KVM: SVM: Disable preemption across AVIC load/put during APICv refresh

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Disable preemption when loading/putting the AVIC during an APICv refresh.
If the vCPU task is preempted and migrated ot a different pCPU, the
unprotected avic_vcpu_load() could set the wrong pCPU in the physical ID
cache/table.

Pull the necessary code out of avic_vcpu_{,un}blocking() and into a new
helper to reduce the probability of introducing this exact bug a third
time.

Fixes: df7e4827c5 ("KVM: SVM: call avic_vcpu_load/avic_vcpu_put when enabling/disabling AVIC")
Cc: stable@vger.kernel.org
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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Sean Christopherson 2022-03-01 09:05:09 -08:00 • committed by Paolo Bonzini

parent aa9f58415a

commit b652de1e3d

3 changed files with 59 additions and 50 deletions

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101

arch/x86/kvm/svm/avic.c

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arch/x86/kvm/svm/svm.c

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4

arch/x86/kvm/svm/svm.h

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