On Thu, 2014-01-02 at 17:52 +0100, Peter Lieven wrote: > Am 11.12.2013 19:59, schrieb Marcelo Tosatti: > > On Wed, Dec 11, 2013 at 04:53:05PM -0200, Marcelo Tosatti wrote: > >> 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". > > > > Just add kvmclock_offset when reading the values (otherwise you have a > > "stale copy" of kvmclock_offset in hv_ref_count). > > > > After some experiments I think we do no need kvm->arch.hv_ref_count at all. > > I was debugging some weird clockjump issues and I think the problem is that > after live migration > kvm->arch.hv_ref_count is initialized to 0. Depending on the uptime of the > vServer when the > hypercall was set up this can lead to series jumps. > > So I would suggest to completely drop kvm->arch.hv_ref_count. > > And use simply this in get_msr_hyperv_pw(). > > case HV_X64_MSR_TIME_REF_COUNT: { > data = div_u64(get_kernel_ns() + kvm->arch.kvmclock_offset, > 100); > break; > } >
Agreed. It should work as long as we rely on kvmclock_offset. Vadim. > It seems that get_kernel_ns() + kvm->arch.kvmclock_offset is exactly the > vServer uptime > in nanoseconds which starts counting at 0. > > 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
