On Thu, Jan 02, 2014 at 02:15:48PM +0100, Peter Lieven wrote: > Am 11.12.2013 19:53, schrieb Marcelo Tosatti: > > On Sun, Dec 08, 2013 at 10:33:38PM +1100, Vadim Rozenfeld wrote: > >> Signed-off: Peter Lieven <pl@xxxxxxx> > >> Signed-off: Gleb Natapov <gleb@xxxxxxxxxx> > >> Signed-off: Vadim Rozenfeld <vrozenfe@xxxxxxxxxx> > >> > >> v1 -> v2 > >> 1. mark TSC page dirty as suggested by > >> Eric Northup <digitaleric@xxxxxxxxxx> and Gleb > >> 2. disable local irq when calling get_kernel_ns, > >> as it was done by Peter Lieven <pl@xxxxxxxxx> > >> 3. move check for TSC page enable from second patch > >> to this one. > >> > >> --- > >> arch/x86/include/asm/kvm_host.h | 2 ++ > >> arch/x86/include/uapi/asm/hyperv.h | 13 +++++++++++++ > >> arch/x86/kvm/x86.c | 39 +++++++++++++++++++++++++++++++++++++- > >> include/uapi/linux/kvm.h | 1 + > >> 4 files changed, 54 insertions(+), 1 deletion(-) > >> > >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > >> index ae5d783..2fd0753 100644 > >> --- a/arch/x86/include/asm/kvm_host.h > >> +++ b/arch/x86/include/asm/kvm_host.h > >> @@ -605,6 +605,8 @@ 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 b8f1c01..462efe7 100644 > >> --- a/arch/x86/include/uapi/asm/hyperv.h > >> +++ b/arch/x86/include/uapi/asm/hyperv.h > >> @@ -28,6 +28,9 @@ > >> /* Partition Reference Counter (HV_X64_MSR_TIME_REF_COUNT) available*/ > >> #define HV_X64_MSR_TIME_REF_COUNT_AVAILABLE (1 << 1) > >> > >> +/* A partition's reference time stamp counter (TSC) page */ > >> +#define HV_X64_MSR_REFERENCE_TSC 0x40000021 > >> + > >> /* > >> * There is a single feature flag that signifies the presence of the MSR > >> * that can be used to retrieve both the local APIC Timer frequency as > >> @@ -198,6 +201,9 @@ > >> #define HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_MASK \ > >> (~((1ull << HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_SHIFT) - 1)) > >> > >> +#define HV_X64_MSR_TSC_REFERENCE_ENABLE 0x00000001 > >> +#define HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT 12 > >> + > >> #define HV_PROCESSOR_POWER_STATE_C0 0 > >> #define HV_PROCESSOR_POWER_STATE_C1 1 > >> #define HV_PROCESSOR_POWER_STATE_C2 2 > >> @@ -210,4 +216,11 @@ > >> #define HV_STATUS_INVALID_ALIGNMENT 4 > >> #define HV_STATUS_INSUFFICIENT_BUFFERS 19 > >> > >> +typedef struct _HV_REFERENCE_TSC_PAGE { > >> + __u32 tsc_sequence; > >> + __u32 res1; > >> + __u64 tsc_scale; > >> + __s64 tsc_offset; > >> +} HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE; > >> + > >> #endif > >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > >> index 21ef1ba..5e4e495a 100644 > >> --- a/arch/x86/kvm/x86.c > >> +++ b/arch/x86/kvm/x86.c > >> @@ -840,7 +840,7 @@ 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, > >> @@ -1826,6 +1826,8 @@ 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; > >> } > >> @@ -1865,6 +1867,29 @@ 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; > >> + local_irq_disable(); > >> + kvm->arch.hv_ref_count = get_kernel_ns() + kvm->arch.kvmclock_offset; > >> + local_irq_enable(); > > > > Where does the docs say that HV_X64_MSR_HYPERCALL is the where the clock > > starts counting? > > > > No need to store kvmclock_offset in hv_ref_count? (moreover > > the name is weird, better name would be "hv_ref_start_time". > > > >> + break; > >> + } > >> + case HV_X64_MSR_REFERENCE_TSC: { > >> + u64 gfn; > >> + unsigned long addr; > >> + HV_REFERENCE_TSC_PAGE tsc_ref; > >> + tsc_ref.tsc_sequence = 0; > >> + if (!(data & HV_X64_MSR_TSC_REFERENCE_ENABLE)) { > >> + kvm->arch.hv_tsc_page = data; > >> + break; > >> + } > >> + gfn = data >> HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT; > >> + addr = gfn_to_hva(kvm, data >> > >> + HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT); > >> + if (kvm_is_error_hva(addr)) > >> + return 1; > >> + if (__copy_to_user((void __user *)addr, &tsc_ref, sizeof(tsc_ref))) > >> + return 1; > >> + mark_page_dirty(kvm, gfn); > >> + kvm->arch.hv_tsc_page = data; > >> break; > >> } > >> default: > >> @@ -2291,6 +2316,17 @@ 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: { > >> + u64 now_ns; > >> + local_irq_disable(); > >> + now_ns = get_kernel_ns() + kvm->arch.kvmclock_offset; > >> + data = div_u64(now_ns - kvm->arch.hv_ref_count, 100); > >> + local_irq_enable(); > > > > No need for irq disable/enable pairs. > > KVM_GET_CLOCK / KVM_SET_CLOCK do the irq disable/enable pairs. What is right? > > Peter local_irq_disable(); now_ns = get_kernel_ns(); delta = user_ns.clock - now_ns; local_irq_enable(); Not using irq disable/enable pairs. The subtraction is not dependant on any particular time. local_irq_disable(); now_ns = get_kernel_ns(); local_irq_enable(); delta = user_ns.clock - now_ns; Any interrupt that would affect the value of get_kernel_ns(), would have a similar effect before the interrupts are disabled. So the disable/enable pair achieves nothing in practice. It was copied from kvm_guest_time_update. -- 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