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. This introduces only the infrastructure enabling
this copy. The first users will follow shortly.
Signed-off-by: Quentin Perret <[email protected]>
---
arch/arm64/include/asm/cpufeature.h | 1 +
arch/arm64/include/asm/kvm_cpufeature.h | 15 +++++++++++++++
arch/arm64/include/asm/kvm_host.h | 4 ++++
arch/arm64/kernel/cpufeature.c | 13 +++++++++++++
arch/arm64/kvm/hyp/nvhe/hyp-smp.c | 7 +++++++
arch/arm64/kvm/sys_regs.c | 19 +++++++++++++++++++
6 files changed, 59 insertions(+)
create mode 100644 arch/arm64/include/asm/kvm_cpufeature.h
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 61177bac49fa..a85cea2cac57 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -607,6 +607,7 @@ void check_local_cpu_capabilities(void);
u64 read_sanitised_ftr_reg(u32 id);
u64 __read_sysreg_by_encoding(u32 sys_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..3fd9f60d2180
--- /dev/null
+++ b/arch/arm64/include/asm/kvm_cpufeature.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 - Google LLC
+ * Author: Quentin Perret <[email protected]>
+ */
+
+#include <asm/cpufeature.h>
+
+#ifndef KVM_HYP_CPU_FTR_REG
+#if defined(__KVM_NVHE_HYPERVISOR__)
+#define KVM_HYP_CPU_FTR_REG(name) extern struct arm64_ftr_reg name
+#else
+#define KVM_HYP_CPU_FTR_REG(name) extern struct arm64_ftr_reg kvm_nvhe_sym(name)
+#endif
+#endif
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 06ca4828005f..459ee557f87c 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -751,9 +751,13 @@ void kvm_clr_pmu_events(u32 clr);
void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu);
void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
+
+void setup_kvm_el2_caps(void);
#else
static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {}
static inline void kvm_clr_pmu_events(u32 clr) {}
+
+static inline void setup_kvm_el2_caps(void) {}
#endif
void kvm_vcpu_load_sysregs_vhe(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 066030717a4c..6252476e4e73 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1154,6 +1154,18 @@ 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;
+
+ *dst = *regp;
+
+ return 0;
+}
+
#define read_sysreg_case(r) \
case r: val = read_sysreg_s(r); break;
@@ -2773,6 +2785,7 @@ void __init setup_cpu_features(void)
setup_system_capabilities();
setup_elf_hwcaps(arm64_elf_hwcaps);
+ setup_kvm_el2_caps();
if (system_supports_32bit_el0())
setup_elf_hwcaps(compat_elf_hwcaps);
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-smp.c b/arch/arm64/kvm/hyp/nvhe/hyp-smp.c
index 879559057dee..cc829b9db0da 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-smp.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-smp.c
@@ -38,3 +38,10 @@ unsigned long __hyp_per_cpu_offset(unsigned int cpu)
elf_base = (unsigned long)&__per_cpu_start;
return this_cpu_base - elf_base;
}
+
+/*
+ * Define the CPU feature registers variables that will hold the copies of
+ * the host's sanitized values.
+ */
+#define KVM_HYP_CPU_FTR_REG(name) struct arm64_ftr_reg name
+#include <asm/kvm_cpufeature.h>
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 4f2f1e3145de..6c5d133689ae 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -21,6 +21,7 @@
#include <asm/debug-monitors.h>
#include <asm/esr.h>
#include <asm/kvm_arm.h>
+#include <asm/kvm_cpufeature.h>
#include <asm/kvm_emulate.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
@@ -2775,3 +2776,21 @@ void kvm_sys_reg_table_init(void)
/* Clear all higher bits. */
cache_levels &= (1 << (i*3))-1;
}
+
+#define CPU_FTR_REG_HYP_COPY(id, name) \
+ { .sys_id = id, .dst = (struct arm64_ftr_reg *)&kvm_nvhe_sym(name) }
+struct __ftr_reg_copy_entry {
+ u32 sys_id;
+ struct arm64_ftr_reg *dst;
+} hyp_ftr_regs[] __initdata = {
+};
+
+void __init setup_kvm_el2_caps(void)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(hyp_ftr_regs); i++) {
+ WARN(copy_ftr_reg(hyp_ftr_regs[i].sys_id, hyp_ftr_regs[i].dst),
+ "%u feature register not found\n", hyp_ftr_regs[i].sys_id);
+ }
+}
--
2.31.0.rc2.261.g7f71774620-goog