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SubjectRe: [PATCH 4/8] KVM: SVM: move guest vmsave/vmload to assembly
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On 11/7/22 16:23, Peter Zijlstra wrote:
>>
>> +3: vmrun %_ASM_AX
>> +4:
>> + cli
>>
>> + /* Pop @svm to RAX while it's the only available register. */
>> pop %_ASM_AX
>>
>> /* Save all guest registers. */
> So Andrew noted that once the vmload has executed any exception taken
> (say at 3) will crash and burn because %gs is scribbled.
>
> Might be good to make a record of this in the code so it can be cleaned
> up some day.
>

Yeah, it won't happen because clgi/stgi blocks setting kvm_rebooting so
I thought of killing the three exception fixups after the first. In the
end I kept them for simplicity and to keep the normal/SEV-ES versions as
similar as possible.

Paolo

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