registers

The CONFIG register available to user-space is ISA. The ISA register is
a read and write register where user-space can only write the desired
VCPU ISA capabilities before running the VCPU.

The CORE registers available to user-space are PC, RA, SP, GP, TP, A0-A7,
T0-T6, S0-S11 and MODE. Most of these are RISC-V general registers except
PC and MODE. The PC register represents program counter whereas the MODE
register represent VCPU privilege mode (i.e. S/U-mode).

The CSRs available to user-space are SSTATUS, SIE, STVEC, SSCRATCH, SEPC,
SCAUSE, STVAL, SIP, and SATP. All of these are read/write registers.

In future, more VCPU register types will be added (such as FP) for the
KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/riscv/include/uapi/asm/kvm.h |  52 ++++++-
 arch/riscv/kvm/vcpu.c             | 246 +++++++++++++++++++++++++++++-
 2 files changed, 294 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 6dbc056d58ba..3a20327242f1 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -41,10 +41,60 @@ struct kvm_guest_debug_arch {
 struct kvm_sync_regs {
 };
 
-/* dummy definition */
+/* for KVM_GET_SREGS and KVM_SET_SREGS */
 struct kvm_sregs {
 };
 
+/* CONFIG registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
+struct kvm_riscv_config {
+	unsigned long isa;
+};
+
+/* CORE registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
+struct kvm_riscv_core {
+	struct user_regs_struct regs;
+	unsigned long mode;
+};
+
+/* Possible privilege modes for kvm_riscv_core */
+#define KVM_RISCV_MODE_S	1
+#define KVM_RISCV_MODE_U	0
+
+/* CSR registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
+struct kvm_riscv_csr {
+	unsigned long sstatus;
+	unsigned long sie;
+	unsigned long stvec;
+	unsigned long sscratch;
+	unsigned long sepc;
+	unsigned long scause;
+	unsigned long stval;
+	unsigned long sip;
+	unsigned long satp;
+};
+
+#define KVM_REG_SIZE(id)		\
+	(1U << (((id) & KVM_REG_SIZE_MASK) >> KVM_REG_SIZE_SHIFT))
+
+/* If you need to interpret the index values, here is the key: */
+#define KVM_REG_RISCV_TYPE_MASK		0x00000000FF000000
+#define KVM_REG_RISCV_TYPE_SHIFT	24
+
+/* Config registers are mapped as type 1 */
+#define KVM_REG_RISCV_CONFIG		(0x01 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_CONFIG_REG(name)	\
+	(offsetof(struct kvm_riscv_config, name) / sizeof(unsigned long))
+
+/* Core registers are mapped as type 2 */
+#define KVM_REG_RISCV_CORE		(0x02 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_CORE_REG(name)	\
+		(offsetof(struct kvm_riscv_core, name) / sizeof(unsigned long))
+
+/* Control and status registers are mapped as type 3 */
+#define KVM_REG_RISCV_CSR		(0x03 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_CSR_REG(name)	\
+		(offsetof(struct kvm_riscv_csr, name) / sizeof(unsigned long))
+
 #endif
 
 #endif /* __LINUX_KVM_RISCV_H */
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 989f2be83c19..39e5f7a66e13 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -18,7 +18,6 @@
 #include <linux/fs.h>
 #include <linux/kvm_host.h>
 #include <asm/csr.h>
-#include <asm/delay.h>
 #include <asm/hwcap.h>
 
 #define VCPU_STAT(x) { #x, offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU }
@@ -162,6 +161,225 @@ vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
 	return VM_FAULT_SIGBUS;
 }
 
+static int kvm_riscv_vcpu_get_reg_config(struct kvm_vcpu *vcpu,
+					 const struct kvm_one_reg *reg)
+{
+	unsigned long __user *uaddr =
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CONFIG);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
+		return -EINVAL;
+
+	switch (reg_num) {
+	case KVM_REG_RISCV_CONFIG_REG(isa):
+		reg_val = vcpu->arch.isa;
+		break;
+	default:
+		return -EINVAL;
+	};
+
+	if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
+					 const struct kvm_one_reg *reg)
+{
+	unsigned long __user *uaddr =
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CONFIG);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
+		return -EINVAL;
+
+	if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	switch (reg_num) {
+	case KVM_REG_RISCV_CONFIG_REG(isa):
+		if (!vcpu->arch.ran_atleast_once) {
+			vcpu->arch.isa = reg_val;
+			vcpu->arch.isa &= riscv_isa_extension_base(NULL);
+			vcpu->arch.isa &= KVM_RISCV_ISA_ALLOWED;
+		} else {
+			return -ENOTSUPP;
+		}
+		break;
+	default:
+		return -EINVAL;
+	};
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_get_reg_core(struct kvm_vcpu *vcpu,
+				       const struct kvm_one_reg *reg)
+{
+	struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
+	unsigned long __user *uaddr =
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CORE);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
+		return -EINVAL;
+	if (reg_num >= sizeof(struct kvm_riscv_core) / sizeof(unsigned long))
+		return -EINVAL;
+
+	if (reg_num == KVM_REG_RISCV_CORE_REG(regs.pc))
+		reg_val = cntx->sepc;
+	else if (KVM_REG_RISCV_CORE_REG(regs.pc) < reg_num &&
+		 reg_num <= KVM_REG_RISCV_CORE_REG(regs.t6))
+		reg_val = ((unsigned long *)cntx)[reg_num];
+	else if (reg_num == KVM_REG_RISCV_CORE_REG(mode))
+		reg_val = (cntx->sstatus & SR_SPP) ?
+				KVM_RISCV_MODE_S : KVM_RISCV_MODE_U;
+	else
+		return -EINVAL;
+
+	if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_set_reg_core(struct kvm_vcpu *vcpu,
+				       const struct kvm_one_reg *reg)
+{
+	struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
+	unsigned long __user *uaddr =
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CORE);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
+		return -EINVAL;
+	if (reg_num >= sizeof(struct kvm_riscv_core) / sizeof(unsigned long))
+		return -EINVAL;
+
+	if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	if (reg_num == KVM_REG_RISCV_CORE_REG(regs.pc))
+		cntx->sepc = reg_val;
+	else if (KVM_REG_RISCV_CORE_REG(regs.pc) < reg_num &&
+		 reg_num <= KVM_REG_RISCV_CORE_REG(regs.t6))
+		((unsigned long *)cntx)[reg_num] = reg_val;
+	else if (reg_num == KVM_REG_RISCV_CORE_REG(mode)) {
+		if (reg_val == KVM_RISCV_MODE_S)
+			cntx->sstatus |= SR_SPP;
+		else
+			cntx->sstatus &= ~SR_SPP;
+	} else
+		return -EINVAL;
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_get_reg_csr(struct kvm_vcpu *vcpu,
+				      const struct kvm_one_reg *reg)
+{
+	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+	unsigned long __user *uaddr =
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CSR);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
+		return -EINVAL;
+	if (reg_num >= sizeof(struct kvm_riscv_csr) / sizeof(unsigned long))
+		return -EINVAL;
+
+	if (reg_num == KVM_REG_RISCV_CSR_REG(sip)) {
+		kvm_riscv_vcpu_flush_interrupts(vcpu);
+		reg_val = csr->hip >> VSIP_TO_HIP_SHIFT;
+		reg_val = reg_val & VSIP_VALID_MASK;
+	} else if (reg_num == KVM_REG_RISCV_CSR_REG(sie)) {
+		reg_val = csr->hie >> VSIP_TO_HIP_SHIFT;
+		reg_val = reg_val & VSIP_VALID_MASK;
+	} else
+		reg_val = ((unsigned long *)csr)[reg_num];
+
+	if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_set_reg_csr(struct kvm_vcpu *vcpu,
+				      const struct kvm_one_reg *reg)
+{
+	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+	unsigned long __user *uaddr =
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_CSR);
+	unsigned long reg_val;
+
+	if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
+		return -EINVAL;
+	if (reg_num >= sizeof(struct kvm_riscv_csr) / sizeof(unsigned long))
+		return -EINVAL;
+
+	if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	if (reg_num == KVM_REG_RISCV_CSR_REG(sip) ||
+	    reg_num == KVM_REG_RISCV_CSR_REG(sie)) {
+		reg_val = reg_val << VSIP_TO_HIP_SHIFT;
+		reg_val = reg_val & VSIP_VALID_MASK;
+	}
+
+	((unsigned long *)csr)[reg_num] = reg_val;
+
+	if (reg_num == KVM_REG_RISCV_CSR_REG(sip))
+		WRITE_ONCE(vcpu->arch.irqs_pending_mask, 0);
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
+				  const struct kvm_one_reg *reg)
+{
+	if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_CONFIG)
+		return kvm_riscv_vcpu_set_reg_config(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_CORE)
+		return kvm_riscv_vcpu_set_reg_core(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_CSR)
+		return kvm_riscv_vcpu_set_reg_csr(vcpu, reg);
+
+	return -EINVAL;
+}
+
+static int kvm_riscv_vcpu_get_reg(struct kvm_vcpu *vcpu,
+				  const struct kvm_one_reg *reg)
+{
+	if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_CONFIG)
+		return kvm_riscv_vcpu_get_reg_config(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_CORE)
+		return kvm_riscv_vcpu_get_reg_core(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_CSR)
+		return kvm_riscv_vcpu_get_reg_csr(vcpu, reg);
+
+	return -EINVAL;
+}
+
 long kvm_arch_vcpu_async_ioctl(struct file *filp,
 			       unsigned int ioctl, unsigned long arg)
 {
@@ -186,8 +404,30 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp,
 long kvm_arch_vcpu_ioctl(struct file *filp,
 			 unsigned int ioctl, unsigned long arg)
 {
-	/* TODO: */
-	return -EINVAL;
+	struct kvm_vcpu *vcpu = filp->private_data;
+	void __user *argp = (void __user *)arg;
+	long r = -EINVAL;
+
+	switch (ioctl) {
+	case KVM_SET_ONE_REG:
+	case KVM_GET_ONE_REG: {
+		struct kvm_one_reg reg;
+
+		r = -EFAULT;
+		if (copy_from_user(&reg, argp, sizeof(reg)))
+			break;
+
+		if (ioctl == KVM_SET_ONE_REG)
+			r = kvm_riscv_vcpu_set_reg(vcpu, &reg);
+		else
+			r = kvm_riscv_vcpu_get_reg(vcpu, &reg);
+		break;
+	}
+	default:
+		break;
+	}
+
+	return r;
 }
 
 int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
-- 
2.17.1

[PATCH v10 08/19] RISC-V: KVM: Implement VCPU world-switch

[Anup Patel]

This patch implements the VCPU world-switch for KVM RISC-V.

The KVM RISC-V world-switch (i.e. __kvm_riscv_switch_to()) mostly
switches general purpose registers, SSTATUS, STVEC, SSCRATCH and
HSTATUS CSRs. Other CSRs are switched via vcpu_load() and vcpu_put()
interface in kvm_arch_vcpu_load() and kvm_arch_vcpu_put() functions
respectively.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 arch/riscv/include/asm/kvm_host.h |   9 +-
 arch/riscv/kernel/asm-offsets.c   |  76 ++++++++++++
 arch/riscv/kvm/Makefile           |   2 +-
 arch/riscv/kvm/vcpu.c             |  30 ++++-
 arch/riscv/kvm/vcpu_switch.S      | 194 ++++++++++++++++++++++++++++++
 5 files changed, 307 insertions(+), 4 deletions(-)
 create mode 100644 arch/riscv/kvm/vcpu_switch.S

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 94ae81220ac6..70413ebcf4db 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -110,6 +110,13 @@ struct kvm_vcpu_arch {
 	/* ISA feature bits (similar to MISA) */
 	unsigned long isa;
 
+	/* SSCRATCH and STVEC of Host */
+	unsigned long host_sscratch;
+	unsigned long host_stvec;
+
+	/* CPU context of Host */
+	struct kvm_cpu_context host_context;
+
 	/* CPU context of Guest VCPU */
 	struct kvm_cpu_context guest_context;
 
@@ -160,7 +167,7 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 			unsigned long scause, unsigned long stval,
 			unsigned long htval, unsigned long htinst);
 
-static inline void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch) {}
+void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch);
 
 int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq);
 int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq);
diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
index 07cb9c10de4e..3a230882b91e 100644
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
@@ -7,7 +7,9 @@
 #define GENERATING_ASM_OFFSETS
 
 #include <linux/kbuild.h>
+#include <linux/mm.h>
 #include <linux/sched.h>
+#include <asm/kvm_host.h>
 #include <asm/thread_info.h>
 #include <asm/ptrace.h>
 
@@ -109,6 +111,80 @@ void asm_offsets(void)
 	OFFSET(PT_BADADDR, pt_regs, badaddr);
 	OFFSET(PT_CAUSE, pt_regs, cause);
 
+	OFFSET(KVM_ARCH_GUEST_ZERO, kvm_vcpu_arch, guest_context.zero);
+	OFFSET(KVM_ARCH_GUEST_RA, kvm_vcpu_arch, guest_context.ra);
+	OFFSET(KVM_ARCH_GUEST_SP, kvm_vcpu_arch, guest_context.sp);
+	OFFSET(KVM_ARCH_GUEST_GP, kvm_vcpu_arch, guest_context.gp);
+	OFFSET(KVM_ARCH_GUEST_TP, kvm_vcpu_arch, guest_context.tp);
+	OFFSET(KVM_ARCH_GUEST_T0, kvm_vcpu_arch, guest_context.t0);
+	OFFSET(KVM_ARCH_GUEST_T1, kvm_vcpu_arch, guest_context.t1);
+	OFFSET(KVM_ARCH_GUEST_T2, kvm_vcpu_arch, guest_context.t2);
+	OFFSET(KVM_ARCH_GUEST_S0, kvm_vcpu_arch, guest_context.s0);
+	OFFSET(KVM_ARCH_GUEST_S1, kvm_vcpu_arch, guest_context.s1);
+	OFFSET(KVM_ARCH_GUEST_A0, kvm_vcpu_arch, guest_context.a0);
+	OFFSET(KVM_ARCH_GUEST_A1, kvm_vcpu_arch, guest_context.a1);
+	OFFSET(KVM_ARCH_GUEST_A2, kvm_vcpu_arch, guest_context.a2);
+	OFFSET(KVM_ARCH_GUEST_A3, kvm_vcpu_arch, guest_context.a3);
+	OFFSET(KVM_ARCH_GUEST_A4, kvm_vcpu_arch, guest_context.a4);
+	OFFSET(KVM_ARCH_GUEST_A5, kvm_vcpu_arch, guest_context.a5);
+	OFFSET(KVM_ARCH_GUEST_A6, kvm_vcpu_arch, guest_context.a6);
+	OFFSET(KVM_ARCH_GUEST_A7, kvm_vcpu_arch, guest_context.a7);
+	OFFSET(KVM_ARCH_GUEST_S2, kvm_vcpu_arch, guest_context.s2);
+	OFFSET(KVM_ARCH_GUEST_S3, kvm_vcpu_arch, guest_context.s3);
+	OFFSET(KVM_ARCH_GUEST_S4, kvm_vcpu_arch, guest_context.s4);
+	OFFSET(KVM_ARCH_GUEST_S5, kvm_vcpu_arch, guest_context.s5);
+	OFFSET(KVM_ARCH_GUEST_S6, kvm_vcpu_arch, guest_context.s6);
+	OFFSET(KVM_ARCH_GUEST_S7, kvm_vcpu_arch, guest_context.s7);
+	OFFSET(KVM_ARCH_GUEST_S8, kvm_vcpu_arch, guest_context.s8);
+	OFFSET(KVM_ARCH_GUEST_S9, kvm_vcpu_arch, guest_context.s9);
+	OFFSET(KVM_ARCH_GUEST_S10, kvm_vcpu_arch, guest_context.s10);
+	OFFSET(KVM_ARCH_GUEST_S11, kvm_vcpu_arch, guest_context.s11);
+	OFFSET(KVM_ARCH_GUEST_T3, kvm_vcpu_arch, guest_context.t3);
+	OFFSET(KVM_ARCH_GUEST_T4, kvm_vcpu_arch, guest_context.t4);
+	OFFSET(KVM_ARCH_GUEST_T5, kvm_vcpu_arch, guest_context.t5);
+	OFFSET(KVM_ARCH_GUEST_T6, kvm_vcpu_arch, guest_context.t6);
+	OFFSET(KVM_ARCH_GUEST_SEPC, kvm_vcpu_arch, guest_context.sepc);
+	OFFSET(KVM_ARCH_GUEST_SSTATUS, kvm_vcpu_arch, guest_context.sstatus);
+	OFFSET(KVM_ARCH_GUEST_HSTATUS, kvm_vcpu_arch, guest_context.hstatus);
+
+	OFFSET(KVM_ARCH_HOST_ZERO, kvm_vcpu_arch, host_context.zero);
+	OFFSET(KVM_ARCH_HOST_RA, kvm_vcpu_arch, host_context.ra);
+	OFFSET(KVM_ARCH_HOST_SP, kvm_vcpu_arch, host_context.sp);
+	OFFSET(KVM_ARCH_HOST_GP, kvm_vcpu_arch, host_context.gp);
+	OFFSET(KVM_ARCH_HOST_TP, kvm_vcpu_arch, host_context.tp);
+	OFFSET(KVM_ARCH_HOST_T0, kvm_vcpu_arch, host_context.t0);
+	OFFSET(KVM_ARCH_HOST_T1, kvm_vcpu_arch, host_context.t1);
+	OFFSET(KVM_ARCH_HOST_T2, kvm_vcpu_arch, host_context.t2);
+	OFFSET(KVM_ARCH_HOST_S0, kvm_vcpu_arch, host_context.s0);
+	OFFSET(KVM_ARCH_HOST_S1, kvm_vcpu_arch, host_context.s1);
+	OFFSET(KVM_ARCH_HOST_A0, kvm_vcpu_arch, host_context.a0);
+	OFFSET(KVM_ARCH_HOST_A1, kvm_vcpu_arch, host_context.a1);
+	OFFSET(KVM_ARCH_HOST_A2, kvm_vcpu_arch, host_context.a2);
+	OFFSET(KVM_ARCH_HOST_A3, kvm_vcpu_arch, host_context.a3);
+	OFFSET(KVM_ARCH_HOST_A4, kvm_vcpu_arch, host_context.a4);
+	OFFSET(KVM_ARCH_HOST_A5, kvm_vcpu_arch, host_context.a5);
+	OFFSET(KVM_ARCH_HOST_A6, kvm_vcpu_arch, host_context.a6);
+	OFFSET(KVM_ARCH_HOST_A7, kvm_vcpu_arch, host_context.a7);
+	OFFSET(KVM_ARCH_HOST_S2, kvm_vcpu_arch, host_context.s2);
+	OFFSET(KVM_ARCH_HOST_S3, kvm_vcpu_arch, host_context.s3);
+	OFFSET(KVM_ARCH_HOST_S4, kvm_vcpu_arch, host_context.s4);
+	OFFSET(KVM_ARCH_HOST_S5, kvm_vcpu_arch, host_context.s5);
+	OFFSET(KVM_ARCH_HOST_S6, kvm_vcpu_arch, host_context.s6);
+	OFFSET(KVM_ARCH_HOST_S7, kvm_vcpu_arch, host_context.s7);
+	OFFSET(KVM_ARCH_HOST_S8, kvm_vcpu_arch, host_context.s8);
+	OFFSET(KVM_ARCH_HOST_S9, kvm_vcpu_arch, host_context.s9);
+	OFFSET(KVM_ARCH_HOST_S10, kvm_vcpu_arch, host_context.s10);
+	OFFSET(KVM_ARCH_HOST_S11, kvm_vcpu_arch, host_context.s11);
+	OFFSET(KVM_ARCH_HOST_T3, kvm_vcpu_arch, host_context.t3);
+	OFFSET(KVM_ARCH_HOST_T4, kvm_vcpu_arch, host_context.t4);
+	OFFSET(KVM_ARCH_HOST_T5, kvm_vcpu_arch, host_context.t5);
+	OFFSET(KVM_ARCH_HOST_T6, kvm_vcpu_arch, host_context.t6);
+	OFFSET(KVM_ARCH_HOST_SEPC, kvm_vcpu_arch, host_context.sepc);
+	OFFSET(KVM_ARCH_HOST_SSTATUS, kvm_vcpu_arch, host_context.sstatus);
+	OFFSET(KVM_ARCH_HOST_HSTATUS, kvm_vcpu_arch, host_context.hstatus);
+	OFFSET(KVM_ARCH_HOST_SSCRATCH, kvm_vcpu_arch, host_sscratch);
+	OFFSET(KVM_ARCH_HOST_STVEC, kvm_vcpu_arch, host_stvec);
+
 	/*
 	 * THREAD_{F,X}* might be larger than a S-type offset can handle, but
 	 * these are used in performance-sensitive assembly so we can't resort
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index 37b5a59d4f4f..845579273727 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -8,6 +8,6 @@ ccflags-y := -Ivirt/kvm -Iarch/riscv/kvm
 
 kvm-objs := $(common-objs-y)
 
-kvm-objs += main.o vm.o mmu.o vcpu.o vcpu_exit.o
+kvm-objs += main.o vm.o mmu.o vcpu.o vcpu_exit.o vcpu_switch.o
 
 obj-$(CONFIG_KVM)	+= kvm.o
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 39e5f7a66e13..ec60f3e783e5 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -594,14 +594,40 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
-	/* TODO: */
+	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+	csr_write(CSR_VSSTATUS, csr->vsstatus);
+	csr_write(CSR_HIE, csr->hie);
+	csr_write(CSR_VSTVEC, csr->vstvec);
+	csr_write(CSR_VSSCRATCH, csr->vsscratch);
+	csr_write(CSR_VSEPC, csr->vsepc);
+	csr_write(CSR_VSCAUSE, csr->vscause);
+	csr_write(CSR_VSTVAL, csr->vstval);
+	csr_write(CSR_HIP, csr->hip);
+	csr_write(CSR_VSATP, csr->vsatp);
 
 	kvm_riscv_stage2_update_hgatp(vcpu);
+
+	vcpu->cpu = cpu;
 }
 
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
+	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+	vcpu->cpu = -1;
+
+	csr_write(CSR_HGATP, 0);
+
+	csr->vsstatus = csr_read(CSR_VSSTATUS);
+	csr->hie = csr_read(CSR_HIE);
+	csr->vstvec = csr_read(CSR_VSTVEC);
+	csr->vsscratch = csr_read(CSR_VSSCRATCH);
+	csr->vsepc = csr_read(CSR_VSEPC);
+	csr->vscause = csr_read(CSR_VSCAUSE);
+	csr->vstval = csr_read(CSR_VSTVAL);
+	csr->hip = csr_read(CSR_HIP);
+	csr->vsatp = csr_read(CSR_VSATP);
 }
 
 static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S
new file mode 100644
index 000000000000..e1a17df1b379
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_switch.S
@@ -0,0 +1,194 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/csr.h>
+
+	.text
+	.altmacro
+	.option norelax
+
+ENTRY(__kvm_riscv_switch_to)
+	/* Save Host GPRs (except A0 and T0-T6) */
+	REG_S	ra, (KVM_ARCH_HOST_RA)(a0)
+	REG_S	sp, (KVM_ARCH_HOST_SP)(a0)
+	REG_S	gp, (KVM_ARCH_HOST_GP)(a0)
+	REG_S	tp, (KVM_ARCH_HOST_TP)(a0)
+	REG_S	s0, (KVM_ARCH_HOST_S0)(a0)
+	REG_S	s1, (KVM_ARCH_HOST_S1)(a0)
+	REG_S	a1, (KVM_ARCH_HOST_A1)(a0)
+	REG_S	a2, (KVM_ARCH_HOST_A2)(a0)
+	REG_S	a3, (KVM_ARCH_HOST_A3)(a0)
+	REG_S	a4, (KVM_ARCH_HOST_A4)(a0)
+	REG_S	a5, (KVM_ARCH_HOST_A5)(a0)
+	REG_S	a6, (KVM_ARCH_HOST_A6)(a0)
+	REG_S	a7, (KVM_ARCH_HOST_A7)(a0)
+	REG_S	s2, (KVM_ARCH_HOST_S2)(a0)
+	REG_S	s3, (KVM_ARCH_HOST_S3)(a0)
+	REG_S	s4, (KVM_ARCH_HOST_S4)(a0)
+	REG_S	s5, (KVM_ARCH_HOST_S5)(a0)
+	REG_S	s6, (KVM_ARCH_HOST_S6)(a0)
+	REG_S	s7, (KVM_ARCH_HOST_S7)(a0)
+	REG_S	s8, (KVM_ARCH_HOST_S8)(a0)
+	REG_S	s9, (KVM_ARCH_HOST_S9)(a0)
+	REG_S	s10, (KVM_ARCH_HOST_S10)(a0)
+	REG_S	s11, (KVM_ARCH_HOST_S11)(a0)
+
+	/* Save Host SSTATUS, HSTATUS, SCRATCH and STVEC */
+	csrr	t0, CSR_SSTATUS
+	REG_S	t0, (KVM_ARCH_HOST_SSTATUS)(a0)
+	csrr	t1, CSR_HSTATUS
+	REG_S	t1, (KVM_ARCH_HOST_HSTATUS)(a0)
+	csrr	t2, CSR_SSCRATCH
+	REG_S	t2, (KVM_ARCH_HOST_SSCRATCH)(a0)
+	csrr	t3, CSR_STVEC
+	REG_S	t3, (KVM_ARCH_HOST_STVEC)(a0)
+
+	/* Change Host exception vector to return path */
+	la	t4, __kvm_switch_return
+	csrw	CSR_STVEC, t4
+
+	/* Restore Guest HSTATUS, SSTATUS and SEPC */
+	REG_L	t4, (KVM_ARCH_GUEST_SEPC)(a0)
+	csrw	CSR_SEPC, t4
+	REG_L	t5, (KVM_ARCH_GUEST_SSTATUS)(a0)
+	csrw	CSR_SSTATUS, t5
+	REG_L	t6, (KVM_ARCH_GUEST_HSTATUS)(a0)
+	csrw	CSR_HSTATUS, t6
+
+	/* Restore Guest GPRs (except A0) */
+	REG_L	ra, (KVM_ARCH_GUEST_RA)(a0)
+	REG_L	sp, (KVM_ARCH_GUEST_SP)(a0)
+	REG_L	gp, (KVM_ARCH_GUEST_GP)(a0)
+	REG_L	tp, (KVM_ARCH_GUEST_TP)(a0)
+	REG_L	t0, (KVM_ARCH_GUEST_T0)(a0)
+	REG_L	t1, (KVM_ARCH_GUEST_T1)(a0)
+	REG_L	t2, (KVM_ARCH_GUEST_T2)(a0)
+	REG_L	s0, (KVM_ARCH_GUEST_S0)(a0)
+	REG_L	s1, (KVM_ARCH_GUEST_S1)(a0)
+	REG_L	a1, (KVM_ARCH_GUEST_A1)(a0)
+	REG_L	a2, (KVM_ARCH_GUEST_A2)(a0)
+	REG_L	a3, (KVM_ARCH_GUEST_A3)(a0)
+	REG_L	a4, (KVM_ARCH_GUEST_A4)(a0)
+	REG_L	a5, (KVM_ARCH_GUEST_A5)(a0)
+	REG_L	a6, (KVM_ARCH_GUEST_A6)(a0)
+	REG_L	a7, (KVM_ARCH_GUEST_A7)(a0)
+	REG_L	s2, (KVM_ARCH_GUEST_S2)(a0)
+	REG_L	s3, (KVM_ARCH_GUEST_S3)(a0)
+	REG_L	s4, (KVM_ARCH_GUEST_S4)(a0)
+	REG_L	s5, (KVM_ARCH_GUEST_S5)(a0)
+	REG_L	s6, (KVM_ARCH_GUEST_S6)(a0)
+	REG_L	s7, (KVM_ARCH_GUEST_S7)(a0)
+	REG_L	s8, (KVM_ARCH_GUEST_S8)(a0)
+	REG_L	s9, (KVM_ARCH_GUEST_S9)(a0)
+	REG_L	s10, (KVM_ARCH_GUEST_S10)(a0)
+	REG_L	s11, (KVM_ARCH_GUEST_S11)(a0)
+	REG_L	t3, (KVM_ARCH_GUEST_T3)(a0)
+	REG_L	t4, (KVM_ARCH_GUEST_T4)(a0)
+	REG_L	t5, (KVM_ARCH_GUEST_T5)(a0)
+	REG_L	t6, (KVM_ARCH_GUEST_T6)(a0)
+
+	/* Save Host A0 in SSCRATCH */
+	csrw	CSR_SSCRATCH, a0
+
+	/* Restore Guest A0 */
+	REG_L	a0, (KVM_ARCH_GUEST_A0)(a0)
+
+	/* Resume Guest */
+	sret
+
+	/* Back to Host */
+	.align 2
+__kvm_switch_return:
+	/* Swap Guest A0 with SSCRATCH */
+	csrrw	a0, CSR_SSCRATCH, a0
+
+	/* Save Guest GPRs (except A0) */
+	REG_S	ra, (KVM_ARCH_GUEST_RA)(a0)
+	REG_S	sp, (KVM_ARCH_GUEST_SP)(a0)
+	REG_S	gp, (KVM_ARCH_GUEST_GP)(a0)
+	REG_S	tp, (KVM_ARCH_GUEST_TP)(a0)
+	REG_S	t0, (KVM_ARCH_GUEST_T0)(a0)
+	REG_S	t1, (KVM_ARCH_GUEST_T1)(a0)
+	REG_S	t2, (KVM_ARCH_GUEST_T2)(a0)
+	REG_S	s0, (KVM_ARCH_GUEST_S0)(a0)
+	REG_S	s1, (KVM_ARCH_GUEST_S1)(a0)
+	REG_S	a1, (KVM_ARCH_GUEST_A1)(a0)
+	REG_S	a2, (KVM_ARCH_GUEST_A2)(a0)
+	REG_S	a3, (KVM_ARCH_GUEST_A3)(a0)
+	REG_S	a4, (KVM_ARCH_GUEST_A4)(a0)
+	REG_S	a5, (KVM_ARCH_GUEST_A5)(a0)
+	REG_S	a6, (KVM_ARCH_GUEST_A6)(a0)
+	REG_S	a7, (KVM_ARCH_GUEST_A7)(a0)
+	REG_S	s2, (KVM_ARCH_GUEST_S2)(a0)
+	REG_S	s3, (KVM_ARCH_GUEST_S3)(a0)
+	REG_S	s4, (KVM_ARCH_GUEST_S4)(a0)
+	REG_S	s5, (KVM_ARCH_GUEST_S5)(a0)
+	REG_S	s6, (KVM_ARCH_GUEST_S6)(a0)
+	REG_S	s7, (KVM_ARCH_GUEST_S7)(a0)
+	REG_S	s8, (KVM_ARCH_GUEST_S8)(a0)
+	REG_S	s9, (KVM_ARCH_GUEST_S9)(a0)
+	REG_S	s10, (KVM_ARCH_GUEST_S10)(a0)
+	REG_S	s11, (KVM_ARCH_GUEST_S11)(a0)
+	REG_S	t3, (KVM_ARCH_GUEST_T3)(a0)
+	REG_S	t4, (KVM_ARCH_GUEST_T4)(a0)
+	REG_S	t5, (KVM_ARCH_GUEST_T5)(a0)
+	REG_S	t6, (KVM_ARCH_GUEST_T6)(a0)
+
+	/* Save Guest A0 */
+	csrr	t0, CSR_SSCRATCH
+	REG_S	t0, (KVM_ARCH_GUEST_A0)(a0)
+
+	/* Save Guest HSTATUS, SSTATUS, and SEPC */
+	csrr	t0, CSR_SEPC
+	REG_S	t0, (KVM_ARCH_GUEST_SEPC)(a0)
+	csrr	t1, CSR_SSTATUS
+	REG_S	t1, (KVM_ARCH_GUEST_SSTATUS)(a0)
+	csrr	t2, CSR_HSTATUS
+	REG_S	t2, (KVM_ARCH_GUEST_HSTATUS)(a0)
+
+	/* Restore Host SSTATUS, HSTATUS, SCRATCH and STVEC */
+	REG_L	t3, (KVM_ARCH_HOST_SSTATUS)(a0)
+	csrw	CSR_SSTATUS, t3
+	REG_L	t4, (KVM_ARCH_HOST_HSTATUS)(a0)
+	csrw	CSR_HSTATUS, t4
+	REG_L	t5, (KVM_ARCH_HOST_SSCRATCH)(a0)
+	csrw	CSR_SSCRATCH, t5
+	REG_L	t6, (KVM_ARCH_HOST_STVEC)(a0)
+	csrw	CSR_STVEC, t6
+
+	/* Restore Host GPRs (except A0 and T0-T6) */
+	REG_L	ra, (KVM_ARCH_HOST_RA)(a0)
+	REG_L	sp, (KVM_ARCH_HOST_SP)(a0)
+	REG_L	gp, (KVM_ARCH_HOST_GP)(a0)
+	REG_L	tp, (KVM_ARCH_HOST_TP)(a0)
+	REG_L	s0, (KVM_ARCH_HOST_S0)(a0)
+	REG_L	s1, (KVM_ARCH_HOST_S1)(a0)
+	REG_L	a1, (KVM_ARCH_HOST_A1)(a0)
+	REG_L	a2, (KVM_ARCH_HOST_A2)(a0)
+	REG_L	a3, (KVM_ARCH_HOST_A3)(a0)
+	REG_L	a4, (KVM_ARCH_HOST_A4)(a0)
+	REG_L	a5, (KVM_ARCH_HOST_A5)(a0)
+	REG_L	a6, (KVM_ARCH_HOST_A6)(a0)
+	REG_L	a7, (KVM_ARCH_HOST_A7)(a0)
+	REG_L	s2, (KVM_ARCH_HOST_S2)(a0)
+	REG_L	s3, (KVM_ARCH_HOST_S3)(a0)
+	REG_L	s4, (KVM_ARCH_HOST_S4)(a0)
+	REG_L	s5, (KVM_ARCH_HOST_S5)(a0)
+	REG_L	s6, (KVM_ARCH_HOST_S6)(a0)
+	REG_L	s7, (KVM_ARCH_HOST_S7)(a0)
+	REG_L	s8, (KVM_ARCH_HOST_S8)(a0)
+	REG_L	s9, (KVM_ARCH_HOST_S9)(a0)
+	REG_L	s10, (KVM_ARCH_HOST_S10)(a0)
+	REG_L	s11, (KVM_ARCH_HOST_S11)(a0)
+
+	/* Return to C code */
+	ret
+ENDPROC(__kvm_riscv_switch_to)
-- 
2.17.1

[PATCH v10 09/19] RISC-V: KVM: Handle MMIO exits for VCPU

[Anup Patel]

We will get stage2 page faults whenever Guest/VM access SW emulated
MMIO device or unmapped Guest RAM.

This patch implements MMIO read/write emulation by extracting MMIO
details from the trapped load/store instruction and forwarding the
MMIO read/write to user-space. The actual MMIO emulation will happen
in user-space and KVM kernel module will only take care of register
updates before resuming the trapped VCPU.

The handling for stage2 page faults for unmapped Guest RAM will be
implemeted by a separate patch later.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 arch/riscv/include/asm/kvm_host.h |  20 ++
 arch/riscv/kvm/mmu.c              |   7 +
 arch/riscv/kvm/vcpu_exit.c        | 533 +++++++++++++++++++++++++++++-
 arch/riscv/kvm/vcpu_switch.S      |  14 +
 4 files changed, 571 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 70413ebcf4db..4e9305f2d43d 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -53,6 +53,13 @@ struct kvm_arch {
 	phys_addr_t pgd_phys;
 };
 
+struct kvm_mmio_decode {
+	unsigned long insn;
+	int len;
+	int shift;
+	int return_handled;
+};
+
 struct kvm_cpu_context {
 	unsigned long zero;
 	unsigned long ra;
@@ -141,6 +148,9 @@ struct kvm_vcpu_arch {
 	unsigned long irqs_pending;
 	unsigned long irqs_pending_mask;
 
+	/* MMIO instruction details */
+	struct kvm_mmio_decode mmio_decode;
+
 	/* VCPU power-off state */
 	bool power_off;
 
@@ -157,11 +167,21 @@ static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
 static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
 
+int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long hva,
+			 bool is_write);
 void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu);
 int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm);
 void kvm_riscv_stage2_free_pgd(struct kvm *kvm);
 void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu);
 
+void __kvm_riscv_unpriv_trap(void);
+
+unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu,
+					 bool read_insn,
+					 unsigned long guest_addr,
+					 unsigned long *trap_scause);
+void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
+				  unsigned long scause, unsigned long stval);
 int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
 int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 			unsigned long scause, unsigned long stval,
diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index 04dd089b86ff..2b965f9aac07 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -61,6 +61,13 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	return 0;
 }
 
+int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long hva,
+			 bool is_write)
+{
+	/* TODO: */
+	return 0;
+}
+
 void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu)
 {
 	/* TODO: */
diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
index dcea9ce4e728..cbf973c5f2fb 100644
--- a/arch/riscv/kvm/vcpu_exit.c
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -6,9 +6,458 @@
  *     Anup Patel <anup.patel@wdc.com>
  */
 
+#include <linux/bitops.h>
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/kvm_host.h>
+#include <asm/csr.h>
+
+#define INSN_MATCH_LB		0x3
+#define INSN_MASK_LB		0x707f
+#define INSN_MATCH_LH		0x1003
+#define INSN_MASK_LH		0x707f
+#define INSN_MATCH_LW		0x2003
+#define INSN_MASK_LW		0x707f
+#define INSN_MATCH_LD		0x3003
+#define INSN_MASK_LD		0x707f
+#define INSN_MATCH_LBU		0x4003
+#define INSN_MASK_LBU		0x707f
+#define INSN_MATCH_LHU		0x5003
+#define INSN_MASK_LHU		0x707f
+#define INSN_MATCH_LWU		0x6003
+#define INSN_MASK_LWU		0x707f
+#define INSN_MATCH_SB		0x23
+#define INSN_MASK_SB		0x707f
+#define INSN_MATCH_SH		0x1023
+#define INSN_MASK_SH		0x707f
+#define INSN_MATCH_SW		0x2023
+#define INSN_MASK_SW		0x707f
+#define INSN_MATCH_SD		0x3023
+#define INSN_MASK_SD		0x707f
+
+#define INSN_MATCH_C_LD		0x6000
+#define INSN_MASK_C_LD		0xe003
+#define INSN_MATCH_C_SD		0xe000
+#define INSN_MASK_C_SD		0xe003
+#define INSN_MATCH_C_LW		0x4000
+#define INSN_MASK_C_LW		0xe003
+#define INSN_MATCH_C_SW		0xc000
+#define INSN_MASK_C_SW		0xe003
+#define INSN_MATCH_C_LDSP	0x6002
+#define INSN_MASK_C_LDSP	0xe003
+#define INSN_MATCH_C_SDSP	0xe002
+#define INSN_MASK_C_SDSP	0xe003
+#define INSN_MATCH_C_LWSP	0x4002
+#define INSN_MASK_C_LWSP	0xe003
+#define INSN_MATCH_C_SWSP	0xc002
+#define INSN_MASK_C_SWSP	0xe003
+
+#define INSN_16BIT_MASK		0x3
+
+#define INSN_IS_16BIT(insn)	(((insn) & INSN_16BIT_MASK) != INSN_16BIT_MASK)
+
+#define INSN_LEN(insn)		(INSN_IS_16BIT(insn) ? 2 : 4)
+
+#ifdef CONFIG_64BIT
+#define LOG_REGBYTES		3
+#else
+#define LOG_REGBYTES		2
+#endif
+#define REGBYTES		(1 << LOG_REGBYTES)
+
+#define SH_RD			7
+#define SH_RS1			15
+#define SH_RS2			20
+#define SH_RS2C			2
+
+#define RV_X(x, s, n)		(((x) >> (s)) & ((1 << (n)) - 1))
+#define RVC_LW_IMM(x)		((RV_X(x, 6, 1) << 2) | \
+				 (RV_X(x, 10, 3) << 3) | \
+				 (RV_X(x, 5, 1) << 6))
+#define RVC_LD_IMM(x)		((RV_X(x, 10, 3) << 3) | \
+				 (RV_X(x, 5, 2) << 6))
+#define RVC_LWSP_IMM(x)		((RV_X(x, 4, 3) << 2) | \
+				 (RV_X(x, 12, 1) << 5) | \
+				 (RV_X(x, 2, 2) << 6))
+#define RVC_LDSP_IMM(x)		((RV_X(x, 5, 2) << 3) | \
+				 (RV_X(x, 12, 1) << 5) | \
+				 (RV_X(x, 2, 3) << 6))
+#define RVC_SWSP_IMM(x)		((RV_X(x, 9, 4) << 2) | \
+				 (RV_X(x, 7, 2) << 6))
+#define RVC_SDSP_IMM(x)		((RV_X(x, 10, 3) << 3) | \
+				 (RV_X(x, 7, 3) << 6))
+#define RVC_RS1S(insn)		(8 + RV_X(insn, SH_RD, 3))
+#define RVC_RS2S(insn)		(8 + RV_X(insn, SH_RS2C, 3))
+#define RVC_RS2(insn)		RV_X(insn, SH_RS2C, 5)
+
+#define SHIFT_RIGHT(x, y)		\
+	((y) < 0 ? ((x) << -(y)) : ((x) >> (y)))
+
+#define REG_MASK			\
+	((1 << (5 + LOG_REGBYTES)) - (1 << LOG_REGBYTES))
+
+#define REG_OFFSET(insn, pos)		\
+	(SHIFT_RIGHT((insn), (pos) - LOG_REGBYTES) & REG_MASK)
+
+#define REG_PTR(insn, pos, regs)	\
+	(ulong *)((ulong)(regs) + REG_OFFSET(insn, pos))
+
+#define GET_RM(insn)		(((insn) >> 12) & 7)
+
+#define GET_RS1(insn, regs)	(*REG_PTR(insn, SH_RS1, regs))
+#define GET_RS2(insn, regs)	(*REG_PTR(insn, SH_RS2, regs))
+#define GET_RS1S(insn, regs)	(*REG_PTR(RVC_RS1S(insn), 0, regs))
+#define GET_RS2S(insn, regs)	(*REG_PTR(RVC_RS2S(insn), 0, regs))
+#define GET_RS2C(insn, regs)	(*REG_PTR(insn, SH_RS2C, regs))
+#define GET_SP(regs)		(*REG_PTR(2, 0, regs))
+#define SET_RD(insn, regs, val)	(*REG_PTR(insn, SH_RD, regs) = (val))
+#define IMM_I(insn)		((s32)(insn) >> 20)
+#define IMM_S(insn)		(((s32)(insn) >> 25 << 5) | \
+				 (s32)(((insn) >> 7) & 0x1f))
+#define MASK_FUNCT3		0x7000
+
+static int emulate_load(struct kvm_vcpu *vcpu, struct kvm_run *run,
+			unsigned long fault_addr, unsigned long htinst)
+{
+	int shift = 0, len = 0;
+	unsigned long insn, ut_scause = 0;
+	struct kvm_cpu_context *ct = &vcpu->arch.guest_context;
+
+	/* Determine trapped instruction */
+	if (htinst & 0x1) {
+		/*
+		 * Bit[0] == 1 implies trapped instruction value is
+		 * transformed instruction or custom instruction.
+		 */
+		insn = htinst | INSN_16BIT_MASK;
+	} else {
+		/*
+		 * Bit[0] == 0 implies trapped instruction value is
+		 * zero or special value.
+		 */
+		insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc,
+						  &ut_scause);
+		if (ut_scause) {
+			/* Redirect trap if we failed to read instruction */
+			if (ut_scause == EXC_LOAD_PAGE_FAULT)
+				ut_scause = EXC_INST_PAGE_FAULT;
+			kvm_riscv_vcpu_trap_redirect(vcpu, ut_scause, ct->sepc);
+			return 1;
+		}
+	}
+
+	/* Decode length of MMIO and shift */
+	if ((insn & INSN_MASK_LW) == INSN_MATCH_LW) {
+		len = 4;
+		shift = 8 * (sizeof(ulong) - len);
+	} else if ((insn & INSN_MASK_LB) == INSN_MATCH_LB) {
+		len = 1;
+		shift = 8 * (sizeof(ulong) - len);
+	} else if ((insn & INSN_MASK_LBU) == INSN_MATCH_LBU) {
+		len = 1;
+		shift = 8 * (sizeof(ulong) - len);
+#ifdef CONFIG_64BIT
+	} else if ((insn & INSN_MASK_LD) == INSN_MATCH_LD) {
+		len = 8;
+		shift = 8 * (sizeof(ulong) - len);
+	} else if ((insn & INSN_MASK_LWU) == INSN_MATCH_LWU) {
+		len = 4;
+#endif
+	} else if ((insn & INSN_MASK_LH) == INSN_MATCH_LH) {
+		len = 2;
+		shift = 8 * (sizeof(ulong) - len);
+	} else if ((insn & INSN_MASK_LHU) == INSN_MATCH_LHU) {
+		len = 2;
+#ifdef CONFIG_64BIT
+	} else if ((insn & INSN_MASK_C_LD) == INSN_MATCH_C_LD) {
+		len = 8;
+		shift = 8 * (sizeof(ulong) - len);
+		insn = RVC_RS2S(insn) << SH_RD;
+	} else if ((insn & INSN_MASK_C_LDSP) == INSN_MATCH_C_LDSP &&
+		   ((insn >> SH_RD) & 0x1f)) {
+		len = 8;
+		shift = 8 * (sizeof(ulong) - len);
+#endif
+	} else if ((insn & INSN_MASK_C_LW) == INSN_MATCH_C_LW) {
+		len = 4;
+		shift = 8 * (sizeof(ulong) - len);
+		insn = RVC_RS2S(insn) << SH_RD;
+	} else if ((insn & INSN_MASK_C_LWSP) == INSN_MATCH_C_LWSP &&
+		   ((insn >> SH_RD) & 0x1f)) {
+		len = 4;
+		shift = 8 * (sizeof(ulong) - len);
+	} else {
+		return -ENOTSUPP;
+	}
+
+	/* Fault address should be aligned to length of MMIO */
+	if (fault_addr & (len - 1))
+		return -EIO;
+
+	/* Save instruction decode info */
+	vcpu->arch.mmio_decode.insn = insn;
+	vcpu->arch.mmio_decode.shift = shift;
+	vcpu->arch.mmio_decode.len = len;
+	vcpu->arch.mmio_decode.return_handled = 0;
+
+	/* Exit to userspace for MMIO emulation */
+	vcpu->stat.mmio_exit_user++;
+	run->exit_reason = KVM_EXIT_MMIO;
+	run->mmio.is_write = false;
+	run->mmio.phys_addr = fault_addr;
+	run->mmio.len = len;
+
+	return 0;
+}
+
+static int emulate_store(struct kvm_vcpu *vcpu, struct kvm_run *run,
+			 unsigned long fault_addr, unsigned long htinst)
+{
+	u8 data8;
+	u16 data16;
+	u32 data32;
+	u64 data64;
+	ulong data;
+	int len = 0;
+	unsigned long insn, ut_scause = 0;
+	struct kvm_cpu_context *ct = &vcpu->arch.guest_context;
+
+	/* Determine trapped instruction */
+	if (htinst & 0x1) {
+		/*
+		 * Bit[0] == 1 implies trapped instruction value is
+		 * transformed instruction or custom instruction.
+		 */
+		insn = htinst | INSN_16BIT_MASK;
+	} else {
+		/*
+		 * Bit[0] == 0 implies trapped instruction value is
+		 * zero or special value.
+		 */
+		insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc,
+						  &ut_scause);
+		if (ut_scause) {
+			/* Redirect trap if we failed to read instruction */
+			if (ut_scause == EXC_LOAD_PAGE_FAULT)
+				ut_scause = EXC_INST_PAGE_FAULT;
+			kvm_riscv_vcpu_trap_redirect(vcpu, ut_scause, ct->sepc);
+			return 1;
+		}
+	}
+
+	data = GET_RS2(insn, &vcpu->arch.guest_context);
+	data8 = data16 = data32 = data64 = data;
+
+	if ((insn & INSN_MASK_SW) == INSN_MATCH_SW) {
+		len = 4;
+	} else if ((insn & INSN_MASK_SB) == INSN_MATCH_SB) {
+		len = 1;
+#ifdef CONFIG_64BIT
+	} else if ((insn & INSN_MASK_SD) == INSN_MATCH_SD) {
+		len = 8;
+#endif
+	} else if ((insn & INSN_MASK_SH) == INSN_MATCH_SH) {
+		len = 2;
+#ifdef CONFIG_64BIT
+	} else if ((insn & INSN_MASK_C_SD) == INSN_MATCH_C_SD) {
+		len = 8;
+		data64 = GET_RS2S(insn, &vcpu->arch.guest_context);
+	} else if ((insn & INSN_MASK_C_SDSP) == INSN_MATCH_C_SDSP &&
+		   ((insn >> SH_RD) & 0x1f)) {
+		len = 8;
+		data64 = GET_RS2C(insn, &vcpu->arch.guest_context);
+#endif
+	} else if ((insn & INSN_MASK_C_SW) == INSN_MATCH_C_SW) {
+		len = 4;
+		data32 = GET_RS2S(insn, &vcpu->arch.guest_context);
+	} else if ((insn & INSN_MASK_C_SWSP) == INSN_MATCH_C_SWSP &&
+		   ((insn >> SH_RD) & 0x1f)) {
+		len = 4;
+		data32 = GET_RS2C(insn, &vcpu->arch.guest_context);
+	} else {
+		return -ENOTSUPP;
+	}
+
+	/* Fault address should be aligned to length of MMIO */
+	if (fault_addr & (len - 1))
+		return -EIO;
+
+	/* Save instruction decode info */
+	vcpu->arch.mmio_decode.insn = insn;
+	vcpu->arch.mmio_decode.shift = 0;
+	vcpu->arch.mmio_decode.len = len;
+	vcpu->arch.mmio_decode.return_handled = 0;
+
+	/* Copy data to kvm_run instance */
+	switch (len) {
+	case 1:
+		*((u8 *)run->mmio.data) = data8;
+		break;
+	case 2:
+		*((u16 *)run->mmio.data) = data16;
+		break;
+	case 4:
+		*((u32 *)run->mmio.data) = data32;
+		break;
+	case 8:
+		*((u64 *)run->mmio.data) = data64;
+		break;
+	default:
+		return -ENOTSUPP;
+	};
+
+	/* Exit to userspace for MMIO emulation */
+	vcpu->stat.mmio_exit_user++;
+	run->exit_reason = KVM_EXIT_MMIO;
+	run->mmio.is_write = true;
+	run->mmio.phys_addr = fault_addr;
+	run->mmio.len = len;
+
+	return 0;
+}
+
+static int stage2_page_fault(struct kvm_vcpu *vcpu, struct kvm_run *run,
+			     unsigned long scause, unsigned long stval,
+			     unsigned long htval, unsigned long htinst)
+{
+	struct kvm_memory_slot *memslot;
+	unsigned long hva, fault_addr;
+	bool writable;
+	gfn_t gfn;
+	int ret;
+
+	fault_addr = (htval << 2) | (stval & 0x3);
+	gfn = fault_addr >> PAGE_SHIFT;
+	memslot = gfn_to_memslot(vcpu->kvm, gfn);
+	hva = gfn_to_hva_memslot_prot(memslot, gfn, &writable);
+
+	if (kvm_is_error_hva(hva) ||
+	    (scause == EXC_STORE_GUEST_PAGE_FAULT && !writable)) {
+		switch (scause) {
+		case EXC_LOAD_GUEST_PAGE_FAULT:
+			return emulate_load(vcpu, run, fault_addr, htinst);
+		case EXC_STORE_GUEST_PAGE_FAULT:
+			return emulate_store(vcpu, run, fault_addr, htinst);
+		default:
+			return -ENOTSUPP;
+		};
+	}
+
+	ret = kvm_riscv_stage2_map(vcpu, fault_addr, hva,
+			(scause == EXC_STORE_GUEST_PAGE_FAULT) ? true : false);
+	if (ret < 0)
+		return ret;
+
+	return 1;
+}
+
+#define STR(x)		XSTR(x)
+#define XSTR(x)		#x
+
+/**
+ * kvm_riscv_vcpu_unpriv_read -- Read machine word from Guest memory
+ *
+ * @vcpu: The VCPU pointer
+ * @read_insn: Flag representing whether we are reading instruction
+ * @guest_addr: Guest address to read
+ * @trap_scause: Output pointer for unprivilege trap cause
+ */
+unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu,
+					 bool read_insn,
+					 unsigned long guest_addr,
+					 unsigned long *trap_scause)
+{
+	register unsigned long tscause asm("a0");
+	register unsigned long val asm("a1");
+	register unsigned long addr asm("a2") = guest_addr;
+	unsigned long guest_sstatus =
+		vcpu->arch.guest_context.sstatus | ((read_insn) ? SR_MXR : 0);
+	unsigned long guest_hstatus =
+		vcpu->arch.guest_context.hstatus | HSTATUS_SPRV;
+	unsigned long old_stvec, tmp;
+
+	BUG_ON(guest_sstatus & SR_SIE);
+
+	guest_sstatus = csr_swap(CSR_SSTATUS, guest_sstatus);
+	old_stvec = csr_swap(CSR_STVEC, (ulong)&__kvm_riscv_unpriv_trap);
+
+	if (read_insn) {
+		asm volatile ("\n"
+			"csrrw %[hstatus], " STR(CSR_HSTATUS) ", %[hstatus]\n"
+			"li %[tscause], 0\n"
+			"lhu %[val], (%[addr])\n"
+			"andi %[tmp], %[val], 3\n"
+			"addi %[tmp], %[tmp], -3\n"
+			"bne %[tmp], zero, 2f\n"
+			"lhu %[tmp], 2(%[addr])\n"
+			"sll %[tmp], %[tmp], 16\n"
+			"add %[val], %[val], %[tmp]\n"
+			"2: csrw " STR(CSR_HSTATUS) ", %[hstatus]"
+		: [hstatus] "+&r"(guest_hstatus), [val] "=&r" (val),
+		  [tmp] "=&r" (tmp), [tscause] "+&r" (tscause)
+		: [addr] "r" (addr));
+	} else {
+		asm volatile ("\n"
+			"csrrw %[hstatus], " STR(CSR_HSTATUS) ", %[hstatus]\n"
+			"li %[tscause], 0\n"
+			".option push\n"
+			".option norvc\n"
+#ifdef CONFIG_64BIT
+			"ld %[val], (%[addr])\n"
+#else
+			"lw %[val], (%[addr])\n"
+#endif
+			".option pop\n"
+			"csrw " STR(CSR_HSTATUS) ", %[hstatus]"
+		: [hstatus] "+&r"(guest_hstatus),
+		  [val] "=&r" (val), [tscause] "+&r" (tscause)
+		: [addr] "r" (addr));
+	}
+
+	csr_write(CSR_STVEC, old_stvec);
+	csr_write(CSR_SSTATUS, guest_sstatus);
+
+	*trap_scause = tscause;
+
+	return val;
+}
+
+/**
+ * kvm_riscv_vcpu_trap_redirect -- Redirect trap to Guest
+ *
+ * @vcpu: The VCPU pointer
+ * @scause: Trap exception cause
+ * @stval: Trap value
+ */
+void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
+				  unsigned long scause, unsigned long stval)
+{
+	unsigned long vsstatus = csr_read(CSR_VSSTATUS);
+
+	/* Change Guest SSTATUS.SPP bit */
+	vsstatus &= ~SR_SPP;
+	if (vcpu->arch.guest_context.sstatus & SR_SPP)
+		vsstatus |= SR_SPP;
+
+	/* Change Guest SSTATUS.SPIE bit */
+	vsstatus &= ~SR_SPIE;
+	if (vsstatus & SR_SIE)
+		vsstatus |= SR_SPIE;
+
+	/* Clear Guest SSTATUS.SIE bit */
+	vsstatus &= ~SR_SIE;
+
+	/* Update Guest SSTATUS */
+	csr_write(CSR_VSSTATUS, vsstatus);
+
+	/* Update Guest SCAUSE, STVAL, and SEPC */
+	csr_write(CSR_VSCAUSE, scause);
+	csr_write(CSR_VSTVAL, stval);
+	csr_write(CSR_VSEPC, vcpu->arch.guest_context.sepc);
+
+	/* Set Guest PC to Guest exception vector */
+	vcpu->arch.guest_context.sepc = csr_read(CSR_VSTVEC);
+}
 
 /**
  * kvm_riscv_vcpu_mmio_return -- Handle MMIO loads after user space emulation
@@ -19,7 +468,54 @@
  */
 int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
 {
-	/* TODO: */
+	u8 data8;
+	u16 data16;
+	u32 data32;
+	u64 data64;
+	ulong insn;
+	int len, shift;
+
+	if (vcpu->arch.mmio_decode.return_handled)
+		return 0;
+
+	vcpu->arch.mmio_decode.return_handled = 1;
+	insn = vcpu->arch.mmio_decode.insn;
+
+	if (run->mmio.is_write)
+		goto done;
+
+	len = vcpu->arch.mmio_decode.len;
+	shift = vcpu->arch.mmio_decode.shift;
+
+	switch (len) {
+	case 1:
+		data8 = *((u8 *)run->mmio.data);
+		SET_RD(insn, &vcpu->arch.guest_context,
+			(ulong)data8 << shift >> shift);
+		break;
+	case 2:
+		data16 = *((u16 *)run->mmio.data);
+		SET_RD(insn, &vcpu->arch.guest_context,
+			(ulong)data16 << shift >> shift);
+		break;
+	case 4:
+		data32 = *((u32 *)run->mmio.data);
+		SET_RD(insn, &vcpu->arch.guest_context,
+			(ulong)data32 << shift >> shift);
+		break;
+	case 8:
+		data64 = *((u64 *)run->mmio.data);
+		SET_RD(insn, &vcpu->arch.guest_context,
+			(ulong)data64 << shift >> shift);
+		break;
+	default:
+		return -ENOTSUPP;
+	};
+
+done:
+	/* Move to next instruction */
+	vcpu->arch.guest_context.sepc += INSN_LEN(insn);
+
 	return 0;
 }
 
@@ -31,6 +527,37 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 			unsigned long scause, unsigned long stval,
 			unsigned long htval, unsigned long htinst)
 {
-	/* TODO: */
-	return 0;
+	int ret;
+
+	/* If we got host interrupt then do nothing */
+	if (scause & CAUSE_IRQ_FLAG)
+		return 1;
+
+	/* Handle guest traps */
+	ret = -EFAULT;
+	run->exit_reason = KVM_EXIT_UNKNOWN;
+	switch (scause) {
+	case EXC_INST_GUEST_PAGE_FAULT:
+	case EXC_LOAD_GUEST_PAGE_FAULT:
+	case EXC_STORE_GUEST_PAGE_FAULT:
+		if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
+			ret = stage2_page_fault(vcpu, run, scause, stval,
+						htval, htinst);
+		break;
+	default:
+		break;
+	};
+
+	/* Print details in-case of error */
+	if (ret < 0) {
+		kvm_err("VCPU exit error %d\n", ret);
+		kvm_err("SEPC=0x%lx SSTATUS=0x%lx HSTATUS=0x%lx\n",
+			vcpu->arch.guest_context.sepc,
+			vcpu->arch.guest_context.sstatus,
+			vcpu->arch.guest_context.hstatus);
+		kvm_err("SCAUSE=0x%lx STVAL=0x%lx\n",
+			scause, stval);
+	}
+
+	return ret;
 }
diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S
index e1a17df1b379..04b318b9eef8 100644
--- a/arch/riscv/kvm/vcpu_switch.S
+++ b/arch/riscv/kvm/vcpu_switch.S
@@ -192,3 +192,17 @@ __kvm_switch_return:
 	/* Return to C code */
 	ret
 ENDPROC(__kvm_riscv_switch_to)
+
+ENTRY(__kvm_riscv_unpriv_trap)
+	/*
+	 * We assume that faulting unpriv load/store instruction is
+	 * is 4-byte long and blindly increment SEPC by 4.
+	 *
+	 * The trap exception cause will be saved in 'A0' register.
+	 */
+	csrr	a0, CSR_SEPC
+	addi	a0, a0, 4
+	csrw	CSR_SEPC, a0
+	csrr	a0, CSR_SCAUSE
+	sret
+ENDPROC(__kvm_riscv_unpriv_trap)
-- 
2.17.1

[PATCH v10 10/19] RISC-V: KVM: Handle WFI exits for VCPU

[Anup Patel]

We get illegal instruction trap whenever Guest/VM executes WFI
instruction.

This patch handles WFI trap by blocking the trapped VCPU using
kvm_vcpu_block() API. The blocked VCPU will be automatically
resumed whenever a VCPU interrupt is injected from user-space
or from in-kernel IRQCHIP emulation.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/riscv/kvm/vcpu_exit.c | 72 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
index cbf973c5f2fb..8d0ae1a23b70 100644
--- a/arch/riscv/kvm/vcpu_exit.c
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -12,6 +12,13 @@
 #include <linux/kvm_host.h>
 #include <asm/csr.h>
 
+#define INSN_OPCODE_MASK	0x007c
+#define INSN_OPCODE_SHIFT	2
+#define INSN_OPCODE_SYSTEM	28
+
+#define INSN_MASK_WFI		0xffffff00
+#define INSN_MATCH_WFI		0x10500000
+
 #define INSN_MATCH_LB		0x3
 #define INSN_MASK_LB		0x707f
 #define INSN_MATCH_LH		0x1003
@@ -116,6 +123,67 @@
 				 (s32)(((insn) >> 7) & 0x1f))
 #define MASK_FUNCT3		0x7000
 
+static int truly_illegal_insn(struct kvm_vcpu *vcpu,
+			      struct kvm_run *run,
+			      ulong insn)
+{
+	/* Redirect trap to Guest VCPU */
+	kvm_riscv_vcpu_trap_redirect(vcpu, EXC_INST_ILLEGAL, insn);
+
+	return 1;
+}
+
+static int system_opcode_insn(struct kvm_vcpu *vcpu,
+			      struct kvm_run *run,
+			      ulong insn)
+{
+	if ((insn & INSN_MASK_WFI) == INSN_MATCH_WFI) {
+		vcpu->stat.wfi_exit_stat++;
+		if (!kvm_arch_vcpu_runnable(vcpu)) {
+			srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+			kvm_vcpu_block(vcpu);
+			vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+			kvm_clear_request(KVM_REQ_UNHALT, vcpu);
+		}
+		vcpu->arch.guest_context.sepc += INSN_LEN(insn);
+		return 1;
+	}
+
+	return truly_illegal_insn(vcpu, run, insn);
+}
+
+static int illegal_inst_fault(struct kvm_vcpu *vcpu, struct kvm_run *run,
+			      unsigned long insn)
+{
+	unsigned long ut_scause = 0;
+	struct kvm_cpu_context *ct;
+
+	if (unlikely(INSN_IS_16BIT(insn))) {
+		if (insn == 0) {
+			ct = &vcpu->arch.guest_context;
+			insn = kvm_riscv_vcpu_unpriv_read(vcpu, true,
+							  ct->sepc,
+							  &ut_scause);
+			if (ut_scause) {
+				if (ut_scause == EXC_LOAD_PAGE_FAULT)
+					ut_scause = EXC_INST_PAGE_FAULT;
+				kvm_riscv_vcpu_trap_redirect(vcpu, ut_scause,
+							     ct->sepc);
+				return 1;
+			}
+		}
+		if (INSN_IS_16BIT(insn))
+			return truly_illegal_insn(vcpu, run, insn);
+	}
+
+	switch ((insn & INSN_OPCODE_MASK) >> INSN_OPCODE_SHIFT) {
+	case INSN_OPCODE_SYSTEM:
+		return system_opcode_insn(vcpu, run, insn);
+	default:
+		return truly_illegal_insn(vcpu, run, insn);
+	}
+}
+
 static int emulate_load(struct kvm_vcpu *vcpu, struct kvm_run *run,
 			unsigned long fault_addr, unsigned long htinst)
 {
@@ -537,6 +605,10 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 	ret = -EFAULT;
 	run->exit_reason = KVM_EXIT_UNKNOWN;
 	switch (scause) {
+	case EXC_INST_ILLEGAL:
+		if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
+			ret = illegal_inst_fault(vcpu, run, stval);
+		break;
 	case EXC_INST_GUEST_PAGE_FAULT:
 	case EXC_LOAD_GUEST_PAGE_FAULT:
 	case EXC_STORE_GUEST_PAGE_FAULT:
-- 
2.17.1

[PATCH v10 11/19] RISC-V: KVM: Implement VMID allocator

[Anup Patel]

We implement a simple VMID allocator for Guests/VMs which:
1. Detects number of VMID bits at boot-time
2. Uses atomic number to track VMID version and increments
   VMID version whenever we run-out of VMIDs
3. Flushes Guest TLBs on all host CPUs whenever we run-out
   of VMIDs
4. Force updates HW Stage2 VMID for each Guest VCPU whenever
   VMID changes using VCPU request KVM_REQ_UPDATE_HGATP

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 arch/riscv/include/asm/kvm_host.h |  25 +++++++
 arch/riscv/kvm/Makefile           |   3 +-
 arch/riscv/kvm/main.c             |   4 +
 arch/riscv/kvm/tlb.S              |  43 +++++++++++
 arch/riscv/kvm/vcpu.c             |   9 +++
 arch/riscv/kvm/vm.c               |   6 ++
 arch/riscv/kvm/vmid.c             | 120 ++++++++++++++++++++++++++++++
 7 files changed, 209 insertions(+), 1 deletion(-)
 create mode 100644 arch/riscv/kvm/tlb.S
 create mode 100644 arch/riscv/kvm/vmid.c

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 4e9305f2d43d..35a291493f05 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -27,6 +27,7 @@
 #define KVM_REQ_SLEEP \
 	KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
 #define KVM_REQ_VCPU_RESET		KVM_ARCH_REQ(1)
+#define KVM_REQ_UPDATE_HGATP		KVM_ARCH_REQ(2)
 
 struct kvm_vm_stat {
 	ulong remote_tlb_flush;
@@ -47,7 +48,19 @@ struct kvm_vcpu_stat {
 struct kvm_arch_memory_slot {
 };
 
+struct kvm_vmid {
+	/*
+	 * Writes to vmid_version and vmid happen with vmid_lock held
+	 * whereas reads happen without any lock held.
+	 */
+	unsigned long vmid_version;
+	unsigned long vmid;
+};
+
 struct kvm_arch {
+	/* stage2 vmid */
+	struct kvm_vmid vmid;
+
 	/* stage2 page table */
 	pgd_t *pgd;
 	phys_addr_t pgd_phys;
@@ -167,6 +180,12 @@ static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
 static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
 
+void __kvm_riscv_hfence_gvma_vmid_gpa(unsigned long vmid,
+				      unsigned long gpa);
+void __kvm_riscv_hfence_gvma_vmid(unsigned long vmid);
+void __kvm_riscv_hfence_gvma_gpa(unsigned long gpa);
+void __kvm_riscv_hfence_gvma_all(void);
+
 int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long hva,
 			 bool is_write);
 void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu);
@@ -174,6 +193,12 @@ int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm);
 void kvm_riscv_stage2_free_pgd(struct kvm *kvm);
 void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu);
 
+void kvm_riscv_stage2_vmid_detect(void);
+unsigned long kvm_riscv_stage2_vmid_bits(void);
+int kvm_riscv_stage2_vmid_init(struct kvm *kvm);
+bool kvm_riscv_stage2_vmid_ver_changed(struct kvm_vmid *vmid);
+void kvm_riscv_stage2_vmid_update(struct kvm_vcpu *vcpu);
+
 void __kvm_riscv_unpriv_trap(void);
 
 unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu,
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index 845579273727..c0f57f26c13d 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -8,6 +8,7 @@ ccflags-y := -Ivirt/kvm -Iarch/riscv/kvm
 
 kvm-objs := $(common-objs-y)
 
-kvm-objs += main.o vm.o mmu.o vcpu.o vcpu_exit.o vcpu_switch.o
+kvm-objs += main.o vm.o vmid.o tlb.o mmu.o
+kvm-objs += vcpu.o vcpu_exit.o vcpu_switch.o
 
 obj-$(CONFIG_KVM)	+= kvm.o
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
index f29768c82fbe..08d09b52fbba 100644
--- a/arch/riscv/kvm/main.c
+++ b/arch/riscv/kvm/main.c
@@ -77,8 +77,12 @@ int kvm_arch_init(void *opaque)
 		return -ENODEV;
 	}
 
+	kvm_riscv_stage2_vmid_detect();
+
 	kvm_info("hypervisor extension available\n");
 
+	kvm_info("host has %ld VMID bits\n", kvm_riscv_stage2_vmid_bits());
+
 	return 0;
 }
 
diff --git a/arch/riscv/kvm/tlb.S b/arch/riscv/kvm/tlb.S
new file mode 100644
index 000000000000..453fca8d7940
--- /dev/null
+++ b/arch/riscv/kvm/tlb.S
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+
+	.text
+	.altmacro
+	.option norelax
+
+	/*
+	 * Instruction encoding of hfence.gvma is:
+	 * 0110001 rs2(5) rs1(5) 000 00000 1110011
+	 */
+
+ENTRY(__kvm_riscv_hfence_gvma_vmid_gpa)
+	/* hfence.gvma a1, a0 */
+	.word 0x62a60073
+	ret
+ENDPROC(__kvm_riscv_hfence_gvma_vmid_gpa)
+
+ENTRY(__kvm_riscv_hfence_gvma_vmid)
+	/* hfence.gvma zero, a0 */
+	.word 0x62a00073
+	ret
+ENDPROC(__kvm_riscv_hfence_gvma_vmid)
+
+ENTRY(__kvm_riscv_hfence_gvma_gpa)
+	/* hfence.gvma a0 */
+	.word 0x62050073
+	ret
+ENDPROC(__kvm_riscv_hfence_gvma_gpa)
+
+ENTRY(__kvm_riscv_hfence_gvma_all)
+	/* hfence.gvma */
+	.word 0x62000073
+	ret
+ENDPROC(__kvm_riscv_hfence_gvma_all)
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index ec60f3e783e5..807fd05aa9a4 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -651,6 +651,12 @@ static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
 
 		if (kvm_check_request(KVM_REQ_VCPU_RESET, vcpu))
 			kvm_riscv_reset_vcpu(vcpu);
+
+		if (kvm_check_request(KVM_REQ_UPDATE_HGATP, vcpu))
+			kvm_riscv_stage2_update_hgatp(vcpu);
+
+		if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu))
+			__kvm_riscv_hfence_gvma_all();
 	}
 }
 
@@ -695,6 +701,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		/* Check conditions before entering the guest */
 		cond_resched();
 
+		kvm_riscv_stage2_vmid_update(vcpu);
+
 		kvm_riscv_check_vcpu_requests(vcpu);
 
 		preempt_disable();
@@ -731,6 +739,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		kvm_riscv_update_hip(vcpu);
 
 		if (ret <= 0 ||
+		    kvm_riscv_stage2_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
 		    kvm_request_pending(vcpu)) {
 			vcpu->mode = OUTSIDE_GUEST_MODE;
 			local_irq_enable();
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index ac0211820521..c5aab5478c38 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -26,6 +26,12 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	if (r)
 		return r;
 
+	r = kvm_riscv_stage2_vmid_init(kvm);
+	if (r) {
+		kvm_riscv_stage2_free_pgd(kvm);
+		return r;
+	}
+
 	return 0;
 }
 
diff --git a/arch/riscv/kvm/vmid.c b/arch/riscv/kvm/vmid.c
new file mode 100644
index 000000000000..2c6253b293bc
--- /dev/null
+++ b/arch/riscv/kvm/vmid.c
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/cpumask.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/kvm_host.h>
+#include <asm/csr.h>
+#include <asm/sbi.h>
+
+static unsigned long vmid_version = 1;
+static unsigned long vmid_next;
+static unsigned long vmid_bits;
+static DEFINE_SPINLOCK(vmid_lock);
+
+void kvm_riscv_stage2_vmid_detect(void)
+{
+	unsigned long old;
+
+	/* Figure-out number of VMID bits in HW */
+	old = csr_read(CSR_HGATP);
+	csr_write(CSR_HGATP, old | HGATP_VMID_MASK);
+	vmid_bits = csr_read(CSR_HGATP);
+	vmid_bits = (vmid_bits & HGATP_VMID_MASK) >> HGATP_VMID_SHIFT;
+	vmid_bits = fls_long(vmid_bits);
+	csr_write(CSR_HGATP, old);
+
+	/* We polluted local TLB so flush all guest TLB */
+	__kvm_riscv_hfence_gvma_all();
+
+	/* We don't use VMID bits if they are not sufficient */
+	if ((1UL << vmid_bits) < num_possible_cpus())
+		vmid_bits = 0;
+}
+
+unsigned long kvm_riscv_stage2_vmid_bits(void)
+{
+	return vmid_bits;
+}
+
+int kvm_riscv_stage2_vmid_init(struct kvm *kvm)
+{
+	/* Mark the initial VMID and VMID version invalid */
+	kvm->arch.vmid.vmid_version = 0;
+	kvm->arch.vmid.vmid = 0;
+
+	return 0;
+}
+
+bool kvm_riscv_stage2_vmid_ver_changed(struct kvm_vmid *vmid)
+{
+	if (!vmid_bits)
+		return false;
+
+	return unlikely(READ_ONCE(vmid->vmid_version) !=
+			READ_ONCE(vmid_version));
+}
+
+void kvm_riscv_stage2_vmid_update(struct kvm_vcpu *vcpu)
+{
+	int i;
+	struct kvm_vcpu *v;
+	struct cpumask hmask;
+	struct kvm_vmid *vmid = &vcpu->kvm->arch.vmid;
+
+	if (!kvm_riscv_stage2_vmid_ver_changed(vmid))
+		return;
+
+	spin_lock(&vmid_lock);
+
+	/*
+	 * We need to re-check the vmid_version here to ensure that if
+	 * another vcpu already allocated a valid vmid for this vm.
+	 */
+	if (!kvm_riscv_stage2_vmid_ver_changed(vmid)) {
+		spin_unlock(&vmid_lock);
+		return;
+	}
+
+	/* First user of a new VMID version? */
+	if (unlikely(vmid_next == 0)) {
+		WRITE_ONCE(vmid_version, READ_ONCE(vmid_version) + 1);
+		vmid_next = 1;
+
+		/*
+		 * We ran out of VMIDs so we increment vmid_version and
+		 * start assigning VMIDs from 1.
+		 *
+		 * This also means existing VMIDs assignement to all Guest
+		 * instances is invalid and we have force VMID re-assignement
+		 * for all Guest instances. The Guest instances that were not
+		 * running will automatically pick-up new VMIDs because will
+		 * call kvm_riscv_stage2_vmid_update() whenever they enter
+		 * in-kernel run loop. For Guest instances that are already
+		 * running, we force VM exits on all host CPUs using IPI and
+		 * flush all Guest TLBs.
+		 */
+		riscv_cpuid_to_hartid_mask(cpu_online_mask, &hmask);
+		sbi_remote_hfence_gvma(cpumask_bits(&hmask), 0, 0);
+	}
+
+	vmid->vmid = vmid_next;
+	vmid_next++;
+	vmid_next &= (1 << vmid_bits) - 1;
+
+	WRITE_ONCE(vmid->vmid_version, READ_ONCE(vmid_version));
+
+	spin_unlock(&vmid_lock);
+
+	/* Request stage2 page table update for all VCPUs */
+	kvm_for_each_vcpu(i, v, vcpu->kvm)
+		kvm_make_request(KVM_REQ_UPDATE_HGATP, v);
+}
-- 
2.17.1

[PATCH v10 12/19] RISC-V: KVM: Implement stage2 page table programming

[Anup Patel]

This patch implements all required functions for programming
the stage2 page table for each Guest/VM.

At high-level, the flow of stage2 related functions is similar
from KVM ARM/ARM64 implementation but the stage2 page table
format is quite different for KVM RISC-V.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/riscv/include/asm/kvm_host.h     |  10 +
 arch/riscv/include/asm/pgtable-bits.h |   1 +
 arch/riscv/kvm/mmu.c                  | 565 +++++++++++++++++++++++++-
 3 files changed, 566 insertions(+), 10 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 35a291493f05..dd1acb011fff 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -73,6 +73,13 @@ struct kvm_mmio_decode {
 	int return_handled;
 };
 
+#define KVM_MMU_PAGE_CACHE_NR_OBJS	32
+
+struct kvm_mmu_page_cache {
+	int nobjs;
+	void *objects[KVM_MMU_PAGE_CACHE_NR_OBJS];
+};
+
 struct kvm_cpu_context {
 	unsigned long zero;
 	unsigned long ra;
@@ -164,6 +171,9 @@ struct kvm_vcpu_arch {
 	/* MMIO instruction details */
 	struct kvm_mmio_decode mmio_decode;
 
+	/* Cache pages needed to program page tables with spinlock held */
+	struct kvm_mmu_page_cache mmu_page_cache;
+
 	/* VCPU power-off state */
 	bool power_off;
 
diff --git a/arch/riscv/include/asm/pgtable-bits.h b/arch/riscv/include/asm/pgtable-bits.h
index bbaeb5d35842..be49d62fcc2b 100644
--- a/arch/riscv/include/asm/pgtable-bits.h
+++ b/arch/riscv/include/asm/pgtable-bits.h
@@ -26,6 +26,7 @@
 
 #define _PAGE_SPECIAL   _PAGE_SOFT
 #define _PAGE_TABLE     _PAGE_PRESENT
+#define _PAGE_LEAF      (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC)
 
 /*
  * _PAGE_PROT_NONE is set on not-present pages (and ignored by the hardware) to
diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index 2b965f9aac07..f491c6aa4502 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -17,6 +17,357 @@
 #include <linux/sched/signal.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
+#include <asm/sbi.h>
+
+#ifdef CONFIG_64BIT
+#define stage2_have_pmd		true
+#define stage2_gpa_size		((phys_addr_t)(1ULL << 39))
+#define stage2_pgd_levels	3
+#define stage2_index_bits	9
+#else
+#define stage2_have_pmd		false
+#define stage2_gpa_size		((phys_addr_t)(1ULL << 32))
+#define stage2_pgd_levels	2
+#define stage2_index_bits	10
+#endif
+
+#define stage2_pte_index(addr, level) \
+(((addr) >> (PAGE_SHIFT + stage2_index_bits * (level))) & (PTRS_PER_PTE - 1))
+
+static inline unsigned long stage2_pte_page_vaddr(pte_t pte)
+{
+	return (unsigned long)pfn_to_virt(pte_val(pte) >> _PAGE_PFN_SHIFT);
+}
+
+static int stage2_page_size_to_level(unsigned long page_size, u32 *out_level)
+{
+	if (page_size == PAGE_SIZE)
+		*out_level = 0;
+	else if (page_size == PMD_SIZE)
+		*out_level = 1;
+	else if (page_size == PGDIR_SIZE)
+		*out_level = (stage2_have_pmd) ? 2 : 1;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static int stage2_level_to_page_size(u32 level, unsigned long *out_pgsize)
+{
+	switch (level) {
+	case 0:
+		*out_pgsize = PAGE_SIZE;
+		break;
+	case 1:
+		*out_pgsize = (stage2_have_pmd) ? PMD_SIZE : PGDIR_SIZE;
+		break;
+	case 2:
+		*out_pgsize = PGDIR_SIZE;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int stage2_cache_topup(struct kvm_mmu_page_cache *pcache,
+			      int min, int max)
+{
+	void *page;
+
+	BUG_ON(max > KVM_MMU_PAGE_CACHE_NR_OBJS);
+	if (pcache->nobjs >= min)
+		return 0;
+	while (pcache->nobjs < max) {
+		page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+		if (!page)
+			return -ENOMEM;
+		pcache->objects[pcache->nobjs++] = page;
+	}
+
+	return 0;
+}
+
+static void stage2_cache_flush(struct kvm_mmu_page_cache *pcache)
+{
+	while (pcache && pcache->nobjs)
+		free_page((unsigned long)pcache->objects[--pcache->nobjs]);
+}
+
+static void *stage2_cache_alloc(struct kvm_mmu_page_cache *pcache)
+{
+	void *p;
+
+	if (!pcache)
+		return NULL;
+
+	BUG_ON(!pcache->nobjs);
+	p = pcache->objects[--pcache->nobjs];
+
+	return p;
+}
+
+static bool stage2_get_leaf_entry(struct kvm *kvm, gpa_t addr,
+				  pte_t **ptepp, u32 *ptep_level)
+{
+	pte_t *ptep;
+	u32 current_level = stage2_pgd_levels - 1;
+
+	*ptep_level = current_level;
+	ptep = (pte_t *)kvm->arch.pgd;
+	ptep = &ptep[stage2_pte_index(addr, current_level)];
+	while (ptep && pte_val(*ptep)) {
+		if (pte_val(*ptep) & _PAGE_LEAF) {
+			*ptep_level = current_level;
+			*ptepp = ptep;
+			return true;
+		}
+
+		if (current_level) {
+			current_level--;
+			*ptep_level = current_level;
+			ptep = (pte_t *)stage2_pte_page_vaddr(*ptep);
+			ptep = &ptep[stage2_pte_index(addr, current_level)];
+		} else {
+			ptep = NULL;
+		}
+	}
+
+	return false;
+}
+
+static void stage2_remote_tlb_flush(struct kvm *kvm, u32 level, gpa_t addr)
+{
+	struct cpumask hmask;
+	unsigned long size = PAGE_SIZE;
+	struct kvm_vmid *vmid = &kvm->arch.vmid;
+
+	if (stage2_level_to_page_size(level, &size))
+		return;
+	addr &= ~(size - 1);
+
+	/*
+	 * TODO: Instead of cpu_online_mask, we should only target CPUs
+	 * where the Guest/VM is running.
+	 */
+	preempt_disable();
+	riscv_cpuid_to_hartid_mask(cpu_online_mask, &hmask);
+	sbi_remote_hfence_gvma_vmid(cpumask_bits(&hmask), addr, size,
+				    READ_ONCE(vmid->vmid));
+	preempt_enable();
+}
+
+static int stage2_set_pte(struct kvm *kvm, u32 level,
+			   struct kvm_mmu_page_cache *pcache,
+			   gpa_t addr, const pte_t *new_pte)
+{
+	u32 current_level = stage2_pgd_levels - 1;
+	pte_t *next_ptep = (pte_t *)kvm->arch.pgd;
+	pte_t *ptep = &next_ptep[stage2_pte_index(addr, current_level)];
+
+	if (current_level < level)
+		return -EINVAL;
+
+	while (current_level != level) {
+		if (pte_val(*ptep) & _PAGE_LEAF)
+			return -EEXIST;
+
+		if (!pte_val(*ptep)) {
+			next_ptep = stage2_cache_alloc(pcache);
+			if (!next_ptep)
+				return -ENOMEM;
+			*ptep = pfn_pte(PFN_DOWN(__pa(next_ptep)),
+					__pgprot(_PAGE_TABLE));
+		} else {
+			if (pte_val(*ptep) & _PAGE_LEAF)
+				return -EEXIST;
+			next_ptep = (pte_t *)stage2_pte_page_vaddr(*ptep);
+		}
+
+		current_level--;
+		ptep = &next_ptep[stage2_pte_index(addr, current_level)];
+	}
+
+	*ptep = *new_pte;
+	if (pte_val(*ptep) & _PAGE_LEAF)
+		stage2_remote_tlb_flush(kvm, current_level, addr);
+
+	return 0;
+}
+
+static int stage2_map_page(struct kvm *kvm,
+			   struct kvm_mmu_page_cache *pcache,
+			   gpa_t gpa, phys_addr_t hpa,
+			   unsigned long page_size, pgprot_t prot)
+{
+	int ret;
+	u32 level = 0;
+	pte_t new_pte;
+
+	ret = stage2_page_size_to_level(page_size, &level);
+	if (ret)
+		return ret;
+
+	new_pte = pfn_pte(PFN_DOWN(hpa), prot);
+	return stage2_set_pte(kvm, level, pcache, gpa, &new_pte);
+}
+
+enum stage2_op {
+	STAGE2_OP_NOP = 0,	/* Nothing */
+	STAGE2_OP_CLEAR,	/* Clear/Unmap */
+	STAGE2_OP_WP,		/* Write-protect */
+};
+
+static void stage2_op_pte(struct kvm *kvm, gpa_t addr,
+			  pte_t *ptep, u32 ptep_level, enum stage2_op op)
+{
+	int i, ret;
+	pte_t *next_ptep;
+	u32 next_ptep_level;
+	unsigned long next_page_size, page_size;
+
+	ret = stage2_level_to_page_size(ptep_level, &page_size);
+	if (ret)
+		return;
+
+	BUG_ON(addr & (page_size - 1));
+
+	if (!pte_val(*ptep))
+		return;
+
+	if (ptep_level && !(pte_val(*ptep) & _PAGE_LEAF)) {
+		next_ptep = (pte_t *)stage2_pte_page_vaddr(*ptep);
+		next_ptep_level = ptep_level - 1;
+		ret = stage2_level_to_page_size(next_ptep_level,
+						&next_page_size);
+		if (ret)
+			return;
+
+		if (op == STAGE2_OP_CLEAR)
+			set_pte(ptep, __pte(0));
+		for (i = 0; i < PTRS_PER_PTE; i++)
+			stage2_op_pte(kvm, addr + i * next_page_size,
+					&next_ptep[i], next_ptep_level, op);
+		if (op == STAGE2_OP_CLEAR)
+			put_page(virt_to_page(next_ptep));
+	} else {
+		if (op == STAGE2_OP_CLEAR)
+			set_pte(ptep, __pte(0));
+		else if (op == STAGE2_OP_WP)
+			set_pte(ptep, __pte(pte_val(*ptep) & ~_PAGE_WRITE));
+		stage2_remote_tlb_flush(kvm, ptep_level, addr);
+	}
+}
+
+static void stage2_unmap_range(struct kvm *kvm, gpa_t start, gpa_t size)
+{
+	int ret;
+	pte_t *ptep;
+	u32 ptep_level;
+	bool found_leaf;
+	unsigned long page_size;
+	gpa_t addr = start, end = start + size;
+
+	while (addr < end) {
+		found_leaf = stage2_get_leaf_entry(kvm, addr,
+						   &ptep, &ptep_level);
+		ret = stage2_level_to_page_size(ptep_level, &page_size);
+		if (ret)
+			break;
+
+		if (!found_leaf)
+			goto next;
+
+		if (!(addr & (page_size - 1)) && ((end - addr) >= page_size))
+			stage2_op_pte(kvm, addr, ptep,
+				      ptep_level, STAGE2_OP_CLEAR);
+
+next:
+		addr += page_size;
+	}
+}
+
+static void stage2_wp_range(struct kvm *kvm, gpa_t start, gpa_t end)
+{
+	int ret;
+	pte_t *ptep;
+	u32 ptep_level;
+	bool found_leaf;
+	gpa_t addr = start;
+	unsigned long page_size;
+
+	while (addr < end) {
+		found_leaf = stage2_get_leaf_entry(kvm, addr,
+						   &ptep, &ptep_level);
+		ret = stage2_level_to_page_size(ptep_level, &page_size);
+		if (ret)
+			break;
+
+		if (!found_leaf)
+			goto next;
+
+		if (!(addr & (page_size - 1)) && ((end - addr) >= page_size))
+			stage2_op_pte(kvm, addr, ptep,
+				      ptep_level, STAGE2_OP_WP);
+
+next:
+		addr += page_size;
+	}
+}
+
+void stage2_wp_memory_region(struct kvm *kvm, int slot)
+{
+	struct kvm_memslots *slots = kvm_memslots(kvm);
+	struct kvm_memory_slot *memslot = id_to_memslot(slots, slot);
+	phys_addr_t start = memslot->base_gfn << PAGE_SHIFT;
+	phys_addr_t end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
+
+	spin_lock(&kvm->mmu_lock);
+	stage2_wp_range(kvm, start, end);
+	spin_unlock(&kvm->mmu_lock);
+	kvm_flush_remote_tlbs(kvm);
+}
+
+int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
+		   unsigned long size, bool writable)
+{
+	pte_t pte;
+	int ret = 0;
+	unsigned long pfn;
+	phys_addr_t addr, end;
+	struct kvm_mmu_page_cache pcache = { 0, };
+
+	end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
+	pfn = __phys_to_pfn(hpa);
+
+	for (addr = gpa; addr < end; addr += PAGE_SIZE) {
+		pte = pfn_pte(pfn, PAGE_KERNEL);
+
+		if (!writable)
+			pte = pte_wrprotect(pte);
+
+		ret = stage2_cache_topup(&pcache,
+					 stage2_pgd_levels,
+					 KVM_MMU_PAGE_CACHE_NR_OBJS);
+		if (ret)
+			goto out;
+
+		spin_lock(&kvm->mmu_lock);
+		ret = stage2_set_pte(kvm, 0, &pcache, addr, &pte);
+		spin_unlock(&kvm->mmu_lock);
+		if (ret)
+			goto out;
+
+		pfn++;
+	}
+
+out:
+	stage2_cache_flush(&pcache);
+	return ret;
+
+}
 
 void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
 			   struct kvm_memory_slot *dont)
@@ -35,7 +386,7 @@ void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
 
 void kvm_arch_flush_shadow_all(struct kvm *kvm)
 {
-	/* TODO: */
+	kvm_riscv_stage2_free_pgd(kvm);
 }
 
 void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
@@ -49,7 +400,13 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 				const struct kvm_memory_slot *new,
 				enum kvm_mr_change change)
 {
-	/* TODO: */
+	/*
+	 * At this point memslot has been committed and there is an
+	 * allocated dirty_bitmap[], dirty pages will be be tracked while the
+	 * memory slot is write protected.
+	 */
+	if (change != KVM_MR_DELETE && mem->flags & KVM_MEM_LOG_DIRTY_PAGES)
+		stage2_wp_memory_region(kvm, mem->slot);
 }
 
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
@@ -57,34 +414,222 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				const struct kvm_userspace_memory_region *mem,
 				enum kvm_mr_change change)
 {
-	/* TODO: */
-	return 0;
+	hva_t hva = mem->userspace_addr;
+	hva_t reg_end = hva + mem->memory_size;
+	bool writable = !(mem->flags & KVM_MEM_READONLY);
+	int ret = 0;
+
+	if (change != KVM_MR_CREATE && change != KVM_MR_MOVE &&
+			change != KVM_MR_FLAGS_ONLY)
+		return 0;
+
+	/*
+	 * Prevent userspace from creating a memory region outside of the GPA
+	 * space addressable by the KVM guest GPA space.
+	 */
+	if ((memslot->base_gfn + memslot->npages) >=
+	    (stage2_gpa_size >> PAGE_SHIFT))
+		return -EFAULT;
+
+	down_read(&current->mm->mmap_sem);
+
+	/*
+	 * A memory region could potentially cover multiple VMAs, and
+	 * any holes between them, so iterate over all of them to find
+	 * out if we can map any of them right now.
+	 *
+	 *     +--------------------------------------------+
+	 * +---------------+----------------+   +----------------+
+	 * |   : VMA 1     |      VMA 2     |   |    VMA 3  :    |
+	 * +---------------+----------------+   +----------------+
+	 *     |               memory region                |
+	 *     +--------------------------------------------+
+	 */
+	do {
+		struct vm_area_struct *vma = find_vma(current->mm, hva);
+		hva_t vm_start, vm_end;
+
+		if (!vma || vma->vm_start >= reg_end)
+			break;
+
+		/*
+		 * Mapping a read-only VMA is only allowed if the
+		 * memory region is configured as read-only.
+		 */
+		if (writable && !(vma->vm_flags & VM_WRITE)) {
+			ret = -EPERM;
+			break;
+		}
+
+		/* Take the intersection of this VMA with the memory region */
+		vm_start = max(hva, vma->vm_start);
+		vm_end = min(reg_end, vma->vm_end);
+
+		if (vma->vm_flags & VM_PFNMAP) {
+			gpa_t gpa = mem->guest_phys_addr +
+				    (vm_start - mem->userspace_addr);
+			phys_addr_t pa;
+
+			pa = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
+			pa += vm_start - vma->vm_start;
+
+			/* IO region dirty page logging not allowed */
+			if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES) {
+				ret = -EINVAL;
+				goto out;
+			}
+
+			ret = stage2_ioremap(kvm, gpa, pa,
+					     vm_end - vm_start, writable);
+			if (ret)
+				break;
+		}
+		hva = vm_end;
+	} while (hva < reg_end);
+
+	if (change == KVM_MR_FLAGS_ONLY)
+		goto out;
+
+	spin_lock(&kvm->mmu_lock);
+	if (ret)
+		stage2_unmap_range(kvm, mem->guest_phys_addr,
+				   mem->memory_size);
+	spin_unlock(&kvm->mmu_lock);
+
+out:
+	up_read(&current->mm->mmap_sem);
+	return ret;
 }
 
 int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long hva,
 			 bool is_write)
 {
-	/* TODO: */
-	return 0;
+	int ret;
+	short lsb;
+	kvm_pfn_t hfn;
+	bool writeable;
+	gfn_t gfn = gpa >> PAGE_SHIFT;
+	struct vm_area_struct *vma;
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_mmu_page_cache *pcache = &vcpu->arch.mmu_page_cache;
+	unsigned long vma_pagesize;
+
+	down_read(&current->mm->mmap_sem);
+
+	vma = find_vma_intersection(current->mm, hva, hva + 1);
+	if (unlikely(!vma)) {
+		kvm_err("Failed to find VMA for hva 0x%lx\n", hva);
+		up_read(&current->mm->mmap_sem);
+		return -EFAULT;
+	}
+
+	vma_pagesize = vma_kernel_pagesize(vma);
+
+	if (vma_pagesize == PMD_SIZE || vma_pagesize == PGDIR_SIZE)
+		gfn = (gpa & huge_page_mask(hstate_vma(vma))) >> PAGE_SHIFT;
+
+	up_read(&current->mm->mmap_sem);
+
+	if (vma_pagesize != PGDIR_SIZE &&
+	    vma_pagesize != PMD_SIZE &&
+	    vma_pagesize != PAGE_SIZE) {
+		kvm_err("Invalid VMA page size 0x%lx\n", vma_pagesize);
+		return -EFAULT;
+	}
+
+	/* We need minimum second+third level pages */
+	ret = stage2_cache_topup(pcache, stage2_pgd_levels,
+				 KVM_MMU_PAGE_CACHE_NR_OBJS);
+	if (ret) {
+		kvm_err("Failed to topup stage2 cache\n");
+		return ret;
+	}
+
+	hfn = gfn_to_pfn_prot(kvm, gfn, is_write, &writeable);
+	if (hfn == KVM_PFN_ERR_HWPOISON) {
+		if (is_vm_hugetlb_page(vma))
+			lsb = huge_page_shift(hstate_vma(vma));
+		else
+			lsb = PAGE_SHIFT;
+
+		send_sig_mceerr(BUS_MCEERR_AR, (void __user *)hva,
+				lsb, current);
+		return 0;
+	}
+	if (is_error_noslot_pfn(hfn))
+		return -EFAULT;
+	if (!writeable && is_write)
+		return -EPERM;
+
+	spin_lock(&kvm->mmu_lock);
+
+	if (writeable) {
+		kvm_set_pfn_dirty(hfn);
+		ret = stage2_map_page(kvm, pcache, gpa, hfn << PAGE_SHIFT,
+				      vma_pagesize, PAGE_WRITE_EXEC);
+	} else {
+		ret = stage2_map_page(kvm, pcache, gpa, hfn << PAGE_SHIFT,
+				      vma_pagesize, PAGE_READ_EXEC);
+	}
+
+	if (ret)
+		kvm_err("Failed to map in stage2\n");
+
+	spin_unlock(&kvm->mmu_lock);
+	kvm_set_pfn_accessed(hfn);
+	kvm_release_pfn_clean(hfn);
+	return ret;
 }
 
 void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
+	stage2_cache_flush(&vcpu->arch.mmu_page_cache);
 }
 
 int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm)
 {
-	/* TODO: */
+	if (kvm->arch.pgd != NULL) {
+		kvm_err("kvm_arch already initialized?\n");
+		return -EINVAL;
+	}
+
+	kvm->arch.pgd = alloc_pages_exact(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
+	if (!kvm->arch.pgd)
+		return -ENOMEM;
+	kvm->arch.pgd_phys = virt_to_phys(kvm->arch.pgd);
+
 	return 0;
 }
 
 void kvm_riscv_stage2_free_pgd(struct kvm *kvm)
 {
-	/* TODO: */
+	void *pgd = NULL;
+
+	spin_lock(&kvm->mmu_lock);
+	if (kvm->arch.pgd) {
+		stage2_unmap_range(kvm, 0UL, stage2_gpa_size);
+		pgd = READ_ONCE(kvm->arch.pgd);
+		kvm->arch.pgd = NULL;
+		kvm->arch.pgd_phys = 0;
+	}
+	spin_unlock(&kvm->mmu_lock);
+
+	/* Free the HW pgd, one page at a time */
+	if (pgd)
+		free_pages_exact(pgd, PAGE_SIZE);
 }
 
 void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
+	unsigned long hgatp = HGATP_MODE;
+	struct kvm_arch *k = &vcpu->kvm->arch;
+
+	hgatp |= (READ_ONCE(k->vmid.vmid) << HGATP_VMID_SHIFT) &
+		 HGATP_VMID_MASK;
+	hgatp |= (k->pgd_phys >> PAGE_SHIFT) & HGATP_PPN;
+
+	csr_write(CSR_HGATP, hgatp);
+
+	if (!kvm_riscv_stage2_vmid_bits())
+		__kvm_riscv_hfence_gvma_all();
 }
-- 
2.17.1

[PATCH v10 13/19] RISC-V: KVM: Implement MMU notifiers

[Anup Patel]

This patch implements MMU notifiers for KVM RISC-V so that Guest
physical address space is in-sync with Host physical address space.

This will allow swapping, page migration, etc to work transparently
with KVM RISC-V.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 arch/riscv/include/asm/kvm_host.h |   7 ++
 arch/riscv/kvm/Kconfig            |   1 +
 arch/riscv/kvm/mmu.c              | 129 +++++++++++++++++++++++++++++-
 arch/riscv/kvm/vm.c               |   1 +
 4 files changed, 137 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index dd1acb011fff..cc0b09918431 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -190,6 +190,13 @@ static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
 static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
 
+#define KVM_ARCH_WANT_MMU_NOTIFIER
+int kvm_unmap_hva_range(struct kvm *kvm,
+			unsigned long start, unsigned long end);
+int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);
+int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end);
+int kvm_test_age_hva(struct kvm *kvm, unsigned long hva);
+
 void __kvm_riscv_hfence_gvma_vmid_gpa(unsigned long vmid,
 				      unsigned long gpa);
 void __kvm_riscv_hfence_gvma_vmid(unsigned long vmid);
diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
index 88edd477b3a8..2356dc52ebb3 100644
--- a/arch/riscv/kvm/Kconfig
+++ b/arch/riscv/kvm/Kconfig
@@ -20,6 +20,7 @@ if VIRTUALIZATION
 config KVM
 	tristate "Kernel-based Virtual Machine (KVM) support (EXPERIMENTAL)"
 	depends on RISCV_SBI && MMU
+	select MMU_NOTIFIER
 	select PREEMPT_NOTIFIERS
 	select ANON_INODES
 	select KVM_MMIO
diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index f491c6aa4502..d88a50cde750 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -369,6 +369,38 @@ int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
 
 }
 
+static int handle_hva_to_gpa(struct kvm *kvm,
+			     unsigned long start,
+			     unsigned long end,
+			     int (*handler)(struct kvm *kvm,
+					    gpa_t gpa, u64 size,
+					    void *data),
+			     void *data)
+{
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *memslot;
+	int ret = 0;
+
+	slots = kvm_memslots(kvm);
+
+	/* we only care about the pages that the guest sees */
+	kvm_for_each_memslot(memslot, slots) {
+		unsigned long hva_start, hva_end;
+		gfn_t gpa;
+
+		hva_start = max(start, memslot->userspace_addr);
+		hva_end = min(end, memslot->userspace_addr +
+					(memslot->npages << PAGE_SHIFT));
+		if (hva_start >= hva_end)
+			continue;
+
+		gpa = hva_to_gfn_memslot(hva_start, memslot) << PAGE_SHIFT;
+		ret |= handler(kvm, gpa, (u64)(hva_end - hva_start), data);
+	}
+
+	return ret;
+}
+
 void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
 			   struct kvm_memory_slot *dont)
 {
@@ -501,6 +533,95 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	return ret;
 }
 
+static int kvm_unmap_hva_handler(struct kvm *kvm,
+				 gpa_t gpa, u64 size, void *data)
+{
+	stage2_unmap_range(kvm, gpa, size);
+	return 0;
+}
+
+int kvm_unmap_hva_range(struct kvm *kvm,
+			unsigned long start, unsigned long end)
+{
+	if (!kvm->arch.pgd)
+		return 0;
+
+	handle_hva_to_gpa(kvm, start, end,
+			  &kvm_unmap_hva_handler, NULL);
+	return 0;
+}
+
+static int kvm_set_spte_handler(struct kvm *kvm,
+				gpa_t gpa, u64 size, void *data)
+{
+	pte_t *pte = (pte_t *)data;
+
+	WARN_ON(size != PAGE_SIZE);
+	stage2_set_pte(kvm, 0, NULL, gpa, pte);
+
+	return 0;
+}
+
+int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
+{
+	unsigned long end = hva + PAGE_SIZE;
+	kvm_pfn_t pfn = pte_pfn(pte);
+	pte_t stage2_pte;
+
+	if (!kvm->arch.pgd)
+		return 0;
+
+	stage2_pte = pfn_pte(pfn, PAGE_WRITE_EXEC);
+	handle_hva_to_gpa(kvm, hva, end,
+			  &kvm_set_spte_handler, &stage2_pte);
+
+	return 0;
+}
+
+static int kvm_age_hva_handler(struct kvm *kvm,
+				gpa_t gpa, u64 size, void *data)
+{
+	pte_t *ptep;
+	u32 ptep_level = 0;
+
+	WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PGDIR_SIZE);
+
+	if (!stage2_get_leaf_entry(kvm, gpa, &ptep, &ptep_level))
+		return 0;
+
+	return ptep_test_and_clear_young(NULL, 0, ptep);
+}
+
+int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end)
+{
+	if (!kvm->arch.pgd)
+		return 0;
+
+	return handle_hva_to_gpa(kvm, start, end, kvm_age_hva_handler, NULL);
+}
+
+static int kvm_test_age_hva_handler(struct kvm *kvm,
+				    gpa_t gpa, u64 size, void *data)
+{
+	pte_t *ptep;
+	u32 ptep_level = 0;
+
+	WARN_ON(size != PAGE_SIZE && size != PMD_SIZE);
+	if (!stage2_get_leaf_entry(kvm, gpa, &ptep, &ptep_level))
+		return 0;
+
+	return pte_young(*ptep);
+}
+
+int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
+{
+	if (!kvm->arch.pgd)
+		return 0;
+
+	return handle_hva_to_gpa(kvm, hva, hva,
+				 kvm_test_age_hva_handler, NULL);
+}
+
 int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long hva,
 			 bool is_write)
 {
@@ -512,7 +633,7 @@ int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long hva,
 	struct vm_area_struct *vma;
 	struct kvm *kvm = vcpu->kvm;
 	struct kvm_mmu_page_cache *pcache = &vcpu->arch.mmu_page_cache;
-	unsigned long vma_pagesize;
+	unsigned long vma_pagesize, mmu_seq;
 
 	down_read(&current->mm->mmap_sem);
 
@@ -545,6 +666,8 @@ int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long hva,
 		return ret;
 	}
 
+	mmu_seq = kvm->mmu_notifier_seq;
+
 	hfn = gfn_to_pfn_prot(kvm, gfn, is_write, &writeable);
 	if (hfn == KVM_PFN_ERR_HWPOISON) {
 		if (is_vm_hugetlb_page(vma))
@@ -563,6 +686,9 @@ int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long hva,
 
 	spin_lock(&kvm->mmu_lock);
 
+	if (mmu_notifier_retry(kvm, mmu_seq))
+		goto out_unlock;
+
 	if (writeable) {
 		kvm_set_pfn_dirty(hfn);
 		ret = stage2_map_page(kvm, pcache, gpa, hfn << PAGE_SHIFT,
@@ -575,6 +701,7 @@ int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long hva,
 	if (ret)
 		kvm_err("Failed to map in stage2\n");
 
+out_unlock:
 	spin_unlock(&kvm->mmu_lock);
 	kvm_set_pfn_accessed(hfn);
 	kvm_release_pfn_clean(hfn);
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index c5aab5478c38..fd84b4d914dc 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -54,6 +54,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	switch (ext) {
 	case KVM_CAP_DEVICE_CTRL:
 	case KVM_CAP_USER_MEMORY:
+	case KVM_CAP_SYNC_MMU:
 	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
 	case KVM_CAP_ONE_REG:
 	case KVM_CAP_READONLY_MEM:
-- 
2.17.1

[PATCH v10 14/19] RISC-V: KVM: Add timer functionality

[Anup Patel]

From: Atish Patra <atish.patra@wdc.com>

The RISC-V hypervisor specification doesn't have any virtual timer
feature.

Due to this, the guest VCPU timer will be programmed via SBI calls.
The host will use a separate hrtimer event for each guest VCPU to
provide timer functionality. We inject a virtual timer interrupt to
the guest VCPU whenever the guest VCPU hrtimer event expires.

This patch adds guest VCPU timer implementation along with ONE_REG
interface to access VCPU timer state from user space.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 arch/riscv/include/asm/kvm_host.h       |   7 +
 arch/riscv/include/asm/kvm_vcpu_timer.h |  44 +++++
 arch/riscv/include/uapi/asm/kvm.h       |  17 ++
 arch/riscv/kvm/Makefile                 |   2 +-
 arch/riscv/kvm/vcpu.c                   |  12 ++
 arch/riscv/kvm/vcpu_timer.c             | 225 ++++++++++++++++++++++++
 arch/riscv/kvm/vm.c                     |   2 +-
 drivers/clocksource/timer-riscv.c       |   8 +
 include/clocksource/timer-riscv.h       |  16 ++
 9 files changed, 331 insertions(+), 2 deletions(-)
 create mode 100644 arch/riscv/include/asm/kvm_vcpu_timer.h
 create mode 100644 arch/riscv/kvm/vcpu_timer.c
 create mode 100644 include/clocksource/timer-riscv.h

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index cc0b09918431..b547f79c2e49 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -12,6 +12,7 @@
 #include <linux/types.h>
 #include <linux/kvm.h>
 #include <linux/kvm_types.h>
+#include <asm/kvm_vcpu_timer.h>
 
 #ifdef CONFIG_64BIT
 #define KVM_MAX_VCPUS			(1U << 16)
@@ -64,6 +65,9 @@ struct kvm_arch {
 	/* stage2 page table */
 	pgd_t *pgd;
 	phys_addr_t pgd_phys;
+
+	/* Guest Timer */
+	struct kvm_guest_timer timer;
 };
 
 struct kvm_mmio_decode {
@@ -168,6 +172,9 @@ struct kvm_vcpu_arch {
 	unsigned long irqs_pending;
 	unsigned long irqs_pending_mask;
 
+	/* VCPU Timer */
+	struct kvm_vcpu_timer timer;
+
 	/* MMIO instruction details */
 	struct kvm_mmio_decode mmio_decode;
 
diff --git a/arch/riscv/include/asm/kvm_vcpu_timer.h b/arch/riscv/include/asm/kvm_vcpu_timer.h
new file mode 100644
index 000000000000..375281eb49e0
--- /dev/null
+++ b/arch/riscv/include/asm/kvm_vcpu_timer.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *	Atish Patra <atish.patra@wdc.com>
+ */
+
+#ifndef __KVM_VCPU_RISCV_TIMER_H
+#define __KVM_VCPU_RISCV_TIMER_H
+
+#include <linux/hrtimer.h>
+
+struct kvm_guest_timer {
+	/* Mult & Shift values to get nanoseconds from cycles */
+	u32 nsec_mult;
+	u32 nsec_shift;
+	/* Time delta value */
+	u64 time_delta;
+};
+
+struct kvm_vcpu_timer {
+	/* Flag for whether init is done */
+	bool init_done;
+	/* Flag for whether timer event is configured */
+	bool next_set;
+	/* Next timer event cycles */
+	u64 next_cycles;
+	/* Underlying hrtimer instance */
+	struct hrtimer hrt;
+};
+
+int kvm_riscv_vcpu_timer_next_event(struct kvm_vcpu *vcpu, u64 ncycles);
+int kvm_riscv_vcpu_get_reg_timer(struct kvm_vcpu *vcpu,
+				 const struct kvm_one_reg *reg);
+int kvm_riscv_vcpu_set_reg_timer(struct kvm_vcpu *vcpu,
+				 const struct kvm_one_reg *reg);
+int kvm_riscv_vcpu_timer_init(struct kvm_vcpu *vcpu);
+int kvm_riscv_vcpu_timer_deinit(struct kvm_vcpu *vcpu);
+int kvm_riscv_vcpu_timer_reset(struct kvm_vcpu *vcpu);
+void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu);
+int kvm_riscv_guest_timer_init(struct kvm *kvm);
+
+#endif
diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 3a20327242f1..8f15eee35a1e 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -73,6 +73,18 @@ struct kvm_riscv_csr {
 	unsigned long satp;
 };
 
+/* TIMER registers for KVM_GET_ONE_REG and KVM_SET_ONE_REG */
+struct kvm_riscv_timer {
+	u64 frequency;
+	u64 time;
+	u64 compare;
+	u64 state;
+};
+
+/* Possible states for kvm_riscv_timer */
+#define KVM_RISCV_TIMER_STATE_OFF	0
+#define KVM_RISCV_TIMER_STATE_ON	1
+
 #define KVM_REG_SIZE(id)		\
 	(1U << (((id) & KVM_REG_SIZE_MASK) >> KVM_REG_SIZE_SHIFT))
 
@@ -95,6 +107,11 @@ struct kvm_riscv_csr {
 #define KVM_REG_RISCV_CSR_REG(name)	\
 		(offsetof(struct kvm_riscv_csr, name) / sizeof(unsigned long))
 
+/* Timer registers are mapped as type 4 */
+#define KVM_REG_RISCV_TIMER		(0x04 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_TIMER_REG(name)	\
+		(offsetof(struct kvm_riscv_timer, name) / sizeof(u64))
+
 #endif
 
 #endif /* __LINUX_KVM_RISCV_H */
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index c0f57f26c13d..3e0c7558320d 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -9,6 +9,6 @@ ccflags-y := -Ivirt/kvm -Iarch/riscv/kvm
 kvm-objs := $(common-objs-y)
 
 kvm-objs += main.o vm.o vmid.o tlb.o mmu.o
-kvm-objs += vcpu.o vcpu_exit.o vcpu_switch.o
+kvm-objs += vcpu.o vcpu_exit.o vcpu_switch.o vcpu_timer.o
 
 obj-$(CONFIG_KVM)	+= kvm.o
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 807fd05aa9a4..a49e1695f11b 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -51,6 +51,8 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
 
 	memcpy(cntx, reset_cntx, sizeof(*cntx));
 
+	kvm_riscv_vcpu_timer_reset(vcpu);
+
 	WRITE_ONCE(vcpu->arch.irqs_pending, 0);
 	WRITE_ONCE(vcpu->arch.irqs_pending_mask, 0);
 }
@@ -105,6 +107,9 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 	cntx->hstatus |= HSTATUS_SP2P;
 	cntx->hstatus |= HSTATUS_SPV;
 
+	/* Setup VCPU timer */
+	kvm_riscv_vcpu_timer_init(vcpu);
+
 	/* Reset VCPU */
 	kvm_riscv_reset_vcpu(vcpu);
 
@@ -113,6 +118,7 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 
 void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
+	kvm_riscv_vcpu_timer_deinit(vcpu);
 	kvm_riscv_stage2_flush_cache(vcpu);
 	kmem_cache_free(kvm_vcpu_cache, vcpu);
 }
@@ -363,6 +369,8 @@ static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
 		return kvm_riscv_vcpu_set_reg_core(vcpu, reg);
 	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_CSR)
 		return kvm_riscv_vcpu_set_reg_csr(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_TIMER)
+		return kvm_riscv_vcpu_set_reg_timer(vcpu, reg);
 
 	return -EINVAL;
 }
@@ -376,6 +384,8 @@ static int kvm_riscv_vcpu_get_reg(struct kvm_vcpu *vcpu,
 		return kvm_riscv_vcpu_get_reg_core(vcpu, reg);
 	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_CSR)
 		return kvm_riscv_vcpu_get_reg_csr(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_TIMER)
+		return kvm_riscv_vcpu_get_reg_timer(vcpu, reg);
 
 	return -EINVAL;
 }
@@ -608,6 +618,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 	kvm_riscv_stage2_update_hgatp(vcpu);
 
+	kvm_riscv_vcpu_timer_restore(vcpu);
+
 	vcpu->cpu = cpu;
 }
 
diff --git a/arch/riscv/kvm/vcpu_timer.c b/arch/riscv/kvm/vcpu_timer.c
new file mode 100644
index 000000000000..5fb9fe378800
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_timer.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Atish Patra <atish.patra@wdc.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/kvm_host.h>
+#include <linux/uaccess.h>
+#include <clocksource/timer-riscv.h>
+#include <asm/csr.h>
+#include <asm/delay.h>
+#include <asm/kvm_vcpu_timer.h>
+
+static u64 kvm_riscv_current_cycles(struct kvm_guest_timer *gt)
+{
+	return get_cycles64() + gt->time_delta;
+}
+
+static u64 kvm_riscv_delta_cycles2ns(u64 cycles,
+				     struct kvm_guest_timer *gt,
+				     struct kvm_vcpu_timer *t)
+{
+	unsigned long flags;
+	u64 cycles_now, cycles_delta, delta_ns;
+
+	local_irq_save(flags);
+	cycles_now = kvm_riscv_current_cycles(gt);
+	if (cycles_now < cycles)
+		cycles_delta = cycles - cycles_now;
+	else
+		cycles_delta = 0;
+	delta_ns = (cycles_delta * gt->nsec_mult) >> gt->nsec_shift;
+	local_irq_restore(flags);
+
+	return delta_ns;
+}
+
+static enum hrtimer_restart kvm_riscv_vcpu_hrtimer_expired(struct hrtimer *h)
+{
+	u64 delta_ns;
+	struct kvm_vcpu_timer *t = container_of(h, struct kvm_vcpu_timer, hrt);
+	struct kvm_vcpu *vcpu = container_of(t, struct kvm_vcpu, arch.timer);
+	struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer;
+
+	if (kvm_riscv_current_cycles(gt) < t->next_cycles) {
+		delta_ns = kvm_riscv_delta_cycles2ns(t->next_cycles, gt, t);
+		hrtimer_forward_now(&t->hrt, ktime_set(0, delta_ns));
+		return HRTIMER_RESTART;
+	}
+
+	t->next_set = false;
+	kvm_riscv_vcpu_set_interrupt(vcpu, IRQ_VS_TIMER);
+
+	return HRTIMER_NORESTART;
+}
+
+static int kvm_riscv_vcpu_timer_cancel(struct kvm_vcpu_timer *t)
+{
+	if (!t->init_done || !t->next_set)
+		return -EINVAL;
+
+	hrtimer_cancel(&t->hrt);
+	t->next_set = false;
+
+	return 0;
+}
+
+int kvm_riscv_vcpu_timer_next_event(struct kvm_vcpu *vcpu, u64 ncycles)
+{
+	struct kvm_vcpu_timer *t = &vcpu->arch.timer;
+	struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer;
+	u64 delta_ns;
+
+	if (!t->init_done)
+		return -EINVAL;
+
+	kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_VS_TIMER);
+
+	delta_ns = kvm_riscv_delta_cycles2ns(ncycles, gt, t);
+	t->next_cycles = ncycles;
+	hrtimer_start(&t->hrt, ktime_set(0, delta_ns), HRTIMER_MODE_REL);
+	t->next_set = true;
+
+	return 0;
+}
+
+int kvm_riscv_vcpu_get_reg_timer(struct kvm_vcpu *vcpu,
+				 const struct kvm_one_reg *reg)
+{
+	struct kvm_vcpu_timer *t = &vcpu->arch.timer;
+	struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer;
+	u64 __user *uaddr = (u64 __user *)(unsigned long)reg->addr;
+	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_TIMER);
+	u64 reg_val;
+
+	if (KVM_REG_SIZE(reg->id) != sizeof(u64))
+		return -EINVAL;
+	if (reg_num >= sizeof(struct kvm_riscv_timer) / sizeof(u64))
+		return -EINVAL;
+
+	switch (reg_num) {
+	case KVM_REG_RISCV_TIMER_REG(frequency):
+		reg_val = riscv_timebase;
+		break;
+	case KVM_REG_RISCV_TIMER_REG(time):
+		reg_val = kvm_riscv_current_cycles(gt);
+		break;
+	case KVM_REG_RISCV_TIMER_REG(compare):
+		reg_val = t->next_cycles;
+		break;
+	case KVM_REG_RISCV_TIMER_REG(state):
+		reg_val = (t->next_set) ? KVM_RISCV_TIMER_STATE_ON :
+					  KVM_RISCV_TIMER_STATE_OFF;
+		break;
+	default:
+		return -EINVAL;
+	};
+
+	if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	return 0;
+}
+
+int kvm_riscv_vcpu_set_reg_timer(struct kvm_vcpu *vcpu,
+				 const struct kvm_one_reg *reg)
+{
+	struct kvm_vcpu_timer *t = &vcpu->arch.timer;
+	struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer;
+	u64 __user *uaddr = (u64 __user *)(unsigned long)reg->addr;
+	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    KVM_REG_RISCV_TIMER);
+	u64 reg_val;
+	int ret = 0;
+
+	if (KVM_REG_SIZE(reg->id) != sizeof(u64))
+		return -EINVAL;
+	if (reg_num >= sizeof(struct kvm_riscv_timer) / sizeof(u64))
+		return -EINVAL;
+
+	if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	switch (reg_num) {
+	case KVM_REG_RISCV_TIMER_REG(frequency):
+		ret = -ENOTSUPP;
+		break;
+	case KVM_REG_RISCV_TIMER_REG(time):
+		gt->time_delta = reg_val - get_cycles64();
+		break;
+	case KVM_REG_RISCV_TIMER_REG(compare):
+		t->next_cycles = reg_val;
+		break;
+	case KVM_REG_RISCV_TIMER_REG(state):
+		if (reg_val == KVM_RISCV_TIMER_STATE_ON)
+			ret = kvm_riscv_vcpu_timer_next_event(vcpu, reg_val);
+		else
+			ret = kvm_riscv_vcpu_timer_cancel(t);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	};
+
+	return ret;
+}
+
+int kvm_riscv_vcpu_timer_init(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_timer *t = &vcpu->arch.timer;
+
+	if (t->init_done)
+		return -EINVAL;
+
+	hrtimer_init(&t->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	t->hrt.function = kvm_riscv_vcpu_hrtimer_expired;
+	t->init_done = true;
+	t->next_set = false;
+
+	return 0;
+}
+
+int kvm_riscv_vcpu_timer_deinit(struct kvm_vcpu *vcpu)
+{
+	int ret;
+
+	ret = kvm_riscv_vcpu_timer_cancel(&vcpu->arch.timer);
+	vcpu->arch.timer.init_done = false;
+
+	return ret;
+}
+
+int kvm_riscv_vcpu_timer_reset(struct kvm_vcpu *vcpu)
+{
+	return kvm_riscv_vcpu_timer_cancel(&vcpu->arch.timer);
+}
+
+void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu)
+{
+	struct kvm_guest_timer *gt = &vcpu->kvm->arch.timer;
+
+#ifdef CONFIG_64BIT
+	csr_write(CSR_HTIMEDELTA, gt->time_delta);
+#else
+	csr_write(CSR_HTIMEDELTA, (u32)(gt->time_delta));
+	csr_write(CSR_HTIMEDELTAH, (u32)(gt->time_delta >> 32));
+#endif
+}
+
+int kvm_riscv_guest_timer_init(struct kvm *kvm)
+{
+	struct kvm_guest_timer *gt = &kvm->arch.timer;
+
+	riscv_cs_get_mult_shift(&gt->nsec_mult, &gt->nsec_shift);
+	gt->time_delta = -get_cycles64();
+
+	return 0;
+}
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index fd84b4d914dc..4f2498198cb5 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -32,7 +32,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 		return r;
 	}
 
-	return 0;
+	return kvm_riscv_guest_timer_init(kvm);
 }
 
 void kvm_arch_destroy_vm(struct kvm *kvm)
diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
index 4e54856ce2a5..df5ad56e1f24 100644
--- a/drivers/clocksource/timer-riscv.c
+++ b/drivers/clocksource/timer-riscv.c
@@ -12,6 +12,7 @@
 #include <linux/cpu.h>
 #include <linux/delay.h>
 #include <linux/irq.h>
+#include <linux/module.h>
 #include <linux/sched_clock.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <asm/smp.h>
@@ -86,6 +87,13 @@ static int riscv_timer_dying_cpu(unsigned int cpu)
 	return 0;
 }
 
+void riscv_cs_get_mult_shift(u32 *mult, u32 *shift)
+{
+	*mult = riscv_clocksource.mult;
+	*shift = riscv_clocksource.shift;
+}
+EXPORT_SYMBOL_GPL(riscv_cs_get_mult_shift);
+
 /* called directly from the low-level interrupt handler */
 void riscv_timer_interrupt(void)
 {
diff --git a/include/clocksource/timer-riscv.h b/include/clocksource/timer-riscv.h
new file mode 100644
index 000000000000..e94e4feecbe8
--- /dev/null
+++ b/include/clocksource/timer-riscv.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *	Atish Patra <atish.patra@wdc.com>
+ */
+
+#ifndef __TIMER_RISCV_H
+#define __TIMER_RISCV_H
+
+#include <linux/types.h>
+
+void riscv_cs_get_mult_shift(u32 *mult, u32 *shift);
+
+#endif
-- 
2.17.1

[PATCH v10 15/19] RISC-V: KVM: FP lazy save/restore

[Anup Patel]

From: Atish Patra <atish.patra@wdc.com>

This patch adds floating point (F and D extension) context save/restore
for guest VCPUs. The FP context is saved and restored lazily only when
kernel enter/exits the in-kernel run loop and not during the KVM world
switch. This way FP save/restore has minimal impact on KVM performance.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 arch/riscv/include/asm/kvm_host.h |   5 +
 arch/riscv/kernel/asm-offsets.c   |  72 +++++++++++++
 arch/riscv/kvm/vcpu.c             |  81 ++++++++++++++
 arch/riscv/kvm/vcpu_switch.S      | 174 ++++++++++++++++++++++++++++++
 4 files changed, 332 insertions(+)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index b547f79c2e49..56a8ab9772ae 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -120,6 +120,7 @@ struct kvm_cpu_context {
 	unsigned long sepc;
 	unsigned long sstatus;
 	unsigned long hstatus;
+	union __riscv_fp_state fp;
 };
 
 struct kvm_vcpu_csr {
@@ -237,6 +238,10 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 			unsigned long htval, unsigned long htinst);
 
 void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch);
+void __kvm_riscv_fp_f_save(struct kvm_cpu_context *context);
+void __kvm_riscv_fp_f_restore(struct kvm_cpu_context *context);
+void __kvm_riscv_fp_d_save(struct kvm_cpu_context *context);
+void __kvm_riscv_fp_d_restore(struct kvm_cpu_context *context);
 
 int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq);
 int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq);
diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
index 3a230882b91e..9016e4e27f3c 100644
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
@@ -185,6 +185,78 @@ void asm_offsets(void)
 	OFFSET(KVM_ARCH_HOST_SSCRATCH, kvm_vcpu_arch, host_sscratch);
 	OFFSET(KVM_ARCH_HOST_STVEC, kvm_vcpu_arch, host_stvec);
 
+	/* F extension */
+
+	OFFSET(KVM_ARCH_FP_F_F0, kvm_cpu_context, fp.f.f[0]);
+	OFFSET(KVM_ARCH_FP_F_F1, kvm_cpu_context, fp.f.f[1]);
+	OFFSET(KVM_ARCH_FP_F_F2, kvm_cpu_context, fp.f.f[2]);
+	OFFSET(KVM_ARCH_FP_F_F3, kvm_cpu_context, fp.f.f[3]);
+	OFFSET(KVM_ARCH_FP_F_F4, kvm_cpu_context, fp.f.f[4]);
+	OFFSET(KVM_ARCH_FP_F_F5, kvm_cpu_context, fp.f.f[5]);
+	OFFSET(KVM_ARCH_FP_F_F6, kvm_cpu_context, fp.f.f[6]);
+	OFFSET(KVM_ARCH_FP_F_F7, kvm_cpu_context, fp.f.f[7]);
+	OFFSET(KVM_ARCH_FP_F_F8, kvm_cpu_context, fp.f.f[8]);
+	OFFSET(KVM_ARCH_FP_F_F9, kvm_cpu_context, fp.f.f[9]);
+	OFFSET(KVM_ARCH_FP_F_F10, kvm_cpu_context, fp.f.f[10]);
+	OFFSET(KVM_ARCH_FP_F_F11, kvm_cpu_context, fp.f.f[11]);
+	OFFSET(KVM_ARCH_FP_F_F12, kvm_cpu_context, fp.f.f[12]);
+	OFFSET(KVM_ARCH_FP_F_F13, kvm_cpu_context, fp.f.f[13]);
+	OFFSET(KVM_ARCH_FP_F_F14, kvm_cpu_context, fp.f.f[14]);
+	OFFSET(KVM_ARCH_FP_F_F15, kvm_cpu_context, fp.f.f[15]);
+	OFFSET(KVM_ARCH_FP_F_F16, kvm_cpu_context, fp.f.f[16]);
+	OFFSET(KVM_ARCH_FP_F_F17, kvm_cpu_context, fp.f.f[17]);
+	OFFSET(KVM_ARCH_FP_F_F18, kvm_cpu_context, fp.f.f[18]);
+	OFFSET(KVM_ARCH_FP_F_F19, kvm_cpu_context, fp.f.f[19]);
+	OFFSET(KVM_ARCH_FP_F_F20, kvm_cpu_context, fp.f.f[20]);
+	OFFSET(KVM_ARCH_FP_F_F21, kvm_cpu_context, fp.f.f[21]);
+	OFFSET(KVM_ARCH_FP_F_F22, kvm_cpu_context, fp.f.f[22]);
+	OFFSET(KVM_ARCH_FP_F_F23, kvm_cpu_context, fp.f.f[23]);
+	OFFSET(KVM_ARCH_FP_F_F24, kvm_cpu_context, fp.f.f[24]);
+	OFFSET(KVM_ARCH_FP_F_F25, kvm_cpu_context, fp.f.f[25]);
+	OFFSET(KVM_ARCH_FP_F_F26, kvm_cpu_context, fp.f.f[26]);
+	OFFSET(KVM_ARCH_FP_F_F27, kvm_cpu_context, fp.f.f[27]);
+	OFFSET(KVM_ARCH_FP_F_F28, kvm_cpu_context, fp.f.f[28]);
+	OFFSET(KVM_ARCH_FP_F_F29, kvm_cpu_context, fp.f.f[29]);
+	OFFSET(KVM_ARCH_FP_F_F30, kvm_cpu_context, fp.f.f[30]);
+	OFFSET(KVM_ARCH_FP_F_F31, kvm_cpu_context, fp.f.f[31]);
+	OFFSET(KVM_ARCH_FP_F_FCSR, kvm_cpu_context, fp.f.fcsr);
+
+	/* D extension */
+
+	OFFSET(KVM_ARCH_FP_D_F0, kvm_cpu_context, fp.d.f[0]);
+	OFFSET(KVM_ARCH_FP_D_F1, kvm_cpu_context, fp.d.f[1]);
+	OFFSET(KVM_ARCH_FP_D_F2, kvm_cpu_context, fp.d.f[2]);
+	OFFSET(KVM_ARCH_FP_D_F3, kvm_cpu_context, fp.d.f[3]);
+	OFFSET(KVM_ARCH_FP_D_F4, kvm_cpu_context, fp.d.f[4]);
+	OFFSET(KVM_ARCH_FP_D_F5, kvm_cpu_context, fp.d.f[5]);
+	OFFSET(KVM_ARCH_FP_D_F6, kvm_cpu_context, fp.d.f[6]);
+	OFFSET(KVM_ARCH_FP_D_F7, kvm_cpu_context, fp.d.f[7]);
+	OFFSET(KVM_ARCH_FP_D_F8, kvm_cpu_context, fp.d.f[8]);
+	OFFSET(KVM_ARCH_FP_D_F9, kvm_cpu_context, fp.d.f[9]);
+	OFFSET(KVM_ARCH_FP_D_F10, kvm_cpu_context, fp.d.f[10]);
+	OFFSET(KVM_ARCH_FP_D_F11, kvm_cpu_context, fp.d.f[11]);
+	OFFSET(KVM_ARCH_FP_D_F12, kvm_cpu_context, fp.d.f[12]);
+	OFFSET(KVM_ARCH_FP_D_F13, kvm_cpu_context, fp.d.f[13]);
+	OFFSET(KVM_ARCH_FP_D_F14, kvm_cpu_context, fp.d.f[14]);
+	OFFSET(KVM_ARCH_FP_D_F15, kvm_cpu_context, fp.d.f[15]);
+	OFFSET(KVM_ARCH_FP_D_F16, kvm_cpu_context, fp.d.f[16]);
+	OFFSET(KVM_ARCH_FP_D_F17, kvm_cpu_context, fp.d.f[17]);
+	OFFSET(KVM_ARCH_FP_D_F18, kvm_cpu_context, fp.d.f[18]);
+	OFFSET(KVM_ARCH_FP_D_F19, kvm_cpu_context, fp.d.f[19]);
+	OFFSET(KVM_ARCH_FP_D_F20, kvm_cpu_context, fp.d.f[20]);
+	OFFSET(KVM_ARCH_FP_D_F21, kvm_cpu_context, fp.d.f[21]);
+	OFFSET(KVM_ARCH_FP_D_F22, kvm_cpu_context, fp.d.f[22]);
+	OFFSET(KVM_ARCH_FP_D_F23, kvm_cpu_context, fp.d.f[23]);
+	OFFSET(KVM_ARCH_FP_D_F24, kvm_cpu_context, fp.d.f[24]);
+	OFFSET(KVM_ARCH_FP_D_F25, kvm_cpu_context, fp.d.f[25]);
+	OFFSET(KVM_ARCH_FP_D_F26, kvm_cpu_context, fp.d.f[26]);
+	OFFSET(KVM_ARCH_FP_D_F27, kvm_cpu_context, fp.d.f[27]);
+	OFFSET(KVM_ARCH_FP_D_F28, kvm_cpu_context, fp.d.f[28]);
+	OFFSET(KVM_ARCH_FP_D_F29, kvm_cpu_context, fp.d.f[29]);
+	OFFSET(KVM_ARCH_FP_D_F30, kvm_cpu_context, fp.d.f[30]);
+	OFFSET(KVM_ARCH_FP_D_F31, kvm_cpu_context, fp.d.f[31]);
+	OFFSET(KVM_ARCH_FP_D_FCSR, kvm_cpu_context, fp.d.fcsr);
+
 	/*
 	 * THREAD_{F,X}* might be larger than a S-type offset can handle, but
 	 * these are used in performance-sensitive assembly so we can't resort
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index a49e1695f11b..a3f1a9d59afc 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -31,6 +31,76 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
 	{ NULL }
 };
 
+#ifdef CONFIG_FPU
+static void kvm_riscv_vcpu_fp_reset(struct kvm_vcpu *vcpu)
+{
+	unsigned long isa = vcpu->arch.isa;
+	struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
+
+	cntx->sstatus &= ~SR_FS;
+	if (riscv_isa_extension_available(&isa, f) ||
+	    riscv_isa_extension_available(&isa, d))
+		cntx->sstatus |= SR_FS_INITIAL;
+	else
+		cntx->sstatus |= SR_FS_OFF;
+}
+
+static void kvm_riscv_vcpu_fp_clean(struct kvm_cpu_context *cntx)
+{
+	cntx->sstatus &= ~SR_FS;
+	cntx->sstatus |= SR_FS_CLEAN;
+}
+
+static void kvm_riscv_vcpu_guest_fp_save(struct kvm_cpu_context *cntx,
+					 unsigned long isa)
+{
+	if ((cntx->sstatus & SR_FS) == SR_FS_DIRTY) {
+		if (riscv_isa_extension_available(&isa, d))
+			__kvm_riscv_fp_d_save(cntx);
+		else if (riscv_isa_extension_available(&isa, f))
+			__kvm_riscv_fp_f_save(cntx);
+		kvm_riscv_vcpu_fp_clean(cntx);
+	}
+}
+
+static void kvm_riscv_vcpu_guest_fp_restore(struct kvm_cpu_context *cntx,
+					    unsigned long isa)
+{
+	if ((cntx->sstatus & SR_FS) != SR_FS_OFF) {
+		if (riscv_isa_extension_available(&isa, d))
+			__kvm_riscv_fp_d_restore(cntx);
+		else if (riscv_isa_extension_available(&isa, f))
+			__kvm_riscv_fp_f_restore(cntx);
+		kvm_riscv_vcpu_fp_clean(cntx);
+	}
+}
+
+static void kvm_riscv_vcpu_host_fp_save(struct kvm_cpu_context *cntx)
+{
+	/* No need to check host sstatus as it can be modified outside */
+	if (riscv_isa_extension_available(NULL, d))
+		__kvm_riscv_fp_d_save(cntx);
+	else if (riscv_isa_extension_available(NULL, f))
+		__kvm_riscv_fp_f_save(cntx);
+}
+
+static void kvm_riscv_vcpu_host_fp_restore(struct kvm_cpu_context *cntx)
+{
+	if (riscv_isa_extension_available(NULL, d))
+		__kvm_riscv_fp_d_restore(cntx);
+	else if (riscv_isa_extension_available(NULL, f))
+		__kvm_riscv_fp_f_restore(cntx);
+}
+#else
+static void kvm_riscv_vcpu_fp_reset(struct kvm_vcpu *vcpu) {}
+static void kvm_riscv_vcpu_guest_fp_save(struct kvm_cpu_context *cntx,
+					 unsigned long isa) {}
+static void kvm_riscv_vcpu_guest_fp_restore(struct kvm_cpu_context *cntx,
+					    unsigned long isa) {}
+static void kvm_riscv_vcpu_host_fp_save(struct kvm_cpu_context *cntx) {}
+static void kvm_riscv_vcpu_host_fp_restore(struct kvm_cpu_context *cntx) {}
+#endif
+
 #define KVM_RISCV_ISA_ALLOWED	(riscv_isa_extension_mask(a) | \
 				 riscv_isa_extension_mask(c) | \
 				 riscv_isa_extension_mask(d) | \
@@ -51,6 +121,8 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
 
 	memcpy(cntx, reset_cntx, sizeof(*cntx));
 
+	kvm_riscv_vcpu_fp_reset(vcpu);
+
 	kvm_riscv_vcpu_timer_reset(vcpu);
 
 	WRITE_ONCE(vcpu->arch.irqs_pending, 0);
@@ -216,6 +288,7 @@ static int kvm_riscv_vcpu_set_reg_config(struct kvm_vcpu *vcpu,
 			vcpu->arch.isa = reg_val;
 			vcpu->arch.isa &= riscv_isa_extension_base(NULL);
 			vcpu->arch.isa &= KVM_RISCV_ISA_ALLOWED;
+			kvm_riscv_vcpu_fp_reset(vcpu);
 		} else {
 			return -ENOTSUPP;
 		}
@@ -620,6 +693,10 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 	kvm_riscv_vcpu_timer_restore(vcpu);
 
+	kvm_riscv_vcpu_host_fp_save(&vcpu->arch.host_context);
+	kvm_riscv_vcpu_guest_fp_restore(&vcpu->arch.guest_context,
+					vcpu->arch.isa);
+
 	vcpu->cpu = cpu;
 }
 
@@ -629,6 +706,10 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 
 	vcpu->cpu = -1;
 
+	kvm_riscv_vcpu_guest_fp_save(&vcpu->arch.guest_context,
+				     vcpu->arch.isa);
+	kvm_riscv_vcpu_host_fp_restore(&vcpu->arch.host_context);
+
 	csr_write(CSR_HGATP, 0);
 
 	csr->vsstatus = csr_read(CSR_VSSTATUS);
diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S
index 04b318b9eef8..20104b42e833 100644
--- a/arch/riscv/kvm/vcpu_switch.S
+++ b/arch/riscv/kvm/vcpu_switch.S
@@ -206,3 +206,177 @@ ENTRY(__kvm_riscv_unpriv_trap)
 	csrr	a0, CSR_SCAUSE
 	sret
 ENDPROC(__kvm_riscv_unpriv_trap)
+
+#ifdef	CONFIG_FPU
+	.align 3
+	.global __kvm_riscv_fp_f_save
+__kvm_riscv_fp_f_save:
+	csrr t2, CSR_SSTATUS
+	li t1, SR_FS
+	csrs CSR_SSTATUS, t1
+	frcsr t0
+	fsw f0,  KVM_ARCH_FP_F_F0(a0)
+	fsw f1,  KVM_ARCH_FP_F_F1(a0)
+	fsw f2,  KVM_ARCH_FP_F_F2(a0)
+	fsw f3,  KVM_ARCH_FP_F_F3(a0)
+	fsw f4,  KVM_ARCH_FP_F_F4(a0)
+	fsw f5,  KVM_ARCH_FP_F_F5(a0)
+	fsw f6,  KVM_ARCH_FP_F_F6(a0)
+	fsw f7,  KVM_ARCH_FP_F_F7(a0)
+	fsw f8,  KVM_ARCH_FP_F_F8(a0)
+	fsw f9,  KVM_ARCH_FP_F_F9(a0)
+	fsw f10, KVM_ARCH_FP_F_F10(a0)
+	fsw f11, KVM_ARCH_FP_F_F11(a0)
+	fsw f12, KVM_ARCH_FP_F_F12(a0)
+	fsw f13, KVM_ARCH_FP_F_F13(a0)
+	fsw f14, KVM_ARCH_FP_F_F14(a0)
+	fsw f15, KVM_ARCH_FP_F_F15(a0)
+	fsw f16, KVM_ARCH_FP_F_F16(a0)
+	fsw f17, KVM_ARCH_FP_F_F17(a0)
+	fsw f18, KVM_ARCH_FP_F_F18(a0)
+	fsw f19, KVM_ARCH_FP_F_F19(a0)
+	fsw f20, KVM_ARCH_FP_F_F20(a0)
+	fsw f21, KVM_ARCH_FP_F_F21(a0)
+	fsw f22, KVM_ARCH_FP_F_F22(a0)
+	fsw f23, KVM_ARCH_FP_F_F23(a0)
+	fsw f24, KVM_ARCH_FP_F_F24(a0)
+	fsw f25, KVM_ARCH_FP_F_F25(a0)
+	fsw f26, KVM_ARCH_FP_F_F26(a0)
+	fsw f27, KVM_ARCH_FP_F_F27(a0)
+	fsw f28, KVM_ARCH_FP_F_F28(a0)
+	fsw f29, KVM_ARCH_FP_F_F29(a0)
+	fsw f30, KVM_ARCH_FP_F_F30(a0)
+	fsw f31, KVM_ARCH_FP_F_F31(a0)
+	sw t0, KVM_ARCH_FP_F_FCSR(a0)
+	csrw CSR_SSTATUS, t2
+	ret
+
+	.align 3
+	.global __kvm_riscv_fp_d_save
+__kvm_riscv_fp_d_save:
+	csrr t2, CSR_SSTATUS
+	li t1, SR_FS
+	csrs CSR_SSTATUS, t1
+	frcsr t0
+	fsd f0,  KVM_ARCH_FP_D_F0(a0)
+	fsd f1,  KVM_ARCH_FP_D_F1(a0)
+	fsd f2,  KVM_ARCH_FP_D_F2(a0)
+	fsd f3,  KVM_ARCH_FP_D_F3(a0)
+	fsd f4,  KVM_ARCH_FP_D_F4(a0)
+	fsd f5,  KVM_ARCH_FP_D_F5(a0)
+	fsd f6,  KVM_ARCH_FP_D_F6(a0)
+	fsd f7,  KVM_ARCH_FP_D_F7(a0)
+	fsd f8,  KVM_ARCH_FP_D_F8(a0)
+	fsd f9,  KVM_ARCH_FP_D_F9(a0)
+	fsd f10, KVM_ARCH_FP_D_F10(a0)
+	fsd f11, KVM_ARCH_FP_D_F11(a0)
+	fsd f12, KVM_ARCH_FP_D_F12(a0)
+	fsd f13, KVM_ARCH_FP_D_F13(a0)
+	fsd f14, KVM_ARCH_FP_D_F14(a0)
+	fsd f15, KVM_ARCH_FP_D_F15(a0)
+	fsd f16, KVM_ARCH_FP_D_F16(a0)
+	fsd f17, KVM_ARCH_FP_D_F17(a0)
+	fsd f18, KVM_ARCH_FP_D_F18(a0)
+	fsd f19, KVM_ARCH_FP_D_F19(a0)
+	fsd f20, KVM_ARCH_FP_D_F20(a0)
+	fsd f21, KVM_ARCH_FP_D_F21(a0)
+	fsd f22, KVM_ARCH_FP_D_F22(a0)
+	fsd f23, KVM_ARCH_FP_D_F23(a0)
+	fsd f24, KVM_ARCH_FP_D_F24(a0)
+	fsd f25, KVM_ARCH_FP_D_F25(a0)
+	fsd f26, KVM_ARCH_FP_D_F26(a0)
+	fsd f27, KVM_ARCH_FP_D_F27(a0)
+	fsd f28, KVM_ARCH_FP_D_F28(a0)
+	fsd f29, KVM_ARCH_FP_D_F29(a0)
+	fsd f30, KVM_ARCH_FP_D_F30(a0)
+	fsd f31, KVM_ARCH_FP_D_F31(a0)
+	sw t0, KVM_ARCH_FP_D_FCSR(a0)
+	csrw CSR_SSTATUS, t2
+	ret
+
+	.align 3
+	.global __kvm_riscv_fp_f_restore
+__kvm_riscv_fp_f_restore:
+	csrr t2, CSR_SSTATUS
+	li t1, SR_FS
+	lw t0, KVM_ARCH_FP_F_FCSR(a0)
+	csrs CSR_SSTATUS, t1
+	flw f0,  KVM_ARCH_FP_F_F0(a0)
+	flw f1,  KVM_ARCH_FP_F_F1(a0)
+	flw f2,  KVM_ARCH_FP_F_F2(a0)
+	flw f3,  KVM_ARCH_FP_F_F3(a0)
+	flw f4,  KVM_ARCH_FP_F_F4(a0)
+	flw f5,  KVM_ARCH_FP_F_F5(a0)
+	flw f6,  KVM_ARCH_FP_F_F6(a0)
+	flw f7,  KVM_ARCH_FP_F_F7(a0)
+	flw f8,  KVM_ARCH_FP_F_F8(a0)
+	flw f9,  KVM_ARCH_FP_F_F9(a0)
+	flw f10, KVM_ARCH_FP_F_F10(a0)
+	flw f11, KVM_ARCH_FP_F_F11(a0)
+	flw f12, KVM_ARCH_FP_F_F12(a0)
+	flw f13, KVM_ARCH_FP_F_F13(a0)
+	flw f14, KVM_ARCH_FP_F_F14(a0)
+	flw f15, KVM_ARCH_FP_F_F15(a0)
+	flw f16, KVM_ARCH_FP_F_F16(a0)
+	flw f17, KVM_ARCH_FP_F_F17(a0)
+	flw f18, KVM_ARCH_FP_F_F18(a0)
+	flw f19, KVM_ARCH_FP_F_F19(a0)
+	flw f20, KVM_ARCH_FP_F_F20(a0)
+	flw f21, KVM_ARCH_FP_F_F21(a0)
+	flw f22, KVM_ARCH_FP_F_F22(a0)
+	flw f23, KVM_ARCH_FP_F_F23(a0)
+	flw f24, KVM_ARCH_FP_F_F24(a0)
+	flw f25, KVM_ARCH_FP_F_F25(a0)
+	flw f26, KVM_ARCH_FP_F_F26(a0)
+	flw f27, KVM_ARCH_FP_F_F27(a0)
+	flw f28, KVM_ARCH_FP_F_F28(a0)
+	flw f29, KVM_ARCH_FP_F_F29(a0)
+	flw f30, KVM_ARCH_FP_F_F30(a0)
+	flw f31, KVM_ARCH_FP_F_F31(a0)
+	fscsr t0
+	csrw CSR_SSTATUS, t2
+	ret
+
+	.align 3
+	.global __kvm_riscv_fp_d_restore
+__kvm_riscv_fp_d_restore:
+	csrr t2, CSR_SSTATUS
+	li t1, SR_FS
+	lw t0, KVM_ARCH_FP_D_FCSR(a0)
+	csrs CSR_SSTATUS, t1
+	fld f0,  KVM_ARCH_FP_D_F0(a0)
+	fld f1,  KVM_ARCH_FP_D_F1(a0)
+	fld f2,  KVM_ARCH_FP_D_F2(a0)
+	fld f3,  KVM_ARCH_FP_D_F3(a0)
+	fld f4,  KVM_ARCH_FP_D_F4(a0)
+	fld f5,  KVM_ARCH_FP_D_F5(a0)
+	fld f6,  KVM_ARCH_FP_D_F6(a0)
+	fld f7,  KVM_ARCH_FP_D_F7(a0)
+	fld f8,  KVM_ARCH_FP_D_F8(a0)
+	fld f9,  KVM_ARCH_FP_D_F9(a0)
+	fld f10, KVM_ARCH_FP_D_F10(a0)
+	fld f11, KVM_ARCH_FP_D_F11(a0)
+	fld f12, KVM_ARCH_FP_D_F12(a0)
+	fld f13, KVM_ARCH_FP_D_F13(a0)
+	fld f14, KVM_ARCH_FP_D_F14(a0)
+	fld f15, KVM_ARCH_FP_D_F15(a0)
+	fld f16, KVM_ARCH_FP_D_F16(a0)
+	fld f17, KVM_ARCH_FP_D_F17(a0)
+	fld f18, KVM_ARCH_FP_D_F18(a0)
+	fld f19, KVM_ARCH_FP_D_F19(a0)
+	fld f20, KVM_ARCH_FP_D_F20(a0)
+	fld f21, KVM_ARCH_FP_D_F21(a0)
+	fld f22, KVM_ARCH_FP_D_F22(a0)
+	fld f23, KVM_ARCH_FP_D_F23(a0)
+	fld f24, KVM_ARCH_FP_D_F24(a0)
+	fld f25, KVM_ARCH_FP_D_F25(a0)
+	fld f26, KVM_ARCH_FP_D_F26(a0)
+	fld f27, KVM_ARCH_FP_D_F27(a0)
+	fld f28, KVM_ARCH_FP_D_F28(a0)
+	fld f29, KVM_ARCH_FP_D_F29(a0)
+	fld f30, KVM_ARCH_FP_D_F30(a0)
+	fld f31, KVM_ARCH_FP_D_F31(a0)
+	fscsr t0
+	csrw CSR_SSTATUS, t2
+	ret
+#endif
-- 
2.17.1

[PATCH v10 16/19] RISC-V: KVM: Implement ONE REG interface for FP registers

[Anup Patel]

From: Atish Patra <atish.patra@wdc.com>

Add a KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctl interface for floating
point registers such as F0-F31 and FCSR. This support is added for
both 'F' and 'D' extensions.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 arch/riscv/include/uapi/asm/kvm.h |  10 +++
 arch/riscv/kvm/vcpu.c             | 104 ++++++++++++++++++++++++++++++
 2 files changed, 114 insertions(+)

diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 8f15eee35a1e..f4274c2e5cdc 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -112,6 +112,16 @@ struct kvm_riscv_timer {
 #define KVM_REG_RISCV_TIMER_REG(name)	\
 		(offsetof(struct kvm_riscv_timer, name) / sizeof(u64))
 
+/* F extension registers are mapped as type 5 */
+#define KVM_REG_RISCV_FP_F		(0x05 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_FP_F_REG(name)	\
+		(offsetof(struct __riscv_f_ext_state, name) / sizeof(u32))
+
+/* D extension registers are mapped as type 6 */
+#define KVM_REG_RISCV_FP_D		(0x06 << KVM_REG_RISCV_TYPE_SHIFT)
+#define KVM_REG_RISCV_FP_D_REG(name)	\
+		(offsetof(struct __riscv_d_ext_state, name) / sizeof(u64))
+
 #endif
 
 #endif /* __LINUX_KVM_RISCV_H */
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index a3f1a9d59afc..a2547517680e 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -433,6 +433,98 @@ static int kvm_riscv_vcpu_set_reg_csr(struct kvm_vcpu *vcpu,
 	return 0;
 }
 
+static int kvm_riscv_vcpu_get_reg_fp(struct kvm_vcpu *vcpu,
+				     const struct kvm_one_reg *reg,
+				     unsigned long rtype)
+{
+	struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
+	unsigned long isa = vcpu->arch.isa;
+	unsigned long __user *uaddr =
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    rtype);
+	void *reg_val;
+
+	if ((rtype == KVM_REG_RISCV_FP_F) &&
+	    riscv_isa_extension_available(&isa, f)) {
+		if (KVM_REG_SIZE(reg->id) != sizeof(u32))
+			return -EINVAL;
+		if (reg_num == KVM_REG_RISCV_FP_F_REG(fcsr))
+			reg_val = &cntx->fp.f.fcsr;
+		else if ((KVM_REG_RISCV_FP_F_REG(f[0]) <= reg_num) &&
+			  reg_num <= KVM_REG_RISCV_FP_F_REG(f[31]))
+			reg_val = &cntx->fp.f.f[reg_num];
+		else
+			return -EINVAL;
+	} else if ((rtype == KVM_REG_RISCV_FP_D) &&
+		   riscv_isa_extension_available(&isa, d)) {
+		if (reg_num == KVM_REG_RISCV_FP_D_REG(fcsr)) {
+			if (KVM_REG_SIZE(reg->id) != sizeof(u32))
+				return -EINVAL;
+			reg_val = &cntx->fp.d.fcsr;
+		} else if ((KVM_REG_RISCV_FP_D_REG(f[0]) <= reg_num) &&
+			   reg_num <= KVM_REG_RISCV_FP_D_REG(f[31])) {
+			if (KVM_REG_SIZE(reg->id) != sizeof(u64))
+				return -EINVAL;
+			reg_val = &cntx->fp.d.f[reg_num];
+		} else
+			return -EINVAL;
+	} else
+		return -EINVAL;
+
+	if (copy_to_user(uaddr, reg_val, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int kvm_riscv_vcpu_set_reg_fp(struct kvm_vcpu *vcpu,
+				     const struct kvm_one_reg *reg,
+				     unsigned long rtype)
+{
+	struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
+	unsigned long isa = vcpu->arch.isa;
+	unsigned long __user *uaddr =
+			(unsigned long __user *)(unsigned long)reg->addr;
+	unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
+					    KVM_REG_SIZE_MASK |
+					    rtype);
+	void *reg_val;
+
+	if ((rtype == KVM_REG_RISCV_FP_F) &&
+	    riscv_isa_extension_available(&isa, f)) {
+		if (KVM_REG_SIZE(reg->id) != sizeof(u32))
+			return -EINVAL;
+		if (reg_num == KVM_REG_RISCV_FP_F_REG(fcsr))
+			reg_val = &cntx->fp.f.fcsr;
+		else if ((KVM_REG_RISCV_FP_F_REG(f[0]) <= reg_num) &&
+			  reg_num <= KVM_REG_RISCV_FP_F_REG(f[31]))
+			reg_val = &cntx->fp.f.f[reg_num];
+		else
+			return -EINVAL;
+	} else if ((rtype == KVM_REG_RISCV_FP_D) &&
+		   riscv_isa_extension_available(&isa, d)) {
+		if (reg_num == KVM_REG_RISCV_FP_D_REG(fcsr)) {
+			if (KVM_REG_SIZE(reg->id) != sizeof(u32))
+				return -EINVAL;
+			reg_val = &cntx->fp.d.fcsr;
+		} else if ((KVM_REG_RISCV_FP_D_REG(f[0]) <= reg_num) &&
+			   reg_num <= KVM_REG_RISCV_FP_D_REG(f[31])) {
+			if (KVM_REG_SIZE(reg->id) != sizeof(u64))
+				return -EINVAL;
+			reg_val = &cntx->fp.d.f[reg_num];
+		} else
+			return -EINVAL;
+	} else
+		return -EINVAL;
+
+	if (copy_from_user(reg_val, uaddr, KVM_REG_SIZE(reg->id)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
 				  const struct kvm_one_reg *reg)
 {
@@ -444,6 +536,12 @@ static int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
 		return kvm_riscv_vcpu_set_reg_csr(vcpu, reg);
 	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_TIMER)
 		return kvm_riscv_vcpu_set_reg_timer(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_FP_F)
+		return kvm_riscv_vcpu_set_reg_fp(vcpu, reg,
+						 KVM_REG_RISCV_FP_F);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_FP_D)
+		return kvm_riscv_vcpu_set_reg_fp(vcpu, reg,
+						 KVM_REG_RISCV_FP_D);
 
 	return -EINVAL;
 }
@@ -459,6 +557,12 @@ static int kvm_riscv_vcpu_get_reg(struct kvm_vcpu *vcpu,
 		return kvm_riscv_vcpu_get_reg_csr(vcpu, reg);
 	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_TIMER)
 		return kvm_riscv_vcpu_get_reg_timer(vcpu, reg);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_FP_F)
+		return kvm_riscv_vcpu_get_reg_fp(vcpu, reg,
+						 KVM_REG_RISCV_FP_F);
+	else if ((reg->id & KVM_REG_RISCV_TYPE_MASK) == KVM_REG_RISCV_FP_D)
+		return kvm_riscv_vcpu_get_reg_fp(vcpu, reg,
+						 KVM_REG_RISCV_FP_D);
 
 	return -EINVAL;
 }
-- 
2.17.1

[PATCH v10 17/19] RISC-V: KVM: Add SBI v0.1 support

[Anup Patel]

From: Atish Patra <atish.patra@wdc.com>

The KVM host kernel is running in HS-mode needs so we need to handle
the SBI calls coming from guest kernel running in VS-mode.

This patch adds SBI v0.1 support in KVM RISC-V. Almost all SBI v0.1
calls are implemented in KVM kernel module except GETCHAR and PUTCHART
calls which are forwarded to user space because these calls cannot be
implemented in kernel space. In future, when we implement SBI v0.2 for
Guest, we will forward SBI v0.2 experimental and vendor extension calls
to user space.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/riscv/include/asm/kvm_host.h |  10 ++
 arch/riscv/kvm/Makefile           |   2 +-
 arch/riscv/kvm/vcpu.c             |   9 ++
 arch/riscv/kvm/vcpu_exit.c        |   4 +
 arch/riscv/kvm/vcpu_sbi.c         | 171 ++++++++++++++++++++++++++++++
 include/uapi/linux/kvm.h          |   8 ++
 6 files changed, 203 insertions(+), 1 deletion(-)
 create mode 100644 arch/riscv/kvm/vcpu_sbi.c

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 56a8ab9772ae..a7ad0a8f5604 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -77,6 +77,10 @@ struct kvm_mmio_decode {
 	int return_handled;
 };
 
+struct kvm_sbi_context {
+	int return_handled;
+};
+
 #define KVM_MMU_PAGE_CACHE_NR_OBJS	32
 
 struct kvm_mmu_page_cache {
@@ -179,6 +183,9 @@ struct kvm_vcpu_arch {
 	/* MMIO instruction details */
 	struct kvm_mmio_decode mmio_decode;
 
+	/* SBI context */
+	struct kvm_sbi_context sbi_context;
+
 	/* Cache pages needed to program page tables with spinlock held */
 	struct kvm_mmu_page_cache mmu_page_cache;
 
@@ -251,4 +258,7 @@ bool kvm_riscv_vcpu_has_interrupts(struct kvm_vcpu *vcpu, unsigned long mask);
 void kvm_riscv_vcpu_power_off(struct kvm_vcpu *vcpu);
 void kvm_riscv_vcpu_power_on(struct kvm_vcpu *vcpu);
 
+int kvm_riscv_vcpu_sbi_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
+int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run);
+
 #endif /* __RISCV_KVM_HOST_H__ */
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index 3e0c7558320d..b56dc1650d2c 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -9,6 +9,6 @@ ccflags-y := -Ivirt/kvm -Iarch/riscv/kvm
 kvm-objs := $(common-objs-y)
 
 kvm-objs += main.o vm.o vmid.o tlb.o mmu.o
-kvm-objs += vcpu.o vcpu_exit.o vcpu_switch.o vcpu_timer.o
+kvm-objs += vcpu.o vcpu_exit.o vcpu_switch.o vcpu_timer.o vcpu_sbi.o
 
 obj-$(CONFIG_KVM)	+= kvm.o
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index a2547517680e..b1ccbbbf679c 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -883,6 +883,15 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		}
 	}
 
+	/* Process SBI value returned from user-space */
+	if (run->exit_reason == KVM_EXIT_RISCV_SBI) {
+		ret = kvm_riscv_vcpu_sbi_return(vcpu, vcpu->run);
+		if (ret) {
+			srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+			return ret;
+		}
+	}
+
 	if (run->immediate_exit) {
 		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
 		return -EINTR;
diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
index 8d0ae1a23b70..ac97a72bd29f 100644
--- a/arch/riscv/kvm/vcpu_exit.c
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -616,6 +616,10 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 			ret = stage2_page_fault(vcpu, run, scause, stval,
 						htval, htinst);
 		break;
+	case EXC_SUPERVISOR_SYSCALL:
+		if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
+			ret = kvm_riscv_vcpu_sbi_ecall(vcpu, run);
+		break;
 	default:
 		break;
 	};
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
new file mode 100644
index 000000000000..5b26a1793108
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * Copyright (c) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ *     Atish Patra <atish.patra@wdc.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/kvm_host.h>
+#include <asm/csr.h>
+#include <asm/sbi.h>
+#include <asm/kvm_vcpu_timer.h>
+
+#define SBI_VERSION_MAJOR			0
+#define SBI_VERSION_MINOR			1
+
+static void kvm_sbi_system_shutdown(struct kvm_vcpu *vcpu,
+				    struct kvm_run *run, u32 type)
+{
+	int i;
+	struct kvm_vcpu *tmp;
+
+	kvm_for_each_vcpu(i, tmp, vcpu->kvm)
+		tmp->arch.power_off = true;
+	kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_SLEEP);
+
+	memset(&run->system_event, 0, sizeof(run->system_event));
+	run->system_event.type = type;
+	run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
+}
+
+static void kvm_riscv_vcpu_sbi_forward(struct kvm_vcpu *vcpu,
+				       struct kvm_run *run)
+{
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+
+	vcpu->arch.sbi_context.return_handled = 0;
+	run->exit_reason = KVM_EXIT_RISCV_SBI;
+	run->riscv_sbi.extension_id = cp->a7;
+	run->riscv_sbi.function_id = cp->a6;
+	run->riscv_sbi.args[0] = cp->a0;
+	run->riscv_sbi.args[1] = cp->a1;
+	run->riscv_sbi.args[2] = cp->a2;
+	run->riscv_sbi.args[3] = cp->a3;
+	run->riscv_sbi.args[4] = cp->a4;
+	run->riscv_sbi.args[5] = cp->a5;
+	run->riscv_sbi.ret[0] = cp->a0;
+	run->riscv_sbi.ret[1] = cp->a1;
+}
+
+int kvm_riscv_vcpu_sbi_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+
+	/* Handle SBI return only once */
+	if (vcpu->arch.sbi_context.return_handled)
+		return 0;
+	vcpu->arch.sbi_context.return_handled = 1;
+
+	/* Update return values */
+	cp->a0 = run->riscv_sbi.ret[0];
+	cp->a1 = run->riscv_sbi.ret[1];
+
+	/* Move to next instruction */
+	vcpu->arch.guest_context.sepc += 4;
+
+	return 0;
+}
+
+int kvm_riscv_vcpu_sbi_ecall(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+	int i, ret = 1;
+	u64 next_cycle;
+	struct kvm_vcpu *rvcpu;
+	bool next_sepc = true;
+	struct cpumask cm, hm;
+	ulong hmask, ut_scause = 0;
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
+
+	if (!cp)
+		return -EINVAL;
+
+	switch (cp->a7) {
+	case SBI_EXT_0_1_CONSOLE_GETCHAR:
+	case SBI_EXT_0_1_CONSOLE_PUTCHAR:
+		/*
+		 * The CONSOLE_GETCHAR/CONSOLE_PUTCHAR SBI calls cannot be
+		 * handled in kernel so we forward these to user-space
+		 */
+		kvm_riscv_vcpu_sbi_forward(vcpu, run);
+		next_sepc = false;
+		ret = 0;
+		break;
+	case SBI_EXT_0_1_SET_TIMER:
+#if __riscv_xlen == 32
+		next_cycle = ((u64)cp->a1 << 32) | (u64)cp->a0;
+#else
+		next_cycle = (u64)cp->a0;
+#endif
+		kvm_riscv_vcpu_timer_next_event(vcpu, next_cycle);
+		break;
+	case SBI_EXT_0_1_CLEAR_IPI:
+		kvm_riscv_vcpu_unset_interrupt(vcpu, IRQ_VS_SOFT);
+		break;
+	case SBI_EXT_0_1_SEND_IPI:
+		if (cp->a0)
+			hmask = kvm_riscv_vcpu_unpriv_read(vcpu, false, cp->a0,
+							   &ut_scause);
+		else
+			hmask = (1UL << atomic_read(&kvm->online_vcpus)) - 1;
+		if (ut_scause) {
+			kvm_riscv_vcpu_trap_redirect(vcpu, ut_scause,
+						     cp->a0);
+			next_sepc = false;
+			break;
+		}
+		for_each_set_bit(i, &hmask, BITS_PER_LONG) {
+			rvcpu = kvm_get_vcpu_by_id(vcpu->kvm, i);
+			kvm_riscv_vcpu_set_interrupt(rvcpu, IRQ_VS_SOFT);
+		}
+		break;
+	case SBI_EXT_0_1_SHUTDOWN:
+		kvm_sbi_system_shutdown(vcpu, run, KVM_SYSTEM_EVENT_SHUTDOWN);
+		next_sepc = false;
+		ret = 0;
+		break;
+	case SBI_EXT_0_1_REMOTE_FENCE_I:
+	case SBI_EXT_0_1_REMOTE_SFENCE_VMA:
+	case SBI_EXT_0_1_REMOTE_SFENCE_VMA_ASID:
+		if (cp->a0)
+			hmask = kvm_riscv_vcpu_unpriv_read(vcpu, false, cp->a0,
+							   &ut_scause);
+		else
+			hmask = (1UL << atomic_read(&kvm->online_vcpus)) - 1;
+		if (ut_scause) {
+			kvm_riscv_vcpu_trap_redirect(vcpu, ut_scause,
+						     cp->a0);
+			next_sepc = false;
+			break;
+		}
+		cpumask_clear(&cm);
+		for_each_set_bit(i, &hmask, BITS_PER_LONG) {
+			rvcpu = kvm_get_vcpu_by_id(vcpu->kvm, i);
+			if (rvcpu->cpu < 0)
+				continue;
+			cpumask_set_cpu(rvcpu->cpu, &cm);
+		}
+		riscv_cpuid_to_hartid_mask(&cm, &hm);
+		if (cp->a7 == SBI_EXT_0_1_REMOTE_FENCE_I)
+			sbi_remote_fence_i(cpumask_bits(&hm));
+		else if (cp->a7 == SBI_EXT_0_1_REMOTE_SFENCE_VMA)
+			sbi_remote_hfence_vvma(cpumask_bits(&hm),
+						cp->a1, cp->a2);
+		else
+			sbi_remote_hfence_vvma_asid(cpumask_bits(&hm),
+						cp->a1, cp->a2, cp->a3);
+		break;
+	default:
+		/* Return error for unsupported SBI calls */
+		cp->a0 = SBI_ERR_NOT_SUPPORTED;
+		break;
+	};
+
+	if (next_sepc)
+		cp->sepc += 4;
+
+	return ret;
+}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index f0a16b4adbbd..b6a90dd8f779 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -236,6 +236,7 @@ struct kvm_hyperv_exit {
 #define KVM_EXIT_IOAPIC_EOI       26
 #define KVM_EXIT_HYPERV           27
 #define KVM_EXIT_ARM_NISV         28
+#define KVM_EXIT_RISCV_SBI        28
 
 /* For KVM_EXIT_INTERNAL_ERROR */
 /* Emulate instruction failed. */
@@ -400,6 +401,13 @@ struct kvm_run {
 			__u64 esr_iss;
 			__u64 fault_ipa;
 		} arm_nisv;
+		/* KVM_EXIT_RISCV_SBI */
+		struct {
+			unsigned long extension_id;
+			unsigned long function_id;
+			unsigned long args[6];
+			unsigned long ret[2];
+		} riscv_sbi;
 		/* Fix the size of the union. */
 		char padding[256];
 	};
-- 
2.17.1

[PATCH v10 18/19] RISC-V: KVM: Document RISC-V specific parts of KVM API.

[Anup Patel]

Document RISC-V specific parts of the KVM API, such as:
 - The interrupt numbers passed to the KVM_INTERRUPT ioctl.
 - The states supported by the KVM_{GET,SET}_MP_STATE ioctls.
 - The registers supported by the KVM_{GET,SET}_ONE_REG interface
   and the encoding of those register ids.
 - The exit reason KVM_EXIT_RISCV_SBI for SBI calls forwarded to
   userspace tool.

CC: Jonathan Corbet <corbet@lwn.net>
CC: linux-doc@vger.kernel.org
Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
 Documentation/virt/kvm/api.txt | 169 +++++++++++++++++++++++++++++++--
 1 file changed, 162 insertions(+), 7 deletions(-)

diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
index ebb37b34dcfc..381a2e6df8c6 100644
--- a/Documentation/virt/kvm/api.txt
+++ b/Documentation/virt/kvm/api.txt
@@ -471,7 +471,7 @@ struct kvm_translation {
 4.16 KVM_INTERRUPT
 
 Capability: basic
-Architectures: x86, ppc, mips
+Architectures: x86, ppc, mips, riscv
 Type: vcpu ioctl
 Parameters: struct kvm_interrupt (in)
 Returns: 0 on success, negative on failure.
@@ -531,6 +531,22 @@ interrupt number dequeues the interrupt.
 
 This is an asynchronous vcpu ioctl and can be invoked from any thread.
 
+RISC-V:
+
+Queues an external interrupt to be injected into the virutal CPU. This ioctl
+is overloaded with 2 different irq values:
+
+a) KVM_INTERRUPT_SET
+
+  This sets external interrupt for a virtual CPU and it will receive
+  once it is ready.
+
+b) KVM_INTERRUPT_UNSET
+
+  This clears pending external interrupt for a virtual CPU.
+
+This is an asynchronous vcpu ioctl and can be invoked from any thread.
+
 
 4.17 KVM_DEBUG_GUEST
 
@@ -1239,7 +1255,7 @@ for vm-wide capabilities.
 4.38 KVM_GET_MP_STATE
 
 Capability: KVM_CAP_MP_STATE
-Architectures: x86, s390, arm, arm64
+Architectures: x86, s390, arm, arm64, riscv
 Type: vcpu ioctl
 Parameters: struct kvm_mp_state (out)
 Returns: 0 on success; -1 on error
@@ -1253,7 +1269,8 @@ uniprocessor guests).
 
 Possible values are:
 
- - KVM_MP_STATE_RUNNABLE:        the vcpu is currently running [x86,arm/arm64]
+ - KVM_MP_STATE_RUNNABLE:        the vcpu is currently running
+                                 [x86,arm/arm64,riscv]
  - KVM_MP_STATE_UNINITIALIZED:   the vcpu is an application processor (AP)
                                  which has not yet received an INIT signal [x86]
  - KVM_MP_STATE_INIT_RECEIVED:   the vcpu has received an INIT signal, and is
@@ -1262,7 +1279,7 @@ Possible values are:
                                  is waiting for an interrupt [x86]
  - KVM_MP_STATE_SIPI_RECEIVED:   the vcpu has just received a SIPI (vector
                                  accessible via KVM_GET_VCPU_EVENTS) [x86]
- - KVM_MP_STATE_STOPPED:         the vcpu is stopped [s390,arm/arm64]
+ - KVM_MP_STATE_STOPPED:         the vcpu is stopped [s390,arm/arm64,riscv]
  - KVM_MP_STATE_CHECK_STOP:      the vcpu is in a special error state [s390]
  - KVM_MP_STATE_OPERATING:       the vcpu is operating (running or halted)
                                  [s390]
@@ -1273,7 +1290,7 @@ On x86, this ioctl is only useful after KVM_CREATE_IRQCHIP. Without an
 in-kernel irqchip, the multiprocessing state must be maintained by userspace on
 these architectures.
 
-For arm/arm64:
+For arm/arm64/riscv:
 
 The only states that are valid are KVM_MP_STATE_STOPPED and
 KVM_MP_STATE_RUNNABLE which reflect if the vcpu is paused or not.
@@ -1281,7 +1298,7 @@ KVM_MP_STATE_RUNNABLE which reflect if the vcpu is paused or not.
 4.39 KVM_SET_MP_STATE
 
 Capability: KVM_CAP_MP_STATE
-Architectures: x86, s390, arm, arm64
+Architectures: x86, s390, arm, arm64, riscv
 Type: vcpu ioctl
 Parameters: struct kvm_mp_state (in)
 Returns: 0 on success; -1 on error
@@ -1293,7 +1310,7 @@ On x86, this ioctl is only useful after KVM_CREATE_IRQCHIP. Without an
 in-kernel irqchip, the multiprocessing state must be maintained by userspace on
 these architectures.
 
-For arm/arm64:
+For arm/arm64/riscv:
 
 The only states that are valid are KVM_MP_STATE_STOPPED and
 KVM_MP_STATE_RUNNABLE which reflect if the vcpu should be paused or not.
@@ -2302,6 +2319,127 @@ following id bit patterns:
   0x7020 0000 0003 02 <0:3> <reg:5>
 
 
+RISC-V registers are mapped using the lower 32 bits. The upper 8 bits of
+that is the register group type.
+
+RISC-V config registers are meant for configuring a Guest VCPU and it has
+the following id bit patterns:
+  0x8020 0000 01 <index into the kvm_riscv_config struct:24> (32bit Host)
+  0x8030 0000 01 <index into the kvm_riscv_config struct:24> (64bit Host)
+
+Following are the RISC-V config registers:
+
+    Encoding            Register  Description
+------------------------------------------------------------------
+  0x80x0 0000 0100 0000 isa       ISA feature bitmap of Guest VCPU
+
+The isa config register can be read anytime but can only be written before
+a Guest VCPU runs. It will have ISA feature bits matching underlying host
+set by default.
+
+RISC-V core registers represent the general excution state of a Guest VCPU
+and it has the following id bit patterns:
+  0x8020 0000 02 <index into the kvm_riscv_core struct:24> (32bit Host)
+  0x8030 0000 02 <index into the kvm_riscv_core struct:24> (64bit Host)
+
+Following are the RISC-V core registers:
+
+    Encoding            Register  Description
+------------------------------------------------------------------
+  0x80x0 0000 0200 0000 regs.pc   Program counter
+  0x80x0 0000 0200 0001 regs.ra   Return address
+  0x80x0 0000 0200 0002 regs.sp   Stack pointer
+  0x80x0 0000 0200 0003 regs.gp   Global pointer
+  0x80x0 0000 0200 0004 regs.tp   Task pointer
+  0x80x0 0000 0200 0005 regs.t0   Caller saved register 0
+  0x80x0 0000 0200 0006 regs.t1   Caller saved register 1
+  0x80x0 0000 0200 0007 regs.t2   Caller saved register 2
+  0x80x0 0000 0200 0008 regs.s0   Callee saved register 0
+  0x80x0 0000 0200 0009 regs.s1   Callee saved register 1
+  0x80x0 0000 0200 000a regs.a0   Function argument (or return value) 0
+  0x80x0 0000 0200 000b regs.a1   Function argument (or return value) 1
+  0x80x0 0000 0200 000c regs.a2   Function argument 2
+  0x80x0 0000 0200 000d regs.a3   Function argument 3
+  0x80x0 0000 0200 000e regs.a4   Function argument 4
+  0x80x0 0000 0200 000f regs.a5   Function argument 5
+  0x80x0 0000 0200 0010 regs.a6   Function argument 6
+  0x80x0 0000 0200 0011 regs.a7   Function argument 7
+  0x80x0 0000 0200 0012 regs.s2   Callee saved register 2
+  0x80x0 0000 0200 0013 regs.s3   Callee saved register 3
+  0x80x0 0000 0200 0014 regs.s4   Callee saved register 4
+  0x80x0 0000 0200 0015 regs.s5   Callee saved register 5
+  0x80x0 0000 0200 0016 regs.s6   Callee saved register 6
+  0x80x0 0000 0200 0017 regs.s7   Callee saved register 7
+  0x80x0 0000 0200 0018 regs.s8   Callee saved register 8
+  0x80x0 0000 0200 0019 regs.s9   Callee saved register 9
+  0x80x0 0000 0200 001a regs.s10  Callee saved register 10
+  0x80x0 0000 0200 001b regs.s11  Callee saved register 11
+  0x80x0 0000 0200 001c regs.t3   Caller saved register 3
+  0x80x0 0000 0200 001d regs.t4   Caller saved register 4
+  0x80x0 0000 0200 001e regs.t5   Caller saved register 5
+  0x80x0 0000 0200 001f regs.t6   Caller saved register 6
+  0x80x0 0000 0200 0020 mode      Privilege mode (1 = S-mode or 0 = U-mode)
+
+RISC-V csr registers represent the supervisor mode control/status registers
+of a Guest VCPU and it has the following id bit patterns:
+  0x8020 0000 03 <index into the kvm_riscv_csr struct:24> (32bit Host)
+  0x8030 0000 03 <index into the kvm_riscv_csr struct:24> (64bit Host)
+
+Following are the RISC-V csr registers:
+
+    Encoding            Register  Description
+------------------------------------------------------------------
+  0x80x0 0000 0300 0000 sstatus   Supervisor status
+  0x80x0 0000 0300 0001 sie       Supervisor interrupt enable
+  0x80x0 0000 0300 0002 stvec     Supervisor trap vector base
+  0x80x0 0000 0300 0003 sscratch  Supervisor scratch register
+  0x80x0 0000 0300 0004 sepc      Supervisor exception program counter
+  0x80x0 0000 0300 0005 scause    Supervisor trap cause
+  0x80x0 0000 0300 0006 stval     Supervisor bad address or instruction
+  0x80x0 0000 0300 0007 sip       Supervisor interrupt pending
+  0x80x0 0000 0300 0008 satp      Supervisor address translation and protection
+
+RISC-V timer registers represent the timer state of a Guest VCPU and it has
+the following id bit patterns:
+  0x8030 0000 04 <index into the kvm_riscv_timer struct:24>
+
+Following are the RISC-V timer registers:
+
+    Encoding            Register  Description
+------------------------------------------------------------------
+  0x8030 0000 0400 0000 frequency Time base frequency (read-only)
+  0x8030 0000 0400 0001 time      Time value visible to Guest
+  0x8030 0000 0400 0002 compare   Time compare programmed by Guest
+  0x8030 0000 0400 0003 state     Time compare state (1 = ON or 0 = OFF)
+
+RISC-V F-extension registers represent the single precision floating point
+state of a Guest VCPU and it has the following id bit patterns:
+  0x8020 0000 05 <index into the __riscv_f_ext_state struct:24>
+
+Following are the RISC-V F-extension registers:
+
+    Encoding            Register  Description
+------------------------------------------------------------------
+  0x8020 0000 0500 0000 f[0]      Floating point register 0
+  ...
+  0x8020 0000 0500 001f f[31]     Floating point register 31
+  0x8020 0000 0500 0020 fcsr      Floating point control and status register
+
+RISC-V D-extension registers represent the double precision floating point
+state of a Guest VCPU and it has the following id bit patterns:
+  0x8020 0000 06 <index into the __riscv_d_ext_state struct:24> (fcsr)
+  0x8030 0000 06 <index into the __riscv_d_ext_state struct:24> (non-fcsr)
+
+Following are the RISC-V D-extension registers:
+
+    Encoding            Register  Description
+------------------------------------------------------------------
+  0x8030 0000 0600 0000 f[0]      Floating point register 0
+  ...
+  0x8030 0000 0600 001f f[31]     Floating point register 31
+  0x8020 0000 0600 0020 fcsr      Floating point control and status register
+
+
 4.69 KVM_GET_ONE_REG
 
 Capability: KVM_CAP_ONE_REG
@@ -4542,6 +4680,23 @@ Note that KVM does not skip the faulting instruction as it does for
 KVM_EXIT_MMIO, but userspace has to emulate any change to the processing state
 if it decides to decode and emulate the instruction.
 
+		/* KVM_EXIT_RISCV_SBI */
+		struct {
+			unsigned long extension_id;
+			unsigned long function_id;
+			unsigned long args[6];
+			unsigned long ret[2];
+		} riscv_sbi;
+If exit reason is KVM_EXIT_RISCV_SBI then it indicates that the VCPU has
+done a SBI call which is not handled by KVM RISC-V kernel module. The details
+of the SBI call are available in 'riscv_sbi' member of kvm_run structure. The
+'extension_id' field of 'riscv_sbi' represents SBI extension ID whereas the
+'function_id' field represents function ID of given SBI extension. The 'args'
+array field of 'riscv_sbi' represents parameters for the SBI call and 'ret'
+array field represents return values. The userspace should update the return
+values of SBI call before resuming the VCPU. For more details on RISC-V SBI
+spec refer, https://github.com/riscv/riscv-sbi-doc.
+
 		/* Fix the size of the union. */
 		char padding[256];
 	};
-- 
2.17.1

[PATCH v10 19/19] RISC-V: KVM: Add MAINTAINERS entry

[Anup Patel]

Add myself as maintainer for KVM RISC-V and Atish as designated reviewer.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
 MAINTAINERS | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index ffa3371bc750..c94a5195b919 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9093,6 +9093,17 @@ F:	arch/powerpc/include/asm/kvm*
 F:	arch/powerpc/kvm/
 F:	arch/powerpc/kernel/kvm*
 
+KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv)
+M:	Anup Patel <anup.patel@wdc.com>
+R:	Atish Patra <atish.patra@wdc.com>
+L:	kvm@vger.kernel.org
+L:	kvm-riscv@lists.infradead.org
+T:	git git://github.com/kvm-riscv/linux.git
+S:	Maintained
+F:	arch/riscv/include/uapi/asm/kvm*
+F:	arch/riscv/include/asm/kvm*
+F:	arch/riscv/kvm/
+
 KERNEL VIRTUAL MACHINE for s390 (KVM/s390)
 M:	Christian Borntraeger <borntraeger@de.ibm.com>
 M:	Janosch Frank <frankja@linux.ibm.com>
-- 
2.17.1

Re: [PATCH v10 00/19] KVM RISC-V Support

[Palmer Dabbelt]

On Mon, 23 Dec 2019 03:35:10 PST (-0800), Anup Patel wrote:
> This series adds initial KVM RISC-V support. Currently, we are able to boot
> RISC-V 64bit Linux Guests with multiple VCPUs.

Thanks for doing this.  I haven't had time to take a real look at the patch
series yet, but it's at the top of my inbox now so I'll try to take a look this
week.

>
> Few key aspects of KVM RISC-V added by this series are:
> 1. Minimal possible KVM world-switch which touches only GPRs and few CSRs.
> 2. Full Guest/VM switch is done via vcpu_get/vcpu_put infrastructure.
> 3. KVM ONE_REG interface for VCPU register access from user-space.
> 4. PLIC emulation is done in user-space.
> 5. Timer and IPI emuation is done in-kernel.
> 6. MMU notifiers supported.
> 7. FP lazy save/restore supported.
> 8. SBI v0.1 emulation for KVM Guest available.
> 9. Forward unhandled SBI calls to KVM userspace.
> 10. Hugepage support for Guest/VM
>
> Here's a brief TODO list which we will work upon after this series:
> 1. SBI v0.2 emulation in-kernel
> 2. SBI v0.2 hart state management emulation in-kernel
> 3. In-kernel PLIC emulation
> 4. ..... and more .....
>
> This series can be found in riscv_kvm_v10 branch at:
> https//github.com/avpatel/linux.git
>
> Our work-in-progress KVMTOOL RISC-V port can be found in riscv_v1 branch
> at: https//github.com/avpatel/kvmtool.git
>
> The QEMU RISC-V hypervisor emulation is done by Alistair and is available
> in mainline/alistair/riscv-hyp-ext-v0.5.1 branch at:
> https://github.com/kvm-riscv/qemu.git
>
> To play around with KVM RISC-V, refer KVM RISC-V wiki at:
> https://github.com/kvm-riscv/howto/wiki
> https://github.com/kvm-riscv/howto/wiki/KVM-RISCV64-on-QEMU
>
> Changes since v9:
>  - Squash PATCH19 and PATCH20 into PATCH5
>  - Squash PATCH18 into PATCH11
>  - Squash PATCH17 into PATCH16
>  - Added ONE_REG interface for VCPU timer in PATCH13
>  - Use HTIMEDELTA for VCPU timer in PATCH13
>  - Updated KVM RISC-V mailing list in MAINTAINERS entry
>  - Update KVM kconfig option to depend on RISCV_SBI and MMU
>  - Check for SBI v0.2 and SBI v0.2 RFENCE extension at boot-time
>  - Use SBI v0.2 RFENCE extension in VMID implementation
>  - Use SBI v0.2 RFENCE extension in Stage2 MMU implementation
>  - Use SBI v0.2 RFENCE extension in SBI implementation
>  - Moved to RISC-V Hypervisor v0.5 draft spec
>  - Updated Documentation/virt/kvm/api.txt for timer ONE_REG interface
>  - Rebased patches on Linux-5.5-rc3
>
> Changes since v8:
>  - Rebased series on Linux-5.4-rc3 and Atish's SBI v0.2 patches
>  - Use HRTIMER_MODE_REL instead of HRTIMER_MODE_ABS in timer emulation
>  - Fixed kvm_riscv_stage2_map() to handle hugepages
>  - Added patch to forward unhandled SBI calls to user-space
>  - Added patch for iterative/recursive stage2 page table programming
>  - Added patch to remove per-CPU vsip_shadow variable
>  - Added patch to fix race-condition in kvm_riscv_vcpu_sync_interrupts()
>
> Changes since v7:
> - Rebased series on Linux-5.4-rc1 and Atish's SBI v0.2 patches
> - Removed PATCH1, PATCH3, and PATCH20 because these already merged
> - Use kernel doc style comments for ISA bitmap functions
> - Don't parse X, Y, and Z extension in riscv_fill_hwcap() because it will
>   be added in-future
> - Mark KVM RISC-V kconfig option as EXPERIMENTAL
> - Typo fix in commit description of PATCH6 of v7 series
> - Use separate structs for CORE and CSR registers of ONE_REG interface
> - Explicitly include asm/sbi.h in kvm/vcpu_sbi.c
> - Removed implicit switch-case fall-through in kvm_riscv_vcpu_exit()
> - No need to set VSSTATUS.MXR bit in kvm_riscv_vcpu_unpriv_read()
> - Removed register for instruction length in kvm_riscv_vcpu_unpriv_read()
> - Added defines for checking/decoding instruction length
> - Added separate patch to forward unhandled SBI calls to userspace tool
>
> Changes since v6:
> - Rebased patches on Linux-5.3-rc7
> - Added "return_handled" in struct kvm_mmio_decode to ensure that
>   kvm_riscv_vcpu_mmio_return() updates SEPC only once
> - Removed trap_stval parameter from kvm_riscv_vcpu_unpriv_read()
> - Updated git repo URL in MAINTAINERS entry
>
> Changes since v5:
> - Renamed KVM_REG_RISCV_CONFIG_TIMEBASE register to
>   KVM_REG_RISCV_CONFIG_TBFREQ register in ONE_REG interface
> - Update SPEC in kvm_riscv_vcpu_mmio_return() for MMIO exits
> - Use switch case instead of illegal instruction opcode table for simplicity
> - Improve comments in stage2_remote_tlb_flush() for a potential remote TLB
>   flush optimization
> - Handle all unsupported SBI calls in default case of
>   kvm_riscv_vcpu_sbi_ecall() function
> - Fixed kvm_riscv_vcpu_sync_interrupts() for software interrupts
> - Improved unprivilege reads to handle traps due to Guest stage1 page table
> - Added separate patch to document RISC-V specific things in
>   Documentation/virt/kvm/api.txt
>
> Changes since v4:
> - Rebased patches on Linux-5.3-rc5
> - Added Paolo's Acked-by and Reviewed-by
> - Updated mailing list in MAINTAINERS entry
>
> Changes since v3:
> - Moved patch for ISA bitmap from KVM prep series to this series
> - Make vsip_shadow as run-time percpu variable instead of compile-time
> - Flush Guest TLBs on all Host CPUs whenever we run-out of VMIDs
>
> Changes since v2:
> - Removed references of KVM_REQ_IRQ_PENDING from all patches
> - Use kvm->srcu within in-kernel KVM run loop
> - Added percpu vsip_shadow to track last value programmed in VSIP CSR
> - Added comments about irqs_pending and irqs_pending_mask
> - Used kvm_arch_vcpu_runnable() in-place-of kvm_riscv_vcpu_has_interrupt()
>   in system_opcode_insn()
> - Removed unwanted smp_wmb() in kvm_riscv_stage2_vmid_update()
> - Use kvm_flush_remote_tlbs() in kvm_riscv_stage2_vmid_update()
> - Use READ_ONCE() in kvm_riscv_stage2_update_hgatp() for vmid
>
> Changes since v1:
> - Fixed compile errors in building KVM RISC-V as module
> - Removed unused kvm_riscv_halt_guest() and kvm_riscv_resume_guest()
> - Set KVM_CAP_SYNC_MMU capability only after MMU notifiers are implemented
> - Made vmid_version as unsigned long instead of atomic
> - Renamed KVM_REQ_UPDATE_PGTBL to KVM_REQ_UPDATE_HGATP
> - Renamed kvm_riscv_stage2_update_pgtbl() to kvm_riscv_stage2_update_hgatp()
> - Configure HIDELEG and HEDELEG in kvm_arch_hardware_enable()
> - Updated ONE_REG interface for CSR access to user-space
> - Removed irqs_pending_lock and use atomic bitops instead
> - Added separate patch for FP ONE_REG interface
> - Added separate patch for updating MAINTAINERS file
>
> Anup Patel (15):
>   RISC-V: Export riscv_cpuid_to_hartid_mask() API
>   RISC-V: Add bitmap reprensenting ISA features common across CPUs
>   RISC-V: Add hypervisor extension related CSR defines
>   RISC-V: Add initial skeletal KVM support
>   RISC-V: KVM: Implement VCPU create, init and destroy functions
>   RISC-V: KVM: Implement VCPU interrupts and requests handling
>   RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls
>   RISC-V: KVM: Implement VCPU world-switch
>   RISC-V: KVM: Handle MMIO exits for VCPU
>   RISC-V: KVM: Handle WFI exits for VCPU
>   RISC-V: KVM: Implement VMID allocator
>   RISC-V: KVM: Implement stage2 page table programming
>   RISC-V: KVM: Implement MMU notifiers
>   RISC-V: KVM: Document RISC-V specific parts of KVM API.
>   RISC-V: KVM: Add MAINTAINERS entry
>
> Atish Patra (4):
>   RISC-V: KVM: Add timer functionality
>   RISC-V: KVM: FP lazy save/restore
>   RISC-V: KVM: Implement ONE REG interface for FP registers
>   RISC-V: KVM: Add SBI v0.1 support
>
>  Documentation/virt/kvm/api.txt          |  169 +++-
>  MAINTAINERS                             |   11 +
>  arch/riscv/Kconfig                      |    2 +
>  arch/riscv/Makefile                     |    2 +
>  arch/riscv/include/asm/csr.h            |   78 +-
>  arch/riscv/include/asm/hwcap.h          |   22 +
>  arch/riscv/include/asm/kvm_host.h       |  264 ++++++
>  arch/riscv/include/asm/kvm_vcpu_timer.h |   44 +
>  arch/riscv/include/asm/pgtable-bits.h   |    1 +
>  arch/riscv/include/uapi/asm/kvm.h       |  127 +++
>  arch/riscv/kernel/asm-offsets.c         |  148 ++++
>  arch/riscv/kernel/cpufeature.c          |   83 +-
>  arch/riscv/kernel/smp.c                 |    2 +
>  arch/riscv/kvm/Kconfig                  |   34 +
>  arch/riscv/kvm/Makefile                 |   14 +
>  arch/riscv/kvm/main.c                   |   97 +++
>  arch/riscv/kvm/mmu.c                    |  762 +++++++++++++++++
>  arch/riscv/kvm/tlb.S                    |   43 +
>  arch/riscv/kvm/vcpu.c                   | 1013 +++++++++++++++++++++++
>  arch/riscv/kvm/vcpu_exit.c              |  639 ++++++++++++++
>  arch/riscv/kvm/vcpu_sbi.c               |  171 ++++
>  arch/riscv/kvm/vcpu_switch.S            |  382 +++++++++
>  arch/riscv/kvm/vcpu_timer.c             |  225 +++++
>  arch/riscv/kvm/vm.c                     |   86 ++
>  arch/riscv/kvm/vmid.c                   |  120 +++
>  drivers/clocksource/timer-riscv.c       |    8 +
>  include/clocksource/timer-riscv.h       |   16 +
>  include/uapi/linux/kvm.h                |    8 +
>  28 files changed, 4558 insertions(+), 13 deletions(-)
>  create mode 100644 arch/riscv/include/asm/kvm_host.h
>  create mode 100644 arch/riscv/include/asm/kvm_vcpu_timer.h
>  create mode 100644 arch/riscv/include/uapi/asm/kvm.h
>  create mode 100644 arch/riscv/kvm/Kconfig
>  create mode 100644 arch/riscv/kvm/Makefile
>  create mode 100644 arch/riscv/kvm/main.c
>  create mode 100644 arch/riscv/kvm/mmu.c
>  create mode 100644 arch/riscv/kvm/tlb.S
>  create mode 100644 arch/riscv/kvm/vcpu.c
>  create mode 100644 arch/riscv/kvm/vcpu_exit.c
>  create mode 100644 arch/riscv/kvm/vcpu_sbi.c
>  create mode 100644 arch/riscv/kvm/vcpu_switch.S
>  create mode 100644 arch/riscv/kvm/vcpu_timer.c
>  create mode 100644 arch/riscv/kvm/vm.c
>  create mode 100644 arch/riscv/kvm/vmid.c
>  create mode 100644 include/clocksource/timer-riscv.h
>
> -- 
> 2.17.1

Re: [PATCH v10 01/19] RISC-V: Export riscv_cpuid_to_hartid_mask() API

[Palmer Dabbelt]

On Mon, 23 Dec 2019 03:35:19 PST (-0800), Anup Patel wrote:
> The riscv_cpuid_to_hartid_mask() API should be exported to allow
> building KVM RISC-V as loadable module.
>
> Signed-off-by: Anup Patel <anup.patel@wdc.com>
> ---
>  arch/riscv/kernel/smp.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
> index eb878abcaaf8..6fc7828d41e4 100644
> --- a/arch/riscv/kernel/smp.c
> +++ b/arch/riscv/kernel/smp.c
> @@ -10,6 +10,7 @@
>  
>  #include <linux/cpu.h>
>  #include <linux/interrupt.h>
> +#include <linux/module.h>
>  #include <linux/profile.h>
>  #include <linux/smp.h>
>  #include <linux/sched.h>
> @@ -63,6 +64,7 @@ void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out)
>  	for_each_cpu(cpu, in)
>  		cpumask_set_cpu(cpuid_to_hartid_map(cpu), out);
>  }
> +EXPORT_SYMBOL_GPL(riscv_cpuid_to_hartid_mask);
>  
>  bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
>  {
> -- 
> 2.17.1

Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>

Re: [PATCH v10 02/19] RISC-V: Add bitmap reprensenting ISA features common across CPUs

[Palmer Dabbelt]

On Mon, 23 Dec 2019 03:35:26 PST (-0800), Anup Patel wrote:
> This patch adds riscv_isa bitmap which represents Host ISA features
> common across all Host CPUs. The riscv_isa is not same as elf_hwcap
> because elf_hwcap will only have ISA features relevant for user-space
> apps whereas riscv_isa will have ISA features relevant to both kernel
> and user-space apps.
>
> One of the use-case for riscv_isa bitmap is in KVM hypervisor where
> we will use it to do following operations:
>
> 1. Check whether hypervisor extension is available
> 2. Find ISA features that need to be virtualized (e.g. floating
>    point support, vector extension, etc.)
>
> Signed-off-by: Anup Patel <anup.patel@wdc.com>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> Reviewed-by: Alexander Graf <graf@amazon.com>
> ---
>  arch/riscv/include/asm/hwcap.h | 22 +++++++++
>  arch/riscv/kernel/cpufeature.c | 83 ++++++++++++++++++++++++++++++++--
>  2 files changed, 102 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index 1bb0cd04aec3..5589c012e004 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -8,6 +8,7 @@
>  #ifndef _ASM_RISCV_HWCAP_H
>  #define _ASM_RISCV_HWCAP_H
>  
> +#include <linux/bits.h>
>  #include <uapi/asm/hwcap.h>
>  
>  #ifndef __ASSEMBLY__
> @@ -22,6 +23,27 @@ enum {
>  };
>  
>  extern unsigned long elf_hwcap;
> +
> +#define RISCV_ISA_EXT_a		('a' - 'a')
> +#define RISCV_ISA_EXT_c		('c' - 'a')
> +#define RISCV_ISA_EXT_d		('d' - 'a')
> +#define RISCV_ISA_EXT_f		('f' - 'a')
> +#define RISCV_ISA_EXT_h		('h' - 'a')
> +#define RISCV_ISA_EXT_i		('i' - 'a')
> +#define RISCV_ISA_EXT_m		('m' - 'a')
> +#define RISCV_ISA_EXT_s		('s' - 'a')
> +#define RISCV_ISA_EXT_u		('u' - 'a')

Unfortunately the ISA doesn't really work this way any more: the single-letter
extensions are just aliases for longer extension strings, each of which
represents a single instruction.  I know we're saddled with some ABI that looks
this way, but I really don't want to add new code that depends on these defunct
assumptions -- there isn't that much in Linux right now, but there's a lot in
the FSF toolchain and getting that all out is going to be a long project.

> +
> +#define RISCV_ISA_EXT_MAX	256

Why so big?  It looks like the rest of the code just touches the first word,
and most of that is explicit.

> +
> +unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap);
> +
> +#define riscv_isa_extension_mask(ext) BIT_MASK(RISCV_ISA_EXT_##ext)
> +
> +bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit);
> +#define riscv_isa_extension_available(isa_bitmap, ext)	\
> +	__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_##ext)
> +
>  #endif
>  
>  #endif /* _ASM_RISCV_HWCAP_H */
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 0b40705567b7..e172a2322b34 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -6,6 +6,7 @@
>   * Copyright (C) 2017 SiFive
>   */
>  
> +#include <linux/bitmap.h>
>  #include <linux/of.h>
>  #include <asm/processor.h>
>  #include <asm/hwcap.h>
> @@ -13,15 +14,57 @@
>  #include <asm/switch_to.h>
>  
>  unsigned long elf_hwcap __read_mostly;
> +
> +/* Host ISA bitmap */
> +static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
> +
>  #ifdef CONFIG_FPU
>  bool has_fpu __read_mostly;
>  #endif
>  
> +/**
> + * riscv_isa_extension_base() - Get base extension word
> + *
> + * @isa_bitmap: ISA bitmap to use
> + * Return: base extension word as unsigned long value
> + *
> + * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
> + */
> +unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap)
> +{
> +	if (!isa_bitmap)
> +		return riscv_isa[0];
> +	return isa_bitmap[0];
> +}
> +EXPORT_SYMBOL_GPL(riscv_isa_extension_base);

This isn't used, which makes it hard to review.  Can you please split out the
changes that don't depend on the V extension to come out of draft?  That would
make it easier to take some of the code early, which lets us keep around less
diff.

> +
> +/**
> + * __riscv_isa_extension_available() - Check whether given extension
> + * is available or not
> + *
> + * @isa_bitmap: ISA bitmap to use
> + * @bit: bit position of the desired extension
> + * Return: true or false
> + *
> + * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
> + */
> +bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
> +{
> +	const unsigned long *bmap = (isa_bitmap) ? isa_bitmap : riscv_isa;
> +
> +	if (bit >= RISCV_ISA_EXT_MAX)
> +		return false;
> +
> +	return test_bit(bit, bmap) ? true : false;
> +}
> +EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
> +
>  void riscv_fill_hwcap(void)
>  {
>  	struct device_node *node;
>  	const char *isa;
> -	size_t i;
> +	char print_str[BITS_PER_LONG + 1];
> +	size_t i, j, isa_len;
>  	static unsigned long isa2hwcap[256] = {0};
>  
>  	isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
> @@ -33,8 +76,11 @@ void riscv_fill_hwcap(void)
>  
>  	elf_hwcap = 0;
>  
> +	bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
> +
>  	for_each_of_cpu_node(node) {
>  		unsigned long this_hwcap = 0;
> +		unsigned long this_isa = 0;
>  
>  		if (riscv_of_processor_hartid(node) < 0)
>  			continue;
> @@ -42,8 +88,24 @@ void riscv_fill_hwcap(void)
>  		if (riscv_read_check_isa(node, &isa) < 0)
>  			continue;
>  
> -		for (i = 0; i < strlen(isa); ++i)
> +		i = 0;
> +		isa_len = strlen(isa);
> +#if IS_ENABLED(CONFIG_32BIT)
> +		if (!strncmp(isa, "rv32", 4))
> +			i += 4;
> +#elif IS_ENABLED(CONFIG_64BIT)
> +		if (!strncmp(isa, "rv64", 4))
> +			i += 4;

We shouldn't be accepting arbitrary inputs and attempting to correct them, just
enforce that an actual ISA string is provided and check it against what the
kernel can support.

> +#endif
> +		for (; i < isa_len; ++i) {
>  			this_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
> +			/*
> +			 * TODO: X, Y and Z extension parsing for Host ISA
> +			 * bitmap will be added in-future.
> +			 */
> +			if ('a' <= isa[i] && isa[i] < 'x')
> +				this_isa |= (1UL << (isa[i] - 'a'));
> +		}
>  
>  		/*
>  		 * All "okay" hart should have same isa. Set HWCAP based on
> @@ -54,6 +116,11 @@ void riscv_fill_hwcap(void)
>  			elf_hwcap &= this_hwcap;
>  		else
>  			elf_hwcap = this_hwcap;
> +
> +		if (riscv_isa[0])
> +			riscv_isa[0] &= this_isa;
> +		else
> +			riscv_isa[0] = this_isa;
>  	}
>  
>  	/* We don't support systems with F but without D, so mask those out
> @@ -63,7 +130,17 @@ void riscv_fill_hwcap(void)
>  		elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
>  	}
>  
> -	pr_info("elf_hwcap is 0x%lx\n", elf_hwcap);
> +	memset(print_str, 0, sizeof(print_str));
> +	for (i = 0, j = 0; i < BITS_PER_LONG; i++)
> +		if (riscv_isa[0] & BIT_MASK(i))
> +			print_str[j++] = (char)('a' + i);
> +	pr_info("riscv: ISA extensions %s\n", print_str);
> +
> +	memset(print_str, 0, sizeof(print_str));
> +	for (i = 0, j = 0; i < BITS_PER_LONG; i++)
> +		if (elf_hwcap & BIT_MASK(i))
> +			print_str[j++] = (char)('a' + i);
> +	pr_info("riscv: ELF capabilities %s\n", print_str);
>  
>  #ifdef CONFIG_FPU
>  	if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
> -- 
> 2.17.1

Re: [PATCH v10 02/19] RISC-V: Add bitmap reprensenting ISA features common across CPUs

[Anup Patel]

On Fri, Jan 17, 2020 at 1:21 AM Palmer Dabbelt <palmerdabbelt@google.com> wrote:
>
> On Mon, 23 Dec 2019 03:35:26 PST (-0800), Anup Patel wrote:
> > This patch adds riscv_isa bitmap which represents Host ISA features
> > common across all Host CPUs. The riscv_isa is not same as elf_hwcap
> > because elf_hwcap will only have ISA features relevant for user-space
> > apps whereas riscv_isa will have ISA features relevant to both kernel
> > and user-space apps.
> >
> > One of the use-case for riscv_isa bitmap is in KVM hypervisor where
> > we will use it to do following operations:
> >
> > 1. Check whether hypervisor extension is available
> > 2. Find ISA features that need to be virtualized (e.g. floating
> >    point support, vector extension, etc.)
> >
> > Signed-off-by: Anup Patel <anup.patel@wdc.com>
> > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > Reviewed-by: Alexander Graf <graf@amazon.com>
> > ---
> >  arch/riscv/include/asm/hwcap.h | 22 +++++++++
> >  arch/riscv/kernel/cpufeature.c | 83 ++++++++++++++++++++++++++++++++--
> >  2 files changed, 102 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> > index 1bb0cd04aec3..5589c012e004 100644
> > --- a/arch/riscv/include/asm/hwcap.h
> > +++ b/arch/riscv/include/asm/hwcap.h
> > @@ -8,6 +8,7 @@
> >  #ifndef _ASM_RISCV_HWCAP_H
> >  #define _ASM_RISCV_HWCAP_H
> >
> > +#include <linux/bits.h>
> >  #include <uapi/asm/hwcap.h>
> >
> >  #ifndef __ASSEMBLY__
> > @@ -22,6 +23,27 @@ enum {
> >  };
> >
> >  extern unsigned long elf_hwcap;
> > +
> > +#define RISCV_ISA_EXT_a              ('a' - 'a')
> > +#define RISCV_ISA_EXT_c              ('c' - 'a')
> > +#define RISCV_ISA_EXT_d              ('d' - 'a')
> > +#define RISCV_ISA_EXT_f              ('f' - 'a')
> > +#define RISCV_ISA_EXT_h              ('h' - 'a')
> > +#define RISCV_ISA_EXT_i              ('i' - 'a')
> > +#define RISCV_ISA_EXT_m              ('m' - 'a')
> > +#define RISCV_ISA_EXT_s              ('s' - 'a')
> > +#define RISCV_ISA_EXT_u              ('u' - 'a')
>
> Unfortunately the ISA doesn't really work this way any more: the single-letter
> extensions are just aliases for longer extension strings, each of which
> represents a single instruction.  I know we're saddled with some ABI that looks
> this way, but I really don't want to add new code that depends on these defunct
> assumptions -- there isn't that much in Linux right now, but there's a lot in
> the FSF toolchain and getting that all out is going to be a long project.

Yes, I am aware of this.

Paul had raised similar concerns so we are using bitmap to tackle this

For example:
BIT['h' - 'a'] represents whether 'h' extension is present or not
In future, when we have incremental hxyz change in 'h' extension
we will assign some bitpostion Bhxyz for this and BIT[Bhxyz]
will represent whether 'hxyz' is present or not.

>
> > +
> > +#define RISCV_ISA_EXT_MAX    256
>
> Why so big?  It looks like the rest of the code just touches the first word,
> and most of that is explicit.

Please see previous comment.

Here 256 is a ballpark size of bitmap. If you have any preferences then
I can change to that value. I am sure this value will change in the future.

>
> > +
> > +unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap);
> > +
> > +#define riscv_isa_extension_mask(ext) BIT_MASK(RISCV_ISA_EXT_##ext)
> > +
> > +bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit);
> > +#define riscv_isa_extension_available(isa_bitmap, ext)       \
> > +     __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_##ext)
> > +
> >  #endif
> >
> >  #endif /* _ASM_RISCV_HWCAP_H */
> > diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> > index 0b40705567b7..e172a2322b34 100644
> > --- a/arch/riscv/kernel/cpufeature.c
> > +++ b/arch/riscv/kernel/cpufeature.c
> > @@ -6,6 +6,7 @@
> >   * Copyright (C) 2017 SiFive
> >   */
> >
> > +#include <linux/bitmap.h>
> >  #include <linux/of.h>
> >  #include <asm/processor.h>
> >  #include <asm/hwcap.h>
> > @@ -13,15 +14,57 @@
> >  #include <asm/switch_to.h>
> >
> >  unsigned long elf_hwcap __read_mostly;
> > +
> > +/* Host ISA bitmap */
> > +static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
> > +
> >  #ifdef CONFIG_FPU
> >  bool has_fpu __read_mostly;
> >  #endif
> >
> > +/**
> > + * riscv_isa_extension_base() - Get base extension word
> > + *
> > + * @isa_bitmap: ISA bitmap to use
> > + * Return: base extension word as unsigned long value
> > + *
> > + * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
> > + */
> > +unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap)
> > +{
> > +     if (!isa_bitmap)
> > +             return riscv_isa[0];
> > +     return isa_bitmap[0];
> > +}
> > +EXPORT_SYMBOL_GPL(riscv_isa_extension_base);
>
> This isn't used, which makes it hard to review.  Can you please split out the
> changes that don't depend on the V extension to come out of draft?  That would
> make it easier to take some of the code early, which lets us keep around less
> diff.

This is used by KVM RISC-V patches hence it is part of KVM RISC-V series.

>
> > +
> > +/**
> > + * __riscv_isa_extension_available() - Check whether given extension
> > + * is available or not
> > + *
> > + * @isa_bitmap: ISA bitmap to use
> > + * @bit: bit position of the desired extension
> > + * Return: true or false
> > + *
> > + * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used.
> > + */
> > +bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
> > +{
> > +     const unsigned long *bmap = (isa_bitmap) ? isa_bitmap : riscv_isa;
> > +
> > +     if (bit >= RISCV_ISA_EXT_MAX)
> > +             return false;
> > +
> > +     return test_bit(bit, bmap) ? true : false;
> > +}
> > +EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
> > +
> >  void riscv_fill_hwcap(void)
> >  {
> >       struct device_node *node;
> >       const char *isa;
> > -     size_t i;
> > +     char print_str[BITS_PER_LONG + 1];
> > +     size_t i, j, isa_len;
> >       static unsigned long isa2hwcap[256] = {0};
> >
> >       isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
> > @@ -33,8 +76,11 @@ void riscv_fill_hwcap(void)
> >
> >       elf_hwcap = 0;
> >
> > +     bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX);
> > +
> >       for_each_of_cpu_node(node) {
> >               unsigned long this_hwcap = 0;
> > +             unsigned long this_isa = 0;
> >
> >               if (riscv_of_processor_hartid(node) < 0)
> >                       continue;
> > @@ -42,8 +88,24 @@ void riscv_fill_hwcap(void)
> >               if (riscv_read_check_isa(node, &isa) < 0)
> >                       continue;
> >
> > -             for (i = 0; i < strlen(isa); ++i)
> > +             i = 0;
> > +             isa_len = strlen(isa);
> > +#if IS_ENABLED(CONFIG_32BIT)
> > +             if (!strncmp(isa, "rv32", 4))
> > +                     i += 4;
> > +#elif IS_ENABLED(CONFIG_64BIT)
> > +             if (!strncmp(isa, "rv64", 4))
> > +                     i += 4;
>
> We shouldn't be accepting arbitrary inputs and attempting to correct them, just
> enforce that an actual ISA string is provided and check it against what the
> kernel can support.

I agree that ISA string parsing is not perfect and will improve over time but
ISA bitmap should have all the features set as provided via CPU DT nodes.

We allow KVM RISC-V initialization to proceed only when 'H' extension is
supported.

>
> > +#endif
> > +             for (; i < isa_len; ++i) {
> >                       this_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
> > +                     /*
> > +                      * TODO: X, Y and Z extension parsing for Host ISA
> > +                      * bitmap will be added in-future.
> > +                      */
> > +                     if ('a' <= isa[i] && isa[i] < 'x')
> > +                             this_isa |= (1UL << (isa[i] - 'a'));
> > +             }
> >
> >               /*
> >                * All "okay" hart should have same isa. Set HWCAP based on
> > @@ -54,6 +116,11 @@ void riscv_fill_hwcap(void)
> >                       elf_hwcap &= this_hwcap;
> >               else
> >                       elf_hwcap = this_hwcap;
> > +
> > +             if (riscv_isa[0])
> > +                     riscv_isa[0] &= this_isa;
> > +             else
> > +                     riscv_isa[0] = this_isa;
> >       }
> >
> >       /* We don't support systems with F but without D, so mask those out
> > @@ -63,7 +130,17 @@ void riscv_fill_hwcap(void)
> >               elf_hwcap &= ~COMPAT_HWCAP_ISA_F;
> >       }
> >
> > -     pr_info("elf_hwcap is 0x%lx\n", elf_hwcap);
> > +     memset(print_str, 0, sizeof(print_str));
> > +     for (i = 0, j = 0; i < BITS_PER_LONG; i++)
> > +             if (riscv_isa[0] & BIT_MASK(i))
> > +                     print_str[j++] = (char)('a' + i);
> > +     pr_info("riscv: ISA extensions %s\n", print_str);
> > +
> > +     memset(print_str, 0, sizeof(print_str));
> > +     for (i = 0, j = 0; i < BITS_PER_LONG; i++)
> > +             if (elf_hwcap & BIT_MASK(i))
> > +                     print_str[j++] = (char)('a' + i);
> > +     pr_info("riscv: ELF capabilities %s\n", print_str);
> >
> >  #ifdef CONFIG_FPU
> >       if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
> > --
> > 2.17.1

Regards,
Anup

Re: [PATCH v10 03/19] RISC-V: Add hypervisor extension related CSR defines

[Palmer Dabbelt]

On Mon, 23 Dec 2019 03:35:33 PST (-0800), Anup Patel wrote:
> This patch extends asm/csr.h by adding RISC-V hypervisor extension
> related defines.
>
> Signed-off-by: Anup Patel <anup.patel@wdc.com>
> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> Reviewed-by: Alexander Graf <graf@amazon.com>
> ---
>  arch/riscv/include/asm/csr.h | 78 ++++++++++++++++++++++++++++++++++--
>  1 file changed, 75 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
> index 0a62d2d68455..afb6733475c2 100644
> --- a/arch/riscv/include/asm/csr.h
> +++ b/arch/riscv/include/asm/csr.h
> @@ -30,6 +30,8 @@
>  #define SR_XS_CLEAN	_AC(0x00010000, UL)
>  #define SR_XS_DIRTY	_AC(0x00018000, UL)
>  
> +#define SR_MXR		_AC(0x00080000, UL)
> +
>  #ifndef CONFIG_64BIT
>  #define SR_SD		_AC(0x80000000, UL) /* FS/XS dirty */
>  #else
> @@ -51,26 +53,74 @@
>  #define CAUSE_IRQ_FLAG		(_AC(1, UL) << (__riscv_xlen - 1))
>  
>  /* Interrupt causes (minus the high bit) */
> -#define IRQ_U_SOFT		0
>  #define IRQ_S_SOFT		1
> +#define IRQ_VS_SOFT		2

Again: please don't mix up cleanups with the KVM port.  It's reasonable to
remove the N extension cruft as it's still in draft and we probably won't
implement it in Linux, but that shouldn't be mixed up with the KVM
implementation.

>  #define IRQ_M_SOFT		3
> -#define IRQ_U_TIMER		4
>  #define IRQ_S_TIMER		5
> +#define IRQ_VS_TIMER		6
>  #define IRQ_M_TIMER		7
> -#define IRQ_U_EXT		8
>  #define IRQ_S_EXT		9
> +#define IRQ_VS_EXT		10
>  #define IRQ_M_EXT		11
>  
>  /* Exception causes */
>  #define EXC_INST_MISALIGNED	0
>  #define EXC_INST_ACCESS		1
> +#define EXC_INST_ILLEGAL	2
>  #define EXC_BREAKPOINT		3
>  #define EXC_LOAD_ACCESS		5
>  #define EXC_STORE_ACCESS	7
>  #define EXC_SYSCALL		8
> +#define EXC_HYPERVISOR_SYSCALL	9
> +#define EXC_SUPERVISOR_SYSCALL	10
>  #define EXC_INST_PAGE_FAULT	12
>  #define EXC_LOAD_PAGE_FAULT	13
>  #define EXC_STORE_PAGE_FAULT	15
> +#define EXC_INST_GUEST_PAGE_FAULT	20
> +#define EXC_LOAD_GUEST_PAGE_FAULT	21
> +#define EXC_STORE_GUEST_PAGE_FAULT	23
> +
> +/* HSTATUS flags */
> +#define HSTATUS_VTSR		_AC(0x00400000, UL)
> +#define HSTATUS_VTVM		_AC(0x00100000, UL)
> +#define HSTATUS_SP2V		_AC(0x00000200, UL)
> +#define HSTATUS_SP2P		_AC(0x00000100, UL)
> +#define HSTATUS_SPV		_AC(0x00000080, UL)
> +#define HSTATUS_SPRV		_AC(0x00000001, UL)
> +
> +/* HGATP flags */
> +#define HGATP_MODE_OFF		_AC(0, UL)
> +#define HGATP_MODE_SV32X4	_AC(1, UL)
> +#define HGATP_MODE_SV39X4	_AC(8, UL)
> +#define HGATP_MODE_SV48X4	_AC(9, UL)
> +
> +#define HGATP32_MODE_SHIFT	31
> +#define HGATP32_VMID_SHIFT	22
> +#define HGATP32_VMID_MASK	_AC(0x1FC00000, UL)
> +#define HGATP32_PPN		_AC(0x003FFFFF, UL)
> +
> +#define HGATP64_MODE_SHIFT	60
> +#define HGATP64_VMID_SHIFT	44
> +#define HGATP64_VMID_MASK	_AC(0x03FFF00000000000, UL)
> +#define HGATP64_PPN		_AC(0x00000FFFFFFFFFFF, UL)
> +
> +#ifdef CONFIG_64BIT
> +#define HGATP_PPN		HGATP64_PPN
> +#define HGATP_VMID_SHIFT	HGATP64_VMID_SHIFT
> +#define HGATP_VMID_MASK		HGATP64_VMID_MASK
> +#define HGATP_MODE		(HGATP_MODE_SV39X4 << HGATP64_MODE_SHIFT)
> +#else
> +#define HGATP_PPN		HGATP32_PPN
> +#define HGATP_VMID_SHIFT	HGATP32_VMID_SHIFT
> +#define HGATP_VMID_MASK		HGATP32_VMID_MASK
> +#define HGATP_MODE		(HGATP_MODE_SV32X4 << HGATP32_MODE_SHIFT)
> +#endif
> +
> +/* VSIP & HIP relation */
> +#define VSIP_TO_HIP_SHIFT	(IRQ_VS_SOFT - IRQ_S_SOFT)
> +#define VSIP_VALID_MASK		((_AC(1, UL) << IRQ_S_SOFT) | \
> +				 (_AC(1, UL) << IRQ_S_TIMER) | \
> +				 (_AC(1, UL) << IRQ_S_EXT))
>  
>  /* symbolic CSR names: */
>  #define CSR_CYCLE		0xc00
> @@ -91,6 +141,28 @@
>  #define CSR_SIP			0x144
>  #define CSR_SATP		0x180
>  
> +#define CSR_VSSTATUS		0x200
> +#define CSR_VSIE		0x204
> +#define CSR_VSTVEC		0x205
> +#define CSR_VSSCRATCH		0x240
> +#define CSR_VSEPC		0x241
> +#define CSR_VSCAUSE		0x242
> +#define CSR_VSTVAL		0x243
> +#define CSR_VSIP		0x244
> +#define CSR_VSATP		0x280
> +
> +#define CSR_HSTATUS		0x600
> +#define CSR_HEDELEG		0x602
> +#define CSR_HIDELEG		0x603
> +#define CSR_HIE			0x604
> +#define CSR_HTIMEDELTA		0x605
> +#define CSR_HTIMEDELTAH		0x615
> +#define CSR_HCOUNTERNEN		0x606
> +#define CSR_HTVAL		0x643
> +#define CSR_HIP			0x644
> +#define CSR_HTINST		0x64a
> +#define CSR_HGATP		0x680
> +
>  #define CSR_MSTATUS		0x300
>  #define CSR_MISA		0x301
>  #define CSR_MIE			0x304
> -- 
> 2.17.1

Re: [PATCH v10 03/19] RISC-V: Add hypervisor extension related CSR defines

[Anup Patel]

On Fri, Jan 17, 2020 at 1:21 AM Palmer Dabbelt <palmerdabbelt@google.com> wrote:
>
> On Mon, 23 Dec 2019 03:35:33 PST (-0800), Anup Patel wrote:
> > This patch extends asm/csr.h by adding RISC-V hypervisor extension
> > related defines.
> >
> > Signed-off-by: Anup Patel <anup.patel@wdc.com>
> > Acked-by: Paolo Bonzini <pbonzini@redhat.com>
> > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> > Reviewed-by: Alexander Graf <graf@amazon.com>
> > ---
> >  arch/riscv/include/asm/csr.h | 78 ++++++++++++++++++++++++++++++++++--
> >  1 file changed, 75 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
> > index 0a62d2d68455..afb6733475c2 100644
> > --- a/arch/riscv/include/asm/csr.h
> > +++ b/arch/riscv/include/asm/csr.h
> > @@ -30,6 +30,8 @@
> >  #define SR_XS_CLEAN  _AC(0x00010000, UL)
> >  #define SR_XS_DIRTY  _AC(0x00018000, UL)
> >
> > +#define SR_MXR               _AC(0x00080000, UL)
> > +
> >  #ifndef CONFIG_64BIT
> >  #define SR_SD                _AC(0x80000000, UL) /* FS/XS dirty */
> >  #else
> > @@ -51,26 +53,74 @@
> >  #define CAUSE_IRQ_FLAG               (_AC(1, UL) << (__riscv_xlen - 1))
> >
> >  /* Interrupt causes (minus the high bit) */
> > -#define IRQ_U_SOFT           0
> >  #define IRQ_S_SOFT           1
> > +#define IRQ_VS_SOFT          2
>
> Again: please don't mix up cleanups with the KVM port.  It's reasonable to
> remove the N extension cruft as it's still in draft and we probably won't
> implement it in Linux, but that shouldn't be mixed up with the KVM
> implementation.

Sure, I will send separate patch for removing IRQ_U_xyz defines
and have only H-extension related defines here.

Regards,
Anup

>
> >  #define IRQ_M_SOFT           3
> > -#define IRQ_U_TIMER          4
> >  #define IRQ_S_TIMER          5
> > +#define IRQ_VS_TIMER         6
> >  #define IRQ_M_TIMER          7
> > -#define IRQ_U_EXT            8
> >  #define IRQ_S_EXT            9
> > +#define IRQ_VS_EXT           10
> >  #define IRQ_M_EXT            11
> >
> >  /* Exception causes */
> >  #define EXC_INST_MISALIGNED  0
> >  #define EXC_INST_ACCESS              1
> > +#define EXC_INST_ILLEGAL     2
> >  #define EXC_BREAKPOINT               3
> >  #define EXC_LOAD_ACCESS              5
> >  #define EXC_STORE_ACCESS     7
> >  #define EXC_SYSCALL          8
> > +#define EXC_HYPERVISOR_SYSCALL       9
> > +#define EXC_SUPERVISOR_SYSCALL       10
> >  #define EXC_INST_PAGE_FAULT  12
> >  #define EXC_LOAD_PAGE_FAULT  13
> >  #define EXC_STORE_PAGE_FAULT 15
> > +#define EXC_INST_GUEST_PAGE_FAULT    20
> > +#define EXC_LOAD_GUEST_PAGE_FAULT    21
> > +#define EXC_STORE_GUEST_PAGE_FAULT   23
> > +
> > +/* HSTATUS flags */
> > +#define HSTATUS_VTSR         _AC(0x00400000, UL)
> > +#define HSTATUS_VTVM         _AC(0x00100000, UL)
> > +#define HSTATUS_SP2V         _AC(0x00000200, UL)
> > +#define HSTATUS_SP2P         _AC(0x00000100, UL)
> > +#define HSTATUS_SPV          _AC(0x00000080, UL)
> > +#define HSTATUS_SPRV         _AC(0x00000001, UL)
> > +
> > +/* HGATP flags */
> > +#define HGATP_MODE_OFF               _AC(0, UL)
> > +#define HGATP_MODE_SV32X4    _AC(1, UL)
> > +#define HGATP_MODE_SV39X4    _AC(8, UL)
> > +#define HGATP_MODE_SV48X4    _AC(9, UL)
> > +
> > +#define HGATP32_MODE_SHIFT   31
> > +#define HGATP32_VMID_SHIFT   22
> > +#define HGATP32_VMID_MASK    _AC(0x1FC00000, UL)
> > +#define HGATP32_PPN          _AC(0x003FFFFF, UL)
> > +
> > +#define HGATP64_MODE_SHIFT   60
> > +#define HGATP64_VMID_SHIFT   44
> > +#define HGATP64_VMID_MASK    _AC(0x03FFF00000000000, UL)
> > +#define HGATP64_PPN          _AC(0x00000FFFFFFFFFFF, UL)
> > +
> > +#ifdef CONFIG_64BIT
> > +#define HGATP_PPN            HGATP64_PPN
> > +#define HGATP_VMID_SHIFT     HGATP64_VMID_SHIFT
> > +#define HGATP_VMID_MASK              HGATP64_VMID_MASK
> > +#define HGATP_MODE           (HGATP_MODE_SV39X4 << HGATP64_MODE_SHIFT)
> > +#else
> > +#define HGATP_PPN            HGATP32_PPN
> > +#define HGATP_VMID_SHIFT     HGATP32_VMID_SHIFT
> > +#define HGATP_VMID_MASK              HGATP32_VMID_MASK
> > +#define HGATP_MODE           (HGATP_MODE_SV32X4 << HGATP32_MODE_SHIFT)
> > +#endif
> > +
> > +/* VSIP & HIP relation */
> > +#define VSIP_TO_HIP_SHIFT    (IRQ_VS_SOFT - IRQ_S_SOFT)
> > +#define VSIP_VALID_MASK              ((_AC(1, UL) << IRQ_S_SOFT) | \
> > +                              (_AC(1, UL) << IRQ_S_TIMER) | \
> > +                              (_AC(1, UL) << IRQ_S_EXT))
> >
> >  /* symbolic CSR names: */
> >  #define CSR_CYCLE            0xc00
> > @@ -91,6 +141,28 @@
> >  #define CSR_SIP                      0x144
> >  #define CSR_SATP             0x180
> >
> > +#define CSR_VSSTATUS         0x200
> > +#define CSR_VSIE             0x204
> > +#define CSR_VSTVEC           0x205
> > +#define CSR_VSSCRATCH                0x240
> > +#define CSR_VSEPC            0x241
> > +#define CSR_VSCAUSE          0x242
> > +#define CSR_VSTVAL           0x243
> > +#define CSR_VSIP             0x244
> > +#define CSR_VSATP            0x280
> > +
> > +#define CSR_HSTATUS          0x600
> > +#define CSR_HEDELEG          0x602
> > +#define CSR_HIDELEG          0x603
> > +#define CSR_HIE                      0x604
> > +#define CSR_HTIMEDELTA               0x605
> > +#define CSR_HTIMEDELTAH              0x615
> > +#define CSR_HCOUNTERNEN              0x606
> > +#define CSR_HTVAL            0x643
> > +#define CSR_HIP                      0x644
> > +#define CSR_HTINST           0x64a
> > +#define CSR_HGATP            0x680
> > +
> >  #define CSR_MSTATUS          0x300
> >  #define CSR_MISA             0x301
> >  #define CSR_MIE                      0x304
> > --
> > 2.17.1

Re: [PATCH v10 04/19] RISC-V: Add initial skeletal KVM support

[Palmer Dabbelt]

On Mon, 23 Dec 2019 03:35:46 PST (-0800), Anup Patel wrote:
> This patch adds initial skeletal KVM RISC-V support which has:
> 1. A simple implementation of arch specific VM functions
>    except kvm_vm_ioctl_get_dirty_log() which will implemeted
>    in-future as part of stage2 page loging.
> 2. Stubs of required arch specific VCPU functions except
>    kvm_arch_vcpu_ioctl_run() which is semi-complete and
>    extended by subsequent patches.
> 3. Stubs for required arch specific stage2 MMU functions.
>
> Signed-off-by: Anup Patel <anup.patel@wdc.com>
> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> Reviewed-by: Alexander Graf <graf@amazon.com>
> ---
>  arch/riscv/Kconfig                |   2 +
>  arch/riscv/Makefile               |   2 +
>  arch/riscv/include/asm/kvm_host.h |  82 ++++++++
>  arch/riscv/include/uapi/asm/kvm.h |  47 +++++
>  arch/riscv/kvm/Kconfig            |  33 ++++
>  arch/riscv/kvm/Makefile           |  13 ++
>  arch/riscv/kvm/main.c             |  93 +++++++++
>  arch/riscv/kvm/mmu.c              |  83 ++++++++
>  arch/riscv/kvm/vcpu.c             | 316 ++++++++++++++++++++++++++++++
>  arch/riscv/kvm/vcpu_exit.c        |  36 ++++
>  arch/riscv/kvm/vm.c               |  79 ++++++++
>  11 files changed, 786 insertions(+)
>  create mode 100644 arch/riscv/include/asm/kvm_host.h
>  create mode 100644 arch/riscv/include/uapi/asm/kvm.h
>  create mode 100644 arch/riscv/kvm/Kconfig
>  create mode 100644 arch/riscv/kvm/Makefile
>  create mode 100644 arch/riscv/kvm/main.c
>  create mode 100644 arch/riscv/kvm/mmu.c
>  create mode 100644 arch/riscv/kvm/vcpu.c
>  create mode 100644 arch/riscv/kvm/vcpu_exit.c
>  create mode 100644 arch/riscv/kvm/vm.c
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index baf0943c80d0..2e8551a9cd32 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -366,3 +366,5 @@ menu "Power management options"
>  source "kernel/power/Kconfig"
>  
>  endmenu
> +
> +source "arch/riscv/kvm/Kconfig"
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index b9009a2fbaf5..65b58cec9abd 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -77,6 +77,8 @@ head-y := arch/riscv/kernel/head.o
>  
>  core-y += arch/riscv/
>  
> +core-$(CONFIG_KVM) += arch/riscv/kvm/
> +
>  libs-y += arch/riscv/lib/
>  
>  PHONY += vdso_install
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> new file mode 100644
> index 000000000000..e0b633f616a4
> --- /dev/null
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -0,0 +1,82 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> + *
> + * Authors:
> + *     Anup Patel <anup.patel@wdc.com>
> + */
> +
> +#ifndef __RISCV_KVM_HOST_H__
> +#define __RISCV_KVM_HOST_H__
> +
> +#include <linux/types.h>
> +#include <linux/kvm.h>
> +#include <linux/kvm_types.h>
> +
> +#ifdef CONFIG_64BIT
> +#define KVM_MAX_VCPUS			(1U << 16)
> +#else
> +#define KVM_MAX_VCPUS			(1U << 9)
> +#endif
> +
> +#define KVM_USER_MEM_SLOTS		512
> +#define KVM_HALT_POLL_NS_DEFAULT	500000
> +
> +#define KVM_VCPU_MAX_FEATURES		0
> +
> +#define KVM_REQ_SLEEP \
> +	KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
> +#define KVM_REQ_VCPU_RESET		KVM_ARCH_REQ(1)
> +
> +struct kvm_vm_stat {
> +	ulong remote_tlb_flush;
> +};
> +
> +struct kvm_vcpu_stat {
> +	u64 halt_successful_poll;
> +	u64 halt_attempted_poll;
> +	u64 halt_poll_invalid;
> +	u64 halt_wakeup;
> +	u64 ecall_exit_stat;
> +	u64 wfi_exit_stat;
> +	u64 mmio_exit_user;
> +	u64 mmio_exit_kernel;
> +	u64 exits;
> +};

Presumably at least this came from arm64, as it's exactly the same.  If that's
the case then this file, and probably a bunch of others, should be attributed
somehow.  IIRC we left the copyrights in our copied files and it looks like
arch/arm64 has done the same:

    $ head -n10 arch/arm64/include/asm/kvm_host.h 
    /* SPDX-License-Identifier: GPL-2.0-only */
    /*
     * Copyright (C) 2012,2013 - ARM Ltd
     * Author: Marc Zyngier <marc.zyngier@arm.com>
     *
     * Derived from arch/arm/include/asm/kvm_host.h:
     * Copyright (C) 2012 - Virtual Open Systems and Columbia University
     * Author: Christoffer Dall <c.dall@virtualopensystems.com>
     */

> +
> +struct kvm_arch_memory_slot {
> +};
> +
> +struct kvm_arch {
> +	/* stage2 page table */
> +	pgd_t *pgd;
> +	phys_addr_t pgd_phys;
> +};
> +
> +struct kvm_vcpu_arch {
> +	/* Don't run the VCPU (blocked) */
> +	bool pause;
> +
> +	/* SRCU lock index for in-kernel run loop */
> +	int srcu_idx;
> +};
> +
> +static inline void kvm_arch_hardware_unsetup(void) {}
> +static inline void kvm_arch_sync_events(struct kvm *kvm) {}
> +static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
> +static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
> +static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
> +
> +void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu);
> +int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm);
> +void kvm_riscv_stage2_free_pgd(struct kvm *kvm);
> +void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu);
> +
> +int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
> +int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
> +			unsigned long scause, unsigned long stval,
> +			unsigned long htval, unsigned long htinst);
> +
> +static inline void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch) {}
> +
> +#endif /* __RISCV_KVM_HOST_H__ */
> diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> new file mode 100644
> index 000000000000..d15875818b6e
> --- /dev/null
> +++ b/arch/riscv/include/uapi/asm/kvm.h
> @@ -0,0 +1,47 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> + *
> + * Authors:
> + *     Anup Patel <anup.patel@wdc.com>
> + */
> +
> +#ifndef __LINUX_KVM_RISCV_H
> +#define __LINUX_KVM_RISCV_H
> +
> +#ifndef __ASSEMBLY__
> +
> +#include <linux/types.h>
> +#include <asm/ptrace.h>
> +
> +#define __KVM_HAVE_READONLY_MEM
> +
> +#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
> +
> +/* for KVM_GET_REGS and KVM_SET_REGS */
> +struct kvm_regs {
> +};
> +
> +/* for KVM_GET_FPU and KVM_SET_FPU */
> +struct kvm_fpu {
> +};
> +
> +/* KVM Debug exit structure */
> +struct kvm_debug_exit_arch {
> +};
> +
> +/* for KVM_SET_GUEST_DEBUG */
> +struct kvm_guest_debug_arch {
> +};
> +
> +/* definition of registers in kvm_run */
> +struct kvm_sync_regs {
> +};
> +
> +/* dummy definition */
> +struct kvm_sregs {
> +};
> +
> +#endif
> +
> +#endif /* __LINUX_KVM_RISCV_H */
> diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
> new file mode 100644
> index 000000000000..88edd477b3a8
> --- /dev/null
> +++ b/arch/riscv/kvm/Kconfig
> @@ -0,0 +1,33 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# KVM configuration
> +#
> +
> +source "virt/kvm/Kconfig"
> +
> +menuconfig VIRTUALIZATION
> +	bool "Virtualization"
> +	help
> +	  Say Y here to get to see options for using your Linux host to run
> +	  other operating systems inside virtual machines (guests).
> +	  This option alone does not add any kernel code.
> +
> +	  If you say N, all options in this submenu will be skipped and
> +	  disabled.
> +
> +if VIRTUALIZATION
> +
> +config KVM
> +	tristate "Kernel-based Virtual Machine (KVM) support (EXPERIMENTAL)"
> +	depends on RISCV_SBI && MMU
> +	select PREEMPT_NOTIFIERS
> +	select ANON_INODES
> +	select KVM_MMIO
> +	select HAVE_KVM_VCPU_ASYNC_IOCTL
> +	select SRCU
> +	help
> +	  Support hosting virtualized guest machines.
> +
> +	  If unsure, say N.
> +
> +endif # VIRTUALIZATION
> diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
> new file mode 100644
> index 000000000000..37b5a59d4f4f
> --- /dev/null
> +++ b/arch/riscv/kvm/Makefile
> @@ -0,0 +1,13 @@
> +# SPDX-License-Identifier: GPL-2.0
> +# Makefile for RISC-V KVM support
> +#
> +
> +common-objs-y = $(addprefix ../../../virt/kvm/, kvm_main.o coalesced_mmio.o)
> +
> +ccflags-y := -Ivirt/kvm -Iarch/riscv/kvm
> +
> +kvm-objs := $(common-objs-y)
> +
> +kvm-objs += main.o vm.o mmu.o vcpu.o vcpu_exit.o
> +
> +obj-$(CONFIG_KVM)	+= kvm.o
> diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
> new file mode 100644
> index 000000000000..f29768c82fbe
> --- /dev/null
> +++ b/arch/riscv/kvm/main.c
> @@ -0,0 +1,93 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> + *
> + * Authors:
> + *     Anup Patel <anup.patel@wdc.com>
> + */
> +
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/kvm_host.h>
> +#include <asm/csr.h>
> +#include <asm/hwcap.h>
> +#include <asm/sbi.h>
> +
> +long kvm_arch_dev_ioctl(struct file *filp,
> +			unsigned int ioctl, unsigned long arg)
> +{
> +	return -EINVAL;
> +}
> +
> +int kvm_arch_check_processor_compat(void)
> +{
> +	return 0;
> +}
> +
> +int kvm_arch_hardware_setup(void)
> +{
> +	return 0;
> +}
> +
> +int kvm_arch_hardware_enable(void)
> +{
> +	unsigned long hideleg, hedeleg;
> +
> +	hedeleg = 0;
> +	hedeleg |= (1UL << EXC_INST_MISALIGNED);
> +	hedeleg |= (1UL << EXC_BREAKPOINT);
> +	hedeleg |= (1UL << EXC_SYSCALL);
> +	hedeleg |= (1UL << EXC_INST_PAGE_FAULT);
> +	hedeleg |= (1UL << EXC_LOAD_PAGE_FAULT);
> +	hedeleg |= (1UL << EXC_STORE_PAGE_FAULT);
> +	csr_write(CSR_HEDELEG, hedeleg);
> +
> +	hideleg = 0;
> +	hideleg |= (1UL << IRQ_S_SOFT);
> +	hideleg |= (1UL << IRQ_S_TIMER);
> +	hideleg |= (1UL << IRQ_S_EXT);
> +	csr_write(CSR_HIDELEG, hideleg);
> +
> +	csr_write(CSR_HIP, 0);
> +
> +	return 0;
> +}
> +
> +void kvm_arch_hardware_disable(void)
> +{
> +	csr_write(CSR_HEDELEG, 0);
> +	csr_write(CSR_HIDELEG, 0);
> +}
> +
> +int kvm_arch_init(void *opaque)
> +{
> +	if (!riscv_isa_extension_available(NULL, h)) {
> +		kvm_info("hypervisor extension not available\n");
> +		return -ENODEV;
> +	}
> +
> +	if (sbi_spec_is_0_1()) {
> +		kvm_info("require SBI v0.2 or higher\n");
> +		return -ENODEV;
> +	}
> +
> +	if (sbi_probe_extension(SBI_EXT_RFENCE) <= 0) {
> +		kvm_info("require SBI RFENCE extension\n");
> +		return -ENODEV;
> +	}
> +
> +	kvm_info("hypervisor extension available\n");
> +
> +	return 0;
> +}
> +
> +void kvm_arch_exit(void)
> +{
> +}
> +
> +static int riscv_kvm_init(void)
> +{
> +	return kvm_init(NULL, sizeof(struct kvm_vcpu), 0, THIS_MODULE);
> +}
> +module_init(riscv_kvm_init);
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> new file mode 100644
> index 000000000000..04dd089b86ff
> --- /dev/null
> +++ b/arch/riscv/kvm/mmu.c
> @@ -0,0 +1,83 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> + *
> + * Authors:
> + *     Anup Patel <anup.patel@wdc.com>
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/hugetlb.h>
> +#include <linux/module.h>
> +#include <linux/uaccess.h>
> +#include <linux/vmalloc.h>
> +#include <linux/kvm_host.h>
> +#include <linux/sched/signal.h>
> +#include <asm/page.h>
> +#include <asm/pgtable.h>
> +
> +void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
> +			   struct kvm_memory_slot *dont)
> +{
> +}
> +
> +int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
> +			    unsigned long npages)
> +{
> +	return 0;
> +}
> +
> +void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
> +{
> +}
> +
> +void kvm_arch_flush_shadow_all(struct kvm *kvm)
> +{
> +	/* TODO: */
> +}
> +
> +void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
> +				   struct kvm_memory_slot *slot)
> +{
> +}
> +
> +void kvm_arch_commit_memory_region(struct kvm *kvm,
> +				const struct kvm_userspace_memory_region *mem,
> +				const struct kvm_memory_slot *old,
> +				const struct kvm_memory_slot *new,
> +				enum kvm_mr_change change)
> +{
> +	/* TODO: */
> +}
> +
> +int kvm_arch_prepare_memory_region(struct kvm *kvm,
> +				struct kvm_memory_slot *memslot,
> +				const struct kvm_userspace_memory_region *mem,
> +				enum kvm_mr_change change)
> +{
> +	/* TODO: */
> +	return 0;
> +}
> +
> +void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu)
> +{
> +	/* TODO: */
> +}
> +
> +int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm)
> +{
> +	/* TODO: */
> +	return 0;
> +}
> +
> +void kvm_riscv_stage2_free_pgd(struct kvm *kvm)
> +{
> +	/* TODO: */
> +}
> +
> +void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu)
> +{
> +	/* TODO: */
> +}
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> new file mode 100644
> index 000000000000..bd7d6b154f61
> --- /dev/null
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -0,0 +1,316 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> + *
> + * Authors:
> + *     Anup Patel <anup.patel@wdc.com>
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/kdebug.h>
> +#include <linux/module.h>
> +#include <linux/uaccess.h>
> +#include <linux/vmalloc.h>
> +#include <linux/sched/signal.h>
> +#include <linux/fs.h>
> +#include <linux/kvm_host.h>
> +#include <asm/csr.h>
> +#include <asm/delay.h>
> +#include <asm/hwcap.h>
> +
> +#define VCPU_STAT(x) { #x, offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU }
> +
> +struct kvm_stats_debugfs_item debugfs_entries[] = {
> +	VCPU_STAT(ecall_exit_stat),
> +	VCPU_STAT(wfi_exit_stat),
> +	VCPU_STAT(mmio_exit_user),
> +	VCPU_STAT(mmio_exit_kernel),
> +	VCPU_STAT(exits),
> +	{ NULL }
> +};
> +
> +struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
> +{
> +	/* TODO: */
> +	return NULL;
> +}
> +
> +int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
> +{
> +	return 0;
> +}
> +
> +void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
> +{
> +}
> +
> +int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
> +{
> +	/* TODO: */
> +	return 0;
> +}
> +
> +void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
> +{
> +	/* TODO: */
> +}
> +
> +int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
> +{
> +	/* TODO: */
> +	return 0;
> +}
> +
> +void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu)
> +{
> +}
> +
> +void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
> +{
> +}
> +
> +int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
> +{
> +	/* TODO: */
> +	return 0;
> +}
> +
> +int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
> +{
> +	/* TODO: */
> +	return 0;
> +}
> +
> +bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
> +{
> +	/* TODO: */
> +	return false;
> +}
> +
> +bool kvm_arch_has_vcpu_debugfs(void)
> +{
> +	return false;
> +}
> +
> +int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
> +{
> +	return 0;
> +}
> +
> +vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
> +{
> +	return VM_FAULT_SIGBUS;
> +}
> +
> +long kvm_arch_vcpu_async_ioctl(struct file *filp,
> +			       unsigned int ioctl, unsigned long arg)
> +{
> +	/* TODO; */
> +	return -ENOIOCTLCMD;
> +}
> +
> +long kvm_arch_vcpu_ioctl(struct file *filp,
> +			 unsigned int ioctl, unsigned long arg)
> +{
> +	/* TODO: */
> +	return -EINVAL;
> +}
> +
> +int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
> +				  struct kvm_sregs *sregs)
> +{
> +	return -EINVAL;
> +}
> +
> +int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
> +				  struct kvm_sregs *sregs)
> +{
> +	return -EINVAL;
> +}
> +
> +int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
> +{
> +	return -EINVAL;
> +}
> +
> +int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
> +{
> +	return -EINVAL;
> +}
> +
> +int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
> +				  struct kvm_translation *tr)
> +{
> +	return -EINVAL;
> +}
> +
> +int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
> +{
> +	return -EINVAL;
> +}
> +
> +int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
> +{
> +	return -EINVAL;
> +}
> +
> +int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
> +				    struct kvm_mp_state *mp_state)
> +{
> +	/* TODO: */
> +	return 0;
> +}
> +
> +int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
> +				    struct kvm_mp_state *mp_state)
> +{
> +	/* TODO: */
> +	return 0;
> +}
> +
> +int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
> +					struct kvm_guest_debug *dbg)
> +{
> +	/* TODO; To be implemented later. */
> +	return -EINVAL;
> +}
> +
> +void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> +{
> +	/* TODO: */
> +
> +	kvm_riscv_stage2_update_hgatp(vcpu);
> +}
> +
> +void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
> +{
> +	/* TODO: */
> +}
> +
> +static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
> +{
> +	/* TODO: */
> +}
> +
> +int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
> +{
> +	int ret;
> +	unsigned long scause, stval, htval, htinst;
> +
> +	vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
> +
> +	/* Process MMIO value returned from user-space */
> +	if (run->exit_reason == KVM_EXIT_MMIO) {
> +		ret = kvm_riscv_vcpu_mmio_return(vcpu, vcpu->run);
> +		if (ret) {
> +			srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
> +			return ret;
> +		}
> +	}
> +
> +	if (run->immediate_exit) {
> +		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
> +		return -EINTR;
> +	}
> +
> +	vcpu_load(vcpu);
> +
> +	kvm_sigset_activate(vcpu);
> +
> +	ret = 1;
> +	run->exit_reason = KVM_EXIT_UNKNOWN;
> +	while (ret > 0) {
> +		/* Check conditions before entering the guest */
> +		cond_resched();
> +
> +		kvm_riscv_check_vcpu_requests(vcpu);
> +
> +		preempt_disable();
> +
> +		local_irq_disable();
> +
> +		/*
> +		 * Exit if we have a signal pending so that we can deliver
> +		 * the signal to user space.
> +		 */
> +		if (signal_pending(current)) {
> +			ret = -EINTR;
> +			run->exit_reason = KVM_EXIT_INTR;
> +		}
> +
> +		/*
> +		 * Ensure we set mode to IN_GUEST_MODE after we disable
> +		 * interrupts and before the final VCPU requests check.
> +		 * See the comment in kvm_vcpu_exiting_guest_mode() and
> +		 * Documentation/virtual/kvm/vcpu-requests.rst
> +		 */
> +		vcpu->mode = IN_GUEST_MODE;
> +
> +		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
> +		smp_mb__after_srcu_read_unlock();
> +
> +		if (ret <= 0 ||
> +		    kvm_request_pending(vcpu)) {
> +			vcpu->mode = OUTSIDE_GUEST_MODE;
> +			local_irq_enable();
> +			preempt_enable();
> +			vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
> +			continue;
> +		}
> +
> +		guest_enter_irqoff();
> +
> +		__kvm_riscv_switch_to(&vcpu->arch);
> +
> +		vcpu->mode = OUTSIDE_GUEST_MODE;
> +		vcpu->stat.exits++;
> +
> +		/*
> +		 * Save SCAUSE, STVAL, HTVAL, and HTINST because we might
> +		 * get an interrupt between __kvm_riscv_switch_to() and
> +		 * local_irq_enable() which can potentially change CSRs.
> +		 */
> +		scause = csr_read(CSR_SCAUSE);
> +		stval = csr_read(CSR_STVAL);
> +		htval = csr_read(CSR_HTVAL);
> +		htinst = csr_read(CSR_HTINST);
> +
> +		/*
> +		 * We may have taken a host interrupt in VS/VU-mode (i.e.
> +		 * while executing the guest). This interrupt is still
> +		 * pending, as we haven't serviced it yet!
> +		 *
> +		 * We're now back in HS-mode with interrupts disabled
> +		 * so enabling the interrupts now will have the effect
> +		 * of taking the interrupt again, in HS-mode this time.
> +		 */
> +		local_irq_enable();
> +
> +		/*
> +		 * We do local_irq_enable() before calling guest_exit() so
> +		 * that if a timer interrupt hits while running the guest
> +		 * we account that tick as being spent in the guest. We
> +		 * enable preemption after calling guest_exit() so that if
> +		 * we get preempted we make sure ticks after that is not
> +		 * counted as guest time.
> +		 */
> +		guest_exit();
> +
> +		preempt_enable();
> +
> +		vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
> +
> +		ret = kvm_riscv_vcpu_exit(vcpu, run,
> +					  scause, stval, htval, htinst);
> +	}
> +
> +	kvm_sigset_deactivate(vcpu);
> +
> +	vcpu_put(vcpu);
> +
> +	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
> +
> +	return ret;
> +}
> diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
> new file mode 100644
> index 000000000000..dcea9ce4e728
> --- /dev/null
> +++ b/arch/riscv/kvm/vcpu_exit.c
> @@ -0,0 +1,36 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> + *
> + * Authors:
> + *     Anup Patel <anup.patel@wdc.com>
> + */
> +
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/kvm_host.h>
> +
> +/**
> + * kvm_riscv_vcpu_mmio_return -- Handle MMIO loads after user space emulation
> + *			     or in-kernel IO emulation
> + *
> + * @vcpu: The VCPU pointer
> + * @run:  The VCPU run struct containing the mmio data
> + */
> +int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
> +{
> +	/* TODO: */
> +	return 0;
> +}
> +
> +/*
> + * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
> + * proper exit to userspace.
> + */
> +int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
> +			unsigned long scause, unsigned long stval,
> +			unsigned long htval, unsigned long htinst)
> +{
> +	/* TODO: */
> +	return 0;
> +}
> diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
> new file mode 100644
> index 000000000000..ac0211820521
> --- /dev/null
> +++ b/arch/riscv/kvm/vm.c
> @@ -0,0 +1,79 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> + *
> + * Authors:
> + *     Anup Patel <anup.patel@wdc.com>
> + */
> +
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/uaccess.h>
> +#include <linux/kvm_host.h>
> +
> +int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
> +{
> +	/* TODO: To be added later. */
> +	return -ENOTSUPP;
> +}
> +
> +int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> +{
> +	int r;
> +
> +	r = kvm_riscv_stage2_alloc_pgd(kvm);
> +	if (r)
> +		return r;
> +
> +	return 0;
> +}
> +
> +void kvm_arch_destroy_vm(struct kvm *kvm)
> +{
> +	int i;
> +
> +	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
> +		if (kvm->vcpus[i]) {
> +			kvm_arch_vcpu_destroy(kvm->vcpus[i]);
> +			kvm->vcpus[i] = NULL;
> +		}
> +	}
> +}
> +
> +int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> +{
> +	int r;
> +
> +	switch (ext) {
> +	case KVM_CAP_DEVICE_CTRL:
> +	case KVM_CAP_USER_MEMORY:
> +	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
> +	case KVM_CAP_ONE_REG:
> +	case KVM_CAP_READONLY_MEM:
> +	case KVM_CAP_MP_STATE:
> +	case KVM_CAP_IMMEDIATE_EXIT:
> +		r = 1;
> +		break;
> +	case KVM_CAP_NR_VCPUS:
> +		r = num_online_cpus();
> +		break;
> +	case KVM_CAP_MAX_VCPUS:
> +		r = KVM_MAX_VCPUS;
> +		break;
> +	case KVM_CAP_NR_MEMSLOTS:
> +		r = KVM_USER_MEM_SLOTS;
> +		break;
> +	default:
> +		r = 0;
> +		break;
> +	}
> +
> +	return r;
> +}
> +
> +long kvm_arch_vm_ioctl(struct file *filp,
> +		       unsigned int ioctl, unsigned long arg)
> +{
> +	return -EINVAL;
> +}
> -- 
> 2.17.1

Re: [PATCH v10 04/19] RISC-V: Add initial skeletal KVM support

[Anup Patel]

On Fri, Jan 17, 2020 at 5:07 AM Palmer Dabbelt <palmerdabbelt@google.com> wrote:
>
> On Mon, 23 Dec 2019 03:35:46 PST (-0800), Anup Patel wrote:
> > This patch adds initial skeletal KVM RISC-V support which has:
> > 1. A simple implementation of arch specific VM functions
> >    except kvm_vm_ioctl_get_dirty_log() which will implemeted
> >    in-future as part of stage2 page loging.
> > 2. Stubs of required arch specific VCPU functions except
> >    kvm_arch_vcpu_ioctl_run() which is semi-complete and
> >    extended by subsequent patches.
> > 3. Stubs for required arch specific stage2 MMU functions.
> >
> > Signed-off-by: Anup Patel <anup.patel@wdc.com>
> > Acked-by: Paolo Bonzini <pbonzini@redhat.com>
> > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> > Reviewed-by: Alexander Graf <graf@amazon.com>
> > ---
> >  arch/riscv/Kconfig                |   2 +
> >  arch/riscv/Makefile               |   2 +
> >  arch/riscv/include/asm/kvm_host.h |  82 ++++++++
> >  arch/riscv/include/uapi/asm/kvm.h |  47 +++++
> >  arch/riscv/kvm/Kconfig            |  33 ++++
> >  arch/riscv/kvm/Makefile           |  13 ++
> >  arch/riscv/kvm/main.c             |  93 +++++++++
> >  arch/riscv/kvm/mmu.c              |  83 ++++++++
> >  arch/riscv/kvm/vcpu.c             | 316 ++++++++++++++++++++++++++++++
> >  arch/riscv/kvm/vcpu_exit.c        |  36 ++++
> >  arch/riscv/kvm/vm.c               |  79 ++++++++
> >  11 files changed, 786 insertions(+)
> >  create mode 100644 arch/riscv/include/asm/kvm_host.h
> >  create mode 100644 arch/riscv/include/uapi/asm/kvm.h
> >  create mode 100644 arch/riscv/kvm/Kconfig
> >  create mode 100644 arch/riscv/kvm/Makefile
> >  create mode 100644 arch/riscv/kvm/main.c
> >  create mode 100644 arch/riscv/kvm/mmu.c
> >  create mode 100644 arch/riscv/kvm/vcpu.c
> >  create mode 100644 arch/riscv/kvm/vcpu_exit.c
> >  create mode 100644 arch/riscv/kvm/vm.c
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index baf0943c80d0..2e8551a9cd32 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -366,3 +366,5 @@ menu "Power management options"
> >  source "kernel/power/Kconfig"
> >
> >  endmenu
> > +
> > +source "arch/riscv/kvm/Kconfig"
> > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> > index b9009a2fbaf5..65b58cec9abd 100644
> > --- a/arch/riscv/Makefile
> > +++ b/arch/riscv/Makefile
> > @@ -77,6 +77,8 @@ head-y := arch/riscv/kernel/head.o
> >
> >  core-y += arch/riscv/
> >
> > +core-$(CONFIG_KVM) += arch/riscv/kvm/
> > +
> >  libs-y += arch/riscv/lib/
> >
> >  PHONY += vdso_install
> > diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> > new file mode 100644
> > index 000000000000..e0b633f616a4
> > --- /dev/null
> > +++ b/arch/riscv/include/asm/kvm_host.h
> > @@ -0,0 +1,82 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> > + *
> > + * Authors:
> > + *     Anup Patel <anup.patel@wdc.com>
> > + */
> > +
> > +#ifndef __RISCV_KVM_HOST_H__
> > +#define __RISCV_KVM_HOST_H__
> > +
> > +#include <linux/types.h>
> > +#include <linux/kvm.h>
> > +#include <linux/kvm_types.h>
> > +
> > +#ifdef CONFIG_64BIT
> > +#define KVM_MAX_VCPUS                        (1U << 16)
> > +#else
> > +#define KVM_MAX_VCPUS                        (1U << 9)
> > +#endif
> > +
> > +#define KVM_USER_MEM_SLOTS           512
> > +#define KVM_HALT_POLL_NS_DEFAULT     500000
> > +
> > +#define KVM_VCPU_MAX_FEATURES                0
> > +
> > +#define KVM_REQ_SLEEP \
> > +     KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
> > +#define KVM_REQ_VCPU_RESET           KVM_ARCH_REQ(1)
> > +
> > +struct kvm_vm_stat {
> > +     ulong remote_tlb_flush;
> > +};
> > +
> > +struct kvm_vcpu_stat {
> > +     u64 halt_successful_poll;
> > +     u64 halt_attempted_poll;
> > +     u64 halt_poll_invalid;
> > +     u64 halt_wakeup;
> > +     u64 ecall_exit_stat;
> > +     u64 wfi_exit_stat;
> > +     u64 mmio_exit_user;
> > +     u64 mmio_exit_kernel;
> > +     u64 exits;
> > +};
>
> Presumably at least this came from arm64, as it's exactly the same.  If that's
> the case then this file, and probably a bunch of others, should be attributed
> somehow.  IIRC we left the copyrights in our copied files and it looks like
> arch/arm64 has done the same:

The KVM/riscv port was created after studying KVM/x86, KVM/arm64, and
KVM/mips. It is not based on KVM/arm64 port.

The struct kvm_vcpu_stat looks similar to arm64 kvm_host.h because we
implement the same set of VCPU stats. If you look at subsequent patches
then you will realize that riscv/include/asm/kvm_host.h is very specific to
RISC-V and very different from arm64/include/asm/kvm_host.h.

Further, a lot of members in struct kvm_vcpu_stat are expected by the
core KVM at virt/kvm/kvm_main.c hence you will see these members in
kvm_host.h for all architectures.

>
>     $ head -n10 arch/arm64/include/asm/kvm_host.h
>     /* SPDX-License-Identifier: GPL-2.0-only */
>     /*
>      * Copyright (C) 2012,2013 - ARM Ltd
>      * Author: Marc Zyngier <marc.zyngier@arm.com>
>      *
>      * Derived from arch/arm/include/asm/kvm_host.h:
>      * Copyright (C) 2012 - Virtual Open Systems and Columbia University
>      * Author: Christoffer Dall <c.dall@virtualopensystems.com>
>      */

Based on the above rationale, I think we don't require need this
copyright notice.

The KVM/arm64 kvm_host.h has above notice because:
1. KVM/arm64 actually shares a lot of code with KVM/arm under
   virt/kvm/arm directory
2. Initial KVM/arm64 port was actaully based on KVM/arm port.

>
> > +
> > +struct kvm_arch_memory_slot {
> > +};
> > +
> > +struct kvm_arch {
> > +     /* stage2 page table */
> > +     pgd_t *pgd;
> > +     phys_addr_t pgd_phys;
> > +};
> > +
> > +struct kvm_vcpu_arch {
> > +     /* Don't run the VCPU (blocked) */
> > +     bool pause;
> > +
> > +     /* SRCU lock index for in-kernel run loop */
> > +     int srcu_idx;
> > +};
> > +
> > +static inline void kvm_arch_hardware_unsetup(void) {}
> > +static inline void kvm_arch_sync_events(struct kvm *kvm) {}
> > +static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
> > +static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
> > +static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
> > +
> > +void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu);
> > +int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm);
> > +void kvm_riscv_stage2_free_pgd(struct kvm *kvm);
> > +void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu);
> > +
> > +int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
> > +int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
> > +                     unsigned long scause, unsigned long stval,
> > +                     unsigned long htval, unsigned long htinst);
> > +
> > +static inline void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch) {}
> > +
> > +#endif /* __RISCV_KVM_HOST_H__ */
> > diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> > new file mode 100644
> > index 000000000000..d15875818b6e
> > --- /dev/null
> > +++ b/arch/riscv/include/uapi/asm/kvm.h
> > @@ -0,0 +1,47 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> > + *
> > + * Authors:
> > + *     Anup Patel <anup.patel@wdc.com>
> > + */
> > +
> > +#ifndef __LINUX_KVM_RISCV_H
> > +#define __LINUX_KVM_RISCV_H
> > +
> > +#ifndef __ASSEMBLY__
> > +
> > +#include <linux/types.h>
> > +#include <asm/ptrace.h>
> > +
> > +#define __KVM_HAVE_READONLY_MEM
> > +
> > +#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
> > +
> > +/* for KVM_GET_REGS and KVM_SET_REGS */
> > +struct kvm_regs {
> > +};
> > +
> > +/* for KVM_GET_FPU and KVM_SET_FPU */
> > +struct kvm_fpu {
> > +};
> > +
> > +/* KVM Debug exit structure */
> > +struct kvm_debug_exit_arch {
> > +};
> > +
> > +/* for KVM_SET_GUEST_DEBUG */
> > +struct kvm_guest_debug_arch {
> > +};
> > +
> > +/* definition of registers in kvm_run */
> > +struct kvm_sync_regs {
> > +};
> > +
> > +/* dummy definition */
> > +struct kvm_sregs {
> > +};
> > +
> > +#endif
> > +
> > +#endif /* __LINUX_KVM_RISCV_H */
> > diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
> > new file mode 100644
> > index 000000000000..88edd477b3a8
> > --- /dev/null
> > +++ b/arch/riscv/kvm/Kconfig
> > @@ -0,0 +1,33 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +#
> > +# KVM configuration
> > +#
> > +
> > +source "virt/kvm/Kconfig"
> > +
> > +menuconfig VIRTUALIZATION
> > +     bool "Virtualization"
> > +     help
> > +       Say Y here to get to see options for using your Linux host to run
> > +       other operating systems inside virtual machines (guests).
> > +       This option alone does not add any kernel code.
> > +
> > +       If you say N, all options in this submenu will be skipped and
> > +       disabled.
> > +
> > +if VIRTUALIZATION
> > +
> > +config KVM
> > +     tristate "Kernel-based Virtual Machine (KVM) support (EXPERIMENTAL)"
> > +     depends on RISCV_SBI && MMU
> > +     select PREEMPT_NOTIFIERS
> > +     select ANON_INODES
> > +     select KVM_MMIO
> > +     select HAVE_KVM_VCPU_ASYNC_IOCTL
> > +     select SRCU
> > +     help
> > +       Support hosting virtualized guest machines.
> > +
> > +       If unsure, say N.
> > +
> > +endif # VIRTUALIZATION
> > diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
> > new file mode 100644
> > index 000000000000..37b5a59d4f4f
> > --- /dev/null
> > +++ b/arch/riscv/kvm/Makefile
> > @@ -0,0 +1,13 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Makefile for RISC-V KVM support
> > +#
> > +
> > +common-objs-y = $(addprefix ../../../virt/kvm/, kvm_main.o coalesced_mmio.o)
> > +
> > +ccflags-y := -Ivirt/kvm -Iarch/riscv/kvm
> > +
> > +kvm-objs := $(common-objs-y)
> > +
> > +kvm-objs += main.o vm.o mmu.o vcpu.o vcpu_exit.o
> > +
> > +obj-$(CONFIG_KVM)    += kvm.o
> > diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
> > new file mode 100644
> > index 000000000000..f29768c82fbe
> > --- /dev/null
> > +++ b/arch/riscv/kvm/main.c
> > @@ -0,0 +1,93 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> > + *
> > + * Authors:
> > + *     Anup Patel <anup.patel@wdc.com>
> > + */
> > +
> > +#include <linux/errno.h>
> > +#include <linux/err.h>
> > +#include <linux/module.h>
> > +#include <linux/kvm_host.h>
> > +#include <asm/csr.h>
> > +#include <asm/hwcap.h>
> > +#include <asm/sbi.h>
> > +
> > +long kvm_arch_dev_ioctl(struct file *filp,
> > +                     unsigned int ioctl, unsigned long arg)
> > +{
> > +     return -EINVAL;
> > +}
> > +
> > +int kvm_arch_check_processor_compat(void)
> > +{
> > +     return 0;
> > +}
> > +
> > +int kvm_arch_hardware_setup(void)
> > +{
> > +     return 0;
> > +}
> > +
> > +int kvm_arch_hardware_enable(void)
> > +{
> > +     unsigned long hideleg, hedeleg;
> > +
> > +     hedeleg = 0;
> > +     hedeleg |= (1UL << EXC_INST_MISALIGNED);
> > +     hedeleg |= (1UL << EXC_BREAKPOINT);
> > +     hedeleg |= (1UL << EXC_SYSCALL);
> > +     hedeleg |= (1UL << EXC_INST_PAGE_FAULT);
> > +     hedeleg |= (1UL << EXC_LOAD_PAGE_FAULT);
> > +     hedeleg |= (1UL << EXC_STORE_PAGE_FAULT);
> > +     csr_write(CSR_HEDELEG, hedeleg);
> > +
> > +     hideleg = 0;
> > +     hideleg |= (1UL << IRQ_S_SOFT);
> > +     hideleg |= (1UL << IRQ_S_TIMER);
> > +     hideleg |= (1UL << IRQ_S_EXT);
> > +     csr_write(CSR_HIDELEG, hideleg);
> > +
> > +     csr_write(CSR_HIP, 0);
> > +
> > +     return 0;
> > +}
> > +
> > +void kvm_arch_hardware_disable(void)
> > +{
> > +     csr_write(CSR_HEDELEG, 0);
> > +     csr_write(CSR_HIDELEG, 0);
> > +}
> > +
> > +int kvm_arch_init(void *opaque)
> > +{
> > +     if (!riscv_isa_extension_available(NULL, h)) {
> > +             kvm_info("hypervisor extension not available\n");
> > +             return -ENODEV;
> > +     }
> > +
> > +     if (sbi_spec_is_0_1()) {
> > +             kvm_info("require SBI v0.2 or higher\n");
> > +             return -ENODEV;
> > +     }
> > +
> > +     if (sbi_probe_extension(SBI_EXT_RFENCE) <= 0) {
> > +             kvm_info("require SBI RFENCE extension\n");
> > +             return -ENODEV;
> > +     }
> > +
> > +     kvm_info("hypervisor extension available\n");
> > +
> > +     return 0;
> > +}
> > +
> > +void kvm_arch_exit(void)
> > +{
> > +}
> > +
> > +static int riscv_kvm_init(void)
> > +{
> > +     return kvm_init(NULL, sizeof(struct kvm_vcpu), 0, THIS_MODULE);
> > +}
> > +module_init(riscv_kvm_init);
> > diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> > new file mode 100644
> > index 000000000000..04dd089b86ff
> > --- /dev/null
> > +++ b/arch/riscv/kvm/mmu.c
> > @@ -0,0 +1,83 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> > + *
> > + * Authors:
> > + *     Anup Patel <anup.patel@wdc.com>
> > + */
> > +
> > +#include <linux/bitops.h>
> > +#include <linux/errno.h>
> > +#include <linux/err.h>
> > +#include <linux/hugetlb.h>
> > +#include <linux/module.h>
> > +#include <linux/uaccess.h>
> > +#include <linux/vmalloc.h>
> > +#include <linux/kvm_host.h>
> > +#include <linux/sched/signal.h>
> > +#include <asm/page.h>
> > +#include <asm/pgtable.h>
> > +
> > +void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
> > +                        struct kvm_memory_slot *dont)
> > +{
> > +}
> > +
> > +int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
> > +                         unsigned long npages)
> > +{
> > +     return 0;
> > +}
> > +
> > +void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
> > +{
> > +}
> > +
> > +void kvm_arch_flush_shadow_all(struct kvm *kvm)
> > +{
> > +     /* TODO: */
> > +}
> > +
> > +void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
> > +                                struct kvm_memory_slot *slot)
> > +{
> > +}
> > +
> > +void kvm_arch_commit_memory_region(struct kvm *kvm,
> > +                             const struct kvm_userspace_memory_region *mem,
> > +                             const struct kvm_memory_slot *old,
> > +                             const struct kvm_memory_slot *new,
> > +                             enum kvm_mr_change change)
> > +{
> > +     /* TODO: */
> > +}
> > +
> > +int kvm_arch_prepare_memory_region(struct kvm *kvm,
> > +                             struct kvm_memory_slot *memslot,
> > +                             const struct kvm_userspace_memory_region *mem,
> > +                             enum kvm_mr_change change)
> > +{
> > +     /* TODO: */
> > +     return 0;
> > +}
> > +
> > +void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu)
> > +{
> > +     /* TODO: */
> > +}
> > +
> > +int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm)
> > +{
> > +     /* TODO: */
> > +     return 0;
> > +}
> > +
> > +void kvm_riscv_stage2_free_pgd(struct kvm *kvm)
> > +{
> > +     /* TODO: */
> > +}
> > +
> > +void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu)
> > +{
> > +     /* TODO: */
> > +}
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > new file mode 100644
> > index 000000000000..bd7d6b154f61
> > --- /dev/null
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -0,0 +1,316 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> > + *
> > + * Authors:
> > + *     Anup Patel <anup.patel@wdc.com>
> > + */
> > +
> > +#include <linux/bitops.h>
> > +#include <linux/errno.h>
> > +#include <linux/err.h>
> > +#include <linux/kdebug.h>
> > +#include <linux/module.h>
> > +#include <linux/uaccess.h>
> > +#include <linux/vmalloc.h>
> > +#include <linux/sched/signal.h>
> > +#include <linux/fs.h>
> > +#include <linux/kvm_host.h>
> > +#include <asm/csr.h>
> > +#include <asm/delay.h>
> > +#include <asm/hwcap.h>
> > +
> > +#define VCPU_STAT(x) { #x, offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU }
> > +
> > +struct kvm_stats_debugfs_item debugfs_entries[] = {
> > +     VCPU_STAT(ecall_exit_stat),
> > +     VCPU_STAT(wfi_exit_stat),
> > +     VCPU_STAT(mmio_exit_user),
> > +     VCPU_STAT(mmio_exit_kernel),
> > +     VCPU_STAT(exits),
> > +     { NULL }
> > +};
> > +
> > +struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
> > +{
> > +     /* TODO: */
> > +     return NULL;
> > +}
> > +
> > +int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
> > +{
> > +     return 0;
> > +}
> > +
> > +void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
> > +{
> > +}
> > +
> > +int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
> > +{
> > +     /* TODO: */
> > +     return 0;
> > +}
> > +
> > +void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
> > +{
> > +     /* TODO: */
> > +}
> > +
> > +int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
> > +{
> > +     /* TODO: */
> > +     return 0;
> > +}
> > +
> > +void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu)
> > +{
> > +}
> > +
> > +void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
> > +{
> > +}
> > +
> > +int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
> > +{
> > +     /* TODO: */
> > +     return 0;
> > +}
> > +
> > +int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
> > +{
> > +     /* TODO: */
> > +     return 0;
> > +}
> > +
> > +bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
> > +{
> > +     /* TODO: */
> > +     return false;
> > +}
> > +
> > +bool kvm_arch_has_vcpu_debugfs(void)
> > +{
> > +     return false;
> > +}
> > +
> > +int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
> > +{
> > +     return 0;
> > +}
> > +
> > +vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
> > +{
> > +     return VM_FAULT_SIGBUS;
> > +}
> > +
> > +long kvm_arch_vcpu_async_ioctl(struct file *filp,
> > +                            unsigned int ioctl, unsigned long arg)
> > +{
> > +     /* TODO; */
> > +     return -ENOIOCTLCMD;
> > +}
> > +
> > +long kvm_arch_vcpu_ioctl(struct file *filp,
> > +                      unsigned int ioctl, unsigned long arg)
> > +{
> > +     /* TODO: */
> > +     return -EINVAL;
> > +}
> > +
> > +int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
> > +                               struct kvm_sregs *sregs)
> > +{
> > +     return -EINVAL;
> > +}
> > +
> > +int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
> > +                               struct kvm_sregs *sregs)
> > +{
> > +     return -EINVAL;
> > +}
> > +
> > +int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
> > +{
> > +     return -EINVAL;
> > +}
> > +
> > +int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
> > +{
> > +     return -EINVAL;
> > +}
> > +
> > +int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
> > +                               struct kvm_translation *tr)
> > +{
> > +     return -EINVAL;
> > +}
> > +
> > +int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
> > +{
> > +     return -EINVAL;
> > +}
> > +
> > +int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
> > +{
> > +     return -EINVAL;
> > +}
> > +
> > +int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
> > +                                 struct kvm_mp_state *mp_state)
> > +{
> > +     /* TODO: */
> > +     return 0;
> > +}
> > +
> > +int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
> > +                                 struct kvm_mp_state *mp_state)
> > +{
> > +     /* TODO: */
> > +     return 0;
> > +}
> > +
> > +int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
> > +                                     struct kvm_guest_debug *dbg)
> > +{
> > +     /* TODO; To be implemented later. */
> > +     return -EINVAL;
> > +}
> > +
> > +void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> > +{
> > +     /* TODO: */
> > +
> > +     kvm_riscv_stage2_update_hgatp(vcpu);
> > +}
> > +
> > +void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
> > +{
> > +     /* TODO: */
> > +}
> > +
> > +static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
> > +{
> > +     /* TODO: */
> > +}
> > +
> > +int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
> > +{
> > +     int ret;
> > +     unsigned long scause, stval, htval, htinst;
> > +
> > +     vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
> > +
> > +     /* Process MMIO value returned from user-space */
> > +     if (run->exit_reason == KVM_EXIT_MMIO) {
> > +             ret = kvm_riscv_vcpu_mmio_return(vcpu, vcpu->run);
> > +             if (ret) {
> > +                     srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
> > +                     return ret;
> > +             }
> > +     }
> > +
> > +     if (run->immediate_exit) {
> > +             srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
> > +             return -EINTR;
> > +     }
> > +
> > +     vcpu_load(vcpu);
> > +
> > +     kvm_sigset_activate(vcpu);
> > +
> > +     ret = 1;
> > +     run->exit_reason = KVM_EXIT_UNKNOWN;
> > +     while (ret > 0) {
> > +             /* Check conditions before entering the guest */
> > +             cond_resched();
> > +
> > +             kvm_riscv_check_vcpu_requests(vcpu);
> > +
> > +             preempt_disable();
> > +
> > +             local_irq_disable();
> > +
> > +             /*
> > +              * Exit if we have a signal pending so that we can deliver
> > +              * the signal to user space.
> > +              */
> > +             if (signal_pending(current)) {
> > +                     ret = -EINTR;
> > +                     run->exit_reason = KVM_EXIT_INTR;
> > +             }
> > +
> > +             /*
> > +              * Ensure we set mode to IN_GUEST_MODE after we disable
> > +              * interrupts and before the final VCPU requests check.
> > +              * See the comment in kvm_vcpu_exiting_guest_mode() and
> > +              * Documentation/virtual/kvm/vcpu-requests.rst
> > +              */
> > +             vcpu->mode = IN_GUEST_MODE;
> > +
> > +             srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
> > +             smp_mb__after_srcu_read_unlock();
> > +
> > +             if (ret <= 0 ||
> > +                 kvm_request_pending(vcpu)) {
> > +                     vcpu->mode = OUTSIDE_GUEST_MODE;
> > +                     local_irq_enable();
> > +                     preempt_enable();
> > +                     vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
> > +                     continue;
> > +             }
> > +
> > +             guest_enter_irqoff();
> > +
> > +             __kvm_riscv_switch_to(&vcpu->arch);
> > +
> > +             vcpu->mode = OUTSIDE_GUEST_MODE;
> > +             vcpu->stat.exits++;
> > +
> > +             /*
> > +              * Save SCAUSE, STVAL, HTVAL, and HTINST because we might
> > +              * get an interrupt between __kvm_riscv_switch_to() and
> > +              * local_irq_enable() which can potentially change CSRs.
> > +              */
> > +             scause = csr_read(CSR_SCAUSE);
> > +             stval = csr_read(CSR_STVAL);
> > +             htval = csr_read(CSR_HTVAL);
> > +             htinst = csr_read(CSR_HTINST);
> > +
> > +             /*
> > +              * We may have taken a host interrupt in VS/VU-mode (i.e.
> > +              * while executing the guest). This interrupt is still
> > +              * pending, as we haven't serviced it yet!
> > +              *
> > +              * We're now back in HS-mode with interrupts disabled
> > +              * so enabling the interrupts now will have the effect
> > +              * of taking the interrupt again, in HS-mode this time.
> > +              */
> > +             local_irq_enable();
> > +
> > +             /*
> > +              * We do local_irq_enable() before calling guest_exit() so
> > +              * that if a timer interrupt hits while running the guest
> > +              * we account that tick as being spent in the guest. We
> > +              * enable preemption after calling guest_exit() so that if
> > +              * we get preempted we make sure ticks after that is not
> > +              * counted as guest time.
> > +              */
> > +             guest_exit();
> > +
> > +             preempt_enable();
> > +
> > +             vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
> > +
> > +             ret = kvm_riscv_vcpu_exit(vcpu, run,
> > +                                       scause, stval, htval, htinst);
> > +     }
> > +
> > +     kvm_sigset_deactivate(vcpu);
> > +
> > +     vcpu_put(vcpu);
> > +
> > +     srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
> > +
> > +     return ret;
> > +}
> > diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
> > new file mode 100644
> > index 000000000000..dcea9ce4e728
> > --- /dev/null
> > +++ b/arch/riscv/kvm/vcpu_exit.c
> > @@ -0,0 +1,36 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> > + *
> > + * Authors:
> > + *     Anup Patel <anup.patel@wdc.com>
> > + */
> > +
> > +#include <linux/errno.h>
> > +#include <linux/err.h>
> > +#include <linux/kvm_host.h>
> > +
> > +/**
> > + * kvm_riscv_vcpu_mmio_return -- Handle MMIO loads after user space emulation
> > + *                        or in-kernel IO emulation
> > + *
> > + * @vcpu: The VCPU pointer
> > + * @run:  The VCPU run struct containing the mmio data
> > + */
> > +int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run)
> > +{
> > +     /* TODO: */
> > +     return 0;
> > +}
> > +
> > +/*
> > + * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
> > + * proper exit to userspace.
> > + */
> > +int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
> > +                     unsigned long scause, unsigned long stval,
> > +                     unsigned long htval, unsigned long htinst)
> > +{
> > +     /* TODO: */
> > +     return 0;
> > +}
> > diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
> > new file mode 100644
> > index 000000000000..ac0211820521
> > --- /dev/null
> > +++ b/arch/riscv/kvm/vm.c
> > @@ -0,0 +1,79 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> > + *
> > + * Authors:
> > + *     Anup Patel <anup.patel@wdc.com>
> > + */
> > +
> > +#include <linux/errno.h>
> > +#include <linux/err.h>
> > +#include <linux/module.h>
> > +#include <linux/uaccess.h>
> > +#include <linux/kvm_host.h>
> > +
> > +int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
> > +{
> > +     /* TODO: To be added later. */
> > +     return -ENOTSUPP;
> > +}
> > +
> > +int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
> > +{
> > +     int r;
> > +
> > +     r = kvm_riscv_stage2_alloc_pgd(kvm);
> > +     if (r)
> > +             return r;
> > +
> > +     return 0;
> > +}
> > +
> > +void kvm_arch_destroy_vm(struct kvm *kvm)
> > +{
> > +     int i;
> > +
> > +     for (i = 0; i < KVM_MAX_VCPUS; ++i) {
> > +             if (kvm->vcpus[i]) {
> > +                     kvm_arch_vcpu_destroy(kvm->vcpus[i]);
> > +                     kvm->vcpus[i] = NULL;
> > +             }
> > +     }
> > +}
> > +
> > +int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> > +{
> > +     int r;
> > +
> > +     switch (ext) {
> > +     case KVM_CAP_DEVICE_CTRL:
> > +     case KVM_CAP_USER_MEMORY:
> > +     case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
> > +     case KVM_CAP_ONE_REG:
> > +     case KVM_CAP_READONLY_MEM:
> > +     case KVM_CAP_MP_STATE:
> > +     case KVM_CAP_IMMEDIATE_EXIT:
> > +             r = 1;
> > +             break;
> > +     case KVM_CAP_NR_VCPUS:
> > +             r = num_online_cpus();
> > +             break;
> > +     case KVM_CAP_MAX_VCPUS:
> > +             r = KVM_MAX_VCPUS;
> > +             break;
> > +     case KVM_CAP_NR_MEMSLOTS:
> > +             r = KVM_USER_MEM_SLOTS;
> > +             break;
> > +     default:
> > +             r = 0;
> > +             break;
> > +     }
> > +
> > +     return r;
> > +}
> > +
> > +long kvm_arch_vm_ioctl(struct file *filp,
> > +                    unsigned int ioctl, unsigned long arg)
> > +{
> > +     return -EINVAL;
> > +}
> > --
> > 2.17.1

Regards,
Anup

Re: [PATCH v10 05/19] RISC-V: KVM: Implement VCPU create, init and destroy functions

[Palmer Dabbelt]

On Mon, 23 Dec 2019 03:35:55 PST (-0800), Anup Patel wrote:
> This patch implements VCPU create, init and destroy functions
> required by generic KVM module. We don't have much dynamic
> resources in struct kvm_vcpu_arch so these functions are quite
> simple for KVM RISC-V.
>
> Signed-off-by: Anup Patel <anup.patel@wdc.com>
> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> Reviewed-by: Alexander Graf <graf@amazon.com>
> ---
>  arch/riscv/include/asm/kvm_host.h | 68 +++++++++++++++++++++++++++++++
>  arch/riscv/kvm/vcpu.c             | 68 +++++++++++++++++++++++++++++--
>  2 files changed, 132 insertions(+), 4 deletions(-)
>
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> index e0b633f616a4..297431660be6 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -53,7 +53,75 @@ struct kvm_arch {
>  	phys_addr_t pgd_phys;
>  };
>  
> +struct kvm_cpu_context {
> +	unsigned long zero;
> +	unsigned long ra;
> +	unsigned long sp;
> +	unsigned long gp;
> +	unsigned long tp;
> +	unsigned long t0;
> +	unsigned long t1;
> +	unsigned long t2;
> +	unsigned long s0;
> +	unsigned long s1;
> +	unsigned long a0;
> +	unsigned long a1;
> +	unsigned long a2;
> +	unsigned long a3;
> +	unsigned long a4;
> +	unsigned long a5;
> +	unsigned long a6;
> +	unsigned long a7;
> +	unsigned long s2;
> +	unsigned long s3;
> +	unsigned long s4;
> +	unsigned long s5;
> +	unsigned long s6;
> +	unsigned long s7;
> +	unsigned long s8;
> +	unsigned long s9;
> +	unsigned long s10;
> +	unsigned long s11;
> +	unsigned long t3;
> +	unsigned long t4;
> +	unsigned long t5;
> +	unsigned long t6;
> +	unsigned long sepc;
> +	unsigned long sstatus;
> +	unsigned long hstatus;
> +};

Looks like pretty much everyone else is putting 'struct kvm_regs' at the start
of 'struct kvm_cpu_context', which I'm assuming avoids duplication when
implementing KVM_{GET,SET}_REGS.  That would probably be cleaner, but if I
think it'd be best to just have this match our mcontext.

> +
> +struct kvm_vcpu_csr {
> +	unsigned long vsstatus;
> +	unsigned long hie;
> +	unsigned long vstvec;
> +	unsigned long vsscratch;
> +	unsigned long vsepc;
> +	unsigned long vscause;
> +	unsigned long vstval;
> +	unsigned long hip;
> +	unsigned long vsatp;
> +};
> +
>  struct kvm_vcpu_arch {
> +	/* VCPU ran atleast once */
> +	bool ran_atleast_once;
> +
> +	/* ISA feature bits (similar to MISA) */
> +	unsigned long isa;
> +
> +	/* CPU context of Guest VCPU */
> +	struct kvm_cpu_context guest_context;
> +
> +	/* CPU CSR context of Guest VCPU */
> +	struct kvm_vcpu_csr guest_csr;

It looks like other architectures either put the entire CPU state in 'struct
kvm_cpu_context' (arm64, for example) or inline all the definitions (mips, for
example).  I'd lean the arm64 way here, but I haven't gotten sufficiently far
until the user ABI to figure out if this would help in a meaningful fashion.

> +	/* CPU context upon Guest VCPU reset */
> +	struct kvm_cpu_context guest_reset_context;
> +
> +	/* CPU CSR context upon Guest VCPU reset */
> +	struct kvm_vcpu_csr guest_reset_csr;
> +
>  	/* Don't run the VCPU (blocked) */
>  	bool pause;
>  
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index bd7d6b154f61..cf8ca8d4a9ea 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -31,10 +31,48 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
>  	{ NULL }
>  };
>  
> +#define KVM_RISCV_ISA_ALLOWED	(riscv_isa_extension_mask(a) | \
> +				 riscv_isa_extension_mask(c) | \
> +				 riscv_isa_extension_mask(d) | \
> +				 riscv_isa_extension_mask(f) | \
> +				 riscv_isa_extension_mask(i) | \
> +				 riscv_isa_extension_mask(m) | \
> +				 riscv_isa_extension_mask(s) | \
> +				 riscv_isa_extension_mask(u))
> +
> +static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
> +{
> +	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
> +	struct kvm_vcpu_csr *reset_csr = &vcpu->arch.guest_reset_csr;
> +	struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
> +	struct kvm_cpu_context *reset_cntx = &vcpu->arch.guest_reset_context;
> +
> +	memcpy(csr, reset_csr, sizeof(*csr));
> +
> +	memcpy(cntx, reset_cntx, sizeof(*cntx));
> +}
> +
>  struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
>  {
> -	/* TODO: */
> -	return NULL;
> +	int err;
> +	struct kvm_vcpu *vcpu;
> +
> +	vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL);
> +	if (!vcpu) {
> +		err = -ENOMEM;
> +		goto out;
> +	}
> +
> +	err = kvm_vcpu_init(vcpu, kvm, id);
> +	if (err)
> +		goto free_vcpu;
> +
> +	return vcpu;
> +
> +free_vcpu:
> +	kmem_cache_free(kvm_vcpu_cache, vcpu);
> +out:
> +	return ERR_PTR(err);
>  }
>  
>  int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
> @@ -48,13 +86,32 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
>  
>  int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
>  {
> -	/* TODO: */
> +	struct kvm_cpu_context *cntx;
> +
> +	/* Mark this VCPU never ran */
> +	vcpu->arch.ran_atleast_once = false;
> +
> +	/* Setup ISA features available to VCPU */
> +	vcpu->arch.isa = riscv_isa_extension_base(NULL) & KVM_RISCV_ISA_ALLOWED;
> +
> +	/* Setup reset state of shadow SSTATUS and HSTATUS CSRs */
> +	cntx = &vcpu->arch.guest_reset_context;
> +	cntx->sstatus = SR_SPP | SR_SPIE;
> +	cntx->hstatus = 0;
> +	cntx->hstatus |= HSTATUS_SP2V;
> +	cntx->hstatus |= HSTATUS_SP2P;
> +	cntx->hstatus |= HSTATUS_SPV;
> +
> +	/* Reset VCPU */
> +	kvm_riscv_reset_vcpu(vcpu);
> +
>  	return 0;
>  }
>  
>  void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
>  {
> -	/* TODO: */
> +	kvm_riscv_stage2_flush_cache(vcpu);

There needs to be a comment as to why there's a flush here.

The definition of kvm_riscv_stage2_flush_cache() should also have a comment
describing what it actually does.

> +	kmem_cache_free(kvm_vcpu_cache, vcpu);
>  }
>  
>  int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
> @@ -199,6 +256,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  	int ret;
>  	unsigned long scause, stval, htval, htinst;
>  
> +	/* Mark this VCPU ran atleast once */
> +	vcpu->arch.ran_atleast_once = true;

I'm having some trouble figuring out how this doesn't have a race condition,
but that's probably more applicable to the patch that uses it.  Also, a bit of
a nit pick: "at least" is two words.  I don't care that much about the variable
name, but the comments should use real words.

> +
>  	vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
>  
>  	/* Process MMIO value returned from user-space */
> -- 
> 2.17.1

Re: [PATCH v10 05/19] RISC-V: KVM: Implement VCPU create, init and destroy functions

[Anup Patel]

On Thu, Jan 23, 2020 at 12:34 AM Palmer Dabbelt
<palmerdabbelt@google.com> wrote:
>
> On Mon, 23 Dec 2019 03:35:55 PST (-0800), Anup Patel wrote:
> > This patch implements VCPU create, init and destroy functions
> > required by generic KVM module. We don't have much dynamic
> > resources in struct kvm_vcpu_arch so these functions are quite
> > simple for KVM RISC-V.
> >
> > Signed-off-by: Anup Patel <anup.patel@wdc.com>
> > Acked-by: Paolo Bonzini <pbonzini@redhat.com>
> > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> > Reviewed-by: Alexander Graf <graf@amazon.com>
> > ---
> >  arch/riscv/include/asm/kvm_host.h | 68 +++++++++++++++++++++++++++++++
> >  arch/riscv/kvm/vcpu.c             | 68 +++++++++++++++++++++++++++++--
> >  2 files changed, 132 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> > index e0b633f616a4..297431660be6 100644
> > --- a/arch/riscv/include/asm/kvm_host.h
> > +++ b/arch/riscv/include/asm/kvm_host.h
> > @@ -53,7 +53,75 @@ struct kvm_arch {
> >       phys_addr_t pgd_phys;
> >  };
> >
> > +struct kvm_cpu_context {
> > +     unsigned long zero;
> > +     unsigned long ra;
> > +     unsigned long sp;
> > +     unsigned long gp;
> > +     unsigned long tp;
> > +     unsigned long t0;
> > +     unsigned long t1;
> > +     unsigned long t2;
> > +     unsigned long s0;
> > +     unsigned long s1;
> > +     unsigned long a0;
> > +     unsigned long a1;
> > +     unsigned long a2;
> > +     unsigned long a3;
> > +     unsigned long a4;
> > +     unsigned long a5;
> > +     unsigned long a6;
> > +     unsigned long a7;
> > +     unsigned long s2;
> > +     unsigned long s3;
> > +     unsigned long s4;
> > +     unsigned long s5;
> > +     unsigned long s6;
> > +     unsigned long s7;
> > +     unsigned long s8;
> > +     unsigned long s9;
> > +     unsigned long s10;
> > +     unsigned long s11;
> > +     unsigned long t3;
> > +     unsigned long t4;
> > +     unsigned long t5;
> > +     unsigned long t6;
> > +     unsigned long sepc;
> > +     unsigned long sstatus;
> > +     unsigned long hstatus;
> > +};
>
> Looks like pretty much everyone else is putting 'struct kvm_regs' at the start
> of 'struct kvm_cpu_context', which I'm assuming avoids duplication when
> implementing KVM_{GET,SET}_REGS.  That would probably be cleaner, but if I
> think it'd be best to just have this match our mcontext.

The "struct kvm_cpu_context" is internal to KVM RISC-V whereas the
"struct kvm_vcpu_arch" is expected by core KVM

>
> > +
> > +struct kvm_vcpu_csr {
> > +     unsigned long vsstatus;
> > +     unsigned long hie;
> > +     unsigned long vstvec;
> > +     unsigned long vsscratch;
> > +     unsigned long vsepc;
> > +     unsigned long vscause;
> > +     unsigned long vstval;
> > +     unsigned long hip;
> > +     unsigned long vsatp;
> > +};
> > +
> >  struct kvm_vcpu_arch {
> > +     /* VCPU ran atleast once */
> > +     bool ran_atleast_once;
> > +
> > +     /* ISA feature bits (similar to MISA) */
> > +     unsigned long isa;
> > +
> > +     /* CPU context of Guest VCPU */
> > +     struct kvm_cpu_context guest_context;
> > +
> > +     /* CPU CSR context of Guest VCPU */
> > +     struct kvm_vcpu_csr guest_csr;
>
> It looks like other architectures either put the entire CPU state in 'struct
> kvm_cpu_context' (arm64, for example) or inline all the definitions (mips, for
> example).  I'd lean the arm64 way here, but I haven't gotten sufficiently far
> until the user ABI to figure out if this would help in a meaningful fashion.

It's an implementation choice. We don't need flow KVM ARM64.

In fact, having separate "struct kvm_cpu_context" and "struct kvm_vcpu_csr"
is much cleaner.

>
> > +     /* CPU context upon Guest VCPU reset */
> > +     struct kvm_cpu_context guest_reset_context;
> > +
> > +     /* CPU CSR context upon Guest VCPU reset */
> > +     struct kvm_vcpu_csr guest_reset_csr;
> > +
> >       /* Don't run the VCPU (blocked) */
> >       bool pause;
> >
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index bd7d6b154f61..cf8ca8d4a9ea 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -31,10 +31,48 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
> >       { NULL }
> >  };
> >
> > +#define KVM_RISCV_ISA_ALLOWED        (riscv_isa_extension_mask(a) | \
> > +                              riscv_isa_extension_mask(c) | \
> > +                              riscv_isa_extension_mask(d) | \
> > +                              riscv_isa_extension_mask(f) | \
> > +                              riscv_isa_extension_mask(i) | \
> > +                              riscv_isa_extension_mask(m) | \
> > +                              riscv_isa_extension_mask(s) | \
> > +                              riscv_isa_extension_mask(u))
> > +
> > +static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
> > +{
> > +     struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
> > +     struct kvm_vcpu_csr *reset_csr = &vcpu->arch.guest_reset_csr;
> > +     struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
> > +     struct kvm_cpu_context *reset_cntx = &vcpu->arch.guest_reset_context;
> > +
> > +     memcpy(csr, reset_csr, sizeof(*csr));
> > +
> > +     memcpy(cntx, reset_cntx, sizeof(*cntx));
> > +}
> > +
> >  struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
> >  {
> > -     /* TODO: */
> > -     return NULL;
> > +     int err;
> > +     struct kvm_vcpu *vcpu;
> > +
> > +     vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL);
> > +     if (!vcpu) {
> > +             err = -ENOMEM;
> > +             goto out;
> > +     }
> > +
> > +     err = kvm_vcpu_init(vcpu, kvm, id);
> > +     if (err)
> > +             goto free_vcpu;
> > +
> > +     return vcpu;
> > +
> > +free_vcpu:
> > +     kmem_cache_free(kvm_vcpu_cache, vcpu);
> > +out:
> > +     return ERR_PTR(err);
> >  }
> >
> >  int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
> > @@ -48,13 +86,32 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
> >
> >  int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
> >  {
> > -     /* TODO: */
> > +     struct kvm_cpu_context *cntx;
> > +
> > +     /* Mark this VCPU never ran */
> > +     vcpu->arch.ran_atleast_once = false;
> > +
> > +     /* Setup ISA features available to VCPU */
> > +     vcpu->arch.isa = riscv_isa_extension_base(NULL) & KVM_RISCV_ISA_ALLOWED;
> > +
> > +     /* Setup reset state of shadow SSTATUS and HSTATUS CSRs */
> > +     cntx = &vcpu->arch.guest_reset_context;
> > +     cntx->sstatus = SR_SPP | SR_SPIE;
> > +     cntx->hstatus = 0;
> > +     cntx->hstatus |= HSTATUS_SP2V;
> > +     cntx->hstatus |= HSTATUS_SP2P;
> > +     cntx->hstatus |= HSTATUS_SPV;
> > +
> > +     /* Reset VCPU */
> > +     kvm_riscv_reset_vcpu(vcpu);
> > +
> >       return 0;
> >  }
> >
> >  void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
> >  {
> > -     /* TODO: */
> > +     kvm_riscv_stage2_flush_cache(vcpu);
>
> There needs to be a comment as to why there's a flush here.
>
> The definition of kvm_riscv_stage2_flush_cache() should also have a comment
> describing what it actually does.

From the implementation its pretty obvious but I will add single line
comment anyway.

>
> > +     kmem_cache_free(kvm_vcpu_cache, vcpu);
> >  }
> >
> >  int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
> > @@ -199,6 +256,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
> >       int ret;
> >       unsigned long scause, stval, htval, htinst;
> >
> > +     /* Mark this VCPU ran atleast once */
> > +     vcpu->arch.ran_atleast_once = true;
>
> I'm having some trouble figuring out how this doesn't have a race condition,
> but that's probably more applicable to the patch that uses it.  Also, a bit of
> a nit pick: "at least" is two words.  I don't care that much about the variable
> name, but the comments should use real words.

This variable touched from a single thread only hence no need for protection.

I will fix the comment like you suggested.

>
> > +
> >       vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
> >
> >       /* Process MMIO value returned from user-space */
> > --
> > 2.17.1

Regards,
Anup