On Tue, May 21, 2013 at 09:46:14PM -0300, Marcelo Tosatti wrote:
> On Sun, May 19, 2013 at 05:06:36PM +1000, 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 | 14 ++++++++++++++
> > arch/x86/kvm/x86.c | 39
> > +++++++++++++++++++++++++++++++++++++-
> > include/uapi/linux/kvm.h | 1 +
> > 4 files changed, 55 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..890dfc3 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
> > @@ -179,6 +182,9 @@
> > #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
> > @@ -191,4 +197,12 @@
> > #define HV_STATUS_INVALID_ALIGNMENT 4
> > #define HV_STATUS_INSUFFICIENT_BUFFERS 19
> >
> > +typedef struct _HV_REFERENCE_TSC_PAGE {
> > + __u32 TscSequence;
> > + __u32 Rserved1;
> > + __u64 TscScale;
> > + __s64 TscOffset;
> > +} HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE;
> > +
> > +
> > #endif
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 8d28810..9645dab 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, not needed.
> > - 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,
> > @@ -1788,6 +1788,8 @@ 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;
> > }
> > @@ -1827,6 +1829,29 @@ 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();
> > + local_irq_enable();
> > + break;
>
> local_irq_disable/local_irq_enable not needed.
>
get_kernel_ns has WARN_ON(preemptible()) so at least preempt_disable()
is needed, but all callers of the function disable interrupts.
> What is the reasoning behind reading this time value at msr write time?
>
> > + }
> > + case HV_X64_MSR_REFERENCE_TSC: {
> > + u64 gfn;
> > + unsigned long addr;
> > + HV_REFERENCE_TSC_PAGE tsc_ref;
> > + tsc_ref.TscSequence = 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:
> > @@ -2253,6 +2278,17 @@ 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();
> > + break;
> > + }
>
> local_irq_disable/enable not needed.
>
> It would be nice to have a testcase to compare reference tsc versus MSR.
--
Gleb.
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