* [PATCH] kvm: x86: Update tsc multiplier on change.
@ 2016-03-01 21:36 Owen Hofmann
2016-03-02 1:39 ` Haozhong Zhang
2016-03-02 9:38 ` Paolo Bonzini
0 siblings, 2 replies; 3+ messages in thread
From: Owen Hofmann @ 2016-03-01 21:36 UTC (permalink / raw)
To: kvm; +Cc: Owen Hofmann, Haozhong Zhang, Paolo Bonzini
vmx.c writes the TSC_MULTIPLIER field in vmx_vcpu_load, but only when a
vcpu has migrated physical cpus. Record the last value written and
update in vmx_vcpu_load on any change, otherwise a cpu migration must
occur for TSC frequency scaling to take effect.
Fixes: ff2c3a1803775cc72dc6f624b59554956396b0ee
Signed-off-by: Owen Hofmann <osh@google.com>
---
arch/x86/kvm/vmx.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e2951b6..0ff4537 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -596,6 +596,8 @@ struct vcpu_vmx {
/* Support for PML */
#define PML_ENTITY_NUM 512
struct page *pml_pg;
+
+ u64 current_tsc_ratio;
};
enum segment_cache_field {
@@ -2127,14 +2129,16 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp);
vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */
- /* Setup TSC multiplier */
- if (cpu_has_vmx_tsc_scaling())
- vmcs_write64(TSC_MULTIPLIER,
- vcpu->arch.tsc_scaling_ratio);
-
vmx->loaded_vmcs->cpu = cpu;
}
+ /* Setup TSC multiplier */
+ if (kvm_has_tsc_control &&
+ vmx->current_tsc_ratio != vcpu->arch.tsc_scaling_ratio) {
+ vmx->current_tsc_ratio = vcpu->arch.tsc_scaling_ratio;
+ vmcs_write64(TSC_MULTIPLIER, vmx->current_tsc_ratio);
+ }
+
vmx_vcpu_pi_load(vcpu, cpu);
}
--
2.7.0.rc3.207.g0ac5344
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] kvm: x86: Update tsc multiplier on change.
2016-03-01 21:36 [PATCH] kvm: x86: Update tsc multiplier on change Owen Hofmann
@ 2016-03-02 1:39 ` Haozhong Zhang
2016-03-02 9:38 ` Paolo Bonzini
1 sibling, 0 replies; 3+ messages in thread
From: Haozhong Zhang @ 2016-03-02 1:39 UTC (permalink / raw)
To: Owen Hofmann; +Cc: kvm, Paolo Bonzini
On 03/01/16 13:36, Owen Hofmann wrote:
> vmx.c writes the TSC_MULTIPLIER field in vmx_vcpu_load, but only when a
> vcpu has migrated physical cpus. Record the last value written and
> update in vmx_vcpu_load on any change, otherwise a cpu migration must
> occur for TSC frequency scaling to take effect.
>
> Fixes: ff2c3a1803775cc72dc6f624b59554956396b0ee
> Signed-off-by: Owen Hofmann <osh@google.com>
looks good for me.
Reviewed-by: Haozhong Zhang <haozhong.zhang@intel.com>
> ---
> arch/x86/kvm/vmx.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index e2951b6..0ff4537 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -596,6 +596,8 @@ struct vcpu_vmx {
> /* Support for PML */
> #define PML_ENTITY_NUM 512
> struct page *pml_pg;
> +
> + u64 current_tsc_ratio;
> };
>
> enum segment_cache_field {
> @@ -2127,14 +2129,16 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp);
> vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */
>
> - /* Setup TSC multiplier */
> - if (cpu_has_vmx_tsc_scaling())
> - vmcs_write64(TSC_MULTIPLIER,
> - vcpu->arch.tsc_scaling_ratio);
> -
> vmx->loaded_vmcs->cpu = cpu;
> }
>
> + /* Setup TSC multiplier */
> + if (kvm_has_tsc_control &&
> + vmx->current_tsc_ratio != vcpu->arch.tsc_scaling_ratio) {
> + vmx->current_tsc_ratio = vcpu->arch.tsc_scaling_ratio;
> + vmcs_write64(TSC_MULTIPLIER, vmx->current_tsc_ratio);
> + }
> +
> vmx_vcpu_pi_load(vcpu, cpu);
> }
>
> --
> 2.7.0.rc3.207.g0ac5344
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] kvm: x86: Update tsc multiplier on change.
2016-03-01 21:36 [PATCH] kvm: x86: Update tsc multiplier on change Owen Hofmann
2016-03-02 1:39 ` Haozhong Zhang
@ 2016-03-02 9:38 ` Paolo Bonzini
1 sibling, 0 replies; 3+ messages in thread
From: Paolo Bonzini @ 2016-03-02 9:38 UTC (permalink / raw)
To: Owen Hofmann, kvm; +Cc: Haozhong Zhang
On 01/03/2016 22:36, Owen Hofmann wrote:
> vmx.c writes the TSC_MULTIPLIER field in vmx_vcpu_load, but only when a
> vcpu has migrated physical cpus. Record the last value written and
> update in vmx_vcpu_load on any change, otherwise a cpu migration must
> occur for TSC frequency scaling to take effect.
>
> Fixes: ff2c3a1803775cc72dc6f624b59554956396b0ee
> Signed-off-by: Owen Hofmann <osh@google.com>
> ---
> arch/x86/kvm/vmx.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index e2951b6..0ff4537 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -596,6 +596,8 @@ struct vcpu_vmx {
> /* Support for PML */
> #define PML_ENTITY_NUM 512
> struct page *pml_pg;
> +
> + u64 current_tsc_ratio;
> };
>
> enum segment_cache_field {
> @@ -2127,14 +2129,16 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp);
> vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */
>
> - /* Setup TSC multiplier */
> - if (cpu_has_vmx_tsc_scaling())
> - vmcs_write64(TSC_MULTIPLIER,
> - vcpu->arch.tsc_scaling_ratio);
> -
> vmx->loaded_vmcs->cpu = cpu;
> }
>
> + /* Setup TSC multiplier */
> + if (kvm_has_tsc_control &&
> + vmx->current_tsc_ratio != vcpu->arch.tsc_scaling_ratio) {
> + vmx->current_tsc_ratio = vcpu->arch.tsc_scaling_ratio;
> + vmcs_write64(TSC_MULTIPLIER, vmx->current_tsc_ratio);
> + }
> +
> vmx_vcpu_pi_load(vcpu, cpu);
> }
>
>
Applied for 4.5 and Cc: stable@vger.kernel.org.
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-03-01 21:36 [PATCH] kvm: x86: Update tsc multiplier on change Owen Hofmann
2016-03-02 1:39 ` Haozhong Zhang
2016-03-02 9:38 ` Paolo Bonzini
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