KVM: nVMX: Update vmcs12 for MSR_IA32_DEBUGCTLMSR when it's written

KVM unconditionally intercepts WRMSR to MSR_IA32_DEBUGCTLMSR.  In the
unlikely event that L1 allows L2 to write L1's MSR_IA32_DEBUGCTLMSR, but
but saves L2's value on VM-Exit, update vmcs12 during L2's WRMSR so as
to eliminate the need to VMREAD the value from vmcs02 on nested VM-Exit.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index c096e803e6f00b0599d77169a674301a3abe68e9..ba7f16b3771914b1c2a45d7c515ef8150190446c 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3563,10 +3563,8 @@ static void sync_vmcs02_to_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
                (vmcs12->vm_entry_controls & ~VM_ENTRY_IA32E_MODE) |
                (vm_entry_controls_get(to_vmx(vcpu)) & VM_ENTRY_IA32E_MODE);
 
-       if (vmcs12->vm_exit_controls & VM_EXIT_SAVE_DEBUG_CONTROLS) {
+       if (vmcs12->vm_exit_controls & VM_EXIT_SAVE_DEBUG_CONTROLS)
                kvm_get_dr(vcpu, 7, (unsigned long *)&vmcs12->guest_dr7);
-               vmcs12->guest_ia32_debugctl = vmcs_read64(GUEST_IA32_DEBUGCTL);
-       }
 
        if (vmcs12->vm_exit_controls & VM_EXIT_SAVE_IA32_EFER)
                vmcs12->guest_ia32_efer = vcpu->arch.efer;

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 248fca1f0c4593004008a24ba13785569ca275dc..6e414d69813043aa819b64495469a1623592e9a9 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1845,6 +1845,14 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
                        get_vmcs12(vcpu)->guest_sysenter_esp = data;
                vmcs_writel(GUEST_SYSENTER_ESP, data);
                break;
+       case MSR_IA32_DEBUGCTLMSR:
+               if (is_guest_mode(vcpu) && get_vmcs12(vcpu)->vm_exit_controls &
+                                               VM_EXIT_SAVE_DEBUG_CONTROLS)
+                       get_vmcs12(vcpu)->guest_ia32_debugctl = data;
+
+               ret = kvm_set_msr_common(vcpu, msr_info);
+               break;
+
        case MSR_IA32_BNDCFGS:
                if (!kvm_mpx_supported() ||
                    (!msr_info->host_initiated &&