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    SubjectRe: [PATCH v3 17/18] KVM: x86: Force kvm_rebooting=true during emergency reboot/crash
    Date
    On Fri, 2023-05-12 at 16:50 -0700, Sean Christopherson wrote:
    > Set kvm_rebooting when virtualization is disabled in an emergency so that
    > KVM eats faults on virtualization instructions even if kvm_reboot() isn't
    > reached.
    >
    > Signed-off-by: Sean Christopherson <seanjc@google.com>
    > ---
    > arch/x86/kvm/svm/svm.c | 2 ++
    > arch/x86/kvm/vmx/vmx.c | 2 ++
    > 2 files changed, 4 insertions(+)
    >
    > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
    > index 2cc195d95d32..d00da133b14f 100644
    > --- a/arch/x86/kvm/svm/svm.c
    > +++ b/arch/x86/kvm/svm/svm.c
    > @@ -611,6 +611,8 @@ static inline void kvm_cpu_svm_disable(void)
    >
    > static void svm_emergency_disable(void)
    > {
    > + kvm_rebooting = true;
    > +
    > kvm_cpu_svm_disable();
    > }
    >
    > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
    > index 008914396180..1dec932aff21 100644
    > --- a/arch/x86/kvm/vmx/vmx.c
    > +++ b/arch/x86/kvm/vmx/vmx.c
    > @@ -771,6 +771,8 @@ static void vmx_emergency_disable(void)
    > int cpu = raw_smp_processor_id();
    > struct loaded_vmcs *v;
    >
    > + kvm_rebooting = true;

    Do we need a memory barrier here?

    > +
    > list_for_each_entry(v, &per_cpu(loaded_vmcss_on_cpu, cpu),
    > loaded_vmcss_on_cpu_link)
    > vmcs_clear(v->vmcs);
    > --
    > 2.40.1.606.ga4b1b128d6-goog
    >

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