On 20/10/2015 09:39, Haozhong Zhang wrote:
> This patchset adds support for VMX TSC scaling feature which is
> available on Intel Skylake CPU. The specification of VMX TSC scaling
> can be found at
> http://www.intel.com/content/www/us/en/processors/timestamp-counter-scaling-virtualization-white-paper.html
>
> VMX TSC scaling allows guest TSC which is read by guest rdtsc(p)
> instructions increases in a rate that is customized by the hypervisor
> and can be different than the host TSC rate. Basically, VMX TSC
> scaling adds a 64-bit field called TSC multiplier in VMCS so that, if
> VMX TSC scaling is enabled, TSC read by guest rdtsc(p) instructions
> will be calculated by the following formula:
>
> guest EDX:EAX = (Host TSC * TSC multiplier) >> 48 + VMX TSC Offset
>
> where, Host TSC = Host MSR_IA32_TSC + Host MSR_IA32_TSC_ADJUST.
>
> This patchset, when cooperating with another QEMU patchset (sent in
> another email "target-i386: save/restore vcpu's TSC rate during
> migration"), allows guest programs observe a consistent TSC rate even
> though they are migrated among machines with different host TSC rates.
>
> VMX TSC scaling shares some common logics with SVM TSC ratio which
> is already supported by KVM. Patch 1 ~ 8 move those common logics from
> SVM code to the common code. Upon them, patch 9 ~ 12 add VMX-specific
> support for VMX TSC scaling.
>
> Changes in v2:
> * Remove the duplicated variable 'kvm_tsc_scaling_ratio_rsvd'.
> * Remove an unnecessary error check in original patch 2.
> * Do 64-bit arithmetic by functions recommended by Paolo.
> * Make kvm_set_tsc_khz() returns an error number so that ioctl
> KVM_SET_TSC_KHZ does not return 0 if errors happen.
>
> Reviewed-by: Eric Northup <[email protected]>
Thanks for the patches. There are a couple changes that I can do myself:
1) kvm_default_tsc_scaling_ratio can be initialized in
kvm_arch_hardware_setup, since it's just 1ULL <<
kvm_tsc_scaling_ratio_frac_bits
2) things that you are adding to include/linux/kvm_host.h should instead
go in arch/x86/include/linux/kvm_host.h
That's it. I'll commit it as soon as I test on AMD (today hopefully).
Paolo
> Haozhong Zhang (12):
> KVM: x86: Collect information for setting TSC scaling ratio
> KVM: x86: Add a common TSC scaling ratio field in kvm_vcpu_arch
> KVM: x86: Add a common TSC scaling function
> KVM: x86: Replace call-back set_tsc_khz() with a common function
> KVM: x86: Replace call-back compute_tsc_offset() with a common function
> KVM: x86: Move TSC scaling logic out of call-back adjust_tsc_offset()
> KVM: x86: Move TSC scaling logic out of call-back read_l1_tsc()
> KVM: x86: Use the correct vcpu's TSC rate to compute time scale
> KVM: VMX: Enable and initialize VMX TSC scaling
> KVM: VMX: Setup TSC scaling ratio when a vcpu is loaded
> KVM: VMX: Use a scaled host TSC for guest readings of MSR_IA32_TSC
> KVM: VMX: Dump TSC multiplier in dump_vmcs()
>
> arch/x86/include/asm/kvm_host.h | 24 +++----
> arch/x86/include/asm/vmx.h | 3 +
> arch/x86/kvm/lapic.c | 4 +-
> arch/x86/kvm/svm.c | 116 ++++------------------------------
> arch/x86/kvm/vmx.c | 64 ++++++++++---------
> arch/x86/kvm/x86.c | 134 +++++++++++++++++++++++++++++++++++-----
> include/linux/kvm_host.h | 20 ++++++
> include/linux/math64.h | 99 +++++++++++++++++++++++++++++
> 8 files changed, 297 insertions(+), 167 deletions(-)
>
On 11/06/15 11:49, Paolo Bonzini wrote:
>
>
> On 20/10/2015 09:39, Haozhong Zhang wrote:
> > This patchset adds support for VMX TSC scaling feature which is
> > available on Intel Skylake CPU. The specification of VMX TSC scaling
> > can be found at
> > http://www.intel.com/content/www/us/en/processors/timestamp-counter-scaling-virtualization-white-paper.html
> >
> > VMX TSC scaling allows guest TSC which is read by guest rdtsc(p)
> > instructions increases in a rate that is customized by the hypervisor
> > and can be different than the host TSC rate. Basically, VMX TSC
> > scaling adds a 64-bit field called TSC multiplier in VMCS so that, if
> > VMX TSC scaling is enabled, TSC read by guest rdtsc(p) instructions
> > will be calculated by the following formula:
> >
> > guest EDX:EAX = (Host TSC * TSC multiplier) >> 48 + VMX TSC Offset
> >
> > where, Host TSC = Host MSR_IA32_TSC + Host MSR_IA32_TSC_ADJUST.
> >
> > This patchset, when cooperating with another QEMU patchset (sent in
> > another email "target-i386: save/restore vcpu's TSC rate during
> > migration"), allows guest programs observe a consistent TSC rate even
> > though they are migrated among machines with different host TSC rates.
> >
> > VMX TSC scaling shares some common logics with SVM TSC ratio which
> > is already supported by KVM. Patch 1 ~ 8 move those common logics from
> > SVM code to the common code. Upon them, patch 9 ~ 12 add VMX-specific
> > support for VMX TSC scaling.
> >
> > Changes in v2:
> > * Remove the duplicated variable 'kvm_tsc_scaling_ratio_rsvd'.
> > * Remove an unnecessary error check in original patch 2.
> > * Do 64-bit arithmetic by functions recommended by Paolo.
> > * Make kvm_set_tsc_khz() returns an error number so that ioctl
> > KVM_SET_TSC_KHZ does not return 0 if errors happen.
> >
> > Reviewed-by: Eric Northup <[email protected]>
>
> Thanks for the patches. There are a couple changes that I can do myself:
>
> 1) kvm_default_tsc_scaling_ratio can be initialized in
> kvm_arch_hardware_setup, since it's just 1ULL <<
> kvm_tsc_scaling_ratio_frac_bits
>
Agree
> 2) things that you are adding to include/linux/kvm_host.h should instead
> go in arch/x86/include/linux/kvm_host.h
>
Agree, because they are x86 specific.
> That's it. I'll commit it as soon as I test on AMD (today hopefully).
>
Thanks,
Haozhong
> Paolo
>
> > Haozhong Zhang (12):
> > KVM: x86: Collect information for setting TSC scaling ratio
> > KVM: x86: Add a common TSC scaling ratio field in kvm_vcpu_arch
> > KVM: x86: Add a common TSC scaling function
> > KVM: x86: Replace call-back set_tsc_khz() with a common function
> > KVM: x86: Replace call-back compute_tsc_offset() with a common function
> > KVM: x86: Move TSC scaling logic out of call-back adjust_tsc_offset()
> > KVM: x86: Move TSC scaling logic out of call-back read_l1_tsc()
> > KVM: x86: Use the correct vcpu's TSC rate to compute time scale
> > KVM: VMX: Enable and initialize VMX TSC scaling
> > KVM: VMX: Setup TSC scaling ratio when a vcpu is loaded
> > KVM: VMX: Use a scaled host TSC for guest readings of MSR_IA32_TSC
> > KVM: VMX: Dump TSC multiplier in dump_vmcs()
> >
> > arch/x86/include/asm/kvm_host.h | 24 +++----
> > arch/x86/include/asm/vmx.h | 3 +
> > arch/x86/kvm/lapic.c | 4 +-
> > arch/x86/kvm/svm.c | 116 ++++------------------------------
> > arch/x86/kvm/vmx.c | 64 ++++++++++---------
> > arch/x86/kvm/x86.c | 134 +++++++++++++++++++++++++++++++++++-----
> > include/linux/kvm_host.h | 20 ++++++
> > include/linux/math64.h | 99 +++++++++++++++++++++++++++++
> > 8 files changed, 297 insertions(+), 167 deletions(-)
> >
On 06/11/2015 13:42, Haozhong Zhang wrote:
> On 11/06/15 11:49, Paolo Bonzini wrote:
>>
>>
>> On 20/10/2015 09:39, Haozhong Zhang wrote:
>>> This patchset adds support for VMX TSC scaling feature which is
>>> available on Intel Skylake CPU. The specification of VMX TSC scaling
>>> can be found at
>>> http://www.intel.com/content/www/us/en/processors/timestamp-counter-scaling-virtualization-white-paper.html
>>>
>>> VMX TSC scaling allows guest TSC which is read by guest rdtsc(p)
>>> instructions increases in a rate that is customized by the hypervisor
>>> and can be different than the host TSC rate. Basically, VMX TSC
>>> scaling adds a 64-bit field called TSC multiplier in VMCS so that, if
>>> VMX TSC scaling is enabled, TSC read by guest rdtsc(p) instructions
>>> will be calculated by the following formula:
>>>
>>> guest EDX:EAX = (Host TSC * TSC multiplier) >> 48 + VMX TSC Offset
>>>
>>> where, Host TSC = Host MSR_IA32_TSC + Host MSR_IA32_TSC_ADJUST.
>>>
>>> This patchset, when cooperating with another QEMU patchset (sent in
>>> another email "target-i386: save/restore vcpu's TSC rate during
>>> migration"), allows guest programs observe a consistent TSC rate even
>>> though they are migrated among machines with different host TSC rates.
>>>
>>> VMX TSC scaling shares some common logics with SVM TSC ratio which
>>> is already supported by KVM. Patch 1 ~ 8 move those common logics from
>>> SVM code to the common code. Upon them, patch 9 ~ 12 add VMX-specific
>>> support for VMX TSC scaling.
>>>
>>> Changes in v2:
>>> * Remove the duplicated variable 'kvm_tsc_scaling_ratio_rsvd'.
>>> * Remove an unnecessary error check in original patch 2.
>>> * Do 64-bit arithmetic by functions recommended by Paolo.
>>> * Make kvm_set_tsc_khz() returns an error number so that ioctl
>>> KVM_SET_TSC_KHZ does not return 0 if errors happen.
>>>
>>> Reviewed-by: Eric Northup <[email protected]>
>>
>> Thanks for the patches. There are a couple changes that I can do myself:
>>
>> 1) kvm_default_tsc_scaling_ratio can be initialized in
>> kvm_arch_hardware_setup, since it's just 1ULL <<
>> kvm_tsc_scaling_ratio_frac_bits
>>
> Agree
>
>> 2) things that you are adding to include/linux/kvm_host.h should instead
>> go in arch/x86/include/linux/kvm_host.h
>>
> Agree, because they are x86 specific.
>
>> That's it. I'll commit it as soon as I test on AMD (today hopefully).
It tested fine. I'll give it a shot with the 32-bit mul_u64_u64_shr on
Monday as well, but I don't expect any issue.
Thanks, the patches are neat!
Paolo
On 11/06/15 21:40, Paolo Bonzini wrote:
>
>
> On 06/11/2015 13:42, Haozhong Zhang wrote:
> > On 11/06/15 11:49, Paolo Bonzini wrote:
> >>
> >>
> >> On 20/10/2015 09:39, Haozhong Zhang wrote:
> >>> This patchset adds support for VMX TSC scaling feature which is
> >>> available on Intel Skylake CPU. The specification of VMX TSC scaling
> >>> can be found at
> >>> http://www.intel.com/content/www/us/en/processors/timestamp-counter-scaling-virtualization-white-paper.html
> >>>
> >>> VMX TSC scaling allows guest TSC which is read by guest rdtsc(p)
> >>> instructions increases in a rate that is customized by the hypervisor
> >>> and can be different than the host TSC rate. Basically, VMX TSC
> >>> scaling adds a 64-bit field called TSC multiplier in VMCS so that, if
> >>> VMX TSC scaling is enabled, TSC read by guest rdtsc(p) instructions
> >>> will be calculated by the following formula:
> >>>
> >>> guest EDX:EAX = (Host TSC * TSC multiplier) >> 48 + VMX TSC Offset
> >>>
> >>> where, Host TSC = Host MSR_IA32_TSC + Host MSR_IA32_TSC_ADJUST.
> >>>
> >>> This patchset, when cooperating with another QEMU patchset (sent in
> >>> another email "target-i386: save/restore vcpu's TSC rate during
> >>> migration"), allows guest programs observe a consistent TSC rate even
> >>> though they are migrated among machines with different host TSC rates.
> >>>
> >>> VMX TSC scaling shares some common logics with SVM TSC ratio which
> >>> is already supported by KVM. Patch 1 ~ 8 move those common logics from
> >>> SVM code to the common code. Upon them, patch 9 ~ 12 add VMX-specific
> >>> support for VMX TSC scaling.
> >>>
> >>> Changes in v2:
> >>> * Remove the duplicated variable 'kvm_tsc_scaling_ratio_rsvd'.
> >>> * Remove an unnecessary error check in original patch 2.
> >>> * Do 64-bit arithmetic by functions recommended by Paolo.
> >>> * Make kvm_set_tsc_khz() returns an error number so that ioctl
> >>> KVM_SET_TSC_KHZ does not return 0 if errors happen.
> >>>
> >>> Reviewed-by: Eric Northup <[email protected]>
> >>
> >> Thanks for the patches. There are a couple changes that I can do myself:
> >>
> >> 1) kvm_default_tsc_scaling_ratio can be initialized in
> >> kvm_arch_hardware_setup, since it's just 1ULL <<
> >> kvm_tsc_scaling_ratio_frac_bits
> >>
> > Agree
> >
> >> 2) things that you are adding to include/linux/kvm_host.h should instead
> >> go in arch/x86/include/linux/kvm_host.h
> >>
> > Agree, because they are x86 specific.
> >
> >> That's it. I'll commit it as soon as I test on AMD (today hopefully).
>
> It tested fine. I'll give it a shot with the 32-bit mul_u64_u64_shr on
> Monday as well, but I don't expect any issue.
>
> Thanks, the patches are neat!
>
> Paolo
Thank you for the test!
Haozhong
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