[PATCH v2 19/46] KVM: x86: Move EDX initialization at vCPU RESET to common code

From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Reiji Watanabe <reijiw@google.com>
Subject: [PATCH v2 19/46] KVM: x86: Move EDX initialization at vCPU RESET to common code
Date: Tue, 13 Jul 2021 09:32:57 -0700	[thread overview]
Message-ID: <20210713163324.627647-20-seanjc@google.com> (raw)
In-Reply-To: <20210713163324.627647-1-seanjc@google.com>

Move the EDX initialization at vCPU RESET, which is now identical between
VMX and SVM, into common code.

No functional change intended.

Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/kvm_host.h |  5 -----
 arch/x86/kvm/svm/svm.c          | 13 -------------
 arch/x86/kvm/vmx/vmx.c          |  6 ------
 arch/x86/kvm/x86.c              | 13 +++++++++++++
 4 files changed, 13 insertions(+), 24 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 974cbfb1eefe..0ec988778db1 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1772,11 +1772,6 @@ static inline unsigned long read_msr(unsigned long msr)
 }
 #endif
 
-static inline u32 get_rdx_init_val(void)
-{
-	return 0x600; /* P6 family */
-}
-
 static inline void kvm_inject_gp(struct kvm_vcpu *vcpu, u32 error_code)
 {
 	kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index f7486b1645de..268580713938 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1343,25 +1343,12 @@ static void init_vmcb(struct kvm_vcpu *vcpu)
 static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
-	u32 dummy;
-	u32 eax = 1;
 
 	svm->spec_ctrl = 0;
 	svm->virt_spec_ctrl = 0;
 
 	init_vmcb(vcpu);
 
-	/*
-	 * Fall back to KVM's default Family/Model/Stepping if no CPUID match
-	 * is found.  Note, it's impossible to get a match at RESET since KVM
-	 * emulates RESET before exposing the vCPU to userspace, i.e. it's
-	 * impossible for kvm_cpuid() to find a valid entry on RESET.  But, go
-	 * through the motions in case that's ever remedied, and to be pedantic.
-	 */
-	if (!kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy, true))
-		eax = get_rdx_init_val();
-	kvm_rdx_write(vcpu, eax);
-
 	if (kvm_vcpu_apicv_active(vcpu) && !init_event)
 		avic_update_vapic_bar(svm, APIC_DEFAULT_PHYS_BASE);
 }
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index ff82c05b948b..f506b94539ab 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4387,7 +4387,6 @@ static void init_vmcs(struct vcpu_vmx *vmx)
 static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
-	u32 eax, dummy;
 	u64 cr0;
 
 	if (!init_event)
@@ -4398,11 +4397,6 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 
 	vmx->msr_ia32_umwait_control = 0;
 
-	eax = 1;
-	if (!kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy, true))
-		eax = get_rdx_init_val();
-	kvm_rdx_write(vcpu, eax);
-
 	vmx->hv_deadline_tsc = -1;
 	kvm_set_cr8(vcpu, 0);
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4ffc4ca7d7b0..fd9026437fdd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10787,6 +10787,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
 	unsigned long old_cr0 = kvm_read_cr0(vcpu);
+	u32 eax, dummy;
 
 	kvm_lapic_reset(vcpu, init_event);
 
@@ -10853,6 +10854,18 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 	vcpu->arch.regs_avail = ~0;
 	vcpu->arch.regs_dirty = ~0;
 
+	/*
+	 * Fall back to KVM's default Family/Model/Stepping of 0x600 (P6/Athlon)
+	 * if no CPUID match is found.  Note, it's impossible to get a match at
+	 * RESET since KVM emulates RESET before exposing the vCPU to userspace,
+	 * i.e. it'simpossible for kvm_cpuid() to find a valid entry on RESET.
+	 * But, go through the motions in case that's ever remedied.
+	 */
+	eax = 1;
+	if (!kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy, true))
+		eax = 0x600;
+	kvm_rdx_write(vcpu, eax);
+
 	vcpu->arch.ia32_xss = 0;
 
 	static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
-- 
2.32.0.93.g670b81a890-goog

