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

From: Sean Christopherson
Date: Tue Jul 13 2021 - 12:34:36 EST


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@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
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