[PATCH v4 00/10] Independent per-CPU data section for nVHE

[PATCH v4 00/10] Independent per-CPU data section for nVHE

[David Brazdil]

Introduce '.hyp.data..percpu' as part of ongoing effort to make nVHE
hyp code self-contained and independent of the rest of the kernel.

Main benefits:
 * independent nVHE per-CPU data section that can be unmapped from host,
 * more robust linking of nVHE hyp code,
 * no need for hyp-specific macros to access per-CPU variables.

The series is structured as follows:

 - patch 1: Improve existing hyp build rules. This could be sent and merged
    independently of per-CPU but this series builds on it.

 - patches 2-3: Minor cleanups.

 - patches 4-5: Replace hyp helpers for accessing per-CPU variables
     with common helpers modified to work correctly in hyp. Per-CPU
     variables can now be accessed with one API anywhere.

 - patches 6-8: Where VHE and nVHE use per-CPU variables defined in
     kernel proper, move their definitions to hyp/ where they are
     duplicated and owned by VHE/nVHE, respectively. Non-VHE hyp code
     now refers only to per-CPU variables defined in its source files.
     Helpers are added so that kernel proper can continue to access
     nVHE hyp variables, same way as it does with other nVHE symbols.

 - patches 9-10: Introduce '.hyp.data..percpu' ELF section and allocate
     memory for every CPU core during KVM init. All nVHE per-CPU state
     is now grouped together in ELF and in memory. Introducing a new
     per-CPU variable does not require adding new memory mappings any
     more. nVHE hyp code cannot accidentally refer to kernel-proper
     per-CPU data as it only has the pointer to its own per-CPU memory.

Patches are rebased on v5.9-rc6 and available in branch 'topic/percpu-v4' at:
    https://android-kvm.googlesource.com/linux

For maintainers: In case of interest, there are patches that remove the need
for redefining macros under DEBUG_PREEMPT available at the same repo, branch
'topic/percpu-v3-debug-preempt'. Since they are non-trivial, I am not going
to post them here so late in the 5.10 window. I plan to post them for 5.11
when they will also be useful for other patches.

Changes v3 -> v4:
 * Drop patch that marked pages allocated for hyp reserved
 * Copy arm64_ssbd_callback_required at cpu_init_hyp_mode
 * Use read_sysreg in __hyp_my_cpu_offset
 * Simplify per-CPU region allocation code
 * Use same subsection name regex as other kernel linker scripts
 * Rename helper per-CPU macros
 * Add .gitignore for hyp linker script

Changes v2 -> v3:
 * Use PERCPU_INPUT in hyp.ld instead of modifying PERCPU_SECTION
 * Only pass linker script once to LD (fix error message)
 * Renamed '.hyp.o' to '.nvhe.o'
 * Use __KVM_VHE_HYPERVISOR__ to select TPIDR_EL2 instead of alternatives
 * Move all prefixing-related macros to hyp_image.h

Changes v1 -> v2:
 * partially link hyp code, add linker script

David Brazdil (10):
  kvm: arm64: Partially link nVHE hyp code, simplify HYPCOPY
  kvm: arm64: Move nVHE hyp namespace macros to hyp_image.h
  kvm: arm64: Only define __kvm_ex_table for CONFIG_KVM
  kvm: arm64: Remove __hyp_this_cpu_read
  kvm: arm64: Remove hyp_adr/ldr_this_cpu
  kvm: arm64: Add helpers for accessing nVHE hyp per-cpu vars
  kvm: arm64: Duplicate arm64_ssbd_callback_required for nVHE hyp
  kvm: arm64: Create separate instances of kvm_host_data for VHE/nVHE
  kvm: arm64: Set up hyp percpu data for nVHE
  kvm: arm64: Remove unnecessary hyp mappings

 arch/arm64/include/asm/assembler.h        | 29 +++++---
 arch/arm64/include/asm/hyp_image.h        | 36 ++++++++++
 arch/arm64/include/asm/kvm_asm.h          | 82 +++++++++++------------
 arch/arm64/include/asm/kvm_host.h         |  2 +-
 arch/arm64/include/asm/kvm_mmu.h          | 22 ++----
 arch/arm64/include/asm/percpu.h           | 28 +++++++-
 arch/arm64/kernel/image-vars.h            |  4 --
 arch/arm64/kernel/vmlinux.lds.S           | 13 ++++
 arch/arm64/kvm/arm.c                      | 61 +++++++++++++----
 arch/arm64/kvm/hyp/hyp-entry.S            |  2 +-
 arch/arm64/kvm/hyp/include/hyp/debug-sr.h |  4 +-
 arch/arm64/kvm/hyp/include/hyp/switch.h   |  8 +--
 arch/arm64/kvm/hyp/nvhe/.gitignore        |  2 +
 arch/arm64/kvm/hyp/nvhe/Makefile          | 60 +++++++++--------
 arch/arm64/kvm/hyp/nvhe/hyp.lds.S         | 19 ++++++
 arch/arm64/kvm/hyp/nvhe/switch.c          |  8 ++-
 arch/arm64/kvm/hyp/vhe/switch.c           |  5 +-
 arch/arm64/kvm/hyp/vhe/sysreg-sr.c        |  4 +-
 arch/arm64/kvm/pmu.c                      | 13 ++--
 19 files changed, 272 insertions(+), 130 deletions(-)
 create mode 100644 arch/arm64/include/asm/hyp_image.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/.gitignore
 create mode 100644 arch/arm64/kvm/hyp/nvhe/hyp.lds.S

--
2.28.0.681.g6f77f65b4e-goog

[PATCH v4 01/10] kvm: arm64: Partially link nVHE hyp code, simplify HYPCOPY

[David Brazdil]

Relying on objcopy to prefix the ELF section names of the nVHE hyp code
is brittle and prevents us from using wildcards to match specific
section names.

Improve the build rules by partially linking all '.nvhe.o' files and
prefixing their ELF section names using a linker script. Continue using
objcopy for prefixing ELF symbol names.

One immediate advantage of this approach is that all subsections
matching a pattern can be merged into a single prefixed section, eg.
.text and .text.* can be linked into a single '.hyp.text'. This removes
the need for -fno-reorder-functions on GCC and will be useful in the
future too: LTO builds use .text subsections, compilers routinely
generate .rodata subsections, etc.

Partially linking all hyp code into a single object file also makes it
easier to analyze.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/include/asm/hyp_image.h | 24 ++++++++++++
 arch/arm64/kvm/hyp/nvhe/.gitignore |  2 +
 arch/arm64/kvm/hyp/nvhe/Makefile   | 60 ++++++++++++++++--------------
 arch/arm64/kvm/hyp/nvhe/hyp.lds.S  | 13 +++++++
 4 files changed, 72 insertions(+), 27 deletions(-)
 create mode 100644 arch/arm64/include/asm/hyp_image.h
 create mode 100644 arch/arm64/kvm/hyp/nvhe/.gitignore
 create mode 100644 arch/arm64/kvm/hyp/nvhe/hyp.lds.S

diff --git a/arch/arm64/include/asm/hyp_image.h b/arch/arm64/include/asm/hyp_image.h
new file mode 100644
index 000000000000..2e38fcda02fc
--- /dev/null
+++ b/arch/arm64/include/asm/hyp_image.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 Google LLC.
+ * Written by David Brazdil <dbrazdil@google.com>
+ */
+
+#ifndef __ARM64_HYP_IMAGE_H__
+#define __ARM64_HYP_IMAGE_H__
+
+#ifdef LINKER_SCRIPT
+
+/*
+ * KVM nVHE ELF section names are prefixed with .hyp, to separate them
+ * from the kernel proper.
+ */
+#define HYP_SECTION_NAME(NAME)	.hyp##NAME
+
+/* Defines an ELF hyp section from input section @NAME and its subsections. */
+#define HYP_SECTION(NAME) \
+	HYP_SECTION_NAME(NAME) : { *(NAME NAME##.*) }
+
+#endif /* LINKER_SCRIPT */
+
+#endif /* __ARM64_HYP_IMAGE_H__ */
diff --git a/arch/arm64/kvm/hyp/nvhe/.gitignore b/arch/arm64/kvm/hyp/nvhe/.gitignore
new file mode 100644
index 000000000000..695d73d0249e
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+hyp.lds
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index aef76487edc2..2b27b60182f9 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -10,40 +10,46 @@ obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o
 
-obj-y := $(patsubst %.o,%.hyp.o,$(obj-y))
-extra-y := $(patsubst %.hyp.o,%.hyp.tmp.o,$(obj-y))
+##
+## Build rules for compiling nVHE hyp code
+## Output of this folder is `kvm_nvhe.o`, a partially linked object
+## file containing all nVHE hyp code and data.
+##
 
-$(obj)/%.hyp.tmp.o: $(src)/%.c FORCE
+hyp-obj := $(patsubst %.o,%.nvhe.o,$(obj-y))
+obj-y := kvm_nvhe.o
+extra-y := $(hyp-obj) kvm_nvhe.tmp.o hyp.lds
+
+# 1) Compile all source files to `.nvhe.o` object files. The file extension
+#    avoids file name clashes for files shared with VHE.
+$(obj)/%.nvhe.o: $(src)/%.c FORCE
 	$(call if_changed_rule,cc_o_c)
-$(obj)/%.hyp.tmp.o: $(src)/%.S FORCE
+$(obj)/%.nvhe.o: $(src)/%.S FORCE
 	$(call if_changed_rule,as_o_S)
-$(obj)/%.hyp.o: $(obj)/%.hyp.tmp.o FORCE
-	$(call if_changed,hypcopy)
 
-# Disable reordering functions by GCC (enabled at -O2).
-# This pass puts functions into '.text.*' sections to aid the linker
-# in optimizing ELF layout. See HYPCOPY comment below for more info.
-ccflags-y += $(call cc-option,-fno-reorder-functions)
+# 2) Compile linker script.
+$(obj)/hyp.lds: $(src)/hyp.lds.S FORCE
+	$(call if_changed_dep,cpp_lds_S)
+
+# 3) Partially link all '.nvhe.o' files and apply the linker script.
+#    Prefixes names of ELF sections with '.hyp', eg. '.hyp.text'.
+#    Note: The following rule assumes that the 'ld' rule puts LDFLAGS before
+#          the list of dependencies to form '-T $(obj)/hyp.lds'. This is to
+#          keep the dependency on the target while avoiding an error from
+#          GNU ld if the linker script is passed to it twice.
+LDFLAGS_kvm_nvhe.tmp.o := -r -T
+$(obj)/kvm_nvhe.tmp.o: $(obj)/hyp.lds $(addprefix $(obj)/,$(hyp-obj)) FORCE
+	$(call if_changed,ld)
+
+# 4) Produce the final 'kvm_nvhe.o', ready to be linked into 'vmlinux'.
+#    Prefixes names of ELF symbols with '__kvm_nvhe_'.
+$(obj)/kvm_nvhe.o: $(obj)/kvm_nvhe.tmp.o FORCE
+	$(call if_changed,hypcopy)
 
 # The HYPCOPY command uses `objcopy` to prefix all ELF symbol names
-# and relevant ELF section names to avoid clashes with VHE code/data.
-#
-# Hyp code is assumed to be in the '.text' section of the input object
-# files (with the exception of specialized sections such as
-# '.hyp.idmap.text'). This assumption may be broken by a compiler that
-# divides code into sections like '.text.unlikely' so as to optimize
-# ELF layout. HYPCOPY checks that no such sections exist in the input
-# using `objdump`, otherwise they would be linked together with other
-# kernel code and not memory-mapped correctly at runtime.
+# to avoid clashes with VHE code/data.
 quiet_cmd_hypcopy = HYPCOPY $@
-      cmd_hypcopy =							\
-	if $(OBJDUMP) -h $< | grep -F '.text.'; then			\
-		echo "$@: function reordering not supported in nVHE hyp code" >&2; \
-		/bin/false;						\
-	fi;								\
-	$(OBJCOPY) --prefix-symbols=__kvm_nvhe_				\
-		   --rename-section=.text=.hyp.text			\
-		   $< $@
+      cmd_hypcopy = $(OBJCOPY) --prefix-symbols=__kvm_nvhe_ $< $@
 
 # Remove ftrace and Shadow Call Stack CFLAGS.
 # This is equivalent to the 'notrace' and '__noscs' annotations.
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
new file mode 100644
index 000000000000..3b13d1c7cd1a
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 Google LLC.
+ * Written by David Brazdil <dbrazdil@google.com>
+ *
+ * Linker script used for partial linking of nVHE EL2 object files.
+ */
+
+#include <asm/hyp_image.h>
+
+SECTIONS {
+	HYP_SECTION(.text)
+}
-- 
2.28.0.681.g6f77f65b4e-goog

[PATCH v4 02/10] kvm: arm64: Move nVHE hyp namespace macros to hyp_image.h

[David Brazdil]

Minor cleanup to move all macros related to prefixing nVHE hyp section
and symbol names into one place: hyp_image.h.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/include/asm/hyp_image.h | 12 ++++++++++++
 arch/arm64/include/asm/kvm_asm.h   |  8 +-------
 arch/arm64/kernel/image-vars.h     |  2 --
 arch/arm64/kernel/vmlinux.lds.S    |  1 +
 4 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/include/asm/hyp_image.h b/arch/arm64/include/asm/hyp_image.h
index 2e38fcda02fc..daa1a1da539e 100644
--- a/arch/arm64/include/asm/hyp_image.h
+++ b/arch/arm64/include/asm/hyp_image.h
@@ -7,6 +7,12 @@
 #ifndef __ARM64_HYP_IMAGE_H__
 #define __ARM64_HYP_IMAGE_H__
 
+/*
+ * KVM nVHE code has its own symbol namespace prefixed with __kvm_nvhe_,
+ * to separate it from the kernel proper.
+ */
+#define kvm_nvhe_sym(sym)	__kvm_nvhe_##sym
+
 #ifdef LINKER_SCRIPT
 
 /*
@@ -19,6 +25,12 @@
 #define HYP_SECTION(NAME) \
 	HYP_SECTION_NAME(NAME) : { *(NAME NAME##.*) }
 
+/*
+ * Defines a linker script alias of a kernel-proper symbol referenced by
+ * KVM nVHE hyp code.
+ */
+#define KVM_NVHE_ALIAS(sym)	kvm_nvhe_sym(sym) = sym;
+
 #endif /* LINKER_SCRIPT */
 
 #endif /* __ARM64_HYP_IMAGE_H__ */
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 6f98fbd0ac81..c085032e2e3e 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -7,6 +7,7 @@
 #ifndef __ARM_KVM_ASM_H__
 #define __ARM_KVM_ASM_H__
 
+#include <asm/hyp_image.h>
 #include <asm/virt.h>
 
 #define	VCPU_WORKAROUND_2_FLAG_SHIFT	0
@@ -42,13 +43,6 @@
 
 #include <linux/mm.h>
 
-/*
- * Translate name of a symbol defined in nVHE hyp to the name seen
- * by kernel proper. All nVHE symbols are prefixed by the build system
- * to avoid clashes with the VHE variants.
- */
-#define kvm_nvhe_sym(sym)	__kvm_nvhe_##sym
-
 #define DECLARE_KVM_VHE_SYM(sym)	extern char sym[]
 #define DECLARE_KVM_NVHE_SYM(sym)	extern char kvm_nvhe_sym(sym)[]
 
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 8982b68289b7..76da2ad1010c 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -61,8 +61,6 @@ __efistub__ctype		= _ctype;
  * memory mappings.
  */
 
-#define KVM_NVHE_ALIAS(sym) __kvm_nvhe_##sym = sym;
-
 /* Alternative callbacks for init-time patching of nVHE hyp code. */
 KVM_NVHE_ALIAS(arm64_enable_wa2_handling);
 KVM_NVHE_ALIAS(kvm_patch_vector_branch);
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 7cba7623fcec..fbb13f38d0c5 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -9,6 +9,7 @@
 
 #include <asm-generic/vmlinux.lds.h>
 #include <asm/cache.h>
+#include <asm/hyp_image.h>
 #include <asm/kernel-pgtable.h>
 #include <asm/memory.h>
 #include <asm/page.h>
-- 
2.28.0.681.g6f77f65b4e-goog

[PATCH v4 03/10] kvm: arm64: Only define __kvm_ex_table for CONFIG_KVM

[David Brazdil]

Minor cleanup that only creates __kvm_ex_table ELF section and
related symbols if CONFIG_KVM is enabled. Also useful as more
hyp-specific sections will be added.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/kernel/vmlinux.lds.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index fbb13f38d0c5..d14166012e51 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -22,11 +22,15 @@ ENTRY(_text)
 jiffies = jiffies_64;
 
 
+#ifdef CONFIG_KVM
 #define HYPERVISOR_EXTABLE					\
 	. = ALIGN(SZ_8);					\
 	__start___kvm_ex_table = .;				\
 	*(__kvm_ex_table)					\
 	__stop___kvm_ex_table = .;
+#else /* CONFIG_KVM */
+#define HYPERVISOR_EXTABLE
+#endif
 
 #define HYPERVISOR_TEXT					\
 	/*						\
-- 
2.28.0.681.g6f77f65b4e-goog

[PATCH v4 04/10] kvm: arm64: Remove __hyp_this_cpu_read

[David Brazdil]

this_cpu_ptr is meant for use in kernel proper because it selects between
TPIDR_EL1/2 based on nVHE/VHE. __hyp_this_cpu_ptr was used in hyp to always
select TPIDR_EL2. Unify all users behind this_cpu_ptr and friends by
selecting _EL2 register under __KVM_NVHE_HYPERVISOR__. VHE continues
selecting the register using alternatives.

Under CONFIG_DEBUG_PREEMPT, the kernel helpers perform a preemption check
which is omitted by the hyp helpers. Preserve the behavior for nVHE by
overriding the corresponding macros under __KVM_NVHE_HYPERVISOR__. Extend
the checks into VHE hyp code.

Acked-by: Andrew Scull <ascull@google.com>
Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/include/asm/kvm_asm.h          | 20 ----------------
 arch/arm64/include/asm/percpu.h           | 28 +++++++++++++++++++++--
 arch/arm64/kvm/hyp/include/hyp/debug-sr.h |  4 ++--
 arch/arm64/kvm/hyp/include/hyp/switch.h   |  8 +++----
 arch/arm64/kvm/hyp/nvhe/switch.c          |  2 +-
 arch/arm64/kvm/hyp/vhe/switch.c           |  2 +-
 arch/arm64/kvm/hyp/vhe/sysreg-sr.c        |  4 ++--
 7 files changed, 36 insertions(+), 32 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index c085032e2e3e..c196eec25498 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -143,26 +143,6 @@ extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
 		addr;							\
 	})
 
-/*
- * Home-grown __this_cpu_{ptr,read} variants that always work at HYP,
- * provided that sym is really a *symbol* and not a pointer obtained from
- * a data structure. As for SHIFT_PERCPU_PTR(), the creative casting keeps
- * sparse quiet.
- */
-#define __hyp_this_cpu_ptr(sym)						\
-	({								\
-		void *__ptr;						\
-		__verify_pcpu_ptr(&sym);				\
-		__ptr = hyp_symbol_addr(sym);				\
-		__ptr += read_sysreg(tpidr_el2);			\
-		(typeof(sym) __kernel __force *)__ptr;			\
-	 })
-
-#define __hyp_this_cpu_read(sym)					\
-	({								\
-		*__hyp_this_cpu_ptr(sym);				\
-	 })
-
 #define __KVM_EXTABLE(from, to)						\
 	"	.pushsection	__kvm_ex_table, \"a\"\n"		\
 	"	.align		3\n"					\
diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h
index 0b6409b89e5e..1599e17379d8 100644
--- a/arch/arm64/include/asm/percpu.h
+++ b/arch/arm64/include/asm/percpu.h
@@ -19,7 +19,16 @@ static inline void set_my_cpu_offset(unsigned long off)
 			:: "r" (off) : "memory");
 }
 
-static inline unsigned long __my_cpu_offset(void)
+static inline unsigned long __hyp_my_cpu_offset(void)
+{
+	/*
+	 * Non-VHE hyp code runs with preemption disabled. No need to hazard
+	 * the register access against barrier() as in __kern_my_cpu_offset.
+	 */
+	return read_sysreg(tpidr_el2);
+}
+
+static inline unsigned long __kern_my_cpu_offset(void)
 {
 	unsigned long off;
 
@@ -35,7 +44,12 @@ static inline unsigned long __my_cpu_offset(void)
 
 	return off;
 }
-#define __my_cpu_offset __my_cpu_offset()
+
+#ifdef __KVM_NVHE_HYPERVISOR__
+#define __my_cpu_offset __hyp_my_cpu_offset()
+#else
+#define __my_cpu_offset __kern_my_cpu_offset()
+#endif
 
 #define PERCPU_RW_OPS(sz)						\
 static inline unsigned long __percpu_read_##sz(void *ptr)		\
@@ -227,4 +241,14 @@ PERCPU_RET_OP(add, add, ldadd)
 
 #include <asm-generic/percpu.h>
 
+/* Redefine macros for nVHE hyp under DEBUG_PREEMPT to avoid its dependencies. */
+#if defined(__KVM_NVHE_HYPERVISOR__) && defined(CONFIG_DEBUG_PREEMPT)
+#undef	this_cpu_ptr
+#define	this_cpu_ptr		raw_cpu_ptr
+#undef	__this_cpu_read
+#define	__this_cpu_read		raw_cpu_read
+#undef	__this_cpu_write
+#define	__this_cpu_write	raw_cpu_write
+#endif
+
 #endif /* __ASM_PERCPU_H */
diff --git a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h
index 5e28ea6aa097..4ebe9f558f3a 100644
--- a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h
+++ b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h
@@ -135,7 +135,7 @@ static inline void __debug_switch_to_guest_common(struct kvm_vcpu *vcpu)
 	if (!(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY))
 		return;
 
-	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
+	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
 	guest_ctxt = &vcpu->arch.ctxt;
 	host_dbg = &vcpu->arch.host_debug_state.regs;
 	guest_dbg = kern_hyp_va(vcpu->arch.debug_ptr);
@@ -154,7 +154,7 @@ static inline void __debug_switch_to_host_common(struct kvm_vcpu *vcpu)
 	if (!(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY))
 		return;
 
-	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
+	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
 	guest_ctxt = &vcpu->arch.ctxt;
 	host_dbg = &vcpu->arch.host_debug_state.regs;
 	guest_dbg = kern_hyp_va(vcpu->arch.debug_ptr);
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 5b6b8fa00f0a..f150407fa798 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -386,7 +386,7 @@ static inline bool __hyp_handle_ptrauth(struct kvm_vcpu *vcpu)
 	    !esr_is_ptrauth_trap(kvm_vcpu_get_esr(vcpu)))
 		return false;
 
-	ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
+	ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
 	__ptrauth_save_key(ctxt, APIA);
 	__ptrauth_save_key(ctxt, APIB);
 	__ptrauth_save_key(ctxt, APDA);
@@ -495,7 +495,7 @@ static inline void __set_guest_arch_workaround_state(struct kvm_vcpu *vcpu)
 	 * guest wants it disabled, so be it...
 	 */
 	if (__needs_ssbd_off(vcpu) &&
-	    __hyp_this_cpu_read(arm64_ssbd_callback_required))
+	    __this_cpu_read(arm64_ssbd_callback_required))
 		arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, 0, NULL);
 #endif
 }
@@ -507,7 +507,7 @@ static inline void __set_host_arch_workaround_state(struct kvm_vcpu *vcpu)
 	 * If the guest has disabled the workaround, bring it back on.
 	 */
 	if (__needs_ssbd_off(vcpu) &&
-	    __hyp_this_cpu_read(arm64_ssbd_callback_required))
+	    __this_cpu_read(arm64_ssbd_callback_required))
 		arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, 1, NULL);
 #endif
 }
@@ -521,7 +521,7 @@ static inline void __kvm_unexpected_el2_exception(void)
 
 	entry = hyp_symbol_addr(__start___kvm_ex_table);
 	end = hyp_symbol_addr(__stop___kvm_ex_table);
-	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
+	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
 
 	while (entry < end) {
 		addr = (unsigned long)&entry->insn + entry->insn;
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 0970442d2dbc..cc4f8e790fb3 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -175,7 +175,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 
 	vcpu = kern_hyp_va(vcpu);
 
-	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
+	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
 	host_ctxt->__hyp_running_vcpu = vcpu;
 	guest_ctxt = &vcpu->arch.ctxt;
 
diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index c1da4f86ccac..575e8054f116 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -108,7 +108,7 @@ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
 	struct kvm_cpu_context *guest_ctxt;
 	u64 exit_code;
 
-	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
+	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
 	host_ctxt->__hyp_running_vcpu = vcpu;
 	guest_ctxt = &vcpu->arch.ctxt;
 
diff --git a/arch/arm64/kvm/hyp/vhe/sysreg-sr.c b/arch/arm64/kvm/hyp/vhe/sysreg-sr.c
index 996471e4c138..2a0b8c88d74f 100644
--- a/arch/arm64/kvm/hyp/vhe/sysreg-sr.c
+++ b/arch/arm64/kvm/hyp/vhe/sysreg-sr.c
@@ -66,7 +66,7 @@ void kvm_vcpu_load_sysregs_vhe(struct kvm_vcpu *vcpu)
 	struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
 	struct kvm_cpu_context *host_ctxt;
 
-	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
+	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
 	__sysreg_save_user_state(host_ctxt);
 
 	/*
@@ -100,7 +100,7 @@ void kvm_vcpu_put_sysregs_vhe(struct kvm_vcpu *vcpu)
 	struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
 	struct kvm_cpu_context *host_ctxt;
 
-	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
+	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
 	deactivate_traps_vhe_put();
 
 	__sysreg_save_el1_state(guest_ctxt);
-- 
2.28.0.681.g6f77f65b4e-goog

Re: [PATCH v4 04/10] kvm: arm64: Remove __hyp_this_cpu_read

[Will Deacon]

On Tue, Sep 22, 2020 at 09:49:04PM +0100, David Brazdil wrote:
> this_cpu_ptr is meant for use in kernel proper because it selects between
> TPIDR_EL1/2 based on nVHE/VHE. __hyp_this_cpu_ptr was used in hyp to always
> select TPIDR_EL2. Unify all users behind this_cpu_ptr and friends by
> selecting _EL2 register under __KVM_NVHE_HYPERVISOR__. VHE continues
> selecting the register using alternatives.
> 
> Under CONFIG_DEBUG_PREEMPT, the kernel helpers perform a preemption check
> which is omitted by the hyp helpers. Preserve the behavior for nVHE by
> overriding the corresponding macros under __KVM_NVHE_HYPERVISOR__. Extend
> the checks into VHE hyp code.
> 
> Acked-by: Andrew Scull <ascull@google.com>
> Signed-off-by: David Brazdil <dbrazdil@google.com>
> ---
>  arch/arm64/include/asm/kvm_asm.h          | 20 ----------------
>  arch/arm64/include/asm/percpu.h           | 28 +++++++++++++++++++++--
>  arch/arm64/kvm/hyp/include/hyp/debug-sr.h |  4 ++--
>  arch/arm64/kvm/hyp/include/hyp/switch.h   |  8 +++----
>  arch/arm64/kvm/hyp/nvhe/switch.c          |  2 +-
>  arch/arm64/kvm/hyp/vhe/switch.c           |  2 +-
>  arch/arm64/kvm/hyp/vhe/sysreg-sr.c        |  4 ++--
>  7 files changed, 36 insertions(+), 32 deletions(-)

Looks good, thanks for the respin!

Acked-by: Will Deacon <will@kernel.org>

Will

[PATCH v4 05/10] kvm: arm64: Remove hyp_adr/ldr_this_cpu

[David Brazdil]

The hyp_adr/ldr_this_cpu helpers were introduced for use in hyp code
because they always needed to use TPIDR_EL2 for base, while
adr/ldr_this_cpu from kernel proper would select between TPIDR_EL2 and
_EL1 based on VHE/nVHE.

Simplify this now that the hyp mode case can be handled using the
__KVM_VHE/NVHE_HYPERVISOR__ macros.

Acked-by: Andrew Scull <ascull@google.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/include/asm/assembler.h | 29 +++++++++++++++++++----------
 arch/arm64/include/asm/kvm_asm.h   | 14 +-------------
 arch/arm64/kvm/hyp/hyp-entry.S     |  2 +-
 3 files changed, 21 insertions(+), 24 deletions(-)

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 54d181177656..86e0ef79a799 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -218,6 +218,23 @@ lr	.req	x30		// link register
 	str	\src, [\tmp, :lo12:\sym]
 	.endm
 
+	/*
+	 * @dst: destination register (32 or 64 bit wide)
+	 */
+#if defined(__KVM_NVHE_HYPERVISOR__) || defined(__KVM_VHE_HYPERVISOR__)
+	.macro	this_cpu_offset, dst
+	mrs	\dst, tpidr_el2
+	.endm
+#else
+	.macro	this_cpu_offset, dst
+alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
+	mrs	\dst, tpidr_el1
+alternative_else
+	mrs	\dst, tpidr_el2
+alternative_endif
+	.endm
+#endif
+
 	/*
 	 * @dst: Result of per_cpu(sym, smp_processor_id()) (can be SP)
 	 * @sym: The name of the per-cpu variable
@@ -226,11 +243,7 @@ lr	.req	x30		// link register
 	.macro adr_this_cpu, dst, sym, tmp
 	adrp	\tmp, \sym
 	add	\dst, \tmp, #:lo12:\sym
-alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
-	mrs	\tmp, tpidr_el1
-alternative_else
-	mrs	\tmp, tpidr_el2
-alternative_endif
+	this_cpu_offset \tmp
 	add	\dst, \dst, \tmp
 	.endm
 
@@ -241,11 +254,7 @@ alternative_endif
 	 */
 	.macro ldr_this_cpu dst, sym, tmp
 	adr_l	\dst, \sym
-alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
-	mrs	\tmp, tpidr_el1
-alternative_else
-	mrs	\tmp, tpidr_el2
-alternative_endif
+	this_cpu_offset \tmp
 	ldr	\dst, [\dst, \tmp]
 	.endm
 
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index c196eec25498..cf9456663289 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -173,20 +173,8 @@ extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
 
 #else /* __ASSEMBLY__ */
 
-.macro hyp_adr_this_cpu reg, sym, tmp
-	adr_l	\reg, \sym
-	mrs	\tmp, tpidr_el2
-	add	\reg, \reg, \tmp
-.endm
-
-.macro hyp_ldr_this_cpu reg, sym, tmp
-	adr_l	\reg, \sym
-	mrs	\tmp, tpidr_el2
-	ldr	\reg,  [\reg, \tmp]
-.endm
-
 .macro get_host_ctxt reg, tmp
-	hyp_adr_this_cpu \reg, kvm_host_data, \tmp
+	adr_this_cpu \reg, kvm_host_data, \tmp
 	add	\reg, \reg, #HOST_DATA_CONTEXT
 .endm
 
diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index 46b4dab933d0..fba91c2ab410 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -132,7 +132,7 @@ alternative_cb_end
 	str	x0, [x2, #VCPU_WORKAROUND_FLAGS]
 
 	/* Check that we actually need to perform the call */
-	hyp_ldr_this_cpu x0, arm64_ssbd_callback_required, x2
+	ldr_this_cpu x0, arm64_ssbd_callback_required, x2
 	cbz	x0, wa2_end
 
 	mov	w0, #ARM_SMCCC_ARCH_WORKAROUND_2
-- 
2.28.0.681.g6f77f65b4e-goog

Re: [PATCH v4 05/10] kvm: arm64: Remove hyp_adr/ldr_this_cpu

[Will Deacon]

On Tue, Sep 22, 2020 at 09:49:05PM +0100, David Brazdil wrote:
> The hyp_adr/ldr_this_cpu helpers were introduced for use in hyp code
> because they always needed to use TPIDR_EL2 for base, while
> adr/ldr_this_cpu from kernel proper would select between TPIDR_EL2 and
> _EL1 based on VHE/nVHE.
> 
> Simplify this now that the hyp mode case can be handled using the
> __KVM_VHE/NVHE_HYPERVISOR__ macros.
> 
> Acked-by: Andrew Scull <ascull@google.com>
> Acked-by: Will Deacon <will@kernel.org>
> Signed-off-by: David Brazdil <dbrazdil@google.com>
> ---
>  arch/arm64/include/asm/assembler.h | 29 +++++++++++++++++++----------
>  arch/arm64/include/asm/kvm_asm.h   | 14 +-------------
>  arch/arm64/kvm/hyp/hyp-entry.S     |  2 +-
>  3 files changed, 21 insertions(+), 24 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
> index 54d181177656..86e0ef79a799 100644
> --- a/arch/arm64/include/asm/assembler.h
> +++ b/arch/arm64/include/asm/assembler.h
> @@ -218,6 +218,23 @@ lr	.req	x30		// link register
>  	str	\src, [\tmp, :lo12:\sym]
>  	.endm
>  
> +	/*
> +	 * @dst: destination register (32 or 64 bit wide)

nit: this comment is wrong as I don't think mrs can take a W register
as the destination argument. I'm assuming Marc can fix that up.

Will

Re: [PATCH v4 05/10] kvm: arm64: Remove hyp_adr/ldr_this_cpu

[Marc Zyngier]

On 2020-09-29 18:34, Will Deacon wrote:
> On Tue, Sep 22, 2020 at 09:49:05PM +0100, David Brazdil wrote:
>> The hyp_adr/ldr_this_cpu helpers were introduced for use in hyp code
>> because they always needed to use TPIDR_EL2 for base, while
>> adr/ldr_this_cpu from kernel proper would select between TPIDR_EL2 and
>> _EL1 based on VHE/nVHE.
>> 
>> Simplify this now that the hyp mode case can be handled using the
>> __KVM_VHE/NVHE_HYPERVISOR__ macros.
>> 
>> Acked-by: Andrew Scull <ascull@google.com>
>> Acked-by: Will Deacon <will@kernel.org>
>> Signed-off-by: David Brazdil <dbrazdil@google.com>
>> ---
>>  arch/arm64/include/asm/assembler.h | 29 +++++++++++++++++++----------
>>  arch/arm64/include/asm/kvm_asm.h   | 14 +-------------
>>  arch/arm64/kvm/hyp/hyp-entry.S     |  2 +-
>>  3 files changed, 21 insertions(+), 24 deletions(-)
>> 
>> diff --git a/arch/arm64/include/asm/assembler.h 
>> b/arch/arm64/include/asm/assembler.h
>> index 54d181177656..86e0ef79a799 100644
>> --- a/arch/arm64/include/asm/assembler.h
>> +++ b/arch/arm64/include/asm/assembler.h
>> @@ -218,6 +218,23 @@ lr	.req	x30		// link register
>>  	str	\src, [\tmp, :lo12:\sym]
>>  	.endm
>> 
>> +	/*
>> +	 * @dst: destination register (32 or 64 bit wide)
> 
> nit: this comment is wrong as I don't think mrs can take a W register
> as the destination argument. I'm assuming Marc can fix that up.

Indeed. I'll fix it locally.

Another thing is that this patch is going to clash with the Ghostbuster
branch (the hyp-entry.S hunk goes), but we can deal with that.

         M.
-- 
Jazz is not dead. It just smells funny...

[PATCH v4 06/10] kvm: arm64: Add helpers for accessing nVHE hyp per-cpu vars

[David Brazdil]

Defining a per-CPU variable in hyp/nvhe will result in its name being
prefixed with __kvm_nvhe_. Add helpers for declaring these variables
in kernel proper and accessing them with this_cpu_ptr and per_cpu_ptr.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/include/asm/kvm_asm.h | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index cf9456663289..911d91787fa0 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -54,9 +54,21 @@
 	DECLARE_KVM_VHE_SYM(sym);		\
 	DECLARE_KVM_NVHE_SYM(sym)
 
+#define DECLARE_KVM_VHE_PER_CPU(type, sym)	\
+	DECLARE_PER_CPU(type, sym)
+#define DECLARE_KVM_NVHE_PER_CPU(type, sym)	\
+	DECLARE_PER_CPU(type, kvm_nvhe_sym(sym))
+
+#define DECLARE_KVM_HYP_PER_CPU(type, sym)	\
+	DECLARE_KVM_VHE_PER_CPU(type, sym);	\
+	DECLARE_KVM_NVHE_PER_CPU(type, sym)
+
 #define CHOOSE_VHE_SYM(sym)	sym
 #define CHOOSE_NVHE_SYM(sym)	kvm_nvhe_sym(sym)
 
+#define this_cpu_ptr_nvhe_sym(sym)	this_cpu_ptr(&kvm_nvhe_sym(sym))
+#define per_cpu_ptr_nvhe_sym(sym, cpu)	per_cpu_ptr(&kvm_nvhe_sym(sym), cpu)
+
 #ifndef __KVM_NVHE_HYPERVISOR__
 /*
  * BIG FAT WARNINGS:
@@ -69,12 +81,21 @@
  * - Don't let the nVHE hypervisor have access to this, as it will
  *   pick the *wrong* symbol (yes, it runs at EL2...).
  */
-#define CHOOSE_HYP_SYM(sym)	(is_kernel_in_hyp_mode() ? CHOOSE_VHE_SYM(sym) \
+#define CHOOSE_HYP_SYM(sym)		(is_kernel_in_hyp_mode()	\
+					   ? CHOOSE_VHE_SYM(sym)	\
 					   : CHOOSE_NVHE_SYM(sym))
+#define this_cpu_ptr_hyp_sym(sym)	(is_kernel_in_hyp_mode()	\
+					   ? this_cpu_ptr(&sym)		\
+					   : this_cpu_ptr_nvhe_sym(sym))
+#define per_cpu_ptr_hyp_sym(sym, cpu)	(is_kernel_in_hyp_mode()	\
+					   ? per_cpu_ptr(&sym, cpu)	\
+					   : per_cpu_ptr_nvhe_sym(sym, cpu))
 #else
 /* The nVHE hypervisor shouldn't even try to access anything */
 extern void *__nvhe_undefined_symbol;
-#define CHOOSE_HYP_SYM(sym)	__nvhe_undefined_symbol
+#define CHOOSE_HYP_SYM(sym)		__nvhe_undefined_symbol
+#define this_cpu_ptr_hyp_sym(sym)	(&__nvhe_undefined_symbol)
+#define per_cpu_ptr_hyp_sym(sym, cpu)	(&__nvhe_undefined_symbol)
 #endif
 
 /* Translate a kernel address @ptr into its equivalent linear mapping */
-- 
2.28.0.681.g6f77f65b4e-goog

[PATCH v4 07/10] kvm: arm64: Duplicate arm64_ssbd_callback_required for nVHE hyp

[David Brazdil]

Hyp keeps track of which cores require SSBD callback by accessing a
kernel-proper global variable. Create an nVHE symbol of the same name
and copy the value from kernel proper to nVHE as KVM is being enabled
on a core.

Done in preparation for separating percpu memory owned by kernel
proper and nVHE.

Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/include/asm/kvm_mmu.h | 14 +++++++++++++-
 arch/arm64/kernel/image-vars.h   |  1 -
 arch/arm64/kvm/arm.c             |  3 +++
 arch/arm64/kvm/hyp/nvhe/switch.c |  3 +++
 4 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 189839c3706a..e134c2ba2c5d 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -529,6 +529,7 @@ static inline int kvm_map_vectors(void)
 
 #ifdef CONFIG_ARM64_SSBD
 DECLARE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required);
+DECLARE_KVM_NVHE_PER_CPU(u64, arm64_ssbd_callback_required);
 
 static inline int hyp_map_aux_data(void)
 {
@@ -537,18 +538,29 @@ static inline int hyp_map_aux_data(void)
 	for_each_possible_cpu(cpu) {
 		u64 *ptr;
 
-		ptr = per_cpu_ptr(&arm64_ssbd_callback_required, cpu);
+		ptr = per_cpu_ptr_nvhe_sym(arm64_ssbd_callback_required, cpu);
 		err = create_hyp_mappings(ptr, ptr + 1, PAGE_HYP);
 		if (err)
 			return err;
 	}
 	return 0;
 }
+
+static inline void hyp_init_aux_data(void)
+{
+	u64 *ptr;
+
+	/* Copy arm64_ssbd_callback_required value from kernel to hyp. */
+	ptr = this_cpu_ptr_nvhe_sym(arm64_ssbd_callback_required);
+	*ptr = __this_cpu_read(arm64_ssbd_callback_required);
+}
 #else
 static inline int hyp_map_aux_data(void)
 {
 	return 0;
 }
+
+static inline void hyp_init_aux_data(void) {}
 #endif
 
 #define kvm_phys_to_vttbr(addr)		phys_to_ttbr(addr)
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 76da2ad1010c..59d12a0b4622 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -67,7 +67,6 @@ KVM_NVHE_ALIAS(kvm_patch_vector_branch);
 KVM_NVHE_ALIAS(kvm_update_va_mask);
 
 /* Global kernel state accessed by nVHE hyp code. */
-KVM_NVHE_ALIAS(arm64_ssbd_callback_required);
 KVM_NVHE_ALIAS(kvm_host_data);
 KVM_NVHE_ALIAS(kvm_vgic_global_state);
 
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index b588c3b5c2f0..76be11d31e5d 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1298,6 +1298,9 @@ static void cpu_init_hyp_mode(void)
 	    arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE) {
 		kvm_call_hyp_nvhe(__kvm_enable_ssbs);
 	}
+
+	/* Copy information whether SSBD callback is required to hyp. */
+	hyp_init_aux_data();
 }
 
 static void cpu_hyp_reset(void)
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index cc4f8e790fb3..4662df6330d7 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -27,6 +27,9 @@
 #include <asm/processor.h>
 #include <asm/thread_info.h>
 
+/* Non-VHE copy of the kernel symbol. */
+DEFINE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required);
+
 static void __activate_traps(struct kvm_vcpu *vcpu)
 {
 	u64 val;
-- 
2.28.0.681.g6f77f65b4e-goog

Re: [PATCH v4 07/10] kvm: arm64: Duplicate arm64_ssbd_callback_required for nVHE hyp

[Will Deacon]

On Tue, Sep 22, 2020 at 09:49:07PM +0100, David Brazdil wrote:
> Hyp keeps track of which cores require SSBD callback by accessing a
> kernel-proper global variable. Create an nVHE symbol of the same name
> and copy the value from kernel proper to nVHE as KVM is being enabled
> on a core.
> 
> Done in preparation for separating percpu memory owned by kernel
> proper and nVHE.
> 
> Signed-off-by: David Brazdil <dbrazdil@google.com>
> ---
>  arch/arm64/include/asm/kvm_mmu.h | 14 +++++++++++++-
>  arch/arm64/kernel/image-vars.h   |  1 -
>  arch/arm64/kvm/arm.c             |  3 +++
>  arch/arm64/kvm/hyp/nvhe/switch.c |  3 +++
>  4 files changed, 19 insertions(+), 2 deletions(-)

Acked-by: Will Deacon <will@kernel.org>

Marc: please take a look at for-next/ghostbusters on the arm64 tree, as
that has the patches which remove this stuff entirely. I had to rebase
the branch today because I screwed up some of the SoBs but the HEAD is
now stable at 780c083a8f84.

Will

[PATCH v4 08/10] kvm: arm64: Create separate instances of kvm_host_data for VHE/nVHE

[David Brazdil]

Host CPU context is stored in a global per-cpu variable `kvm_host_data`.
In preparation for introducing independent per-CPU region for nVHE hyp,
create two separate instances of `kvm_host_data`, one for VHE and one
for nVHE.

Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/include/asm/kvm_host.h | 2 +-
 arch/arm64/kernel/image-vars.h    | 1 -
 arch/arm64/kvm/arm.c              | 5 ++---
 arch/arm64/kvm/hyp/nvhe/switch.c  | 3 +++
 arch/arm64/kvm/hyp/vhe/switch.c   | 3 +++
 arch/arm64/kvm/pmu.c              | 8 ++++----
 6 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 905c2b87e05a..5d8c63f5e97e 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -565,7 +565,7 @@ void kvm_set_sei_esr(struct kvm_vcpu *vcpu, u64 syndrome);
 
 struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
 
-DECLARE_PER_CPU(kvm_host_data_t, kvm_host_data);
+DECLARE_KVM_HYP_PER_CPU(kvm_host_data_t, kvm_host_data);
 
 static inline void kvm_init_host_cpu_context(struct kvm_cpu_context *cpu_ctxt)
 {
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 59d12a0b4622..80da861b8180 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -67,7 +67,6 @@ KVM_NVHE_ALIAS(kvm_patch_vector_branch);
 KVM_NVHE_ALIAS(kvm_update_va_mask);
 
 /* Global kernel state accessed by nVHE hyp code. */
-KVM_NVHE_ALIAS(kvm_host_data);
 KVM_NVHE_ALIAS(kvm_vgic_global_state);
 
 /* Kernel constant needed to compute idmap addresses. */
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 76be11d31e5d..0424667c4c0a 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -46,7 +46,6 @@
 __asm__(".arch_extension	virt");
 #endif
 
-DEFINE_PER_CPU(kvm_host_data_t, kvm_host_data);
 static DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
 
 /* The VMID used in the VTTBR */
@@ -1311,7 +1310,7 @@ static void cpu_hyp_reset(void)
 
 static void cpu_hyp_reinit(void)
 {
-	kvm_init_host_cpu_context(&this_cpu_ptr(&kvm_host_data)->host_ctxt);
+	kvm_init_host_cpu_context(&this_cpu_ptr_hyp_sym(kvm_host_data)->host_ctxt);
 
 	cpu_hyp_reset();
 
@@ -1546,7 +1545,7 @@ static int init_hyp_mode(void)
 	for_each_possible_cpu(cpu) {
 		kvm_host_data_t *cpu_data;
 
-		cpu_data = per_cpu_ptr(&kvm_host_data, cpu);
+		cpu_data = per_cpu_ptr_hyp_sym(kvm_host_data, cpu);
 		err = create_hyp_mappings(cpu_data, cpu_data + 1, PAGE_HYP);
 
 		if (err) {
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 4662df6330d7..a7e9b03bd9d1 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -30,6 +30,9 @@
 /* Non-VHE copy of the kernel symbol. */
 DEFINE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required);
 
+/* Non-VHE instance of kvm_host_data. */
+DEFINE_PER_CPU(kvm_host_data_t, kvm_host_data);
+
 static void __activate_traps(struct kvm_vcpu *vcpu)
 {
 	u64 val;
diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index 575e8054f116..0949fc97bf03 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -28,6 +28,9 @@
 
 const char __hyp_panic_string[] = "HYP panic:\nPS:%08llx PC:%016llx ESR:%08llx\nFAR:%016llx HPFAR:%016llx PAR:%016llx\nVCPU:%p\n";
 
+/* VHE instance of kvm_host_data. */
+DEFINE_PER_CPU(kvm_host_data_t, kvm_host_data);
+
 static void __activate_traps(struct kvm_vcpu *vcpu)
 {
 	u64 val;
diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index 3c224162b3dd..c869c851d2dd 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -31,7 +31,7 @@ static bool kvm_pmu_switch_needed(struct perf_event_attr *attr)
  */
 void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr)
 {
-	struct kvm_host_data *ctx = this_cpu_ptr(&kvm_host_data);
+	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
 
 	if (!kvm_pmu_switch_needed(attr))
 		return;
@@ -47,7 +47,7 @@ void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr)
  */
 void kvm_clr_pmu_events(u32 clr)
 {
-	struct kvm_host_data *ctx = this_cpu_ptr(&kvm_host_data);
+	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
 
 	ctx->pmu_events.events_host &= ~clr;
 	ctx->pmu_events.events_guest &= ~clr;
@@ -173,7 +173,7 @@ void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu)
 		return;
 
 	preempt_disable();
-	host = this_cpu_ptr(&kvm_host_data);
+	host = this_cpu_ptr_hyp_sym(kvm_host_data);
 	events_guest = host->pmu_events.events_guest;
 	events_host = host->pmu_events.events_host;
 
@@ -193,7 +193,7 @@ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu)
 	if (!has_vhe())
 		return;
 
-	host = this_cpu_ptr(&kvm_host_data);
+	host = this_cpu_ptr_hyp_sym(kvm_host_data);
 	events_guest = host->pmu_events.events_guest;
 	events_host = host->pmu_events.events_host;
 
-- 
2.28.0.681.g6f77f65b4e-goog

[PATCH v4 09/10] kvm: arm64: Set up hyp percpu data for nVHE

[David Brazdil]

Add hyp percpu section to linker script and rename the corresponding ELF
sections of hyp/nvhe object files. This moves all nVHE-specific percpu
variables to the new hyp percpu section.

Allocate sufficient amount of memory for all percpu hyp regions at global KVM
init time and create corresponding hyp mappings.

The base addresses of hyp percpu regions are kept in a dynamically allocated
array in the kernel.

Add NULL checks in PMU event-reset code as it may run before KVM memory is
initialized.

Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/include/asm/kvm_asm.h  | 19 +++++++++--
 arch/arm64/kernel/vmlinux.lds.S   |  8 +++++
 arch/arm64/kvm/arm.c              | 55 +++++++++++++++++++++++++++++--
 arch/arm64/kvm/hyp/nvhe/hyp.lds.S |  6 ++++
 arch/arm64/kvm/pmu.c              |  5 ++-
 5 files changed, 87 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 911d91787fa0..863f669d4dc8 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -66,8 +66,19 @@
 #define CHOOSE_VHE_SYM(sym)	sym
 #define CHOOSE_NVHE_SYM(sym)	kvm_nvhe_sym(sym)
 
-#define this_cpu_ptr_nvhe_sym(sym)	this_cpu_ptr(&kvm_nvhe_sym(sym))
-#define per_cpu_ptr_nvhe_sym(sym, cpu)	per_cpu_ptr(&kvm_nvhe_sym(sym), cpu)
+/*
+ * Compute pointer to a symbol defined in nVHE percpu region.
+ * Returns NULL if percpu memory has not been allocated yet.
+ */
+#define this_cpu_ptr_nvhe_sym(sym)	per_cpu_ptr_nvhe_sym(sym, smp_processor_id())
+#define per_cpu_ptr_nvhe_sym(sym, cpu)						\
+	({									\
+		unsigned long base, off;					\
+		base = kvm_arm_hyp_percpu_base[cpu];				\
+		off = (unsigned long)&CHOOSE_NVHE_SYM(sym) -			\
+		      (unsigned long)&CHOOSE_NVHE_SYM(__per_cpu_start);		\
+		base ? (typeof(CHOOSE_NVHE_SYM(sym))*)(base + off) : NULL;	\
+	})
 
 #ifndef __KVM_NVHE_HYPERVISOR__
 /*
@@ -117,6 +128,10 @@ DECLARE_KVM_HYP_SYM(__kvm_hyp_vector);
 #define __kvm_hyp_init		CHOOSE_NVHE_SYM(__kvm_hyp_init)
 #define __kvm_hyp_vector	CHOOSE_HYP_SYM(__kvm_hyp_vector)
 
+extern unsigned long kvm_arm_hyp_percpu_base[NR_CPUS];
+DECLARE_KVM_NVHE_SYM(__per_cpu_start);
+DECLARE_KVM_NVHE_SYM(__per_cpu_end);
+
 #ifdef CONFIG_KVM_INDIRECT_VECTORS
 extern atomic_t arm64_el2_vector_last_slot;
 DECLARE_KVM_HYP_SYM(__bp_harden_hyp_vecs);
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index d14166012e51..d52e6b5dbfd3 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -28,8 +28,15 @@ jiffies = jiffies_64;
 	__start___kvm_ex_table = .;				\
 	*(__kvm_ex_table)					\
 	__stop___kvm_ex_table = .;
+
+#define HYPERVISOR_PERCPU_SECTION				\
+	. = ALIGN(PAGE_SIZE);					\
+	HYP_SECTION_NAME(.data..percpu) : {			\
+		*(HYP_SECTION_NAME(.data..percpu))		\
+	}
 #else /* CONFIG_KVM */
 #define HYPERVISOR_EXTABLE
+#define HYPERVISOR_PERCPU_SECTION
 #endif
 
 #define HYPERVISOR_TEXT					\
@@ -195,6 +202,7 @@ SECTIONS
 	}
 
 	PERCPU_SECTION(L1_CACHE_BYTES)
+	HYPERVISOR_PERCPU_SECTION
 
 	.rela.dyn : ALIGN(8) {
 		*(.rela .rela*)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 0424667c4c0a..cd5293e55fec 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -47,6 +47,7 @@ __asm__(".arch_extension	virt");
 #endif
 
 static DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
+unsigned long kvm_arm_hyp_percpu_base[NR_CPUS];
 
 /* The VMID used in the VTTBR */
 static atomic64_t kvm_vmid_gen = ATOMIC64_INIT(1);
@@ -1258,6 +1259,19 @@ long kvm_arch_vm_ioctl(struct file *filp,
 	}
 }
 
+static unsigned long nvhe_percpu_size(void)
+{
+	return (unsigned long)CHOOSE_NVHE_SYM(__per_cpu_end) -
+		(unsigned long)CHOOSE_NVHE_SYM(__per_cpu_start);
+}
+
+static unsigned long nvhe_percpu_order(void)
+{
+	unsigned long size = nvhe_percpu_size();
+
+	return size ? get_order(size) : 0;
+}
+
 static void cpu_init_hyp_mode(void)
 {
 	phys_addr_t pgd_ptr;
@@ -1273,8 +1287,8 @@ static void cpu_init_hyp_mode(void)
 	 * kernel's mapping to the linear mapping, and store it in tpidr_el2
 	 * so that we can use adr_l to access per-cpu variables in EL2.
 	 */
-	tpidr_el2 = ((unsigned long)this_cpu_ptr(&kvm_host_data) -
-		     (unsigned long)kvm_ksym_ref(&kvm_host_data));
+	tpidr_el2 = (unsigned long)this_cpu_ptr_nvhe_sym(__per_cpu_start) -
+		    (unsigned long)kvm_ksym_ref(CHOOSE_NVHE_SYM(__per_cpu_start));
 
 	pgd_ptr = kvm_mmu_get_httbr();
 	hyp_stack_ptr = __this_cpu_read(kvm_arm_hyp_stack_page) + PAGE_SIZE;
@@ -1464,8 +1478,10 @@ static void teardown_hyp_mode(void)
 	int cpu;
 
 	free_hyp_pgds();
-	for_each_possible_cpu(cpu)
+	for_each_possible_cpu(cpu) {
 		free_page(per_cpu(kvm_arm_hyp_stack_page, cpu));
+		free_pages(kvm_arm_hyp_percpu_base[cpu], nvhe_percpu_order());
+	}
 }
 
 /**
@@ -1498,6 +1514,24 @@ static int init_hyp_mode(void)
 		per_cpu(kvm_arm_hyp_stack_page, cpu) = stack_page;
 	}
 
+	/*
+	 * Allocate and initialize pages for Hypervisor-mode percpu regions.
+	 */
+	for_each_possible_cpu(cpu) {
+		struct page *page;
+		void *page_addr;
+
+		page = alloc_pages(GFP_KERNEL, nvhe_percpu_order());
+		if (!page) {
+			err = -ENOMEM;
+			goto out_err;
+		}
+
+		page_addr = page_address(page);
+		memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
+		kvm_arm_hyp_percpu_base[cpu] = (unsigned long)page_addr;
+	}
+
 	/*
 	 * Map the Hyp-code called directly from the host
 	 */
@@ -1542,6 +1576,21 @@ static int init_hyp_mode(void)
 		}
 	}
 
+	/*
+	 * Map Hyp percpu pages
+	 */
+	for_each_possible_cpu(cpu) {
+		char *percpu_begin = (char *)kvm_arm_hyp_percpu_base[cpu];
+		char *percpu_end = percpu_begin + nvhe_percpu_size();
+
+		err = create_hyp_mappings(percpu_begin, percpu_end, PAGE_HYP);
+
+		if (err) {
+			kvm_err("Cannot map hyp percpu region\n");
+			goto out_err;
+		}
+	}
+
 	for_each_possible_cpu(cpu) {
 		kvm_host_data_t *cpu_data;
 
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
index 3b13d1c7cd1a..bb2d986ff696 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
@@ -7,7 +7,13 @@
  */
 
 #include <asm/hyp_image.h>
+#include <asm-generic/vmlinux.lds.h>
+#include <asm/cache.h>
+#include <asm/memory.h>
 
 SECTIONS {
 	HYP_SECTION(.text)
+	HYP_SECTION_NAME(.data..percpu) : {
+		PERCPU_INPUT(L1_CACHE_BYTES)
+	}
 }
diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index c869c851d2dd..faf32a44ba04 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -33,7 +33,7 @@ void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr)
 {
 	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
 
-	if (!kvm_pmu_switch_needed(attr))
+	if (!ctx || !kvm_pmu_switch_needed(attr))
 		return;
 
 	if (!attr->exclude_host)
@@ -49,6 +49,9 @@ void kvm_clr_pmu_events(u32 clr)
 {
 	struct kvm_host_data *ctx = this_cpu_ptr_hyp_sym(kvm_host_data);
 
+	if (!ctx)
+		return;
+
 	ctx->pmu_events.events_host &= ~clr;
 	ctx->pmu_events.events_guest &= ~clr;
 }
-- 
2.28.0.681.g6f77f65b4e-goog

Re: [PATCH v4 09/10] kvm: arm64: Set up hyp percpu data for nVHE

[Will Deacon]

On Tue, Sep 22, 2020 at 09:49:09PM +0100, David Brazdil wrote:
> Add hyp percpu section to linker script and rename the corresponding ELF
> sections of hyp/nvhe object files. This moves all nVHE-specific percpu
> variables to the new hyp percpu section.
> 
> Allocate sufficient amount of memory for all percpu hyp regions at global KVM
> init time and create corresponding hyp mappings.
> 
> The base addresses of hyp percpu regions are kept in a dynamically allocated
> array in the kernel.
> 
> Add NULL checks in PMU event-reset code as it may run before KVM memory is
> initialized.
> 
> Signed-off-by: David Brazdil <dbrazdil@google.com>
> ---
>  arch/arm64/include/asm/kvm_asm.h  | 19 +++++++++--
>  arch/arm64/kernel/vmlinux.lds.S   |  8 +++++
>  arch/arm64/kvm/arm.c              | 55 +++++++++++++++++++++++++++++--
>  arch/arm64/kvm/hyp/nvhe/hyp.lds.S |  6 ++++
>  arch/arm64/kvm/pmu.c              |  5 ++-
>  5 files changed, 87 insertions(+), 6 deletions(-)

Acked-by: Will Deacon <will@kernel.org>

But one comment for Marc below...

> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index 911d91787fa0..863f669d4dc8 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -66,8 +66,19 @@
>  #define CHOOSE_VHE_SYM(sym)	sym
>  #define CHOOSE_NVHE_SYM(sym)	kvm_nvhe_sym(sym)
>  
> -#define this_cpu_ptr_nvhe_sym(sym)	this_cpu_ptr(&kvm_nvhe_sym(sym))
> -#define per_cpu_ptr_nvhe_sym(sym, cpu)	per_cpu_ptr(&kvm_nvhe_sym(sym), cpu)
> +/*
> + * Compute pointer to a symbol defined in nVHE percpu region.
> + * Returns NULL if percpu memory has not been allocated yet.
> + */
> +#define this_cpu_ptr_nvhe_sym(sym)	per_cpu_ptr_nvhe_sym(sym, smp_processor_id())
> +#define per_cpu_ptr_nvhe_sym(sym, cpu)						\
> +	({									\
> +		unsigned long base, off;					\
> +		base = kvm_arm_hyp_percpu_base[cpu];				\
> +		off = (unsigned long)&CHOOSE_NVHE_SYM(sym) -			\
> +		      (unsigned long)&CHOOSE_NVHE_SYM(__per_cpu_start);		\
> +		base ? (typeof(CHOOSE_NVHE_SYM(sym))*)(base + off) : NULL;	\
> +	})
>  
>  #ifndef __KVM_NVHE_HYPERVISOR__
>  /*
> @@ -117,6 +128,10 @@ DECLARE_KVM_HYP_SYM(__kvm_hyp_vector);
>  #define __kvm_hyp_init		CHOOSE_NVHE_SYM(__kvm_hyp_init)
>  #define __kvm_hyp_vector	CHOOSE_HYP_SYM(__kvm_hyp_vector)
>  
> +extern unsigned long kvm_arm_hyp_percpu_base[NR_CPUS];
> +DECLARE_KVM_NVHE_SYM(__per_cpu_start);
> +DECLARE_KVM_NVHE_SYM(__per_cpu_end);
> +
>  #ifdef CONFIG_KVM_INDIRECT_VECTORS
>  extern atomic_t arm64_el2_vector_last_slot;
>  DECLARE_KVM_HYP_SYM(__bp_harden_hyp_vecs);

The changes in this file will collide quite badly with Andrew's "handler"
branch which you've already queued, so you'll probably want to chat with
Andrew and David when you get to resolve that. In particular, I think it
would be good if the this_cpu_ptr_nvhe_sym() macro only ends up in the EL1
block, since I don't think that its use of smp_processor_id() is safe at
EL2. That's not a problem as it stands, as its only used by the host.

Will

[PATCH v4 10/10] kvm: arm64: Remove unnecessary hyp mappings

[David Brazdil]

With all nVHE per-CPU variables being part of the hyp per-CPU region,
mapping them individual is not necessary any longer. They are mapped to hyp
as part of the overall per-CPU region.

Acked-by: Andrew Scull<ascull@google.com>
Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/include/asm/kvm_mmu.h | 20 --------------------
 arch/arm64/kvm/arm.c             | 16 ----------------
 2 files changed, 36 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index e134c2ba2c5d..8e7919801196 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -531,21 +531,6 @@ static inline int kvm_map_vectors(void)
 DECLARE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required);
 DECLARE_KVM_NVHE_PER_CPU(u64, arm64_ssbd_callback_required);
 
-static inline int hyp_map_aux_data(void)
-{
-	int cpu, err;
-
-	for_each_possible_cpu(cpu) {
-		u64 *ptr;
-
-		ptr = per_cpu_ptr_nvhe_sym(arm64_ssbd_callback_required, cpu);
-		err = create_hyp_mappings(ptr, ptr + 1, PAGE_HYP);
-		if (err)
-			return err;
-	}
-	return 0;
-}
-
 static inline void hyp_init_aux_data(void)
 {
 	u64 *ptr;
@@ -555,11 +540,6 @@ static inline void hyp_init_aux_data(void)
 	*ptr = __this_cpu_read(arm64_ssbd_callback_required);
 }
 #else
-static inline int hyp_map_aux_data(void)
-{
-	return 0;
-}
-
 static inline void hyp_init_aux_data(void) {}
 #endif
 
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index cd5293e55fec..22ec7176f95b 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1591,22 +1591,6 @@ static int init_hyp_mode(void)
 		}
 	}
 
-	for_each_possible_cpu(cpu) {
-		kvm_host_data_t *cpu_data;
-
-		cpu_data = per_cpu_ptr_hyp_sym(kvm_host_data, cpu);
-		err = create_hyp_mappings(cpu_data, cpu_data + 1, PAGE_HYP);
-
-		if (err) {
-			kvm_err("Cannot map host CPU state: %d\n", err);
-			goto out_err;
-		}
-	}
-
-	err = hyp_map_aux_data();
-	if (err)
-		kvm_err("Cannot map host auxiliary data: %d\n", err);
-
 	return 0;
 
 out_err:
-- 
2.28.0.681.g6f77f65b4e-goog

Re: [PATCH v4 10/10] kvm: arm64: Remove unnecessary hyp mappings

[Will Deacon]

On Tue, Sep 22, 2020 at 09:49:10PM +0100, David Brazdil wrote:
> With all nVHE per-CPU variables being part of the hyp per-CPU region,
> mapping them individual is not necessary any longer. They are mapped to hyp
> as part of the overall per-CPU region.
> 
> Acked-by: Andrew Scull<ascull@google.com>

^^^ Missing space between "Scull" and "<".

> Signed-off-by: David Brazdil <dbrazdil@google.com>
> ---
>  arch/arm64/include/asm/kvm_mmu.h | 20 --------------------
>  arch/arm64/kvm/arm.c             | 16 ----------------
>  2 files changed, 36 deletions(-)

Acked-by: Will Deacon <will@kernel.org>

Will

Re: [PATCH v4 00/10] Independent per-CPU data section for nVHE

[Christopher Lameter]

On Tue, 22 Sep 2020, David Brazdil wrote:

> Introduce '.hyp.data..percpu' as part of ongoing effort to make nVHE
> hyp code self-contained and independent of the rest of the kernel.

The percpu subsystems point is to enable the use of special hardware
instructions that can perform address calculation and a memory operation
in one interruptible instruction. This is in particular useful to avoid
higher overhead for memory management related counters because preempt
disable/enable etc can be avoided.

ARM cannot do that and thus has a LC/SC loop.

This is a patchset for ARM64 so its not clear to me what kind of advantage
there would be against a simple implementation that does a regular fetch
from a base address with an offset.

> Main benefits:
>  * independent nVHE per-CPU data section that can be unmapped from host,
>  * more robust linking of nVHE hyp code,
>  * no need for hyp-specific macros to access per-CPU variables.

Maybe simply don't use percpu variables for your arm code? Those pointers
to data will be much more indepedent of the rest of the kernel and allow a
much higher degree of being self-contained.

Re: [PATCH v4 00/10] Independent per-CPU data section for nVHE

[Marc Zyngier]

On Tue, 22 Sep 2020 21:49:00 +0100, David Brazdil wrote:
> Introduce '.hyp.data..percpu' as part of ongoing effort to make nVHE
> hyp code self-contained and independent of the rest of the kernel.
> 
> Main benefits:
>  * independent nVHE per-CPU data section that can be unmapped from host,
>  * more robust linking of nVHE hyp code,
>  * no need for hyp-specific macros to access per-CPU variables.
> 
> [...]

Applied to next, thanks!

[01/10] kvm: arm64: Partially link nVHE hyp code, simplify HYPCOPY
        commit: ab25464bdabd45f283cc1194e332040f89071106
[02/10] kvm: arm64: Move nVHE hyp namespace macros to hyp_image.h
        commit: ce492a16ffb8814d9651c3fdafc363bfa1b01189
[03/10] kvm: arm64: Only define __kvm_ex_table for CONFIG_KVM
        commit: 3471ee06e33e413d7fa73c1aa3092e6e794b9e05
[04/10] kvm: arm64: Remove __hyp_this_cpu_read
        commit: 717cf94adb54095d14a6674baea73123188f2901
[05/10] kvm: arm64: Remove hyp_adr/ldr_this_cpu
        commit: ea391027d35546d9155f1350123b5af8bddec706
[06/10] kvm: arm64: Add helpers for accessing nVHE hyp per-cpu vars
        commit: 572494995bc3d282336bfd8162741929402910b9
[07/10] kvm: arm64: Duplicate arm64_ssbd_callback_required for nVHE hyp
        commit: df4c8214a18d202fa0ec221a001f640e020f7e44
[08/10] kvm: arm64: Create separate instances of kvm_host_data for VHE/nVHE
        commit: 2a1198c9b436402582f7beed57028044b819329c
[09/10] kvm: arm64: Set up hyp percpu data for nVHE
        commit: 30c953911c4370bfb622ee1c2fcc7e78c84df800
[10/10] kvm: arm64: Remove unnecessary hyp mappings
        commit: a3bb9c3a00551726590137e3974495ce6cf6b758

Cheers,

	M.
-- 
Without deviation from the norm, progress is not possible.