Re: [PATCH v9 09/17] x86/split_lock: Handle #AC exception for split lock

Paolo Bonzini
2019-10-16T16:38:58Z

On 16/10/19 18:25, Xiaoyao Li wrote:
>>
>>    3 | Y         |     Y       |  N  |   Y     |   x   | Switch
>> MSR_TEST_CTRL on
>>      |           |             |     |         |       | enter/exit,
>> plus:
>>      |           |             |     |         |       | A) #AC
>> forwarded to guest.
>>      |           |             |     |         |       | B) SIGBUS or
>> KVM exit code
>>
>
> I just want to get confirmed that in (3), we should split into 2 case:
>
> a) if host has it enabled, still apply the constraint that guest is
> forcibly enabled? so we don't switch MSR_TEST_CTL.
>
> b) if host has it disabled, we can switch MSR_TEST_CTL on enter/exit.

That's doable, yes.

Paolo