On Tue, May 14, 2013 at 04:14:11PM +0200, Peter Lieven wrote: > On 13.05.2013 13:45, Vadim Rozenfeld wrote: > >Signed-off: Peter Lieven <pl@xxxxxxx> > >Signed-off: Gleb Natapov <gleb@xxxxxxxxxx> > >Signed-off: Vadim Rozenfeld <vrozenfe@xxxxxxxxxx> > > > >The following patch allows to activate Hyper-V > >reference time counter > >--- > > arch/x86/include/asm/kvm_host.h | 2 ++ > > arch/x86/include/uapi/asm/hyperv.h | 3 +++ > > arch/x86/kvm/x86.c | 25 ++++++++++++++++++++++++- > > 3 files changed, 29 insertions(+), 1 deletion(-) > > > >diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > >index 3741c65..f0fee35 100644 > >--- a/arch/x86/include/asm/kvm_host.h > >+++ b/arch/x86/include/asm/kvm_host.h > >@@ -575,6 +575,8 @@ struct kvm_arch { > > /* fields used by HYPER-V emulation */ > > u64 hv_guest_os_id; > > u64 hv_hypercall; > >+ u64 hv_ref_count; > >+ u64 hv_tsc_page; > > > > #ifdef CONFIG_KVM_MMU_AUDIT > > int audit_point; > >diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h > >index b80420b..9711819 100644 > >--- a/arch/x86/include/uapi/asm/hyperv.h > >+++ b/arch/x86/include/uapi/asm/hyperv.h > >@@ -136,6 +136,9 @@ > > /* MSR used to read the per-partition time reference counter */ > > #define HV_X64_MSR_TIME_REF_COUNT 0x40000020 > > > >+/* A partition's reference time stamp counter (TSC) page */ > >+#define HV_X64_MSR_REFERENCE_TSC 0x40000021 > >+ > > /* Define the virtual APIC registers */ > > #define HV_X64_MSR_EOI 0x40000070 > > #define HV_X64_MSR_ICR 0x40000071 > >diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > >index 094b5d9..1a4036d 100644 > >--- a/arch/x86/kvm/x86.c > >+++ b/arch/x86/kvm/x86.c > >@@ -843,7 +843,7 @@ EXPORT_SYMBOL_GPL(kvm_rdpmc); > > static u32 msrs_to_save[] = { > > MSR_KVM_SYSTEM_TIME, MSR_KVM_WALL_CLOCK, > > MSR_KVM_SYSTEM_TIME_NEW, MSR_KVM_WALL_CLOCK_NEW, > >- HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL, > >+ HV_X64_MSR_GUEST_OS_ID, HV_X64_MSR_HYPERCALL,HV_X64_MSR_TIME_REF_COUNT, > > HV_X64_MSR_APIC_ASSIST_PAGE, MSR_KVM_ASYNC_PF_EN, MSR_KVM_STEAL_TIME, > > MSR_KVM_PV_EOI_EN, > > MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP, > >@@ -1764,6 +1764,8 @@ static bool kvm_hv_msr_partition_wide(u32 msr) > > switch (msr) { > > case HV_X64_MSR_GUEST_OS_ID: > > case HV_X64_MSR_HYPERCALL: > >+ case HV_X64_MSR_REFERENCE_TSC: > >+ case HV_X64_MSR_TIME_REF_COUNT: > > r = true; > > break; > > } > >@@ -1803,6 +1805,21 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data) > > if (__copy_to_user((void __user *)addr, instructions, 4)) > > return 1; > > kvm->arch.hv_hypercall = data; > >+ kvm->arch.hv_ref_count = get_kernel_ns(); > >+ break; > >+ } > >+ case HV_X64_MSR_REFERENCE_TSC: { > >+ u64 gfn; > >+ unsigned long addr; > >+ u32 tsc_ref; > >+ gfn = data >> HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT; > >+ addr = gfn_to_hva(kvm, gfn); > >+ if (kvm_is_error_hva(addr)) > >+ return 1; > >+ tsc_ref = 0; > >+ if(__copy_to_user((void __user *)addr, &tsc_ref, sizeof(tsc_ref))) > >+ return 1; > >+ kvm->arch.hv_tsc_page = data; > > break; > > } > > default: > >@@ -2229,6 +2246,12 @@ static int get_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) > > case HV_X64_MSR_HYPERCALL: > > data = kvm->arch.hv_hypercall; > > break; > >+ case HV_X64_MSR_TIME_REF_COUNT: > >+ data = div_u64(get_kernel_ns() - kvm->arch.hv_ref_count,100); > >+ break; > > > in an earlier version of this patch I have the following: > > + case HV_X64_MSR_TIME_REF_COUNT: { > + u64 now_ns; > + local_irq_disable(); > + now_ns = get_kernel_ns(); > + data = div_u64(now_ns + kvm->arch.kvmclock_offset - kvm->arch.hv_ref_count,100); > + local_irq_enable(); > + break; > + } > > I do not know if this is right, but I can report that this one is working without any flaws > since approx. 1.5 years. > get_kernel_ns() should be called at least with preemption disabled and all other callers disable irq around it too, also without kvmclock_offset the counter will be incorrect after migration. Marcelo, is kvmclock_offset guaranties migration correctness or more is required? -- Gleb. -- 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