[RFC PATCH 13/27] KVM: arm64: Enable access to sanitized CPU features at EL2
From: Quentin Perret
Date: Tue Nov 17 2020 - 13:16:53 EST
Introduce the infrastructure in KVM enabling to copy CPU feature
registers into EL2-owned data-structures, to allow reading sanitised
values directly at EL2 in nVHE.
Given that only a subset of these features are being read by the
hypervisor, the ones that need to be copied are to be listed under
<asm/kvm_cpufeature.h> together with the name of the nVHE variable that
will hold the copy.
While at it, introduce the first user of this infrastructure by
implementing __flush_dcache_area at EL2, which needs
arm64_ftr_reg_ctrel0.
Signed-off-by: Quentin Perret <qperret@xxxxxxxxxx>
---
arch/arm64/include/asm/cpufeature.h | 1 +
arch/arm64/include/asm/kvm_cpufeature.h | 17 ++++++++++++++
arch/arm64/kernel/cpufeature.c | 12 ++++++++++
arch/arm64/kernel/image-vars.h | 2 ++
arch/arm64/kvm/arm.c | 31 +++++++++++++++++++++++++
arch/arm64/kvm/hyp/nvhe/Makefile | 3 ++-
arch/arm64/kvm/hyp/nvhe/cache.S | 13 +++++++++++
arch/arm64/kvm/hyp/nvhe/cpufeature.c | 8 +++++++
8 files changed, 86 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/include/asm/kvm_cpufeature.h
create mode 100644 arch/arm64/kvm/hyp/nvhe/cache.S
create mode 100644 arch/arm64/kvm/hyp/nvhe/cpufeature.c
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index da250e4741bd..3dfbd76fb647 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -600,6 +600,7 @@ void __init setup_cpu_features(void);
void check_local_cpu_capabilities(void);
u64 read_sanitised_ftr_reg(u32 id);
+int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst);
static inline bool cpu_supports_mixed_endian_el0(void)
{
diff --git a/arch/arm64/include/asm/kvm_cpufeature.h b/arch/arm64/include/asm/kvm_cpufeature.h
new file mode 100644
index 000000000000..d34f85cba358
--- /dev/null
+++ b/arch/arm64/include/asm/kvm_cpufeature.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 - Google LLC
+ * Author: Quentin Perret <qperret@xxxxxxxxxx>
+ */
+
+#include <asm/cpufeature.h>
+
+#ifndef KVM_HYP_CPU_FTR_REG
+#if defined(__KVM_NVHE_HYPERVISOR__)
+#define KVM_HYP_CPU_FTR_REG(id, name) extern struct arm64_ftr_reg name;
+#else
+#define KVM_HYP_CPU_FTR_REG(id, name) DECLARE_KVM_NVHE_SYM(name);
+#endif
+#endif
+
+KVM_HYP_CPU_FTR_REG(SYS_CTR_EL0, arm64_ftr_reg_ctrel0)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index dd5bc0f0cf0d..3bc86d1423f8 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1116,6 +1116,18 @@ u64 read_sanitised_ftr_reg(u32 id)
}
EXPORT_SYMBOL_GPL(read_sanitised_ftr_reg);
+int copy_ftr_reg(u32 id, struct arm64_ftr_reg *dst)
+{
+ struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id);
+
+ if (!regp)
+ return -EINVAL;
+
+ memcpy(dst, regp, sizeof(*regp));
+
+ return 0;
+}
+
#define read_sysreg_case(r) \
case r: return read_sysreg_s(r)
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index dd8ccc9efb6a..c35d768672eb 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -116,6 +116,8 @@ __kvm_nvhe___memcpy = __kvm_nvhe___pi_memcpy;
__kvm_nvhe___memset = __kvm_nvhe___pi_memset;
#endif
+_kvm_nvhe___flush_dcache_area = __kvm_nvhe___pi___flush_dcache_area;
+
#endif /* CONFIG_KVM */
#endif /* __ARM64_KERNEL_IMAGE_VARS_H */
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 391cf6753a13..c7f8fca97202 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -34,6 +34,7 @@
#include <asm/virt.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_asm.h>
+#include <asm/kvm_cpufeature.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_emulate.h>
#include <asm/sections.h>
@@ -1636,6 +1637,29 @@ static void teardown_hyp_mode(void)
}
}
+#undef KVM_HYP_CPU_FTR_REG
+#define KVM_HYP_CPU_FTR_REG(id, name) \
+ { .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) },
+static const struct __ftr_reg_copy_entry {
+ u32 sys_id;
+ struct arm64_ftr_reg *dst;
+} hyp_ftr_regs[] = {
+ #include <asm/kvm_cpufeature.h>
+};
+
+static int copy_cpu_ftr_regs(void)
+{
+ int i, ret;
+
+ for (i = 0; i < ARRAY_SIZE(hyp_ftr_regs); i++) {
+ ret = copy_ftr_reg(hyp_ftr_regs[i].sys_id, hyp_ftr_regs[i].dst);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
/**
* Inits Hyp-mode on all online CPUs
*/
@@ -1644,6 +1668,13 @@ static int init_hyp_mode(void)
int cpu;
int err = 0;
+ /*
+ * Copy the required CPU feature register in their EL2 counterpart
+ */
+ err = copy_cpu_ftr_regs();
+ if (err)
+ return err;
+
/*
* Allocate Hyp PGD and setup Hyp identity mapping
*/
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 9e5eacfec6ec..72cfe53f106f 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -10,7 +10,8 @@ lib-objs := clear_page.o copy_page.o memcpy.o memset.o
lib-objs := $(addprefix ../../../lib/, $(lib-objs))
obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
- hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o page_alloc.o
+ hyp-main.o hyp-smp.o psci-relay.o early_alloc.o stub.o page_alloc.o \
+ cache.o cpufeature.o
obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
../fpsimd.o ../hyp-entry.o ../exception.o
obj-y += $(lib-objs)
diff --git a/arch/arm64/kvm/hyp/nvhe/cache.S b/arch/arm64/kvm/hyp/nvhe/cache.S
new file mode 100644
index 000000000000..36cef6915428
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/cache.S
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Code copied from arch/arm64/mm/cache.S.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/alternative.h>
+
+SYM_FUNC_START_PI(__flush_dcache_area)
+ dcache_by_line_op civac, sy, x0, x1, x2, x3
+ ret
+SYM_FUNC_END_PI(__flush_dcache_area)
diff --git a/arch/arm64/kvm/hyp/nvhe/cpufeature.c b/arch/arm64/kvm/hyp/nvhe/cpufeature.c
new file mode 100644
index 000000000000..a887508f996f
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/cpufeature.c
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 - Google LLC
+ * Author: Quentin Perret <qperret@xxxxxxxxxx>
+ */
+
+#define KVM_HYP_CPU_FTR_REG(id, name) struct arm64_ftr_reg name;
+#include <asm/kvm_cpufeature.h>
--
2.29.2.299.gdc1121823c-goog