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KVM: x86: Bail to userspace if emulation of atomic user access faults

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Exit to userspace when emulating an atomic guest access if the CMPXCHG on
the userspace address faults.  Emulating the access as a write and thus
likely treating it as emulated MMIO is wrong, as KVM has already
confirmed there is a valid, writable memslot.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220202004945.2540433-6-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-02-02 00:49:45 +00:00 committed by Paolo Bonzini
parent 1c2361f667
commit 5d6c7de644
1 changed files with 1 additions and 1 deletions
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arch/x86/kvm/x86.c
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@ -7319,7 +7319,7 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
}
if (r < 0)
goto emul_write;
return X86EMUL_UNHANDLEABLE;
if (r)
return X86EMUL_CMPXCHG_FAILED;