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Subject[PATCH v4 7/7] x86/cpu, kvm: Propagate the AMD Automatic IBRS feature to the guest
Date
Add the AMD Automatic IBRS feature bit to those being
propagated to the guest, and enable the guest EFER bit.

Signed-off-by: Kim Phillips <kim.phillips@amd.com>
---
arch/x86/kvm/cpuid.c | 2 +-
arch/x86/kvm/reverse_cpuid.h | 2 ++
arch/x86/kvm/svm/svm.c | 3 +++
arch/x86/kvm/x86.c | 3 +++
4 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index dd0fe79521eb..0ed3ad3e9341 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -732,7 +732,7 @@ void kvm_set_cpu_caps(void)

kvm_cpu_cap_init_scattered(CPUID_8000_0021_EAX,
SF(NO_NESTED_DATA_BP) | SF(LFENCE_RDTSC) | 0 /* SmmPgCfgLock */ |
- SF(NULL_SEL_CLR_BASE) | 0 /* PrefetchCtlMsr */
+ SF(NULL_SEL_CLR_BASE) | SF(AUTOIBRS) | 0 /* PrefetchCtlMsr */
);
if (cpu_feature_enabled(X86_FEATURE_LFENCE_RDTSC))
kvm_cpu_cap_set(X86_FEATURE_LFENCE_RDTSC);
diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
index 184614e27d5b..0bf02c02bb0a 100644
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -30,6 +30,7 @@ enum kvm_only_cpuid_leafs {
#define KVM_X86_FEATURE_NO_NESTED_DATA_BP KVM_X86_FEATURE(CPUID_8000_0021_EAX, 0)
#define KVM_X86_FEATURE_LFENCE_RDTSC KVM_X86_FEATURE(CPUID_8000_0021_EAX, 2)
#define KVM_X86_FEATURE_NULL_SEL_CLR_BASE KVM_X86_FEATURE(CPUID_8000_0021_EAX, 6)
+#define KVM_X86_FEATURE_AUTOIBRS KVM_X86_FEATURE(CPUID_8000_0021_EAX, 8)

struct cpuid_reg {
u32 function;
@@ -89,6 +90,7 @@ static __always_inline u32 __feature_translate(int x86_feature)
case X86_FEATURE_NO_NESTED_DATA_BP: return KVM_X86_FEATURE_NO_NESTED_DATA_BP;
case X86_FEATURE_LFENCE_RDTSC: return KVM_X86_FEATURE_LFENCE_RDTSC;
case X86_FEATURE_NULL_SEL_CLR_BASE: return KVM_X86_FEATURE_NULL_SEL_CLR_BASE;
+ case X86_FEATURE_AUTOIBRS: return KVM_X86_FEATURE_AUTOIBRS;
default: break;
}

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 4b6d2b050e57..3ac3d4cfce24 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4960,6 +4960,9 @@ static __init int svm_hardware_setup(void)

tsc_aux_uret_slot = kvm_add_user_return_msr(MSR_TSC_AUX);

+ if (boot_cpu_has(X86_FEATURE_AUTOIBRS))
+ kvm_enable_efer_bits(EFER_AUTOIBRS);
+
/* Check for pause filtering support */
if (!boot_cpu_has(X86_FEATURE_PAUSEFILTER)) {
pause_filter_count = 0;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 490ec23c8450..db0f522fd597 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1682,6 +1682,9 @@ static int do_get_msr_feature(struct kvm_vcpu *vcpu, unsigned index, u64 *data)

static bool __kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
{
+ if (efer & EFER_AUTOIBRS && !guest_cpuid_has(vcpu, X86_FEATURE_AUTOIBRS))
+ return false;
+
if (efer & EFER_FFXSR && !guest_cpuid_has(vcpu, X86_FEATURE_FXSR_OPT))
return false;

--
2.34.1
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