Subject: Re: [RFC PATCH 03/10] KVM: PPC: BOOK3S: PR: Emulate instruction counter

From: Alexander Graf <[email-masked]>
Date: Wed, 29 Jan 2014 17:40:40 +0100

On 01/28/2014 05:44 PM, Aneesh Kumar K.V wrote:
> Writing to IC is not allowed in the privileged mode.

This is not a patch description.

>
> Signed-off-by: Aneesh Kumar K.V <[email-masked]>
> ---
>   arch/powerpc/include/asm/kvm_host.h | 1 +
>   arch/powerpc/kvm/book3s_emulate.c   | 3 +++
>   arch/powerpc/kvm/book3s_pr.c        | 2 ++
>   3 files changed, 6 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index 9ebdd12e50a9..e0b13aca98e6 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -509,6 +509,7 @@ struct kvm_vcpu_arch {
>   	/* Time base value when we entered the guest */
>   	u64 entry_tb;
>   	u64 entry_vtb;
> +	u64 entry_ic;
>   	u32 tcr;
>   	ulong tsr; /* we need to perform set/clr_bits() which requires ulong */
>   	u32 ivor[64];
> diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
> index 4b58d8a90cb5..abe6f3057e5b 100644
> --- a/arch/powerpc/kvm/book3s_emulate.c
> +++ b/arch/powerpc/kvm/book3s_emulate.c
> @@ -531,6 +531,9 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val
>   	case SPRN_VTB:
>   		*spr_val = vcpu->arch.vtb;
>   		break;
> +	case SPRN_IC:
> +		*spr_val = vcpu->arch.ic;
> +		break;
>   	case SPRN_GQR0:
>   	case SPRN_GQR1:
>   	case SPRN_GQR2:
> diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
> index b5598e9cdd09..51d469f8c9fd 100644
> --- a/arch/powerpc/kvm/book3s_pr.c
> +++ b/arch/powerpc/kvm/book3s_pr.c
> @@ -121,6 +121,7 @@ void kvmppc_copy_to_svcpu(struct kvmppc_book3s_shadow_vcpu *svcpu,
>   	 */
>   	vcpu->arch.entry_tb = get_tb();
>   	vcpu->arch.entry_vtb = get_vtb();
> +	vcpu->arch.entry_ic = mfspr(SPRN_IC);

Is this implemented on all systems?

>   
>   }
>   
> @@ -174,6 +175,7 @@ out:
>   	vcpu->arch.purr += get_tb() - vcpu->arch.entry_tb;
>   	vcpu->arch.spurr += get_tb() - vcpu->arch.entry_tb;
>   	vcpu->arch.vtb += get_vtb() - vcpu->arch.entry_vtb;
> +	vcpu->arch.ic += mfspr(SPRN_IC) - vcpu->arch.entry_ic;

This is getting quite convoluted. How about we act slightly more fuzzy 
and put all of this into vcpu_load/put?

Alex