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 <digitaleric@xxxxxxxxxx> > > 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(-) > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
