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

Vadim Rozenfeld
2013-05-16T14:26:42Z

On Thu, 2013-05-16 at 15:44 +0200, Paolo Bonzini wrote:
> Il 16/05/2013 11:28, Vadim Rozenfeld ha scritto:
> > On Thu, 2013-05-16 at 12:21 +0300, Gleb Natapov wrote:
> >> 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();
>
> Please rename to kvm->arch.hv_ref_count_base.
>
> >>>>> + 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.
> > OK, will do it.
>
> Or better, remove all the handling of HV_X64_MSR_REFERENCE_TSC from this
> patch, and leave it all to the second.
>

What for? Could you please elaborate?
Vadim.

> Paolo
>
> >>>>
> >>>>> + 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.
> >
> >
> > --
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