[PATCH 11/15] KVM: nVMX: Update vmcs12 for SYSENTER MSRs when they're written

[Sean Christopherson <sean.j.christopherson@intel.com>]

For L2, KVM always intercepts WRMSR to SYSENTER MSRs.  Update vmcs12 in
the WRMSR handler so that they don't need to be (re)read from vmcs02 on
every nested VM-Exit.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/vmx/nested.c | 3 ---
 arch/x86/kvm/vmx/vmx.c    | 6 ++++++
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 135773679d5b..2e9c7bc3fb1f 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3485,9 +3485,6 @@ static void sync_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 
 	if (vmcs12->vm_exit_controls & VM_EXIT_SAVE_IA32_EFER)
 		vmcs12->guest_ia32_efer = vcpu->arch.efer;
-	vmcs12->guest_sysenter_cs = vmcs_read32(GUEST_SYSENTER_CS);
-	vmcs12->guest_sysenter_esp = vmcs_readl(GUEST_SYSENTER_ESP);
-	vmcs12->guest_sysenter_eip = vmcs_readl(GUEST_SYSENTER_EIP);
 	if (kvm_mpx_supported())
 		vmcs12->guest_bndcfgs = vmcs_read64(GUEST_BNDCFGS);
 }
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index baa79c5a8ce7..6db16ca1b43d 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1831,12 +1831,18 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		break;
 #endif
 	case MSR_IA32_SYSENTER_CS:
+		if (is_guest_mode(vcpu))
+			get_vmcs12(vcpu)->guest_sysenter_cs = data;
 		vmcs_write32(GUEST_SYSENTER_CS, data);
 		break;
 	case MSR_IA32_SYSENTER_EIP:
+		if (is_guest_mode(vcpu))
+			get_vmcs12(vcpu)->guest_sysenter_eip = data;
 		vmcs_writel(GUEST_SYSENTER_EIP, data);
 		break;
 	case MSR_IA32_SYSENTER_ESP:
+		if (is_guest_mode(vcpu))
+			get_vmcs12(vcpu)->guest_sysenter_esp = data;
 		vmcs_writel(GUEST_SYSENTER_ESP, data);
 		break;
 	case MSR_IA32_POWER_CTL:
-- 
2.21.0