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* [PATCH v19 00/17] KVM RISC-V Support
@ 2021-07-27  5:54 Anup Patel
  2021-07-27  5:54 ` [PATCH v19 01/17] RISC-V: Add hypervisor extension related CSR defines Anup Patel
                   ` (16 more replies)
  0 siblings, 17 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	Anup Patel

This series adds initial KVM RISC-V support. Currently, we are able to boot
Linux on RV64/RV32 Guest with multiple VCPUs.

Key aspects of KVM RISC-V added by this series are:
1. No RISC-V specific KVM IOCTL
2. Minimal possible KVM world-switch which touches only GPRs and few CSRs
3. Both RV64 and RV32 host supported
4. Full Guest/VM switch is done via vcpu_get/vcpu_put infrastructure
5. KVM ONE_REG interface for VCPU register access from user-space
6. PLIC emulation is done in user-space
7. Timer and IPI emuation is done in-kernel
8. Both Sv39x4 and Sv48x4 supported for RV64 host
9. MMU notifiers supported
10. Generic dirtylog supported
11. FP lazy save/restore supported
12. SBI v0.1 emulation for KVM Guest available
13. Forward unhandled SBI calls to KVM userspace
14. Hugepage support for Guest/VM
15. IOEVENTFD support for Vhost

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_v19 branch at:
https//github.com/avpatel/linux.git

Our work-in-progress KVMTOOL RISC-V port can be found in riscv_v8 branch
at: https//github.com/avpatel/kvmtool.git

The QEMU RISC-V hypervisor emulation is done by Alistair and is available
in master branch at: https://git.qemu.org/git/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
https://github.com/kvm-riscv/howto/wiki/KVM-RISCV64-on-Spike

Changes since v18:
 - Rebased on Linux-5.14-rc3
 - Moved to new KVM debugfs interface
 - Dropped PATCH17 of v18 series for having KVM RISC-V in drivers/staging

Changes since v17:
 - Rebased on Linux-5.13-rc2
 - Moved to new KVM MMU notifier APIs
 - Removed redundant kvm_arch_vcpu_uninit()
 - Moved KVM RISC-V sources to drivers/staging for compliance with
   Linux RISC-V patch acceptance policy

Changes since v16:
 - Rebased on Linux-5.12-rc5
 - Remove redundant kvm_arch_create_memslot(), kvm_arch_vcpu_setup(),
   kvm_arch_vcpu_init(), kvm_arch_has_vcpu_debugfs(), and
   kvm_arch_create_vcpu_debugfs() from PATCH5
 - Make stage2_wp_memory_region() and stage2_ioremap() as static
   in PATCH13

Changes since v15:
 - Rebased on Linux-5.11-rc3
 - Fixed kvm_stage2_map() to use gfn_to_pfn_prot() for determing
   writeability of a host pfn.
 - Use "__u64" in-place of "u64" and "__u32" in-place of "u32" for
   uapi/asm/kvm.h

Changes since v14:
 - Rebased on Linux-5.10-rc3
 - Fixed Stage2 (G-stage) PDG allocation to ensure it is 16KB aligned

Changes since v13:
 - Rebased on Linux-5.9-rc3
 - Fixed kvm_riscv_vcpu_set_reg_csr() for SIP updation in PATCH5
 - Fixed instruction length computation in PATCH7
 - Added ioeventfd support in PATCH7
 - Ensure HSTATUS.SPVP is set to correct value before using HLV/HSV
   intructions in PATCH7
 - Fixed stage2_map_page() to set PTE 'A' and 'D' bits correctly
   in PATCH10
 - Added stage2 dirty page logging in PATCH10
 - Allow KVM user-space to SET/GET SCOUNTER CSR in PATCH5
 - Save/restore SCOUNTEREN in PATCH6
 - Reduced quite a few instructions for __kvm_riscv_switch_to() by
   using CSR swap instruction in PATCH6
 - Detect and use Sv48x4 when available in PATCH10

Changes since v12:
 - Rebased patches on Linux-5.8-rc4
 - By default enable all counters in HCOUNTEREN
 - RISC-V H-Extension v0.6.1 spec support

Changes since v11:
 - Rebased patches on Linux-5.7-rc3
 - Fixed typo in typecast of stage2_map_size define
 - Introduced struct kvm_cpu_trap to represent trap details and
   use it as function parameter wherever applicable
 - Pass memslot to kvm_riscv_stage2_map() for supporing dirty page
   logging in future
 - RISC-V H-Extension v0.6 spec support
 - Send-out first three patches as separate series so that it can
   be taken by Palmer for Linux RISC-V

Changes since v10:
 - Rebased patches on Linux-5.6-rc5
 - Reduce RISCV_ISA_EXT_MAX from 256 to 64
 - Separate PATCH for removing N-extension related defines
 - Added comments as requested by Palmer
 - Fixed HIDELEG CSR programming

Changes since v9:
 - Rebased patches on Linux-5.5-rc3
 - 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

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 (13):
  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.rst          |  193 ++++-
 MAINTAINERS                             |   12 +
 arch/riscv/Kconfig                      |    1 +
 arch/riscv/Makefile                     |    1 +
 arch/riscv/include/asm/csr.h            |   87 ++
 arch/riscv/include/asm/kvm_host.h       |  266 ++++++
 arch/riscv/include/asm/kvm_types.h      |    7 +
 arch/riscv/include/asm/kvm_vcpu_timer.h |   44 +
 arch/riscv/include/uapi/asm/kvm.h       |  128 +++
 arch/riscv/kernel/asm-offsets.c         |  156 ++++
 arch/riscv/kvm/Kconfig                  |   36 +
 arch/riscv/kvm/Makefile                 |   25 +
 arch/riscv/kvm/main.c                   |  118 +++
 arch/riscv/kvm/mmu.c                    |  802 ++++++++++++++++++
 arch/riscv/kvm/tlb.S                    |   74 ++
 arch/riscv/kvm/vcpu.c                   | 1002 +++++++++++++++++++++++
 arch/riscv/kvm/vcpu_exit.c              |  701 ++++++++++++++++
 arch/riscv/kvm/vcpu_sbi.c               |  173 ++++
 arch/riscv/kvm/vcpu_switch.S            |  400 +++++++++
 arch/riscv/kvm/vcpu_timer.c             |  225 +++++
 arch/riscv/kvm/vm.c                     |   96 +++
 arch/riscv/kvm/vmid.c                   |  120 +++
 drivers/clocksource/timer-riscv.c       |    9 +
 include/clocksource/timer-riscv.h       |   16 +
 include/uapi/linux/kvm.h                |    8 +
 25 files changed, 4691 insertions(+), 9 deletions(-)
 create mode 100644 arch/riscv/include/asm/kvm_host.h
 create mode 100644 arch/riscv/include/asm/kvm_types.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

-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 01/17] RISC-V: Add hypervisor extension related CSR defines
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 02/17] RISC-V: Add initial skeletal KVM support Anup Patel
                   ` (15 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	Anup Patel

This patch adds asm/kvm_csr.h for 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 | 87 ++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 87ac65696871..5046f431645c 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -58,22 +58,32 @@
 
 /* Interrupt causes (minus the high bit) */
 #define IRQ_S_SOFT		1
+#define IRQ_VS_SOFT		2
 #define IRQ_M_SOFT		3
 #define IRQ_S_TIMER		5
+#define IRQ_VS_TIMER		6
 #define IRQ_M_TIMER		7
 #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_VIRTUAL_INST_FAULT		22
+#define EXC_STORE_GUEST_PAGE_FAULT	23
 
 /* PMP configuration */
 #define PMP_R			0x01
@@ -85,6 +95,58 @@
 #define PMP_A_NAPOT		0x18
 #define PMP_L			0x80
 
+/* HSTATUS flags */
+#ifdef CONFIG_64BIT
+#define HSTATUS_VSXL		_AC(0x300000000, UL)
+#define HSTATUS_VSXL_SHIFT	32
+#endif
+#define HSTATUS_VTSR		_AC(0x00400000, UL)
+#define HSTATUS_VTW		_AC(0x00200000, UL)
+#define HSTATUS_VTVM		_AC(0x00100000, UL)
+#define HSTATUS_VGEIN		_AC(0x0003f000, UL)
+#define HSTATUS_VGEIN_SHIFT	12
+#define HSTATUS_HU		_AC(0x00000200, UL)
+#define HSTATUS_SPVP		_AC(0x00000100, UL)
+#define HSTATUS_SPV		_AC(0x00000080, UL)
+#define HSTATUS_GVA		_AC(0x00000040, UL)
+#define HSTATUS_VSBE		_AC(0x00000020, 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)
+
+#define HGATP_PAGE_SHIFT	12
+
+#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_SHIFT	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_SHIFT	HGATP32_MODE_SHIFT
+#endif
+
+/* VSIP & HVIP relation */
+#define VSIP_TO_HVIP_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
 #define CSR_TIME		0xc01
@@ -104,6 +166,31 @@
 #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_HCOUNTEREN		0x606
+#define CSR_HGEIE		0x607
+#define CSR_HTIMEDELTAH		0x615
+#define CSR_HTVAL		0x643
+#define CSR_HIP			0x644
+#define CSR_HVIP		0x645
+#define CSR_HTINST		0x64a
+#define CSR_HGATP		0x680
+#define CSR_HGEIP		0xe12
+
 #define CSR_MSTATUS		0x300
 #define CSR_MISA		0x301
 #define CSR_MIE			0x304
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 02/17] RISC-V: Add initial skeletal KVM support
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
  2021-07-27  5:54 ` [PATCH v19 01/17] RISC-V: Add hypervisor extension related CSR defines Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 03/17] RISC-V: KVM: Implement VCPU create, init and destroy functions Anup Patel
                   ` (14 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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                 |   1 +
 arch/riscv/Makefile                |   1 +
 arch/riscv/include/asm/kvm_host.h  |  84 ++++++++
 arch/riscv/include/asm/kvm_types.h |   7 +
 arch/riscv/include/uapi/asm/kvm.h  |  47 +++++
 arch/riscv/kvm/Kconfig             |  33 +++
 arch/riscv/kvm/Makefile            |  13 ++
 arch/riscv/kvm/main.c              |  95 +++++++++
 arch/riscv/kvm/mmu.c               |  80 ++++++++
 arch/riscv/kvm/vcpu.c              | 316 +++++++++++++++++++++++++++++
 arch/riscv/kvm/vcpu_exit.c         |  35 ++++
 arch/riscv/kvm/vm.c                |  94 +++++++++
 12 files changed, 806 insertions(+)
 create mode 100644 arch/riscv/include/asm/kvm_host.h
 create mode 100644 arch/riscv/include/asm/kvm_types.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 d8943a25a9af..14cf1ac1bcc7 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -553,4 +553,5 @@ source "kernel/power/Kconfig"
 
 endmenu
 
+source "arch/riscv/kvm/Kconfig"
 source "drivers/firmware/Kconfig"
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index bc74afdbf31e..414852ac21c5 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -100,6 +100,7 @@ endif
 head-y := arch/riscv/kernel/head.o
 
 core-$(CONFIG_RISCV_ERRATA_ALTERNATIVE) += arch/riscv/errata/
+core-$(CONFIG_KVM) += arch/riscv/kvm/
 
 libs-y += arch/riscv/lib/
 libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
new file mode 100644
index 000000000000..08a8f53bf814
--- /dev/null
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -0,0 +1,84 @@
+/* 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_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 {
+	struct kvm_vm_stat_generic generic;
+};
+
+struct kvm_vcpu_stat {
+	struct kvm_vcpu_stat_generic generic;
+	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_cpu_trap {
+	unsigned long sepc;
+	unsigned long scause;
+	unsigned long stval;
+	unsigned long htval;
+	unsigned long htinst;
+};
+
+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_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,
+			struct kvm_cpu_trap *trap);
+
+static inline void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch) {}
+
+#endif /* __RISCV_KVM_HOST_H__ */
diff --git a/arch/riscv/include/asm/kvm_types.h b/arch/riscv/include/asm/kvm_types.h
new file mode 100644
index 000000000000..e476b404eb67
--- /dev/null
+++ b/arch/riscv/include/asm/kvm_types.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_KVM_TYPES_H
+#define _ASM_RISCV_KVM_TYPES_H
+
+#define KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE 40
+
+#endif /* _ASM_RISCV_KVM_TYPES_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..984d041a3e3b
--- /dev/null
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * 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..4732094391bf
--- /dev/null
+++ b/arch/riscv/kvm/Makefile
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for RISC-V KVM support
+#
+
+ccflags-y += -I $(srctree)/$(src)
+
+KVM := ../../../virt/kvm
+
+obj-$(CONFIG_KVM) += kvm.o
+
+kvm-y += $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/binary_stats.o \
+	 main.o vm.o mmu.o vcpu.o vcpu_exit.o
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
new file mode 100644
index 000000000000..47926f0c175d
--- /dev/null
+++ b/arch/riscv/kvm/main.c
@@ -0,0 +1,95 @@
+// 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 *opaque)
+{
+	return 0;
+}
+
+int kvm_arch_hardware_setup(void *opaque)
+{
+	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_VS_SOFT);
+	hideleg |= (1UL << IRQ_VS_TIMER);
+	hideleg |= (1UL << IRQ_VS_EXT);
+	csr_write(CSR_HIDELEG, hideleg);
+
+	csr_write(CSR_HCOUNTEREN, -1UL);
+
+	csr_write(CSR_HVIP, 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..abfd2b22fa8e
--- /dev/null
+++ b/arch/riscv/kvm/mmu.c
@@ -0,0 +1,80 @@
+// 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_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
+{
+}
+
+void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free)
+{
+}
+
+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,
+				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..299442c4a988
--- /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>
+
+const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
+	KVM_GENERIC_VCPU_STATS(),
+	STATS_DESC_COUNTER(VCPU, ecall_exit_stat),
+	STATS_DESC_COUNTER(VCPU, wfi_exit_stat),
+	STATS_DESC_COUNTER(VCPU, mmio_exit_user),
+	STATS_DESC_COUNTER(VCPU, mmio_exit_kernel),
+	STATS_DESC_COUNTER(VCPU, exits)
+};
+static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) ==
+		sizeof(struct kvm_vcpu_stat) / sizeof(u64));
+
+const struct kvm_stats_header kvm_vcpu_stats_header = {
+	.name_size = KVM_STATS_NAME_SIZE,
+	.num_desc = ARRAY_SIZE(kvm_vcpu_stats_desc),
+	.id_offset = sizeof(struct kvm_stats_header),
+	.desc_offset = sizeof(struct kvm_stats_header) + KVM_STATS_NAME_SIZE,
+	.data_offset = sizeof(struct kvm_stats_header) + KVM_STATS_NAME_SIZE +
+		       sizeof(kvm_vcpu_stats_desc),
+};
+
+int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
+{
+	return 0;
+}
+
+int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
+{
+	/* TODO: */
+	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;
+}
+
+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)
+{
+	int ret;
+	struct kvm_cpu_trap trap;
+	struct kvm_run *run = vcpu->run;
+
+	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.
+		 */
+		trap.sepc = 0;
+		trap.scause = csr_read(CSR_SCAUSE);
+		trap.stval = csr_read(CSR_STVAL);
+		trap.htval = csr_read(CSR_HTVAL);
+		trap.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, &trap);
+	}
+
+	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..4484e9200fe4
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -0,0 +1,35 @@
+// 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,
+			struct kvm_cpu_trap *trap)
+{
+	/* TODO: */
+	return 0;
+}
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
new file mode 100644
index 000000000000..6b90ccdbd9c5
--- /dev/null
+++ b/arch/riscv/kvm/vm.c
@@ -0,0 +1,94 @@
+// 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>
+
+const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
+	KVM_GENERIC_VM_STATS()
+};
+static_assert(ARRAY_SIZE(kvm_vm_stats_desc) ==
+		sizeof(struct kvm_vm_stat) / sizeof(u64));
+
+const struct kvm_stats_header kvm_vm_stats_header = {
+	.name_size = KVM_STATS_NAME_SIZE,
+	.num_desc = ARRAY_SIZE(kvm_vm_stats_desc),
+	.id_offset =  sizeof(struct kvm_stats_header),
+	.desc_offset = sizeof(struct kvm_stats_header) + KVM_STATS_NAME_SIZE,
+	.data_offset = sizeof(struct kvm_stats_header) + KVM_STATS_NAME_SIZE +
+		       sizeof(kvm_vm_stats_desc),
+};
+
+int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
+{
+	/* TODO: To be added later. */
+	return -EOPNOTSUPP;
+}
+
+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;
+}
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 03/17] RISC-V: KVM: Implement VCPU create, init and destroy functions
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
  2021-07-27  5:54 ` [PATCH v19 01/17] RISC-V: Add hypervisor extension related CSR defines Anup Patel
  2021-07-27  5:54 ` [PATCH v19 02/17] RISC-V: Add initial skeletal KVM support Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 04/17] RISC-V: KVM: Implement VCPU interrupts and requests handling Anup Patel
                   ` (13 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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 | 69 +++++++++++++++++++++++++++++++
 arch/riscv/kvm/vcpu.c             | 55 ++++++++++++++++++++----
 2 files changed, 115 insertions(+), 9 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 08a8f53bf814..5fd969bd3bfd 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -57,7 +57,76 @@ struct kvm_cpu_trap {
 	unsigned long htinst;
 };
 
+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 hvip;
+	unsigned long vsatp;
+	unsigned long scounteren;
+};
+
 struct kvm_vcpu_arch {
+	/* VCPU ran at least 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 299442c4a988..eef6b772c6e2 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -40,6 +40,27 @@ const struct kvm_stats_header kvm_vcpu_stats_header = {
 		       sizeof(kvm_vcpu_stats_desc),
 };
 
+#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));
+}
+
 int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
 {
 	return 0;
@@ -47,7 +68,25 @@ int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
 
 int kvm_arch_vcpu_create(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_VTW;
+	cntx->hstatus |= HSTATUS_SPVP;
+	cntx->hstatus |= HSTATUS_SPV;
+
+	/* Reset VCPU */
+	kvm_riscv_reset_vcpu(vcpu);
+
 	return 0;
 }
 
@@ -55,15 +94,10 @@ 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: */
+	/* Flush the pages pre-allocated for Stage2 page table mappings */
+	kvm_riscv_stage2_flush_cache(vcpu);
 }
 
 int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
@@ -199,6 +233,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 	struct kvm_cpu_trap trap;
 	struct kvm_run *run = vcpu->run;
 
+	/* Mark this VCPU ran at least once */
+	vcpu->arch.ran_atleast_once = true;
+
 	vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 
 	/* Process MMIO value returned from user-space */
@@ -272,7 +309,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		 * get an interrupt between __kvm_riscv_switch_to() and
 		 * local_irq_enable() which can potentially change CSRs.
 		 */
-		trap.sepc = 0;
+		trap.sepc = vcpu->arch.guest_context.sepc;
 		trap.scause = csr_read(CSR_SCAUSE);
 		trap.stval = csr_read(CSR_STVAL);
 		trap.htval = csr_read(CSR_HTVAL);
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 04/17] RISC-V: KVM: Implement VCPU interrupts and requests handling
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (2 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 03/17] RISC-V: KVM: Implement VCPU create, init and destroy functions Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 05/17] RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls Anup Patel
                   ` (12 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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 5fd969bd3bfd..87871b11d8ec 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -127,6 +127,21 @@ 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;
 
@@ -150,4 +165,12 @@ 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 984d041a3e3b..3d3d703713c6 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 eef6b772c6e2..b6993108f377 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>
@@ -59,6 +60,9 @@ 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);
 }
 
 int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
@@ -102,8 +106,7 @@ 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)
@@ -116,20 +119,18 @@ 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;
 }
 
 vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
@@ -140,7 +141,21 @@ 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;
 }
 
@@ -189,18 +204,121 @@ 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->hvip &= ~mask;
+		csr->hvip |= val;
+	}
+}
+
+void kvm_riscv_vcpu_sync_interrupts(struct kvm_vcpu *vcpu)
+{
+	unsigned long hvip;
+	struct kvm_vcpu_arch *v = &vcpu->arch;
+	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+	/* Read current HVIP and HIE CSRs */
+	hvip = csr_read(CSR_HVIP);
+	csr->hie = csr_read(CSR_HIE);
+
+	/* Sync-up HVIP.VSSIP bit changes does by Guest */
+	if ((csr->hvip ^ hvip) & (1UL << IRQ_VS_SOFT)) {
+		if (hvip & (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,
@@ -224,7 +342,33 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 
 static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
+	struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
+
+	if (kvm_request_pending(vcpu)) {
+		if (kvm_check_request(KVM_REQ_SLEEP, vcpu)) {
+			rcuwait_wait_event(wait,
+				(!vcpu->arch.power_off) && (!vcpu->arch.pause),
+				TASK_INTERRUPTIBLE);
+
+			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_hvip(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+	csr_write(CSR_HVIP, csr->hvip);
 }
 
 int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
@@ -288,6 +432,15 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		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 HVIP CSR for current CPU */
+		kvm_riscv_update_hvip(vcpu);
+
 		if (ret <= 0 ||
 		    kvm_request_pending(vcpu)) {
 			vcpu->mode = OUTSIDE_GUEST_MODE;
@@ -315,6 +468,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		trap.htval = csr_read(CSR_HTVAL);
 		trap.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
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 05/17] RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (3 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 04/17] RISC-V: KVM: Implement VCPU interrupts and requests handling Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 06/17] RISC-V: KVM: Implement VCPU world-switch Anup Patel
                   ` (11 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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 |  53 ++++++-
 arch/riscv/kvm/vcpu.c             | 246 +++++++++++++++++++++++++++++-
 2 files changed, 295 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
index 3d3d703713c6..f7e9dc388d54 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -41,10 +41,61 @@ 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;
+	unsigned long scounteren;
+};
+
+#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 b6993108f377..a67cd9caa911 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>
 
 const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
@@ -138,6 +137,225 @@ 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 -EOPNOTSUPP;
+		}
+		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->hvip >> VSIP_TO_HVIP_SHIFT;
+		reg_val = reg_val & VSIP_VALID_MASK;
+	} else if (reg_num == KVM_REG_RISCV_CSR_REG(sie)) {
+		reg_val = csr->hie >> VSIP_TO_HVIP_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_VALID_MASK;
+		reg_val = reg_val << VSIP_TO_HVIP_SHIFT;
+	}
+
+	((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)
 {
@@ -162,8 +380,30 @@ 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,
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 06/17] RISC-V: KVM: Implement VCPU world-switch
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (4 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 05/17] RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 07/17] RISC-V: KVM: Handle MMIO exits for VCPU Anup Patel
                   ` (10 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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 |  10 +-
 arch/riscv/kernel/asm-offsets.c   |  78 ++++++++++++
 arch/riscv/kvm/Makefile           |   2 +-
 arch/riscv/kvm/vcpu.c             |  30 ++++-
 arch/riscv/kvm/vcpu_switch.S      | 203 ++++++++++++++++++++++++++++++
 5 files changed, 319 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 87871b11d8ec..846f74e587e0 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -115,6 +115,14 @@ struct kvm_vcpu_arch {
 	/* ISA feature bits (similar to MISA) */
 	unsigned long isa;
 
+	/* SSCRATCH, STVEC, and SCOUNTEREN of Host */
+	unsigned long host_sscratch;
+	unsigned long host_stvec;
+	unsigned long host_scounteren;
+
+	/* CPU context of Host */
+	struct kvm_cpu_context host_context;
+
 	/* CPU context of Guest VCPU */
 	struct kvm_cpu_context guest_context;
 
@@ -163,7 +171,7 @@ 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,
 			struct kvm_cpu_trap *trap);
 
-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 90f8ce64fa6f..2fac70303341 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>
 
@@ -111,6 +113,82 @@ 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_GUEST_SCOUNTEREN, kvm_vcpu_arch, guest_csr.scounteren);
+
+	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);
+	OFFSET(KVM_ARCH_HOST_SCOUNTEREN, kvm_vcpu_arch, host_scounteren);
+
 	/*
 	 * 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 4732094391bf..9e8133c898dc 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -10,4 +10,4 @@ KVM := ../../../virt/kvm
 obj-$(CONFIG_KVM) += kvm.o
 
 kvm-y += $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/binary_stats.o \
-	 main.o vm.o mmu.o vcpu.o vcpu_exit.o
+	 main.o vm.o mmu.o vcpu.o vcpu_exit.o vcpu_switch.o
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index a67cd9caa911..91135e12caf6 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -570,14 +570,40 @@ 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_HVIP, csr->hvip);
+	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->hvip = csr_read(CSR_HVIP);
+	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..5174b025ff4e
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_switch.S
@@ -0,0 +1,203 @@
+/* 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 and Restore Guest SSTATUS */
+	REG_L	t0, (KVM_ARCH_GUEST_SSTATUS)(a0)
+	csrrw	t0, CSR_SSTATUS, t0
+	REG_S	t0, (KVM_ARCH_HOST_SSTATUS)(a0)
+
+	/* Save Host and Restore Guest HSTATUS */
+	REG_L	t1, (KVM_ARCH_GUEST_HSTATUS)(a0)
+	csrrw	t1, CSR_HSTATUS, t1
+	REG_S	t1, (KVM_ARCH_HOST_HSTATUS)(a0)
+
+	/* Save Host and Restore Guest SCOUNTEREN */
+	REG_L	t2, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
+	csrrw	t2, CSR_SCOUNTEREN, t2
+	REG_S	t2, (KVM_ARCH_HOST_SCOUNTEREN)(a0)
+
+	/* Save Host SSCRATCH and change it to struct kvm_vcpu_arch pointer */
+	csrrw	t3, CSR_SSCRATCH, a0
+	REG_S	t3, (KVM_ARCH_HOST_SSCRATCH)(a0)
+
+	/* Save Host STVEC and change it to return path */
+	la	t4, __kvm_switch_return
+	csrrw	t4, CSR_STVEC, t4
+	REG_S	t4, (KVM_ARCH_HOST_STVEC)(a0)
+
+	/* Restore Guest SEPC */
+	REG_L	t0, (KVM_ARCH_GUEST_SEPC)(a0)
+	csrw	CSR_SEPC, t0
+
+	/* 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)
+
+	/* 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 SEPC */
+	csrr	t0, CSR_SEPC
+	REG_S	t0, (KVM_ARCH_GUEST_SEPC)(a0)
+
+	/* Restore Host STVEC */
+	REG_L	t1, (KVM_ARCH_HOST_STVEC)(a0)
+	csrw	CSR_STVEC, t1
+
+	/* Save Guest A0 and Restore Host SSCRATCH */
+	REG_L	t2, (KVM_ARCH_HOST_SSCRATCH)(a0)
+	csrrw	t2, CSR_SSCRATCH, t2
+	REG_S	t2, (KVM_ARCH_GUEST_A0)(a0)
+
+	/* Save Guest and Restore Host SCOUNTEREN */
+	REG_L	t3, (KVM_ARCH_HOST_SCOUNTEREN)(a0)
+	csrrw	t3, CSR_SCOUNTEREN, t3
+	REG_S	t3, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
+
+	/* Save Guest and Restore Host HSTATUS */
+	REG_L	t4, (KVM_ARCH_HOST_HSTATUS)(a0)
+	csrrw	t4, CSR_HSTATUS, t4
+	REG_S	t4, (KVM_ARCH_GUEST_HSTATUS)(a0)
+
+	/* Save Guest and Restore Host SSTATUS */
+	REG_L	t5, (KVM_ARCH_HOST_SSTATUS)(a0)
+	csrrw	t5, CSR_SSTATUS, t5
+	REG_S	t5, (KVM_ARCH_GUEST_SSTATUS)(a0)
+
+	/* 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)
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 07/17] RISC-V: KVM: Handle MMIO exits for VCPU
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (5 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 06/17] RISC-V: KVM: Implement VCPU world-switch Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 08/17] RISC-V: KVM: Handle WFI " Anup Patel
                   ` (9 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	Anup Patel, Yifei Jiang

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.

[jiangyifei: ioeventfd and in-kernel mmio device support]
Signed-off-by: Yifei Jiang <jiangyifei@huawei.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 |  22 ++
 arch/riscv/kernel/asm-offsets.c   |   6 +
 arch/riscv/kvm/Kconfig            |   1 +
 arch/riscv/kvm/Makefile           |   2 +-
 arch/riscv/kvm/mmu.c              |   8 +
 arch/riscv/kvm/vcpu_exit.c        | 592 +++++++++++++++++++++++++++++-
 arch/riscv/kvm/vcpu_switch.S      |  23 ++
 arch/riscv/kvm/vm.c               |   1 +
 8 files changed, 651 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 846f74e587e0..dc5ea380178a 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -49,6 +49,14 @@ struct kvm_arch {
 	phys_addr_t pgd_phys;
 };
 
+struct kvm_mmio_decode {
+	unsigned long insn;
+	int insn_len;
+	int len;
+	int shift;
+	int return_handled;
+};
+
 struct kvm_cpu_trap {
 	unsigned long sepc;
 	unsigned long scause;
@@ -147,6 +155,9 @@ 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;
 
@@ -162,11 +173,22 @@ static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 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,
+			 struct kvm_memory_slot *memslot,
+			 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,
+					 struct kvm_cpu_trap *trap);
+void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
+				  struct kvm_cpu_trap *trap);
 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,
 			struct kvm_cpu_trap *trap);
diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
index 2fac70303341..91c77555d914 100644
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
@@ -189,6 +189,12 @@ void asm_offsets(void)
 	OFFSET(KVM_ARCH_HOST_STVEC, kvm_vcpu_arch, host_stvec);
 	OFFSET(KVM_ARCH_HOST_SCOUNTEREN, kvm_vcpu_arch, host_scounteren);
 
+	OFFSET(KVM_ARCH_TRAP_SEPC, kvm_cpu_trap, sepc);
+	OFFSET(KVM_ARCH_TRAP_SCAUSE, kvm_cpu_trap, scause);
+	OFFSET(KVM_ARCH_TRAP_STVAL, kvm_cpu_trap, stval);
+	OFFSET(KVM_ARCH_TRAP_HTVAL, kvm_cpu_trap, htval);
+	OFFSET(KVM_ARCH_TRAP_HTINST, kvm_cpu_trap, htinst);
+
 	/*
 	 * 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/Kconfig b/arch/riscv/kvm/Kconfig
index 88edd477b3a8..b42979f84042 100644
--- a/arch/riscv/kvm/Kconfig
+++ b/arch/riscv/kvm/Kconfig
@@ -24,6 +24,7 @@ config KVM
 	select ANON_INODES
 	select KVM_MMIO
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
+	select HAVE_KVM_EVENTFD
 	select SRCU
 	help
 	  Support hosting virtualized guest machines.
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index 9e8133c898dc..1e1c3e1e4e1b 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -10,4 +10,4 @@ KVM := ../../../virt/kvm
 obj-$(CONFIG_KVM) += kvm.o
 
 kvm-y += $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/binary_stats.o \
-	 main.o vm.o mmu.o vcpu.o vcpu_exit.o vcpu_switch.o
+	 $(KVM)/eventfd.o main.o vm.o mmu.o vcpu.o vcpu_exit.o vcpu_switch.o
diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index abfd2b22fa8e..8ec10ef861e7 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -58,6 +58,14 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	return 0;
 }
 
+int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu,
+			 struct kvm_memory_slot *memslot,
+			 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 4484e9200fe4..dc66be032ad7 100644
--- a/arch/riscv/kvm/vcpu_exit.c
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -6,9 +6,518 @@
  *     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)
+{
+	u8 data_buf[8];
+	unsigned long insn;
+	int shift = 0, len = 0, insn_len = 0;
+	struct kvm_cpu_trap utrap = { 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;
+		insn_len = (htinst & BIT(1)) ? INSN_LEN(insn) : 2;
+	} else {
+		/*
+		 * Bit[0] == 0 implies trapped instruction value is
+		 * zero or special value.
+		 */
+		insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc,
+						  &utrap);
+		if (utrap.scause) {
+			/* Redirect trap if we failed to read instruction */
+			utrap.sepc = ct->sepc;
+			kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
+			return 1;
+		}
+		insn_len = INSN_LEN(insn);
+	}
+
+	/* 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 -EOPNOTSUPP;
+	}
+
+	/* 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.insn_len = insn_len;
+	vcpu->arch.mmio_decode.shift = shift;
+	vcpu->arch.mmio_decode.len = len;
+	vcpu->arch.mmio_decode.return_handled = 0;
+
+	/* Update MMIO details in kvm_run struct */
+	run->mmio.is_write = false;
+	run->mmio.phys_addr = fault_addr;
+	run->mmio.len = len;
+
+	/* Try to handle MMIO access in the kernel */
+	if (!kvm_io_bus_read(vcpu, KVM_MMIO_BUS, fault_addr, len, data_buf)) {
+		/* Successfully handled MMIO access in the kernel so resume */
+		memcpy(run->mmio.data, data_buf, len);
+		vcpu->stat.mmio_exit_kernel++;
+		kvm_riscv_vcpu_mmio_return(vcpu, run);
+		return 1;
+	}
+
+	/* Exit to userspace for MMIO emulation */
+	vcpu->stat.mmio_exit_user++;
+	run->exit_reason = KVM_EXIT_MMIO;
+
+	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;
+	unsigned long insn;
+	int len = 0, insn_len = 0;
+	struct kvm_cpu_trap utrap = { 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;
+		insn_len = (htinst & BIT(1)) ? INSN_LEN(insn) : 2;
+	} else {
+		/*
+		 * Bit[0] == 0 implies trapped instruction value is
+		 * zero or special value.
+		 */
+		insn = kvm_riscv_vcpu_unpriv_read(vcpu, true, ct->sepc,
+						  &utrap);
+		if (utrap.scause) {
+			/* Redirect trap if we failed to read instruction */
+			utrap.sepc = ct->sepc;
+			kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
+			return 1;
+		}
+		insn_len = INSN_LEN(insn);
+	}
+
+	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 -EOPNOTSUPP;
+	}
+
+	/* 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.insn_len = insn_len;
+	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 -EOPNOTSUPP;
+	};
+
+	/* Update MMIO details in kvm_run struct */
+	run->mmio.is_write = true;
+	run->mmio.phys_addr = fault_addr;
+	run->mmio.len = len;
+
+	/* Try to handle MMIO access in the kernel */
+	if (!kvm_io_bus_write(vcpu, KVM_MMIO_BUS,
+			      fault_addr, len, run->mmio.data)) {
+		/* Successfully handled MMIO access in the kernel so resume */
+		vcpu->stat.mmio_exit_kernel++;
+		kvm_riscv_vcpu_mmio_return(vcpu, run);
+		return 1;
+	}
+
+	/* Exit to userspace for MMIO emulation */
+	vcpu->stat.mmio_exit_user++;
+	run->exit_reason = KVM_EXIT_MMIO;
+
+	return 0;
+}
+
+static int stage2_page_fault(struct kvm_vcpu *vcpu, struct kvm_run *run,
+			     struct kvm_cpu_trap *trap)
+{
+	struct kvm_memory_slot *memslot;
+	unsigned long hva, fault_addr;
+	bool writeable;
+	gfn_t gfn;
+	int ret;
+
+	fault_addr = (trap->htval << 2) | (trap->stval & 0x3);
+	gfn = fault_addr >> PAGE_SHIFT;
+	memslot = gfn_to_memslot(vcpu->kvm, gfn);
+	hva = gfn_to_hva_memslot_prot(memslot, gfn, &writeable);
+
+	if (kvm_is_error_hva(hva) ||
+	    (trap->scause == EXC_STORE_GUEST_PAGE_FAULT && !writeable)) {
+		switch (trap->scause) {
+		case EXC_LOAD_GUEST_PAGE_FAULT:
+			return emulate_load(vcpu, run, fault_addr,
+					    trap->htinst);
+		case EXC_STORE_GUEST_PAGE_FAULT:
+			return emulate_store(vcpu, run, fault_addr,
+					     trap->htinst);
+		default:
+			return -EOPNOTSUPP;
+		};
+	}
+
+	ret = kvm_riscv_stage2_map(vcpu, memslot, fault_addr, hva,
+		(trap->scause == EXC_STORE_GUEST_PAGE_FAULT) ? true : false);
+	if (ret < 0)
+		return ret;
+
+	return 1;
+}
+
+/**
+ * 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: Output pointer to trap details
+ */
+unsigned long kvm_riscv_vcpu_unpriv_read(struct kvm_vcpu *vcpu,
+					 bool read_insn,
+					 unsigned long guest_addr,
+					 struct kvm_cpu_trap *trap)
+{
+	register unsigned long taddr asm("a0") = (unsigned long)trap;
+	register unsigned long ttmp asm("a1");
+	register unsigned long val asm("t0");
+	register unsigned long tmp asm("t1");
+	register unsigned long addr asm("t2") = guest_addr;
+	unsigned long flags;
+	unsigned long old_stvec, old_hstatus;
+
+	local_irq_save(flags);
+
+	old_hstatus = csr_swap(CSR_HSTATUS, vcpu->arch.guest_context.hstatus);
+	old_stvec = csr_swap(CSR_STVEC, (ulong)&__kvm_riscv_unpriv_trap);
+
+	if (read_insn) {
+		/*
+		 * HLVX.HU instruction
+		 * 0110010 00011 rs1 100 rd 1110011
+		 */
+		asm volatile ("\n"
+			".option push\n"
+			".option norvc\n"
+			"add %[ttmp], %[taddr], 0\n"
+			/*
+			 * HLVX.HU %[val], (%[addr])
+			 * HLVX.HU t0, (t2)
+			 * 0110010 00011 00111 100 00101 1110011
+			 */
+			".word 0x6433c2f3\n"
+			"andi %[tmp], %[val], 3\n"
+			"addi %[tmp], %[tmp], -3\n"
+			"bne %[tmp], zero, 2f\n"
+			"addi %[addr], %[addr], 2\n"
+			/*
+			 * HLVX.HU %[tmp], (%[addr])
+			 * HLVX.HU t1, (t2)
+			 * 0110010 00011 00111 100 00110 1110011
+			 */
+			".word 0x6433c373\n"
+			"sll %[tmp], %[tmp], 16\n"
+			"add %[val], %[val], %[tmp]\n"
+			"2:\n"
+			".option pop"
+		: [val] "=&r" (val), [tmp] "=&r" (tmp),
+		  [taddr] "+&r" (taddr), [ttmp] "+&r" (ttmp),
+		  [addr] "+&r" (addr) : : "memory");
+
+		if (trap->scause == EXC_LOAD_PAGE_FAULT)
+			trap->scause = EXC_INST_PAGE_FAULT;
+	} else {
+		/*
+		 * HLV.D instruction
+		 * 0110110 00000 rs1 100 rd 1110011
+		 *
+		 * HLV.W instruction
+		 * 0110100 00000 rs1 100 rd 1110011
+		 */
+		asm volatile ("\n"
+			".option push\n"
+			".option norvc\n"
+			"add %[ttmp], %[taddr], 0\n"
+#ifdef CONFIG_64BIT
+			/*
+			 * HLV.D %[val], (%[addr])
+			 * HLV.D t0, (t2)
+			 * 0110110 00000 00111 100 00101 1110011
+			 */
+			".word 0x6c03c2f3\n"
+#else
+			/*
+			 * HLV.W %[val], (%[addr])
+			 * HLV.W t0, (t2)
+			 * 0110100 00000 00111 100 00101 1110011
+			 */
+			".word 0x6803c2f3\n"
+#endif
+			".option pop"
+		: [val] "=&r" (val),
+		  [taddr] "+&r" (taddr), [ttmp] "+&r" (ttmp)
+		: [addr] "r" (addr) : "memory");
+	}
+
+	csr_write(CSR_STVEC, old_stvec);
+	csr_write(CSR_HSTATUS, old_hstatus);
+
+	local_irq_restore(flags);
+
+	return val;
+}
+
+/**
+ * kvm_riscv_vcpu_trap_redirect -- Redirect trap to Guest
+ *
+ * @vcpu: The VCPU pointer
+ * @trap: Trap details
+ */
+void kvm_riscv_vcpu_trap_redirect(struct kvm_vcpu *vcpu,
+				  struct kvm_cpu_trap *trap)
+{
+	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, trap->scause);
+	csr_write(CSR_VSTVAL, trap->stval);
+	csr_write(CSR_VSEPC, trap->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 +528,54 @@
  */
 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 -EOPNOTSUPP;
+	};
+
+done:
+	/* Move to next instruction */
+	vcpu->arch.guest_context.sepc += vcpu->arch.mmio_decode.insn_len;
+
 	return 0;
 }
 
@@ -30,6 +586,36 @@ 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,
 			struct kvm_cpu_trap *trap)
 {
-	/* TODO: */
-	return 0;
+	int ret;
+
+	/* If we got host interrupt then do nothing */
+	if (trap->scause & CAUSE_IRQ_FLAG)
+		return 1;
+
+	/* Handle guest traps */
+	ret = -EFAULT;
+	run->exit_reason = KVM_EXIT_UNKNOWN;
+	switch (trap->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, trap);
+		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 HTVAL=0x%lx HTINST=0x%lx\n",
+			trap->scause, trap->stval, trap->htval, trap->htinst);
+	}
+
+	return ret;
 }
diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S
index 5174b025ff4e..e22721e1b892 100644
--- a/arch/riscv/kvm/vcpu_switch.S
+++ b/arch/riscv/kvm/vcpu_switch.S
@@ -201,3 +201,26 @@ __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
+	 * 4-byte long and blindly increment SEPC by 4.
+	 *
+	 * The trap details will be saved at address pointed by 'A0'
+	 * register and we use 'A1' register as temporary.
+	 */
+	csrr	a1, CSR_SEPC
+	REG_S	a1, (KVM_ARCH_TRAP_SEPC)(a0)
+	addi	a1, a1, 4
+	csrw	CSR_SEPC, a1
+	csrr	a1, CSR_SCAUSE
+	REG_S	a1, (KVM_ARCH_TRAP_SCAUSE)(a0)
+	csrr	a1, CSR_STVAL
+	REG_S	a1, (KVM_ARCH_TRAP_STVAL)(a0)
+	csrr	a1, CSR_HTVAL
+	REG_S	a1, (KVM_ARCH_TRAP_HTVAL)(a0)
+	csrr	a1, CSR_HTINST
+	REG_S	a1, (KVM_ARCH_TRAP_HTINST)(a0)
+	sret
+ENDPROC(__kvm_riscv_unpriv_trap)
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index 6b90ccdbd9c5..d96d8d0f1ef2 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -61,6 +61,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	int r;
 
 	switch (ext) {
+	case KVM_CAP_IOEVENTFD:
 	case KVM_CAP_DEVICE_CTRL:
 	case KVM_CAP_USER_MEMORY:
 	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 08/17] RISC-V: KVM: Handle WFI exits for VCPU
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (6 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 07/17] RISC-V: KVM: Handle MMIO exits for VCPU Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 09/17] RISC-V: KVM: Implement VMID allocator Anup Patel
                   ` (8 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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 | 76 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)

diff --git a/arch/riscv/kvm/vcpu_exit.c b/arch/riscv/kvm/vcpu_exit.c
index dc66be032ad7..1873b8c35101 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 +123,71 @@
 				 (s32)(((insn) >> 7) & 0x1f))
 #define MASK_FUNCT3		0x7000
 
+static int truly_illegal_insn(struct kvm_vcpu *vcpu,
+			      struct kvm_run *run,
+			      ulong insn)
+{
+	struct kvm_cpu_trap utrap = { 0 };
+
+	/* Redirect trap to Guest VCPU */
+	utrap.sepc = vcpu->arch.guest_context.sepc;
+	utrap.scause = EXC_INST_ILLEGAL;
+	utrap.stval = insn;
+	kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
+
+	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 virtual_inst_fault(struct kvm_vcpu *vcpu, struct kvm_run *run,
+			      struct kvm_cpu_trap *trap)
+{
+	unsigned long insn = trap->stval;
+	struct kvm_cpu_trap utrap = { 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,
+							  &utrap);
+			if (utrap.scause) {
+				utrap.sepc = ct->sepc;
+				kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
+				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)
 {
@@ -596,6 +668,10 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 	ret = -EFAULT;
 	run->exit_reason = KVM_EXIT_UNKNOWN;
 	switch (trap->scause) {
+	case EXC_VIRTUAL_INST_FAULT:
+		if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
+			ret = virtual_inst_fault(vcpu, run, trap);
+		break;
 	case EXC_INST_GUEST_PAGE_FAULT:
 	case EXC_LOAD_GUEST_PAGE_FAULT:
 	case EXC_STORE_GUEST_PAGE_FAULT:
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 09/17] RISC-V: KVM: Implement VMID allocator
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (7 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 08/17] RISC-V: KVM: Handle WFI " Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 10/17] RISC-V: KVM: Implement stage2 page table programming Anup Patel
                   ` (7 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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 |  24 ++++++
 arch/riscv/kvm/Makefile           |  14 +++-
 arch/riscv/kvm/main.c             |   4 +
 arch/riscv/kvm/tlb.S              |  74 ++++++++++++++++++
 arch/riscv/kvm/vcpu.c             |   9 +++
 arch/riscv/kvm/vm.c               |   6 ++
 arch/riscv/kvm/vmid.c             | 120 ++++++++++++++++++++++++++++++
 7 files changed, 249 insertions(+), 2 deletions(-)
 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 dc5ea380178a..51e48e70522e 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -26,6 +26,7 @@
 #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 {
 	struct kvm_vm_stat_generic generic;
@@ -43,7 +44,19 @@ 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;
@@ -173,6 +186,11 @@ static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 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 gpa, unsigned long vmid);
+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,
 			 struct kvm_memory_slot *memslot,
 			 gpa_t gpa, unsigned long hva, bool is_write);
@@ -181,6 +199,12 @@ 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 1e1c3e1e4e1b..a0274763e096 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -9,5 +9,15 @@ KVM := ../../../virt/kvm
 
 obj-$(CONFIG_KVM) += kvm.o
 
-kvm-y += $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/binary_stats.o \
-	 $(KVM)/eventfd.o main.o vm.o mmu.o vcpu.o vcpu_exit.o vcpu_switch.o
+kvm-y += $(KVM)/kvm_main.o
+kvm-y += $(KVM)/coalesced_mmio.o
+kvm-y += $(KVM)/binary_stats.o
+kvm-y += $(KVM)/eventfd.o
+kvm-y += main.o
+kvm-y += vm.o
+kvm-y += vmid.o
+kvm-y += tlb.o
+kvm-y += mmu.o
+kvm-y += vcpu.o
+kvm-y += vcpu_exit.o
+kvm-y += vcpu_switch.o
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
index 47926f0c175d..49a4941e3838 100644
--- a/arch/riscv/kvm/main.c
+++ b/arch/riscv/kvm/main.c
@@ -79,8 +79,12 @@ int kvm_arch_init(void *opaque)
 		return -ENODEV;
 	}
 
+	kvm_riscv_stage2_vmid_detect();
+
 	kvm_info("hypervisor extension available\n");
 
+	kvm_info("VMID %ld bits available\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..c858570f0856
--- /dev/null
+++ b/arch/riscv/kvm/tlb.S
@@ -0,0 +1,74 @@
+/* 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:
+	 * HFENCE.GVMA rs1, rs2
+	 * HFENCE.GVMA zero, rs2
+	 * HFENCE.GVMA rs1
+	 * HFENCE.GVMA
+	 *
+	 * rs1!=zero and rs2!=zero ==> HFENCE.GVMA rs1, rs2
+	 * rs1==zero and rs2!=zero ==> HFENCE.GVMA zero, rs2
+	 * rs1!=zero and rs2==zero ==> HFENCE.GVMA rs1
+	 * rs1==zero and rs2==zero ==> HFENCE.GVMA
+	 *
+	 * Instruction encoding of HFENCE.GVMA is:
+	 * 0110001 rs2(5) rs1(5) 000 00000 1110011
+	 */
+
+ENTRY(__kvm_riscv_hfence_gvma_vmid_gpa)
+	/*
+	 * rs1 = a0 (GPA)
+	 * rs2 = a1 (VMID)
+	 * HFENCE.GVMA a0, a1
+	 * 0110001 01011 01010 000 00000 1110011
+	 */
+	.word 0x62b50073
+	ret
+ENDPROC(__kvm_riscv_hfence_gvma_vmid_gpa)
+
+ENTRY(__kvm_riscv_hfence_gvma_vmid)
+	/*
+	 * rs1 = zero
+	 * rs2 = a0 (VMID)
+	 * HFENCE.GVMA zero, a0
+	 * 0110001 01010 00000 000 00000 1110011
+	 */
+	.word 0x62a00073
+	ret
+ENDPROC(__kvm_riscv_hfence_gvma_vmid)
+
+ENTRY(__kvm_riscv_hfence_gvma_gpa)
+	/*
+	 * rs1 = a0 (GPA)
+	 * rs2 = zero
+	 * HFENCE.GVMA a0
+	 * 0110001 00000 01010 000 00000 1110011
+	 */
+	.word 0x62050073
+	ret
+ENDPROC(__kvm_riscv_hfence_gvma_gpa)
+
+ENTRY(__kvm_riscv_hfence_gvma_all)
+	/*
+	 * rs1 = zero
+	 * rs2 = zero
+	 * HFENCE.GVMA
+	 * 0110001 00000 00000 000 00000 1110011
+	 */
+	.word 0x62000073
+	ret
+ENDPROC(__kvm_riscv_hfence_gvma_all)
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 91135e12caf6..e565bb158172 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -627,6 +627,12 @@ 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();
 	}
 }
 
@@ -672,6 +678,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		/* Check conditions before entering the guest */
 		cond_resched();
 
+		kvm_riscv_stage2_vmid_update(vcpu);
+
 		kvm_riscv_check_vcpu_requests(vcpu);
 
 		preempt_disable();
@@ -708,6 +716,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		kvm_riscv_update_hvip(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 d96d8d0f1ef2..a42559ed48c1 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -41,6 +41,12 @@ 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);
+}
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 10/17] RISC-V: KVM: Implement stage2 page table programming
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (8 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 09/17] RISC-V: KVM: Implement VMID allocator Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 11/17] RISC-V: KVM: Implement MMU notifiers Anup Patel
                   ` (6 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	Anup Patel, Yifei Jiang

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.

[jiangyifei: stage2 dirty log support]
Signed-off-by: Yifei Jiang <jiangyifei@huawei.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 |  12 +
 arch/riscv/kvm/Kconfig            |   1 +
 arch/riscv/kvm/main.c             |  19 +
 arch/riscv/kvm/mmu.c              | 654 +++++++++++++++++++++++++++++-
 arch/riscv/kvm/vm.c               |   6 -
 5 files changed, 676 insertions(+), 16 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 51e48e70522e..33255c5dd555 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -70,6 +70,13 @@ 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_trap {
 	unsigned long sepc;
 	unsigned long scause;
@@ -171,6 +178,9 @@ 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;
 
@@ -198,6 +208,8 @@ 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_stage2_mode_detect(void);
+unsigned long kvm_riscv_stage2_mode(void);
 
 void kvm_riscv_stage2_vmid_detect(void);
 unsigned long kvm_riscv_stage2_vmid_bits(void);
diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
index b42979f84042..633063edaee8 100644
--- a/arch/riscv/kvm/Kconfig
+++ b/arch/riscv/kvm/Kconfig
@@ -23,6 +23,7 @@ config KVM
 	select PREEMPT_NOTIFIERS
 	select ANON_INODES
 	select KVM_MMIO
+	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select HAVE_KVM_EVENTFD
 	select SRCU
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
index 49a4941e3838..421ecf4e6360 100644
--- a/arch/riscv/kvm/main.c
+++ b/arch/riscv/kvm/main.c
@@ -64,6 +64,8 @@ void kvm_arch_hardware_disable(void)
 
 int kvm_arch_init(void *opaque)
 {
+	const char *str;
+
 	if (!riscv_isa_extension_available(NULL, h)) {
 		kvm_info("hypervisor extension not available\n");
 		return -ENODEV;
@@ -79,10 +81,27 @@ int kvm_arch_init(void *opaque)
 		return -ENODEV;
 	}
 
+	kvm_riscv_stage2_mode_detect();
+
 	kvm_riscv_stage2_vmid_detect();
 
 	kvm_info("hypervisor extension available\n");
 
+	switch (kvm_riscv_stage2_mode()) {
+	case HGATP_MODE_SV32X4:
+		str = "Sv32x4";
+		break;
+	case HGATP_MODE_SV39X4:
+		str = "Sv39x4";
+		break;
+	case HGATP_MODE_SV48X4:
+		str = "Sv48x4";
+		break;
+	default:
+		return -ENODEV;
+	}
+	kvm_info("using %s G-stage page table format\n", str);
+
 	kvm_info("VMID %ld bits available\n", kvm_riscv_stage2_vmid_bits());
 
 	return 0;
diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index 8ec10ef861e7..fa9a4f9b9542 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -15,13 +15,421 @@
 #include <linux/vmalloc.h>
 #include <linux/kvm_host.h>
 #include <linux/sched/signal.h>
+#include <asm/csr.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
+#include <asm/sbi.h>
+
+#ifdef CONFIG_64BIT
+static unsigned long stage2_mode = (HGATP_MODE_SV39X4 << HGATP_MODE_SHIFT);
+static unsigned long stage2_pgd_levels = 3;
+#define stage2_index_bits	9
+#else
+static unsigned long stage2_mode = (HGATP_MODE_SV32X4 << HGATP_MODE_SHIFT);
+static unsigned long stage2_pgd_levels = 2;
+#define stage2_index_bits	10
+#endif
+
+#define stage2_pgd_xbits	2
+#define stage2_pgd_size	(1UL << (HGATP_PAGE_SHIFT + stage2_pgd_xbits))
+#define stage2_gpa_bits	(HGATP_PAGE_SHIFT + \
+			 (stage2_pgd_levels * stage2_index_bits) + \
+			 stage2_pgd_xbits)
+#define stage2_gpa_size	((gpa_t)(1ULL << stage2_gpa_bits))
+
+#define stage2_pte_leaf(__ptep)	\
+	(pte_val(*(__ptep)) & (_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC))
+
+static inline unsigned long stage2_pte_index(gpa_t addr, u32 level)
+{
+	unsigned long mask;
+	unsigned long shift = HGATP_PAGE_SHIFT + (stage2_index_bits * level);
+
+	if (level == (stage2_pgd_levels - 1))
+		mask = (PTRS_PER_PTE * (1UL << stage2_pgd_xbits)) - 1;
+	else
+		mask = PTRS_PER_PTE - 1;
+
+	return (addr >> shift) & mask;
+}
+
+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)
+{
+	u32 i;
+	unsigned long psz = 1UL << 12;
+
+	for (i = 0; i < stage2_pgd_levels; i++) {
+		if (page_size == (psz << (i * stage2_index_bits))) {
+			*out_level = i;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int stage2_level_to_page_size(u32 level, unsigned long *out_pgsize)
+{
+	if (stage2_pgd_levels < level)
+		return -EINVAL;
+
+	*out_pgsize = 1UL << (12 + (level * stage2_index_bits));
+
+	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 (stage2_pte_leaf(ptep)) {
+			*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 (stage2_pte_leaf(ptep))
+			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 (stage2_pte_leaf(ptep))
+				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 (stage2_pte_leaf(ptep))
+		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,
+			   bool page_rdonly, bool page_exec)
+{
+	int ret;
+	u32 level = 0;
+	pte_t new_pte;
+	pgprot_t prot;
+
+	ret = stage2_page_size_to_level(page_size, &level);
+	if (ret)
+		return ret;
+
+	/*
+	 * A RISC-V implementation can choose to either:
+	 * 1) Update 'A' and 'D' PTE bits in hardware
+	 * 2) Generate page fault when 'A' and/or 'D' bits are not set
+	 *    PTE so that software can update these bits.
+	 *
+	 * We support both options mentioned above. To achieve this, we
+	 * always set 'A' and 'D' PTE bits at time of creating stage2
+	 * mapping. To support KVM dirty page logging with both options
+	 * mentioned above, we will write-protect stage2 PTEs to track
+	 * dirty pages.
+	 */
+
+	if (page_exec) {
+		if (page_rdonly)
+			prot = PAGE_READ_EXEC;
+		else
+			prot = PAGE_WRITE_EXEC;
+	} else {
+		if (page_rdonly)
+			prot = PAGE_READ;
+		else
+			prot = PAGE_WRITE;
+	}
+	new_pte = pfn_pte(PFN_DOWN(hpa), prot);
+	new_pte = pte_mkdirty(new_pte);
+
+	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 && !stage2_pte_leaf(ptep)) {
+		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;
+	}
+}
+
+static 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);
+}
+
+static 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_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
+					     struct kvm_memory_slot *slot,
+					     gfn_t gfn_offset,
+					     unsigned long mask)
+{
+	phys_addr_t base_gfn = slot->base_gfn + gfn_offset;
+	phys_addr_t start = (base_gfn +  __ffs(mask)) << PAGE_SHIFT;
+	phys_addr_t end = (base_gfn + __fls(mask) + 1) << PAGE_SHIFT;
+
+	stage2_wp_range(kvm, start, end);
+}
 
 void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
 {
 }
 
+void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
+					const struct kvm_memory_slot *memslot)
+{
+	kvm_flush_remote_tlbs(kvm);
+}
+
 void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free)
 {
 }
@@ -32,7 +440,7 @@ 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,
@@ -46,7 +454,13 @@ 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 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,
@@ -54,35 +468,255 @@ 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;
+
+	mmap_read_lock(current->mm);
+
+	/*
+	 * 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:
+	mmap_read_unlock(current->mm);
+	return ret;
 }
 
 int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu,
 			 struct kvm_memory_slot *memslot,
 			 gpa_t gpa, unsigned long hva, bool is_write)
 {
-	/* TODO: */
-	return 0;
+	int ret;
+	kvm_pfn_t hfn;
+	bool writeable;
+	short vma_pageshift;
+	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;
+	bool logging = (memslot->dirty_bitmap &&
+			!(memslot->flags & KVM_MEM_READONLY)) ? true : false;
+	unsigned long vma_pagesize;
+
+	mmap_read_lock(current->mm);
+
+	vma = find_vma_intersection(current->mm, hva, hva + 1);
+	if (unlikely(!vma)) {
+		kvm_err("Failed to find VMA for hva 0x%lx\n", hva);
+		mmap_read_unlock(current->mm);
+		return -EFAULT;
+	}
+
+	if (is_vm_hugetlb_page(vma))
+		vma_pageshift = huge_page_shift(hstate_vma(vma));
+	else
+		vma_pageshift = PAGE_SHIFT;
+	vma_pagesize = 1ULL << vma_pageshift;
+	if (logging || (vma->vm_flags & VM_PFNMAP))
+		vma_pagesize = PAGE_SIZE;
+
+	if (vma_pagesize == PMD_SIZE || vma_pagesize == PGDIR_SIZE)
+		gfn = (gpa & huge_page_mask(hstate_vma(vma))) >> PAGE_SHIFT;
+
+	mmap_read_unlock(current->mm);
+
+	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) {
+		send_sig_mceerr(BUS_MCEERR_AR, (void __user *)hva,
+				vma_pageshift, current);
+		return 0;
+	}
+	if (is_error_noslot_pfn(hfn))
+		return -EFAULT;
+
+	/*
+	 * If logging is active then we allow writable pages only
+	 * for write faults.
+	 */
+	if (logging && !is_write)
+		writeable = false;
+
+	spin_lock(&kvm->mmu_lock);
+
+	if (writeable) {
+		kvm_set_pfn_dirty(hfn);
+		mark_page_dirty(kvm, gfn);
+		ret = stage2_map_page(kvm, pcache, gpa, hfn << PAGE_SHIFT,
+				      vma_pagesize, false, true);
+	} else {
+		ret = stage2_map_page(kvm, pcache, gpa, hfn << PAGE_SHIFT,
+				      vma_pagesize, true, true);
+	}
+
+	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: */
+	struct page *pgd_page;
+
+	if (kvm->arch.pgd != NULL) {
+		kvm_err("kvm_arch already initialized?\n");
+		return -EINVAL;
+	}
+
+	pgd_page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
+				get_order(stage2_pgd_size));
+	if (!pgd_page)
+		return -ENOMEM;
+	kvm->arch.pgd = page_to_virt(pgd_page);
+	kvm->arch.pgd_phys = page_to_phys(pgd_page);
+
 	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);
+
+	if (pgd)
+		free_pages((unsigned long)pgd, get_order(stage2_pgd_size));
 }
 
 void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu)
 {
-	/* TODO: */
+	unsigned long hgatp = stage2_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();
+}
+
+void kvm_riscv_stage2_mode_detect(void)
+{
+#ifdef CONFIG_64BIT
+	/* Try Sv48x4 stage2 mode */
+	csr_write(CSR_HGATP, HGATP_MODE_SV48X4 << HGATP_MODE_SHIFT);
+	if ((csr_read(CSR_HGATP) >> HGATP_MODE_SHIFT) == HGATP_MODE_SV48X4) {
+		stage2_mode = (HGATP_MODE_SV48X4 << HGATP_MODE_SHIFT);
+		stage2_pgd_levels = 4;
+	}
+	csr_write(CSR_HGATP, 0);
+
+	__kvm_riscv_hfence_gvma_all();
+#endif
+}
+
+unsigned long kvm_riscv_stage2_mode(void)
+{
+	return stage2_mode >> HGATP_MODE_SHIFT;
 }
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index a42559ed48c1..38a644417627 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -27,12 +27,6 @@ const struct kvm_stats_header kvm_vm_stats_header = {
 		       sizeof(kvm_vm_stats_desc),
 };
 
-int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
-{
-	/* TODO: To be added later. */
-	return -EOPNOTSUPP;
-}
-
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 {
 	int r;
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 11/17] RISC-V: KVM: Implement MMU notifiers
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (9 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 10/17] RISC-V: KVM: Implement stage2 page table programming Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-08-03 13:19   ` limingwang (A)
  2021-07-27  5:54 ` [PATCH v19 12/17] RISC-V: KVM: Add timer functionality Anup Patel
                   ` (5 subsequent siblings)
  16 siblings, 1 reply; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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 |  2 +
 arch/riscv/kvm/Kconfig            |  1 +
 arch/riscv/kvm/mmu.c              | 90 +++++++++++++++++++++++++++++--
 arch/riscv/kvm/vm.c               |  1 +
 4 files changed, 89 insertions(+), 5 deletions(-)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 33255c5dd555..a54a58a4026d 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -196,6 +196,8 @@ static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 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
+
 void __kvm_riscv_hfence_gvma_vmid_gpa(unsigned long gpa, unsigned long vmid);
 void __kvm_riscv_hfence_gvma_vmid(unsigned long vmid);
 void __kvm_riscv_hfence_gvma_gpa(unsigned long gpa);
diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
index 633063edaee8..a712bb910cda 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 fa9a4f9b9542..4b294113c63b 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -300,7 +300,8 @@ static void stage2_op_pte(struct kvm *kvm, gpa_t addr,
 	}
 }
 
-static void stage2_unmap_range(struct kvm *kvm, gpa_t start, gpa_t size)
+static void stage2_unmap_range(struct kvm *kvm, gpa_t start,
+			       gpa_t size, bool may_block)
 {
 	int ret;
 	pte_t *ptep;
@@ -325,6 +326,13 @@ static void stage2_unmap_range(struct kvm *kvm, gpa_t start, gpa_t size)
 
 next:
 		addr += page_size;
+
+		/*
+		 * If the range is too large, release the kvm->mmu_lock
+		 * to prevent starvation and lockup detector warnings.
+		 */
+		if (may_block && addr < end)
+			cond_resched_lock(&kvm->mmu_lock);
 	}
 }
 
@@ -405,7 +413,6 @@ static int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
 out:
 	stage2_cache_flush(&pcache);
 	return ret;
-
 }
 
 void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
@@ -547,7 +554,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	spin_lock(&kvm->mmu_lock);
 	if (ret)
 		stage2_unmap_range(kvm, mem->guest_phys_addr,
-				   mem->memory_size);
+				   mem->memory_size, false);
 	spin_unlock(&kvm->mmu_lock);
 
 out:
@@ -555,6 +562,73 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	return ret;
 }
 
+bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+	if (!kvm->arch.pgd)
+		return 0;
+
+	stage2_unmap_range(kvm, range->start << PAGE_SHIFT,
+			   (range->end - range->start) << PAGE_SHIFT,
+			   range->may_block);
+	return 0;
+}
+
+bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+	int ret;
+	kvm_pfn_t pfn = pte_pfn(range->pte);
+
+	if (!kvm->arch.pgd)
+		return 0;
+
+	WARN_ON(range->end - range->start != 1);
+
+	ret = stage2_map_page(kvm, NULL, range->start << PAGE_SHIFT,
+			      __pfn_to_phys(pfn), PAGE_SIZE, true, true);
+	if (ret) {
+		kvm_err("Failed to map stage2 page (error %d)\n", ret);
+		return 1;
+	}
+
+	return 0;
+}
+
+bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+	pte_t *ptep;
+	u32 ptep_level = 0;
+	u64 size = (range->end - range->start) << PAGE_SHIFT;
+
+	if (!kvm->arch.pgd)
+		return 0;
+
+	WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PGDIR_SIZE);
+
+	if (!stage2_get_leaf_entry(kvm, range->start << PAGE_SHIFT,
+				   &ptep, &ptep_level))
+		return 0;
+
+	return ptep_test_and_clear_young(NULL, 0, ptep);
+}
+
+bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+	pte_t *ptep;
+	u32 ptep_level = 0;
+	u64 size = (range->end - range->start) << PAGE_SHIFT;
+
+	if (!kvm->arch.pgd)
+		return 0;
+
+	WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PGDIR_SIZE);
+
+	if (!stage2_get_leaf_entry(kvm, range->start << PAGE_SHIFT,
+				   &ptep, &ptep_level))
+		return 0;
+
+	return pte_young(*ptep);
+}
+
 int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu,
 			 struct kvm_memory_slot *memslot,
 			 gpa_t gpa, unsigned long hva, bool is_write)
@@ -569,7 +643,7 @@ int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu,
 	struct kvm_mmu_page_cache *pcache = &vcpu->arch.mmu_page_cache;
 	bool logging = (memslot->dirty_bitmap &&
 			!(memslot->flags & KVM_MEM_READONLY)) ? true : false;
-	unsigned long vma_pagesize;
+	unsigned long vma_pagesize, mmu_seq;
 
 	mmap_read_lock(current->mm);
 
@@ -608,6 +682,8 @@ int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu,
 		return ret;
 	}
 
+	mmu_seq = kvm->mmu_notifier_seq;
+
 	hfn = gfn_to_pfn_prot(kvm, gfn, is_write, &writeable);
 	if (hfn == KVM_PFN_ERR_HWPOISON) {
 		send_sig_mceerr(BUS_MCEERR_AR, (void __user *)hva,
@@ -626,6 +702,9 @@ int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu,
 
 	spin_lock(&kvm->mmu_lock);
 
+	if (mmu_notifier_retry(kvm, mmu_seq))
+		goto out_unlock;
+
 	if (writeable) {
 		kvm_set_pfn_dirty(hfn);
 		mark_page_dirty(kvm, gfn);
@@ -639,6 +718,7 @@ int kvm_riscv_stage2_map(struct kvm_vcpu *vcpu,
 	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);
@@ -675,7 +755,7 @@ void kvm_riscv_stage2_free_pgd(struct kvm *kvm)
 
 	spin_lock(&kvm->mmu_lock);
 	if (kvm->arch.pgd) {
-		stage2_unmap_range(kvm, 0UL, stage2_gpa_size);
+		stage2_unmap_range(kvm, 0UL, stage2_gpa_size, false);
 		pgd = READ_ONCE(kvm->arch.pgd);
 		kvm->arch.pgd = NULL;
 		kvm->arch.pgd_phys = 0;
diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index 38a644417627..0110267eb7e3 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -64,6 +64,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_IOEVENTFD:
 	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:
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 12/17] RISC-V: KVM: Add timer functionality
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (10 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 11/17] RISC-V: KVM: Implement MMU notifiers Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 13/17] RISC-V: KVM: FP lazy save/restore Anup Patel
                   ` (4 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	Anup Patel, Daniel Lezcano

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                 |   1 +
 arch/riscv/kvm/vcpu.c                   |  14 ++
 arch/riscv/kvm/vcpu_timer.c             | 225 ++++++++++++++++++++++++
 arch/riscv/kvm/vm.c                     |   2 +-
 drivers/clocksource/timer-riscv.c       |   9 +
 include/clocksource/timer-riscv.h       |  16 ++
 9 files changed, 334 insertions(+), 1 deletion(-)
 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 a54a58a4026d..18b4ec1b5105 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)
@@ -60,6 +61,9 @@ 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 {
@@ -175,6 +179,9 @@ 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 f7e9dc388d54..08691dd27bcf 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -74,6 +74,18 @@ struct kvm_riscv_csr {
 	unsigned long scounteren;
 };
 
+/* 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))
 
@@ -96,6 +108,11 @@ 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 a0274763e096..4beb4e277e96 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -21,3 +21,4 @@ kvm-y += mmu.o
 kvm-y += vcpu.o
 kvm-y += vcpu_exit.o
 kvm-y += vcpu_switch.o
+kvm-y += vcpu_timer.o
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index e565bb158172..f26b249eae8e 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -60,6 +60,8 @@ 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);
 }
@@ -87,6 +89,9 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 	cntx->hstatus |= HSTATUS_SPVP;
 	cntx->hstatus |= HSTATUS_SPV;
 
+	/* Setup VCPU timer */
+	kvm_riscv_vcpu_timer_init(vcpu);
+
 	/* Reset VCPU */
 	kvm_riscv_reset_vcpu(vcpu);
 
@@ -99,6 +104,9 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
 
 void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
+	/* Cleanup VCPU timer */
+	kvm_riscv_vcpu_timer_deinit(vcpu);
+
 	/* Flush the pages pre-allocated for Stage2 page table mappings */
 	kvm_riscv_stage2_flush_cache(vcpu);
 }
@@ -339,6 +347,8 @@ 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;
 }
@@ -352,6 +362,8 @@ 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;
 }
@@ -584,6 +596,8 @@ 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..ddd0ce727b83
--- /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 = -EOPNOTSUPP;
+		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 0110267eb7e3..3b6cfc633d6e 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c
@@ -41,7 +41,7 @@ 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 c51c5ed15aa7..1767f8bf2013 100644
--- a/drivers/clocksource/timer-riscv.c
+++ b/drivers/clocksource/timer-riscv.c
@@ -13,10 +13,12 @@
 #include <linux/delay.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
+#include <linux/module.h>
 #include <linux/sched_clock.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/interrupt.h>
 #include <linux/of_irq.h>
+#include <clocksource/timer-riscv.h>
 #include <asm/smp.h>
 #include <asm/sbi.h>
 #include <asm/timex.h>
@@ -79,6 +81,13 @@ 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 */
 static irqreturn_t riscv_timer_interrupt(int irq, void *dev_id)
 {
diff --git a/include/clocksource/timer-riscv.h b/include/clocksource/timer-riscv.h
new file mode 100644
index 000000000000..d7f455754e60
--- /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>
+
+extern void riscv_cs_get_mult_shift(u32 *mult, u32 *shift);
+
+#endif
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 13/17] RISC-V: KVM: FP lazy save/restore
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (11 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 12/17] RISC-V: KVM: Add timer functionality Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-09-13  4:30   ` Vincent Chen
  2021-07-27  5:54 ` [PATCH v19 14/17] RISC-V: KVM: Implement ONE REG interface for FP registers Anup Patel
                   ` (3 subsequent siblings)
  16 siblings, 1 reply; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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             |  91 ++++++++++++++++
 arch/riscv/kvm/vcpu_switch.S      | 174 ++++++++++++++++++++++++++++++
 4 files changed, 342 insertions(+)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 18b4ec1b5105..99b43229fe7a 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -125,6 +125,7 @@ struct kvm_cpu_context {
 	unsigned long sepc;
 	unsigned long sstatus;
 	unsigned long hstatus;
+	union __riscv_fp_state fp;
 };
 
 struct kvm_vcpu_csr {
@@ -239,6 +240,10 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 			struct kvm_cpu_trap *trap);
 
 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 91c77555d914..24d3827e4837 100644
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
@@ -195,6 +195,78 @@ void asm_offsets(void)
 	OFFSET(KVM_ARCH_TRAP_HTVAL, kvm_cpu_trap, htval);
 	OFFSET(KVM_ARCH_TRAP_HTINST, kvm_cpu_trap, htinst);
 
+	/* 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 f26b249eae8e..024f2c6e7582 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -40,6 +40,86 @@ const struct kvm_stats_header kvm_vcpu_stats_header = {
 		       sizeof(kvm_vcpu_stats_desc),
 };
 
+#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) | \
@@ -60,6 +140,8 @@ 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);
@@ -194,6 +276,7 @@ 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 -EOPNOTSUPP;
 		}
@@ -598,6 +681,10 @@ 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;
 }
 
@@ -607,6 +694,10 @@ 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 e22721e1b892..029a28a195c6 100644
--- a/arch/riscv/kvm/vcpu_switch.S
+++ b/arch/riscv/kvm/vcpu_switch.S
@@ -224,3 +224,177 @@ ENTRY(__kvm_riscv_unpriv_trap)
 	REG_S	a1, (KVM_ARCH_TRAP_HTINST)(a0)
 	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
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 14/17] RISC-V: KVM: Implement ONE REG interface for FP registers
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (12 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 13/17] RISC-V: KVM: FP lazy save/restore Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 15/17] RISC-V: KVM: Add SBI v0.1 support Anup Patel
                   ` (2 subsequent siblings)
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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 08691dd27bcf..f808ad1ce500 100644
--- a/arch/riscv/include/uapi/asm/kvm.h
+++ b/arch/riscv/include/uapi/asm/kvm.h
@@ -113,6 +113,16 @@ 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 024f2c6e7582..333d84015047 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -421,6 +421,98 @@ 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)
 {
@@ -432,6 +524,12 @@ 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;
 }
@@ -447,6 +545,12 @@ 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;
 }
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 15/17] RISC-V: KVM: Add SBI v0.1 support
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (13 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 14/17] RISC-V: KVM: Implement ONE REG interface for FP registers Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 16/17] RISC-V: KVM: Document RISC-V specific parts of KVM API Anup Patel
  2021-07-27  5:54 ` [PATCH v19 17/17] RISC-V: KVM: Add MAINTAINERS entry Anup Patel
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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           |   1 +
 arch/riscv/kvm/vcpu.c             |   9 ++
 arch/riscv/kvm/vcpu_exit.c        |   4 +
 arch/riscv/kvm/vcpu_sbi.c         | 173 ++++++++++++++++++++++++++++++
 include/uapi/linux/kvm.h          |   8 ++
 6 files changed, 205 insertions(+)
 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 99b43229fe7a..d948e17bd59b 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -74,6 +74,10 @@ 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 {
@@ -186,6 +190,9 @@ 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;
 
@@ -253,4 +260,7 @@ 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 4beb4e277e96..3226696b8340 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -21,4 +21,5 @@ kvm-y += mmu.o
 kvm-y += vcpu.o
 kvm-y += vcpu_exit.o
 kvm-y += vcpu_switch.o
+kvm-y += vcpu_sbi.o
 kvm-y += vcpu_timer.o
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 333d84015047..98adf112ed31 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -872,6 +872,15 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		}
 	}
 
+	/* 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 1873b8c35101..6d4e98e2ad6f 100644
--- a/arch/riscv/kvm/vcpu_exit.c
+++ b/arch/riscv/kvm/vcpu_exit.c
@@ -678,6 +678,10 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 		if (vcpu->arch.guest_context.hstatus & HSTATUS_SPV)
 			ret = stage2_page_fault(vcpu, run, trap);
 		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..9d1d25cf217f
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -0,0 +1,173 @@
+// 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;
+	vcpu->stat.ecall_exit_stat++;
+	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)
+{
+	ulong hmask;
+	int i, ret = 1;
+	u64 next_cycle;
+	struct kvm_vcpu *rvcpu;
+	bool next_sepc = true;
+	struct cpumask cm, hm;
+	struct kvm *kvm = vcpu->kvm;
+	struct kvm_cpu_trap utrap = { 0 };
+	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,
+							   &utrap);
+		else
+			hmask = (1UL << atomic_read(&kvm->online_vcpus)) - 1;
+		if (utrap.scause) {
+			utrap.sepc = cp->sepc;
+			kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
+			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,
+							   &utrap);
+		else
+			hmask = (1UL << atomic_read(&kvm->online_vcpus)) - 1;
+		if (utrap.scause) {
+			utrap.sepc = cp->sepc;
+			kvm_riscv_vcpu_trap_redirect(vcpu, &utrap);
+			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 d9e4aabcb31a..8b0f50ca0a4f 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -269,6 +269,7 @@ struct kvm_xen_exit {
 #define KVM_EXIT_AP_RESET_HOLD    32
 #define KVM_EXIT_X86_BUS_LOCK     33
 #define KVM_EXIT_XEN              34
+#define KVM_EXIT_RISCV_SBI        35
 
 /* For KVM_EXIT_INTERNAL_ERROR */
 /* Emulate instruction failed. */
@@ -469,6 +470,13 @@ struct kvm_run {
 		} msr;
 		/* KVM_EXIT_XEN */
 		struct kvm_xen_exit xen;
+		/* 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];
 	};
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 16/17] RISC-V: KVM: Document RISC-V specific parts of KVM API
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (14 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 15/17] RISC-V: KVM: Add SBI v0.1 support Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  2021-07-27  5:54 ` [PATCH v19 17/17] RISC-V: KVM: Add MAINTAINERS entry Anup Patel
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	Anup Patel, Jonathan Corbet, linux-doc

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.rst | 193 +++++++++++++++++++++++++++++++--
 1 file changed, 184 insertions(+), 9 deletions(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index c7b165ca70b6..6510ca68ed73 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -532,7 +532,7 @@ translation mode.
 ------------------
 
 :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.
@@ -601,6 +601,23 @@ 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
 --------------------
@@ -1399,7 +1416,7 @@ for vm-wide capabilities.
 ---------------------
 
 :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
@@ -1416,7 +1433,8 @@ 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
@@ -1425,7 +1443,7 @@ 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]
@@ -1437,8 +1455,8 @@ 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.
@@ -1447,7 +1465,7 @@ KVM_MP_STATE_RUNNABLE which reflect if the vcpu is paused or not.
 ---------------------
 
 :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
@@ -1459,8 +1477,8 @@ 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.
@@ -2577,6 +2595,144 @@ 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
 --------------------
@@ -5824,6 +5980,25 @@ Valid values for 'type' are:
     Userspace is expected to place the hypercall result into the appropriate
     field before invoking KVM_RUN again.
 
+::
+
+		/* 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. */
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* [PATCH v19 17/17] RISC-V: KVM: Add MAINTAINERS entry
  2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
                   ` (15 preceding siblings ...)
  2021-07-27  5:54 ` [PATCH v19 16/17] RISC-V: KVM: Document RISC-V specific parts of KVM API Anup Patel
@ 2021-07-27  5:54 ` Anup Patel
  16 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-07-27  5:54 UTC (permalink / raw)
  To: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel,
	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 | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 19135a9d778e..f972685b9dcc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10176,6 +10176,18 @@ F:	arch/powerpc/include/uapi/asm/kvm*
 F:	arch/powerpc/kernel/kvm*
 F:	arch/powerpc/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
+L:	linux-riscv@lists.infradead.org
+S:	Maintained
+T:	git git://github.com/kvm-riscv/linux.git
+F:	arch/riscv/include/asm/kvm*
+F:	arch/riscv/include/uapi/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>
-- 
2.25.1


^ permalink raw reply	[flat|nested] 23+ messages in thread

* RE: [PATCH v19 11/17] RISC-V: KVM: Implement MMU notifiers
  2021-07-27  5:54 ` [PATCH v19 11/17] RISC-V: KVM: Implement MMU notifiers Anup Patel
@ 2021-08-03 13:19   ` limingwang (A)
  2021-08-04  7:16     ` Anup Patel
  0 siblings, 1 reply; 23+ messages in thread
From: limingwang (A) @ 2021-08-03 13:19 UTC (permalink / raw)
  To: Anup Patel, Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley,
	Albert Ou, Paolo Bonzini
  Cc: Alexander Graf, Atish Patra, Alistair Francis, Damien Le Moal,
	Anup Patel, kvm, kvm-riscv, linux-riscv, linux-kernel

> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c index
> fa9a4f9b9542..4b294113c63b 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -300,7 +300,8 @@ static void stage2_op_pte(struct kvm *kvm, gpa_t
> addr,
>  	}
>  }
> 
> -static void stage2_unmap_range(struct kvm *kvm, gpa_t start, gpa_t size)
> +static void stage2_unmap_range(struct kvm *kvm, gpa_t start,
> +			       gpa_t size, bool may_block)
>  {
>  	int ret;
>  	pte_t *ptep;
> @@ -325,6 +326,13 @@ static void stage2_unmap_range(struct kvm *kvm,
> gpa_t start, gpa_t size)
> 
>  next:
>  		addr += page_size;
> +
> +		/*
> +		 * If the range is too large, release the kvm->mmu_lock
> +		 * to prevent starvation and lockup detector warnings.
> +		 */
> +		if (may_block && addr < end)
> +			cond_resched_lock(&kvm->mmu_lock);
>  	}
>  }
> 
> @@ -405,7 +413,6 @@ static int stage2_ioremap(struct kvm *kvm, gpa_t gpa,
> phys_addr_t hpa,
>  out:
>  	stage2_cache_flush(&pcache);
>  	return ret;
> -
>  }
> 
>  void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, @@
> -547,7 +554,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
>  	spin_lock(&kvm->mmu_lock);
>  	if (ret)
>  		stage2_unmap_range(kvm, mem->guest_phys_addr,
> -				   mem->memory_size);
> +				   mem->memory_size, false);
>  	spin_unlock(&kvm->mmu_lock);
> 
>  out:
> @@ -555,6 +562,73 @@ int kvm_arch_prepare_memory_region(struct kvm
> *kvm,
>  	return ret;
>  }
> 
> +bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
> +{
> +	if (!kvm->arch.pgd)
> +		return 0;
> +
> +	stage2_unmap_range(kvm, range->start << PAGE_SHIFT,
> +			   (range->end - range->start) << PAGE_SHIFT,
> +			   range->may_block);
> +	return 0;
> +}
> +
> +bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range) {
> +	int ret;
> +	kvm_pfn_t pfn = pte_pfn(range->pte);
> +
> +	if (!kvm->arch.pgd)
> +		return 0;
> +
> +	WARN_ON(range->end - range->start != 1);
> +
> +	ret = stage2_map_page(kvm, NULL, range->start << PAGE_SHIFT,
> +			      __pfn_to_phys(pfn), PAGE_SIZE, true, true);
> +	if (ret) {
> +		kvm_err("Failed to map stage2 page (error %d)\n", ret);
> +		return 1;
> +	}

Hi, Anup

I think that it is not appropriate to add kvm_err here, because stage2_set_pte function
may apply for memory based on the pcache parameter. If the value of pcache is NULL,
stage2_set_pte function considers that there is not enough memory and here an invalid
error log is generated.

As an example, this error log is printed when a VM is migrating. But finally the VM migration
is successful. And if the kvm_err is added to the same position in the ARM architecture, the
same error log is also printed.

Mingwang

> +	return 0;
> +}
> +


^ permalink raw reply	[flat|nested] 23+ messages in thread

* Re: [PATCH v19 11/17] RISC-V: KVM: Implement MMU notifiers
  2021-08-03 13:19   ` limingwang (A)
@ 2021-08-04  7:16     ` Anup Patel
  0 siblings, 0 replies; 23+ messages in thread
From: Anup Patel @ 2021-08-04  7:16 UTC (permalink / raw)
  To: limingwang (A)
  Cc: Anup Patel, Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley,
	Albert Ou, Paolo Bonzini, Alexander Graf, Atish Patra,
	Alistair Francis, Damien Le Moal, kvm, kvm-riscv, linux-riscv,
	linux-kernel

On Tue, Aug 3, 2021 at 6:49 PM limingwang (A) <limingwang@huawei.com> wrote:
>
> > diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c index
> > fa9a4f9b9542..4b294113c63b 100644
> > --- a/arch/riscv/kvm/mmu.c
> > +++ b/arch/riscv/kvm/mmu.c
> > @@ -300,7 +300,8 @@ static void stage2_op_pte(struct kvm *kvm, gpa_t
> > addr,
> >       }
> >  }
> >
> > -static void stage2_unmap_range(struct kvm *kvm, gpa_t start, gpa_t size)
> > +static void stage2_unmap_range(struct kvm *kvm, gpa_t start,
> > +                            gpa_t size, bool may_block)
> >  {
> >       int ret;
> >       pte_t *ptep;
> > @@ -325,6 +326,13 @@ static void stage2_unmap_range(struct kvm *kvm,
> > gpa_t start, gpa_t size)
> >
> >  next:
> >               addr += page_size;
> > +
> > +             /*
> > +              * If the range is too large, release the kvm->mmu_lock
> > +              * to prevent starvation and lockup detector warnings.
> > +              */
> > +             if (may_block && addr < end)
> > +                     cond_resched_lock(&kvm->mmu_lock);
> >       }
> >  }
> >
> > @@ -405,7 +413,6 @@ static int stage2_ioremap(struct kvm *kvm, gpa_t gpa,
> > phys_addr_t hpa,
> >  out:
> >       stage2_cache_flush(&pcache);
> >       return ret;
> > -
> >  }
> >
> >  void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, @@
> > -547,7 +554,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
> >       spin_lock(&kvm->mmu_lock);
> >       if (ret)
> >               stage2_unmap_range(kvm, mem->guest_phys_addr,
> > -                                mem->memory_size);
> > +                                mem->memory_size, false);
> >       spin_unlock(&kvm->mmu_lock);
> >
> >  out:
> > @@ -555,6 +562,73 @@ int kvm_arch_prepare_memory_region(struct kvm
> > *kvm,
> >       return ret;
> >  }
> >
> > +bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
> > +{
> > +     if (!kvm->arch.pgd)
> > +             return 0;
> > +
> > +     stage2_unmap_range(kvm, range->start << PAGE_SHIFT,
> > +                        (range->end - range->start) << PAGE_SHIFT,
> > +                        range->may_block);
> > +     return 0;
> > +}
> > +
> > +bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range) {
> > +     int ret;
> > +     kvm_pfn_t pfn = pte_pfn(range->pte);
> > +
> > +     if (!kvm->arch.pgd)
> > +             return 0;
> > +
> > +     WARN_ON(range->end - range->start != 1);
> > +
> > +     ret = stage2_map_page(kvm, NULL, range->start << PAGE_SHIFT,
> > +                           __pfn_to_phys(pfn), PAGE_SIZE, true, true);
> > +     if (ret) {
> > +             kvm_err("Failed to map stage2 page (error %d)\n", ret);
> > +             return 1;
> > +     }
>
> Hi, Anup
>
> I think that it is not appropriate to add kvm_err here, because stage2_set_pte function
> may apply for memory based on the pcache parameter. If the value of pcache is NULL,
> stage2_set_pte function considers that there is not enough memory and here an invalid
> error log is generated.
>
> As an example, this error log is printed when a VM is migrating. But finally the VM migration
> is successful. And if the kvm_err is added to the same position in the ARM architecture, the
> same error log is also printed.

Okay, I have converted kvm_err() to kvm_debug(). In the future, we can totally
remove it as well.

Please try riscv_kvm_v20 branch at:
https://github.com/avpatel/linux.git

Regards,
Anup

>
> Mingwang
>
> > +     return 0;
> > +}
> > +
>

^ permalink raw reply	[flat|nested] 23+ messages in thread

* Re: [PATCH v19 13/17] RISC-V: KVM: FP lazy save/restore
  2021-07-27  5:54 ` [PATCH v19 13/17] RISC-V: KVM: FP lazy save/restore Anup Patel
@ 2021-09-13  4:30   ` Vincent Chen
  2021-09-13  5:04     ` Anup Patel
  0 siblings, 1 reply; 23+ messages in thread
From: Vincent Chen @ 2021-09-13  4:30 UTC (permalink / raw)
  To: Anup Patel
  Cc: Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley, Albert Ou,
	Paolo Bonzini, Alexander Graf, Atish Patra, Alistair Francis,
	Damien Le Moal, Anup Patel, kvm, kvm-riscv, linux-riscv,
	linux-kernel@vger.kernel.org List

On Tue, Jul 27, 2021 at 3:30 PM Anup Patel <anup.patel@wdc.com> wrote:
>
> 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             |  91 ++++++++++++++++
>  arch/riscv/kvm/vcpu_switch.S      | 174 ++++++++++++++++++++++++++++++
>  4 files changed, 342 insertions(+)
>
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> index 18b4ec1b5105..99b43229fe7a 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -125,6 +125,7 @@ struct kvm_cpu_context {
>         unsigned long sepc;
>         unsigned long sstatus;
>         unsigned long hstatus;
> +       union __riscv_fp_state fp;
>  };
>
>  struct kvm_vcpu_csr {
> @@ -239,6 +240,10 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
>                         struct kvm_cpu_trap *trap);
>
>  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 91c77555d914..24d3827e4837 100644
> --- a/arch/riscv/kernel/asm-offsets.c
> +++ b/arch/riscv/kernel/asm-offsets.c
> @@ -195,6 +195,78 @@ void asm_offsets(void)
>         OFFSET(KVM_ARCH_TRAP_HTVAL, kvm_cpu_trap, htval);
>         OFFSET(KVM_ARCH_TRAP_HTINST, kvm_cpu_trap, htinst);
>
> +       /* 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 f26b249eae8e..024f2c6e7582 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -40,6 +40,86 @@ const struct kvm_stats_header kvm_vcpu_stats_header = {
>                        sizeof(kvm_vcpu_stats_desc),
>  };
>
> +#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);

Hi Anup and Atish,
First of all, thank you very much for contributing this patch set to
add H extension support to the Linux kernel.

I tried to do some development based on this patchset and encountered
some strange behaviors related to FPU registers. After diagnosis, I
suspect the root cause of these behaviors is in the
kvm_riscv_vcpu_fp_clean().
In the kvm_riscv_vcpu_fp_clean(), the sstatus.FS field of guest OS
will be set to clean. It will cause the guest kernel to mistakenly
believe the status of the FPU register is clean so that the guest OS
will not save the value of FPU registers to the process context before
this process is scheduled out. However, here the host OS only saves
the FPU register to the guest OS context instead of the process
context. In this case, for the process in the guest OS, the data in
FPU registers may be lost due to the lack of context saving before
scheduling out. Therefore, IMHO, the kvm_riscv_vcpu_fp_clean() might
be unnecessary and could be removed.

> +       }
> +}
> +
> +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);

The reason is the same as above. Here the kvm_riscv_vcpu_fp_clean()
might be unnecessary and could be removed.

> +}
> +
> +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) | \
> @@ -60,6 +140,8 @@ 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);
> @@ -194,6 +276,7 @@ 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 -EOPNOTSUPP;
>                 }
> @@ -598,6 +681,10 @@ 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;
>  }
>
> @@ -607,6 +694,10 @@ 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 e22721e1b892..029a28a195c6 100644
> --- a/arch/riscv/kvm/vcpu_switch.S
> +++ b/arch/riscv/kvm/vcpu_switch.S
> @@ -224,3 +224,177 @@ ENTRY(__kvm_riscv_unpriv_trap)
>         REG_S   a1, (KVM_ARCH_TRAP_HTINST)(a0)
>         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
> --
> 2.25.1
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 23+ messages in thread

* Re: [PATCH v19 13/17] RISC-V: KVM: FP lazy save/restore
  2021-09-13  4:30   ` Vincent Chen
@ 2021-09-13  5:04     ` Anup Patel
  2021-09-13  7:11       ` Vincent Chen
  0 siblings, 1 reply; 23+ messages in thread
From: Anup Patel @ 2021-09-13  5:04 UTC (permalink / raw)
  To: Vincent Chen
  Cc: Anup Patel, Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley,
	Albert Ou, Paolo Bonzini, Alexander Graf, Atish Patra,
	Alistair Francis, Damien Le Moal, KVM General, kvm-riscv,
	linux-riscv, linux-kernel@vger.kernel.org List

On Mon, Sep 13, 2021 at 10:01 AM Vincent Chen <vincent.chen@sifive.com> wrote:
>
> On Tue, Jul 27, 2021 at 3:30 PM Anup Patel <anup.patel@wdc.com> wrote:
> >
> > 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             |  91 ++++++++++++++++
> >  arch/riscv/kvm/vcpu_switch.S      | 174 ++++++++++++++++++++++++++++++
> >  4 files changed, 342 insertions(+)
> >
> > diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> > index 18b4ec1b5105..99b43229fe7a 100644
> > --- a/arch/riscv/include/asm/kvm_host.h
> > +++ b/arch/riscv/include/asm/kvm_host.h
> > @@ -125,6 +125,7 @@ struct kvm_cpu_context {
> >         unsigned long sepc;
> >         unsigned long sstatus;
> >         unsigned long hstatus;
> > +       union __riscv_fp_state fp;
> >  };
> >
> >  struct kvm_vcpu_csr {
> > @@ -239,6 +240,10 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
> >                         struct kvm_cpu_trap *trap);
> >
> >  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 91c77555d914..24d3827e4837 100644
> > --- a/arch/riscv/kernel/asm-offsets.c
> > +++ b/arch/riscv/kernel/asm-offsets.c
> > @@ -195,6 +195,78 @@ void asm_offsets(void)
> >         OFFSET(KVM_ARCH_TRAP_HTVAL, kvm_cpu_trap, htval);
> >         OFFSET(KVM_ARCH_TRAP_HTINST, kvm_cpu_trap, htinst);
> >
> > +       /* 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 f26b249eae8e..024f2c6e7582 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -40,6 +40,86 @@ const struct kvm_stats_header kvm_vcpu_stats_header = {
> >                        sizeof(kvm_vcpu_stats_desc),
> >  };
> >
> > +#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);
>
> Hi Anup and Atish,
> First of all, thank you very much for contributing this patch set to
> add H extension support to the Linux kernel.
>
> I tried to do some development based on this patchset and encountered
> some strange behaviors related to FPU registers. After diagnosis, I
> suspect the root cause of these behaviors is in the
> kvm_riscv_vcpu_fp_clean().
> In the kvm_riscv_vcpu_fp_clean(), the sstatus.FS field of guest OS
> will be set to clean. It will cause the guest kernel to mistakenly
> believe the status of the FPU register is clean so that the guest OS
> will not save the value of FPU registers to the process context before
> this process is scheduled out. However, here the host OS only saves
> the FPU register to the guest OS context instead of the process
> context. In this case, for the process in the guest OS, the data in
> FPU registers may be lost due to the lack of context saving before
> scheduling out. Therefore, IMHO, the kvm_riscv_vcpu_fp_clean() might
> be unnecessary and could be removed.

Please don't confuse the Guest view of sstatus.FS with the Host view of
sstatus.FS.

When the Guest is running (i.e. V=1):
1) The Guest access to SSTATUS CSR are mapped to VSSTATUS CSR
and the actual SSTATUS CSR (in background) represents Host SSTATUS.
2) The FP state (OFF, INIT, CLEAN, and DIRTY) is tracked in two FS fields
VSSTATUS.FS (for Guest OS) and SSTATUS.FS (for Host/Hypervisor).
3) The RISC-V hardware will check and update both actual SSTATUS.FS
and VSSTATUS.FS when running in Guest mode (i.e. V=1)
4) The Hypervisor uses actual SSTATUS.FS to save/restore FP from
Host perspective whereas  the Guest OS uses VSSTATUS.FS to save/restore
FP from Guest perspective

The "cntx->sstatus" in KVM RISC-V code represents the actual Host
SSTATUS CSR while Guest/VM was running and does not represent
the Guest view of SSTATUS (which is in VSSTATUS CSR).

Another way of looking at this is, Hypervisor will save/restore FP based
on it's own view of SSTATUS.FS (i.e. actual SSTATUS CSR) while
Guest OS will save/restore FP based on it's own view of SSTATUS.FS
(i.e. VSSTATUS CSR). It is possible that Guest gets preempted even
before it got chance to save FP registers so the hypervisor ensures that
FP is saved-and-restored based on it's own view of SSTATUS.FS.

The above rationale also applies to V-extension.

Let us know if you still have questions related to this.

>
> > +       }
> > +}
> > +
> > +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);
>
> The reason is the same as above. Here the kvm_riscv_vcpu_fp_clean()
> might be unnecessary and could be removed.

Please see above.

>
> > +}
> > +
> > +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) | \
> > @@ -60,6 +140,8 @@ 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);
> > @@ -194,6 +276,7 @@ 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 -EOPNOTSUPP;
> >                 }
> > @@ -598,6 +681,10 @@ 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;
> >  }
> >
> > @@ -607,6 +694,10 @@ 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 e22721e1b892..029a28a195c6 100644
> > --- a/arch/riscv/kvm/vcpu_switch.S
> > +++ b/arch/riscv/kvm/vcpu_switch.S
> > @@ -224,3 +224,177 @@ ENTRY(__kvm_riscv_unpriv_trap)
> >         REG_S   a1, (KVM_ARCH_TRAP_HTINST)(a0)
> >         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
> > --
> > 2.25.1
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv

Regards,
Anup

^ permalink raw reply	[flat|nested] 23+ messages in thread

* Re: [PATCH v19 13/17] RISC-V: KVM: FP lazy save/restore
  2021-09-13  5:04     ` Anup Patel
@ 2021-09-13  7:11       ` Vincent Chen
  0 siblings, 0 replies; 23+ messages in thread
From: Vincent Chen @ 2021-09-13  7:11 UTC (permalink / raw)
  To: Anup Patel
  Cc: Anup Patel, Palmer Dabbelt, Palmer Dabbelt, Paul Walmsley,
	Albert Ou, Paolo Bonzini, Alexander Graf, Atish Patra,
	Alistair Francis, Damien Le Moal, KVM General, kvm-riscv,
	linux-riscv, linux-kernel@vger.kernel.org List

On Mon, Sep 13, 2021 at 1:04 PM Anup Patel <anup@brainfault.org> wrote:
>
> On Mon, Sep 13, 2021 at 10:01 AM Vincent Chen <vincent.chen@sifive.com> wrote:
> >
> > On Tue, Jul 27, 2021 at 3:30 PM Anup Patel <anup.patel@wdc.com> wrote:
> > >
> > > 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             |  91 ++++++++++++++++
> > >  arch/riscv/kvm/vcpu_switch.S      | 174 ++++++++++++++++++++++++++++++
> > >  4 files changed, 342 insertions(+)
> > >
> > > diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> > > index 18b4ec1b5105..99b43229fe7a 100644
> > > --- a/arch/riscv/include/asm/kvm_host.h
> > > +++ b/arch/riscv/include/asm/kvm_host.h
> > > @@ -125,6 +125,7 @@ struct kvm_cpu_context {
> > >         unsigned long sepc;
> > >         unsigned long sstatus;
> > >         unsigned long hstatus;
> > > +       union __riscv_fp_state fp;
> > >  };
> > >
> > >  struct kvm_vcpu_csr {
> > > @@ -239,6 +240,10 @@ int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
> > >                         struct kvm_cpu_trap *trap);
> > >
> > >  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 91c77555d914..24d3827e4837 100644
> > > --- a/arch/riscv/kernel/asm-offsets.c
> > > +++ b/arch/riscv/kernel/asm-offsets.c
> > > @@ -195,6 +195,78 @@ void asm_offsets(void)
> > >         OFFSET(KVM_ARCH_TRAP_HTVAL, kvm_cpu_trap, htval);
> > >         OFFSET(KVM_ARCH_TRAP_HTINST, kvm_cpu_trap, htinst);
> > >
> > > +       /* 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 f26b249eae8e..024f2c6e7582 100644
> > > --- a/arch/riscv/kvm/vcpu.c
> > > +++ b/arch/riscv/kvm/vcpu.c
> > > @@ -40,6 +40,86 @@ const struct kvm_stats_header kvm_vcpu_stats_header = {
> > >                        sizeof(kvm_vcpu_stats_desc),
> > >  };
> > >
> > > +#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);
> >
> > Hi Anup and Atish,
> > First of all, thank you very much for contributing this patch set to
> > add H extension support to the Linux kernel.
> >
> > I tried to do some development based on this patchset and encountered
> > some strange behaviors related to FPU registers. After diagnosis, I
> > suspect the root cause of these behaviors is in the
> > kvm_riscv_vcpu_fp_clean().
> > In the kvm_riscv_vcpu_fp_clean(), the sstatus.FS field of guest OS
> > will be set to clean. It will cause the guest kernel to mistakenly
> > believe the status of the FPU register is clean so that the guest OS
> > will not save the value of FPU registers to the process context before
> > this process is scheduled out. However, here the host OS only saves
> > the FPU register to the guest OS context instead of the process
> > context. In this case, for the process in the guest OS, the data in
> > FPU registers may be lost due to the lack of context saving before
> > scheduling out. Therefore, IMHO, the kvm_riscv_vcpu_fp_clean() might
> > be unnecessary and could be removed.
>
> Please don't confuse the Guest view of sstatus.FS with the Host view of
> sstatus.FS.
>
> When the Guest is running (i.e. V=1):
> 1) The Guest access to SSTATUS CSR are mapped to VSSTATUS CSR
> and the actual SSTATUS CSR (in background) represents Host SSTATUS.
> 2) The FP state (OFF, INIT, CLEAN, and DIRTY) is tracked in two FS fields
> VSSTATUS.FS (for Guest OS) and SSTATUS.FS (for Host/Hypervisor).
> 3) The RISC-V hardware will check and update both actual SSTATUS.FS
> and VSSTATUS.FS when running in Guest mode (i.e. V=1)
> 4) The Hypervisor uses actual SSTATUS.FS to save/restore FP from
> Host perspective whereas  the Guest OS uses VSSTATUS.FS to save/restore
> FP from Guest perspective
>
> The "cntx->sstatus" in KVM RISC-V code represents the actual Host
> SSTATUS CSR while Guest/VM was running and does not represent
> the Guest view of SSTATUS (which is in VSSTATUS CSR).
>
> Another way of looking at this is, Hypervisor will save/restore FP based
> on it's own view of SSTATUS.FS (i.e. actual SSTATUS CSR) while
> Guest OS will save/restore FP based on it's own view of SSTATUS.FS
> (i.e. VSSTATUS CSR). It is possible that Guest gets preempted even
> before it got chance to save FP registers so the hypervisor ensures that
> FP is saved-and-restored based on it's own view of SSTATUS.FS.
>
> The above rationale also applies to V-extension.
>
> Let us know if you still have questions related to this.
>

Hi Anup,
Thank you for the detailed explanation. I think I am really confused
between SSTATUS and VSSTATUS. Although the strange behavior
disappeared after I removed these two kvm_riscv_vcpu_fp_clean(), it is
clear that the root cause is not what I said. I will continue to find
out the root cause. Thank you.

Regards,
Vincent
> >
> > > +       }
> > > +}
> > > +
> > > +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);
> >
> > The reason is the same as above. Here the kvm_riscv_vcpu_fp_clean()
> > might be unnecessary and could be removed.
>
> Please see above.
>
> >
> > > +}
> > > +
> > > +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) | \
> > > @@ -60,6 +140,8 @@ 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);
> > > @@ -194,6 +276,7 @@ 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 -EOPNOTSUPP;
> > >                 }
> > > @@ -598,6 +681,10 @@ 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;
> > >  }
> > >
> > > @@ -607,6 +694,10 @@ 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 e22721e1b892..029a28a195c6 100644
> > > --- a/arch/riscv/kvm/vcpu_switch.S
> > > +++ b/arch/riscv/kvm/vcpu_switch.S
> > > @@ -224,3 +224,177 @@ ENTRY(__kvm_riscv_unpriv_trap)
> > >         REG_S   a1, (KVM_ARCH_TRAP_HTINST)(a0)
> > >         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
> > > --
> > > 2.25.1
> > >
> > >
> > > _______________________________________________
> > > linux-riscv mailing list
> > > linux-riscv@lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/linux-riscv
>
> Regards,
> Anup

^ permalink raw reply	[flat|nested] 23+ messages in thread

end of thread, other threads:[~2021-09-13  7:11 UTC | newest]

Thread overview: 23+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-27  5:54 [PATCH v19 00/17] KVM RISC-V Support Anup Patel
2021-07-27  5:54 ` [PATCH v19 01/17] RISC-V: Add hypervisor extension related CSR defines Anup Patel
2021-07-27  5:54 ` [PATCH v19 02/17] RISC-V: Add initial skeletal KVM support Anup Patel
2021-07-27  5:54 ` [PATCH v19 03/17] RISC-V: KVM: Implement VCPU create, init and destroy functions Anup Patel
2021-07-27  5:54 ` [PATCH v19 04/17] RISC-V: KVM: Implement VCPU interrupts and requests handling Anup Patel
2021-07-27  5:54 ` [PATCH v19 05/17] RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls Anup Patel
2021-07-27  5:54 ` [PATCH v19 06/17] RISC-V: KVM: Implement VCPU world-switch Anup Patel
2021-07-27  5:54 ` [PATCH v19 07/17] RISC-V: KVM: Handle MMIO exits for VCPU Anup Patel
2021-07-27  5:54 ` [PATCH v19 08/17] RISC-V: KVM: Handle WFI " Anup Patel
2021-07-27  5:54 ` [PATCH v19 09/17] RISC-V: KVM: Implement VMID allocator Anup Patel
2021-07-27  5:54 ` [PATCH v19 10/17] RISC-V: KVM: Implement stage2 page table programming Anup Patel
2021-07-27  5:54 ` [PATCH v19 11/17] RISC-V: KVM: Implement MMU notifiers Anup Patel
2021-08-03 13:19   ` limingwang (A)
2021-08-04  7:16     ` Anup Patel
2021-07-27  5:54 ` [PATCH v19 12/17] RISC-V: KVM: Add timer functionality Anup Patel
2021-07-27  5:54 ` [PATCH v19 13/17] RISC-V: KVM: FP lazy save/restore Anup Patel
2021-09-13  4:30   ` Vincent Chen
2021-09-13  5:04     ` Anup Patel
2021-09-13  7:11       ` Vincent Chen
2021-07-27  5:54 ` [PATCH v19 14/17] RISC-V: KVM: Implement ONE REG interface for FP registers Anup Patel
2021-07-27  5:54 ` [PATCH v19 15/17] RISC-V: KVM: Add SBI v0.1 support Anup Patel
2021-07-27  5:54 ` [PATCH v19 16/17] RISC-V: KVM: Document RISC-V specific parts of KVM API Anup Patel
2021-07-27  5:54 ` [PATCH v19 17/17] RISC-V: KVM: Add MAINTAINERS entry Anup Patel

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