Date:   Thu, 26 Jan 2023 10:12:24 -0000
From:   "tip-bot2 for Kim Phillips" <tip-bot2@linutronix.de>
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To:     linux-tip-commits@vger.kernel.org
Subject: [tip: x86/cpu] KVM: x86: Propagate the AMD Automatic IBRS feature to
 the guest
Cc:     Kim Phillips <kim.phillips@amd.com>,
        "Borislav Petkov (AMD)" <bp@alien8.de>,
        Sean Christopherson <seanjc@google.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org
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The following commit has been merged into the x86/cpu branch of tip:

Commit-ID:     8c19b6f257fa71ed3a7a9df6ce466c6be31ca04c
Gitweb:        https://git.kernel.org/tip/8c19b6f257fa71ed3a7a9df6ce466c6be31ca04c
Author:        Kim Phillips <kim.phillips@amd.com>
AuthorDate:    Tue, 24 Jan 2023 10:33:19 -06:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Wed, 25 Jan 2023 17:21:40 +01:00

KVM: x86: Propagate the AMD Automatic IBRS feature to the guest

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>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20230124163319.2277355-9-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 28071e9..f1f4fe8 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 */
 	);
 
 	/*
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 9a194aa..60c7c88 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 da4bbd0..8dd0cb2 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;