linux-kernel - [PATCH v4 15/16] KVM: SVM: call avic_vcpu_load/avic_vcpu

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Message-Id: <20210810205251.424103-16-mlevitsk@redhat.com>
Date:   Tue, 10 Aug 2021 23:52:50 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Jim Mattson <jmattson@...gle.com>, linux-kernel@...r.kernel.org,
        Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>, Joerg Roedel <joro@...tes.org>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v4 15/16] KVM: SVM: call avic_vcpu_load/avic_vcpu_put when enabling/disabling AVIC

Currently it is possible to have the following scenario:

1. AVIC is disabled by svm_refresh_apicv_exec_ctrl
2. svm_vcpu_blocking calls avic_vcpu_put which does nothing
3. svm_vcpu_unblocking enables the AVIC (due to KVM_REQ_APICV_UPDATE)
   and then calls avic_vcpu_load
4. warning is triggered in avic_vcpu_load since
   AVIC_PHYSICAL_ID_ENTRY_IS_RUNNING_MASK was never cleared

While it is possible to just remove the warning, it seems to be more robust
to fully disable/enable AVIC in svm_refresh_apicv_exec_ctrl by calling the
avic_vcpu_load/avic_vcpu_put

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/svm/avic.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index e7728b16a46f..01c0e83e1b71 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -651,6 +651,11 @@ void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
 	}
 	vmcb_mark_dirty(vmcb, VMCB_AVIC);
 
+	if (activated)
+		avic_vcpu_load(vcpu, vcpu->cpu);
+	else
+		avic_vcpu_put(vcpu);
+
 	svm_set_pi_irte_mode(vcpu, activated);
 }
 
-- 
2.26.3