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

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Fri, 31 Jan 2014 16:55:53 +0530

Alexander Graf <[email-masked]> writes:

> 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?
>

I am not sure whether vcpu_load/put is too early/late to save these
context ?

-aneesh