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    SubjectRe: [PATCH v2 01/21] KVM: nVMX: Unconditionally purge queued/injected events on nested "exit"
    On Tue, Jun 14, 2022 at 1:47 PM Sean Christopherson <seanjc@google.com> wrote:
    >
    > Drop pending exceptions and events queued for re-injection when leaving
    > nested guest mode, even if the "exit" is due to VM-Fail, SMI, or forced
    > by host userspace. Failure to purge events could result in an event
    > belonging to L2 being injected into L1.
    >
    > This _should_ never happen for VM-Fail as all events should be blocked by
    > nested_run_pending, but it's possible if KVM, not the L1 hypervisor, is
    > the source of VM-Fail when running vmcs02.
    >
    > SMI is a nop (barring unknown bugs) as recognition of SMI and thus entry
    > to SMM is blocked by pending exceptions and re-injected events.
    >
    > Forced exit is definitely buggy, but has likely gone unnoticed because
    > userspace probably follows the forced exit with KVM_SET_VCPU_EVENTS (or
    > some other ioctl() that purges the queue).
    >
    > Fixes: 4f350c6dbcb9 ("kvm: nVMX: Handle deferred early VMLAUNCH/VMRESUME failure properly")
    > Cc: stable@vger.kernel.org
    > Signed-off-by: Sean Christopherson <seanjc@google.com>
    Reviewed-by: Jim Mattson <jmattson@google.com>

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