Re: [V0 PATCH 5/6] AMD-PVH: Support TSC_MODE_NEVER_EMULATE for PVH

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 08/18/2014 09:38 PM, Boris Ostrovsky wrote:
> On 08/15/2014 09:53 PM, Mukesh Rathor wrote:
>> On AMD, MSR_AMD64_TSC_RATIO must be set for rdtsc instruction in guest
>> to properly read the cpu tsc. To that end, set tsc_khz in struct domain.
>>
>> Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
>> ---
>>   xen/arch/x86/time.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
>> index bd89219..7512aa4 100644
>> --- a/xen/arch/x86/time.c
>> +++ b/xen/arch/x86/time.c
>> @@ -1908,6 +1908,7 @@ void tsc_set_info(struct domain *d,
>>            * but "always_emulate" does not for some reason. Figure out
>>            * why.
>>            */
>> +        d->arch.tsc_khz = cpu_khz;
>>           switch ( tsc_mode )
>>           {
>>           case TSC_MODE_NEVER_EMULATE:
>
> I suspect that TSC_MODE DEFAULT may actually work for PVH: since we 
> don't support migration it should be equivalent to NEVER_EMULATE.
>
> If you replace in tsc_set_info() is_hvm_domain() with 
> is_hvm_container_domain() and allow TSC_MODE_DEFAULT along with 
> TSC_MODE_NEVER_EMULATE under 'if (is_pvh_domain())' then it seems to 
> me that things should be fine.

(hit RET too soon)

... and if TSC_MODE DEFAULT does work then you don't need to set khz 
above since it (as well as some other things) will be set from 
arch_domain_create().

-boris