Re: [PATCH] kvm: vmx: Properly handle machine check during VM-entry

[Jim Mattson <jmattson@google.com>]

There is the added complication that *none* of the VMCS exit
information fields are valid when vmx->fail is true. However, that
oversight affects more than just this function, so I propose to
address it separately.

On Mon, May 22, 2017 at 7:20 PM, Xiao Guangrong
<guangrong.xiao@gmail.com> wrote:
>
> Right, this is exactly what i wanted to say. :)
>
>
> On 05/23/2017 12:04 AM, Jim Mattson wrote:
>>
>> Ah. I had assumed that vmx->exit_reason recorded ony the basic exit
>> reason, since all of the EXIT_REASON macros have bit 31 stripped. The
>> check at the very beginning of vmx_complete_atomic_exit is therefore
>> wrong, since EXIT_REASON_MCE_DURING_VMENTRY (41) will never be seen in
>> the exit reason field of the VMCS. If a machine check occurs during
>> VM-entry, the exit reason is 0x80000029, not 41.
>>
>> On Mon, May 22, 2017 at 1:26 AM, Xiao Guangrong
>> <guangrong.xiao@gmail.com> wrote:
>>>
>>>
>>>
>>> On 05/19/2017 07:02 AM, Jim Mattson wrote:
>>>>
>>>>
>>>> When bit 31 of the exit reason is set to indicate a VM-entry failure,
>>>> only the exit reason and exit qualification fields are set. All other
>>>> VM-exit information fields, including "VM-exit interruption
>>>> information," are unmodified.
>>>
>>>
>>>
>>> This log does not reflects what it is doing. The case that
>>> exit-reason.bit31 = 1 is skipped by the check at the very beginning of
>>> vmx_complete_atomic_exit().
>>>
>>> Maybe what you want to say is just "exit_intr_info is not valid if vmx
>>> exit is caused by EXIT_REASON_MCE_DURING_VMENTRY"?
>>>
>