Re: [Xen-devel] [PATCH v2 04/14] x86/time.c: Use correct guest TSC frequency in tsc_get_info()

2015-12-09 Thread Haozhong Zhang 
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 
> >>>---
> >>>  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, >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 ?
> >>>+   _cpu(cpu_time).tsc_scale :
> >>>+   >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, >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;
> >>>  }
> 
> 
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Re: [Xen-devel] [PATCH v2 04/14] x86/time.c: Use correct guest TSC frequency in tsc_get_info()

2015-12-08 Thread Boris Ostrovsky 

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 
---
  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, >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 ?
+   _cpu(cpu_time).tsc_scale :
+   >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).


(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)


-boris




Haozhong


-boris



  tsc = rdtsc();
-*elapsed_nsec = scale_delta(tsc, >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;
  }



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Re: [Xen-devel] [PATCH v2 04/14] x86/time.c: Use correct guest TSC frequency in tsc_get_info()

2015-12-07 Thread Boris Ostrovsky 

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 
---
  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).



+
  *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, >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 ?
+   _cpu(cpu_time).tsc_scale :
+   >arch.vtsc_to_ns;


IIUIC tsc_scale is host property and so why would it be used if TSC 
scaling is available to guests?


-boris



  tsc = rdtsc();
-*elapsed_nsec = scale_delta(tsc, >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;
  }



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Re: [Xen-devel] [PATCH v2 04/14] x86/time.c: Use correct guest TSC frequency in tsc_get_info()

2015-12-07 Thread Haozhong Zhang 
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 
> >---
> >  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, >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 ?
> >+   _cpu(cpu_time).tsc_scale :
> >+   >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.

Haozhong

> -boris
> 
> 
> >  tsc = rdtsc();
> >-*elapsed_nsec = scale_delta(tsc, >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;
> >  }
> 

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[Xen-devel] [PATCH v2 04/14] x86/time.c: Use correct guest TSC frequency in tsc_get_info()

2015-12-06 Thread Haozhong Zhang 
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 
---
 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;
+
 *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, >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 ?
+   _cpu(cpu_time).tsc_scale :
+   >arch.vtsc_to_ns;
 tsc = rdtsc();
-*elapsed_nsec = scale_delta(tsc, >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;
 }
-- 
2.6.3


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