Patchwork [RFC,03/10] KVM: PPC: BOOK3S: PR: Emulate instruction counter

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Submitter Aneesh Kumar K.V
Date Jan. 28, 2014, 4:44 p.m.
Message ID <1390927455-3312-4-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/314760/
State New
Headers show

Comments

Aneesh Kumar K.V - Jan. 28, 2014, 4:44 p.m.
Writing to IC is not allowed in the privileged mode.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 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(+)
Alexander Graf - Jan. 29, 2014, 4:40 p.m.
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 <aneesh.kumar@linux.vnet.ibm.com>
> ---
>   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

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Aneesh Kumar K.V - Jan. 31, 2014, 11:25 a.m.
Alexander Graf <agraf@suse.de> 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 <aneesh.kumar@linux.vnet.ibm.com>
>> ---
>>   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

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Alexander Graf - Jan. 31, 2014, 11:28 a.m.
On 31.01.2014, at 12:25, Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> wrote:

> Alexander Graf <agraf@suse.de> 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 <aneesh.kumar@linux.vnet.ibm.com>
>>> ---
>>>  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 ?

It'd mean we treat instruction emulation as part of guest overhead and time, but we'd make the entry/exit path faster. Unlike with HV KVM, guest entry/exit is pretty hot due to the massive amounts of instruction emulation we need to do.


Alex

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Patch

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);
 
 }
 
@@ -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;
 }
 
 static int kvmppc_core_check_requests_pr(struct kvm_vcpu *vcpu)