Re: [PATCH] Allow RDTSC and RDTSCP from userspace

Tom Lendacky
2020-04-24T21:27:39Z

On 4/24/20 4:24 PM, Dave Hansen wrote:
> On 4/24/20 2:03 PM, Mike Stunes wrote:
>> I needed to allow RDTSC(P) from userspace and in early boot in order to
>> get userspace started properly. Patch below.
>>
>> ---
>> SEV-ES guests will need to execute rdtsc and rdtscp from userspace and
>> during early boot. Move the rdtsc(p) #VC handler into common code and
>> extend the #VC handlers.
>
> Do SEV-ES guests _always_ #VC on rdtsc(p)?

Only if the hypervisor is intercepting those instructions.

Thanks,
Tom

>