Am 02.01.2014 14:57, schrieb Marcelo Tosatti: > 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 <[email protected]> >>>> Signed-off: Gleb Natapov <[email protected]> >>>> Signed-off: Vadim Rozenfeld <[email protected]> >>>> >>>> v1 -> v2 >>>> 1. mark TSC page dirty as suggested by >>>> Eric Northup <[email protected]> and Gleb >>>> 2. disable local irq when calling get_kernel_ns, >>>> as it was done by Peter Lieven <[email protected]> >>>> 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. > >
Thanks for clarifying. What about get_kernel_ns() can't this be interrupted? Peter -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
