On 12/06/2015 03:58 PM, Haozhong Zhang wrote:
This patch makes the pvclock return the scaled host TSC and
corresponding scaling parameters to HVM domains if guest TSC is not
emulated and TSC scaling is enabled.
Signed-off-by: Haozhong Zhang <haozhong.zh...@intel.com>
+Joao who has been staring at this code.
Joao, can you run this series through your test with non-native
frequency?
(http://lists.xenproject.org/archives/html/xen-devel/2015-12/msg00683.html
provides an interface to set it in config file).
---
xen/arch/x86/time.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index 95df4f1..732d1e9 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -815,10 +815,18 @@ static void __update_vcpu_system_time(struct vcpu *v, int
force)
}
else
{
- tsc_stamp = t->local_tsc_stamp;
-
- _u.tsc_to_system_mul = t->tsc_scale.mul_frac;
- _u.tsc_shift = (s8)t->tsc_scale.shift;
+ if ( is_hvm_domain(d) && cpu_has_tsc_ratio )
+ {
+ tsc_stamp = hvm_funcs.scale_tsc(v, t->local_tsc_stamp);
+ _u.tsc_to_system_mul = d->arch.vtsc_to_ns.mul_frac;
+ _u.tsc_shift = d->arch.vtsc_to_ns.shift;
I am not sure this is correct (which is why I asked Joao to look at this
and test). The scaler below is calculated as result of TSC calibration
across physical CPUs and what you use above (vtsc_to_ns) is an
uncalibrated value.
-boris
+ }
+ else
+ {
+ tsc_stamp = t->local_tsc_stamp;
+ _u.tsc_to_system_mul = t->tsc_scale.mul_frac;
+ _u.tsc_shift = (s8)t->tsc_scale.shift;
+ }
}
_u.tsc_timestamp = tsc_stamp;
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