On Wed, Mar 17, 2021, Cathy Avery wrote:
> Extend using the vmcb12 control clean field to determine which
> vmcb12.save registers were marked dirty in order to minimize
> register copies by including the CR bit.
>
> This patch also fixes the init of last_vmcb12_gpa by using an invalid
> physical address instead of 0.
>
> Tested:
> kvm-unit-tests
> kvm selftests
> Fedora L1 L2
>
> Signed-off-by: Cathy Avery <cavery@xxxxxxxxxx>
> ---
> arch/x86/kvm/svm/nested.c | 9 ++++++---
> arch/x86/kvm/svm/svm.c | 2 +-
> 2 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index 8523f60adb92..6f9a40e002bc 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -449,9 +449,12 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12
> }
>
> kvm_set_rflags(&svm->vcpu, vmcb12->save.rflags | X86_EFLAGS_FIXED);
> - svm_set_efer(&svm->vcpu, vmcb12->save.efer);
> - svm_set_cr0(&svm->vcpu, vmcb12->save.cr0);
> - svm_set_cr4(&svm->vcpu, vmcb12->save.cr4);
> +
> + if (unlikely(new_vmcb12 || vmcb_is_dirty(vmcb12, VMCB_CR))) {
> + svm_set_efer(&svm->vcpu, vmcb12->save.efer);
> + svm_set_cr0(&svm->vcpu, vmcb12->save.cr0);
> + svm_set_cr4(&svm->vcpu, vmcb12->save.cr4);
This doesn't seem correct. Regardless of when vmcb12 was last touched, KVM
still needs to set L2's state in vcpu->arch and set the correct MMU context.
> + }
>
> svm->vcpu.arch.cr2 = vmcb12->save.cr2;
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 271196400495..41f5cd1009ca 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -1234,7 +1234,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu)
> svm->asid = 0;
>
> svm->nested.vmcb12_gpa = 0;
> - svm->nested.last_vmcb12_gpa = 0;
> + svm->nested.last_vmcb12_gpa = -1;
INVALID_PAGE would be even better.
> vcpu->arch.hflags = 0;
>
> if (!kvm_pause_in_guest(vcpu->kvm)) {
> --
> 2.26.2
>
