2023-09-28 16:22:32

by Maxim Levitsky

Subject: [PATCH 3/5] x86: KVM: SVM: refresh AVIC inhibition in svm_leave_nested()

svm_leave_nested() similar to a nested VM exit, get the vCPU out of nested
mode and thus should end the local inhibition of AVIC on this vCPU.

Failure to do so, can lead to hangs on guest reboot.

Raise the KVM_REQ_APICV_UPDATE request to refresh the AVIC state of the
current vCPU in this case.

Cc: [email protected]

Signed-off-by: Maxim Levitsky <[email protected]>
---
arch/x86/kvm/svm/nested.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index dd496c9e5f91f28..3fea8c47679e689 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1253,6 +1253,9 @@ void svm_leave_nested(struct kvm_vcpu *vcpu)

nested_svm_uninit_mmu_context(vcpu);
vmcb_mark_all_dirty(svm->vmcb);
+
+ if (kvm_apicv_activated(vcpu->kvm))
+ kvm_make_request(KVM_REQ_APICV_UPDATE, vcpu);
}

kvm_clear_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
--
2.26.3

2023-09-28 22:33:37

by Sean Christopherson

Subject: Re: [PATCH 3/5] x86: KVM: SVM: refresh AVIC inhibition in svm_leave_nested()

On Thu, Sep 28, 2023, Maxim Levitsky wrote:
> svm_leave_nested() similar to a nested VM exit, get the vCPU out of nested
> mode and thus should end the local inhibition of AVIC on this vCPU.
>
> Failure to do so, can lead to hangs on guest reboot.
>
> Raise the KVM_REQ_APICV_UPDATE request to refresh the AVIC state of the
> current vCPU in this case.
>
> Cc: [email protected]

Unnecessary newline.

Fixes: f44509f849fe ("KVM: x86: SVM: allow AVIC to co-exist with a nested guest running")

> Signed-off-by: Maxim Levitsky <[email protected]>
> ---
> arch/x86/kvm/svm/nested.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index dd496c9e5f91f28..3fea8c47679e689 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -1253,6 +1253,9 @@ void svm_leave_nested(struct kvm_vcpu *vcpu)
>
> nested_svm_uninit_mmu_context(vcpu);
> vmcb_mark_all_dirty(svm->vmcb);
> +
> + if (kvm_apicv_activated(vcpu->kvm))
> + kvm_make_request(KVM_REQ_APICV_UPDATE, vcpu);
> }
>
> kvm_clear_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
> --
> 2.26.3
>