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

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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@xxxxxxx>
> > Signed-off: Gleb Natapov <gleb@xxxxxxxxxx>
> > Signed-off: Vadim Rozenfeld <vrozenfe@xxxxxxxxxx>
> > 
> > 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.

> 
> > +		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.


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