linux-kernel - [PATCH 07/10] KVM: SVM: Emulate SYSENTER RIP/RSP behavior for all Intel compat vCPUs

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Message-ID: <20240405235603.1173076-8-seanjc@google.com>
Date: Fri,  5 Apr 2024 16:56:00 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Sandipan Das <sandipan.das@....com>, Jim Mattson <jmattson@...gle.com>, 
	Like Xu <like.xu.linux@...il.com>
Subject: [PATCH 07/10] KVM: SVM: Emulate SYSENTER RIP/RSP behavior for all
 Intel compat vCPUs

Emulate bits 63:32 of the SYSENTER_R{I,S}P MSRs for all vCPUs that are
compatible with Intel's architecture, not just strictly vCPUs that have
vendor==Intel.  The behavior of bits 63:32 is architecturally defined in
the SDM, i.e. not some uarch specific quirk of Intel CPUs.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/cpuid.h   |  8 --------
 arch/x86/kvm/svm/svm.c | 14 +++++++-------
 2 files changed, 7 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 23dbb9eb277c..03d015e9ce33 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -112,14 +112,6 @@ static inline bool guest_cpuid_is_amd_or_hygon(struct kvm_vcpu *vcpu)
 		is_guest_vendor_hygon(best->ebx, best->ecx, best->edx));
 }
 
-static inline bool guest_cpuid_is_intel(struct kvm_vcpu *vcpu)
-{
-	struct kvm_cpuid_entry2 *best;
-
-	best = kvm_find_cpuid_entry(vcpu, 0);
-	return best && is_guest_vendor_intel(best->ebx, best->ecx, best->edx);
-}
-
 static inline bool guest_cpuid_is_amd_compatible(struct kvm_vcpu *vcpu)
 {
 	return vcpu->arch.is_amd_compatible;
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index d1a9f9951635..e1266b023203 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1196,7 +1196,7 @@ static inline void init_vmcb_after_set_cpuid(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
-	if (guest_cpuid_is_intel(vcpu)) {
+	if (guest_cpuid_is_intel_compatible(vcpu)) {
 		/*
 		 * We must intercept SYSENTER_EIP and SYSENTER_ESP
 		 * accesses because the processor only stores 32 bits.
@@ -2853,12 +2853,12 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		break;
 	case MSR_IA32_SYSENTER_EIP:
 		msr_info->data = (u32)svm->vmcb01.ptr->save.sysenter_eip;
-		if (guest_cpuid_is_intel(vcpu))
+		if (guest_cpuid_is_intel_compatible(vcpu))
 			msr_info->data |= (u64)svm->sysenter_eip_hi << 32;
 		break;
 	case MSR_IA32_SYSENTER_ESP:
 		msr_info->data = svm->vmcb01.ptr->save.sysenter_esp;
-		if (guest_cpuid_is_intel(vcpu))
+		if (guest_cpuid_is_intel_compatible(vcpu))
 			msr_info->data |= (u64)svm->sysenter_esp_hi << 32;
 		break;
 	case MSR_TSC_AUX:
@@ -3081,11 +3081,11 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 		 * 32 bit part of these msrs to support Intel's
 		 * implementation of SYSENTER/SYSEXIT.
 		 */
-		svm->sysenter_eip_hi = guest_cpuid_is_intel(vcpu) ? (data >> 32) : 0;
+		svm->sysenter_eip_hi = guest_cpuid_is_intel_compatible(vcpu) ? (data >> 32) : 0;
 		break;
 	case MSR_IA32_SYSENTER_ESP:
 		svm->vmcb01.ptr->save.sysenter_esp = (u32)data;
-		svm->sysenter_esp_hi = guest_cpuid_is_intel(vcpu) ? (data >> 32) : 0;
+		svm->sysenter_esp_hi = guest_cpuid_is_intel_compatible(vcpu) ? (data >> 32) : 0;
 		break;
 	case MSR_TSC_AUX:
 		/*
@@ -4328,11 +4328,11 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 	kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_LBRV);
 
 	/*
-	 * Intercept VMLOAD if the vCPU mode is Intel in order to emulate that
+	 * Intercept VMLOAD if the vCPU model is Intel in order to emulate that
 	 * VMLOAD drops bits 63:32 of SYSENTER (ignoring the fact that exposing
 	 * SVM on Intel is bonkers and extremely unlikely to work).
 	 */
-	if (!guest_cpuid_is_intel(vcpu))
+	if (!guest_cpuid_is_intel_compatible(vcpu))
 		kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_V_VMSAVE_VMLOAD);
 
 	kvm_governed_feature_check_and_set(vcpu, X86_FEATURE_PAUSEFILTER);
-- 
2.44.0.478.gd926399ef9-goog