On 12/08/15 13:26, Boris Ostrovsky wrote: > On 12/07/2015 08:08 PM, Haozhong Zhang wrote: > >On 12/07/15 12:53, Boris Ostrovsky wrote: > >>On 12/06/2015 03:58 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.zh...@intel.com> > >>>--- > >>> xen/arch/x86/time.c | 12 +++++++++--- > >>> 1 file changed, 9 insertions(+), 3 deletions(-) > >>> > >>>diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c > >>>index 1091e69..95df4f1 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; > >>&& !d->arch.vtsc ? > >> > >>(assuming my comment to the previous patch is correct). > >> > >enable_tsc_scaling in tsc_get_info() is always used in the condition > >!d->arch.vtsc, so it's not necessary to include it again in > >enable_tsc_scaling. > > > >>>+ > >>> *incarnation = d->arch.incarnation; > >>> *tsc_mode = d->arch.tsc_mode; > >>>@@ -1769,7 +1772,7 @@ void tsc_get_info(struct domain *d, uint32_t > >>>*tsc_mode, > >>> } > >>> tsc = rdtsc(); > >>> *elapsed_nsec = scale_delta(tsc, &d->arch.vtsc_to_ns); > >>>- *gtsc_khz = cpu_khz; > >>>+ *gtsc_khz = enable_tsc_scaling ? d->arch.tsc_khz : cpu_khz; > >>> break; > >>> case TSC_MODE_PVRDTSCP: > >>> if ( d->arch.vtsc ) > >>>@@ -1779,10 +1782,13 @@ void tsc_get_info(struct domain *d, uint32_t > >>>*tsc_mode, > >>> } > >>> else > >>> { > >>>+ struct time_scale *scale = enable_tsc_scaling ? > >>>+ &this_cpu(cpu_time).tsc_scale : > >>>+ &d->arch.vtsc_to_ns; > >>IIUIC tsc_scale is host property and so why would it be used if TSC scaling > >>is available to guests? > >> > >scale is used below to convert a host TSC to nanosec. When TSC scaling is > >used, > >d->arch.vtsc_to_ns may not base on the host TSC frequency, so I turn to the > >host > >tsc_scale instead. > > OK. Can we then use tsc_scale for both with and without TSC scaling? (on the > set side too). > Yes, we can, because early_time_init() calculates tsc_scale based on cpu_khz. I'll change it in the next version.
> (And as a side note, I think that the comment in include/asm-x86/domain.h > describing vtsc_to_ns as being used for emulated cases is rather misleading. > We use it for both emulated and native) > agree, I'll update those comments in the next version. Haozhong > -boris > > > > > >Haozhong > > > >>-boris > >> > >> > >>> tsc = rdtsc(); > >>>- *elapsed_nsec = scale_delta(tsc, &d->arch.vtsc_to_ns) - > >>>+ *elapsed_nsec = scale_delta(tsc, scale) - > >>> d->arch.vtsc_offset; > >>>- *gtsc_khz = 0; /* ignored by tsc_set_info */ > >>>+ *gtsc_khz = enable_tsc_scaling ? d->arch.tsc_khz : 0; > >>> } > >>> break; > >>> } > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel