Re: [PATCH v3 02/13] x86/time.c: Use correct guest TSC frequency in tsc_get_info()

[Haozhong Zhang <haozhong.zhang@intel.com>]

On 01/04/16 12:48, Boris Ostrovsky wrote:
> On 12/30/2015 10:03 PM, Haozhong Zhang wrote:
> >When the TSC mode of a HVM container is TSC_MODE_DEFAULT or
> >TSC_MODE_PVRDTSCP and no TSC emulation is used, the existing
> >tsc_get_info() uses the host TSC frequency (cpu_khz) as the guest TSC
> >frequency. However, tsc_set_info() may set the guest TSC frequency to a
> >value different than the host. In order to keep consistent to
> >tsc_set_info(), this patch makes tsc_get_info() use the value set by
> >tsc_set_info() as the guest TSC frequency.
> >
> >Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
> >---
> >Changes in v3:
> >  (addressing Boris Ostrovsky's comments)
> >  * Use this_cpu(cpu_time).tsc_scale for both scaling and non-scaling cases.
> >
> >  xen/arch/x86/time.c | 9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> >
> >diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
> >index 0059b6a..d83f068 100644
> >--- a/xen/arch/x86/time.c
> >+++ b/xen/arch/x86/time.c
> >@@ -1749,6 +1749,9 @@ void tsc_get_info(struct domain *d, uint32_t *tsc_mode,
> >                    uint64_t *elapsed_nsec, uint32_t *gtsc_khz,
> >                    uint32_t *incarnation)
> >  {
> >+    bool_t enable_tsc_scaling = has_hvm_container_domain(d) &&
> >+                                cpu_has_tsc_ratio;
> >+
> 
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> 
> although I still think that having !d->arch.vtsc would be better, even if
> not strictly required.
>
I'll add in the next version.

Haozhong