KVM: x86: Suppress MMIO that is triggered during task switch emulation

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Explicitly suppress userspace emulated MMIO exits that are triggered when
emulating a task switch as KVM doesn't support userspace MMIO during
complex (multi-step) emulation.  Silently ignoring the exit request can
result in the WARN_ON_ONCE(vcpu->mmio_needed) firing if KVM exits to
userspace for some other reason prior to purging mmio_needed.

See commit 0dc902267c ("KVM: x86: Suppress pending MMIO write exits if
emulator detects exception") for more details on KVM's limitations with
respect to emulated MMIO during complex emulator flows.

Reported-by: syzbot+2fb9f8ed752c01bc9a3f@syzkaller.appspotmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240712144841.1230591-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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Sean Christopherson 2024-07-12 07:48:41 -07:00 • committed by Paolo Bonzini

parent 9fe17d2ada

commit 2a1fc7dc36

1 changed files with 7 additions and 1 deletions

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arch/x86/kvm/x86.c

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