Re: [RFC PATCH 1/2] Hyper-H reference counter

Gleb Natapov
2013-05-16T09:21:31Z

On Thu, May 16, 2013 at 07:13:41PM +1000, Vadim Rozenfeld wrote:
> On Thu, 2013-05-16 at 11:34 +0300, Gleb Natapov wrote:
> > On Mon, May 13, 2013 at 09:45:16PM +1000, Vadim Rozenfeld wrote:
> > > Signed-off: Peter Lieven <pl@dlh.net>
> > > Signed-off: Gleb Natapov <gleb@redhat.com>
> > > Signed-off: Vadim Rozenfeld <vrozenfe@redhat.com>
> > >
> > > The following patch allows to activate Hyper-V
> > > reference time counter
> > > ---
> > > arch/x86/include/asm/kvm_host.h | 2 ++
> > > arch/x86/include/uapi/asm/hyperv.h | 3 +++
> > > arch/x86/kvm/x86.c | 25 ++++++++++++++++++++++++-
> > > 3 files changed, 29 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..9711819 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
> > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > > index 094b5d9..1a4036d 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,
> > > - 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,
> > > @@ -1764,6 +1764,8 @@ 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;
> > > }
> > > @@ -1803,6 +1805,21 @@ 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;
> > > + kvm->arch.hv_ref_count = get_kernel_ns();
> > > + break;
> > > + }
> > > + case HV_X64_MSR_REFERENCE_TSC: {
> > > + u64 gfn;
> > > + unsigned long addr;
> > > + u32 tsc_ref;
> > > + gfn = data >> HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT;
> > Shouldn't you check HV_X64_MSR_TSC_REFERENCE_ENABLE here?
>
> Yes, I have this check added in the second patch.
>
Move it here please.

> >
> > > + addr = gfn_to_hva(kvm, gfn);
> > > + if (kvm_is_error_hva(addr))
> > > + return 1;
> > > + tsc_ref = 0;
> > > + if(__copy_to_user((void __user *)addr, &tsc_ref, sizeof(tsc_ref)))
> > > + return 1;
> > > + kvm->arch.hv_tsc_page = data;
> > > break;
> > > }
> > > default:
> > > @@ -2229,6 +2246,12 @@ 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:
> > > + data = div_u64(get_kernel_ns() - kvm->arch.hv_ref_count,100);
> > > + break;
> > > + case HV_X64_MSR_REFERENCE_TSC:
> > > + data = kvm->arch.hv_tsc_page;
> > > + break;
> > > default:
> > > vcpu_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
> > > return 1;
> > > --
> > > 1.8.1.2
> >
> > --
> > Gleb.
>

--
Gleb.