linux-kernel - [PATCH v2 3/4] x86: KVM: SVM: refresh AVIC inhibition in svm_leave

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Message-Id: <20230928173354.217464-4-mlevitsk@redhat.com>
Date:   Thu, 28 Sep 2023 20:33:53 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     iommu@...ts.linux.dev, "H. Peter Anvin" <hpa@...or.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>, Joerg Roedel <joro@...tes.org>,
        x86@...nel.org,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        linux-kernel@...r.kernel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Will Deacon <will@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        Robin Murphy <robin.murphy@....com>, stable@...r.kernel.org
Subject: [PATCH v2 3/4] 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.

Fixes: f44509f849fe ("KVM: x86: SVM: allow AVIC to co-exist with a nested guest running")
Cc: stable@...r.kernel.org
Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 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