On Tue, 2014-01-07 at 18:52 +0100, Peter Lieven wrote:
> Am 07.01.2014 10:36, schrieb Vadim Rozenfeld:
> > 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 <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".
> >>>
> >>> 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.
>
> I think we can rely on kvmclock_offset. Had you had a chance to do further testing
> during the weekend?
Yes, and still testing.
There is still some inconsistency in the value returned by
QueryPerformanceCounter during migration.
Vadim.
>
> Peter
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