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From:   Kim Phillips <kim.phillips@amd.com>
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Subject: [PATCH v6 7/7] x86/cpu, kvm: Propagate the AMD Automatic IBRS feature to the guest
Date:   Tue, 10 Jan 2023 16:46:43 -0600
Message-ID: <20230110224643.452273-9-kim.phillips@amd.com>
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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/svm/svm.c | 3 +++
 arch/x86/kvm/x86.c     | 3 +++
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 56f00d9cc5c5..6ce0203789cc 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -743,7 +743,7 @@ void kvm_set_cpu_caps(void)
 
 	kvm_cpu_cap_mask(CPUID_8000_0021_EAX,
 		F(NO_NESTED_DATA_BP) | F(LFENCE_RDTSC) | 0 /* SmmPgCfgLock */ |
-		F(NULL_SEL_CLR_BASE) | 0 /* PrefetchCtlMsr */
+		F(NULL_SEL_CLR_BASE) | F(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/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 9a194aa1a75a..60c7c880266b 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4969,6 +4969,9 @@ 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 da4bbd043a7b..8dd0cb230ef5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1685,6 +1685,9 @@ 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