Patchwork KVM: PPC: booke: Added DECAR support

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Submitter Bharat Bhushan
Date May 15, 2012, 7:33 a.m.
Message ID <1337067209-26435-1-git-send-email-bharat.bhushan@freescale.com>
Download mbox | patch
Permalink /patch/159234/
State New
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Bharat Bhushan - May 15, 2012, 7:33 a.m.
Added the decrementer auto-reload support.

Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
---
 arch/powerpc/include/asm/kvm_host.h |    2 ++
 arch/powerpc/kvm/booke.c            |    5 +++++
 arch/powerpc/kvm/booke_emulate.c    |    7 ++++++-
 3 files changed, 13 insertions(+), 1 deletions(-)
Alexander Graf - May 15, 2012, 2:28 p.m.
On 05/15/2012 09:33 AM, Bharat Bhushan wrote:
> Added the decrementer auto-reload support.
>
> Signed-off-by: Bharat Bhushan<bharat.bhushan@freescale.com>
> ---
>   arch/powerpc/include/asm/kvm_host.h |    2 ++
>   arch/powerpc/kvm/booke.c            |    5 +++++
>   arch/powerpc/kvm/booke_emulate.c    |    7 ++++++-
>   3 files changed, 13 insertions(+), 1 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index d848cdc..1d6f89e 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -414,7 +414,9 @@ struct kvm_vcpu_arch {
>   	ulong mcsrr1;
>   	ulong mcsr;
>   	u32 dec;
> +#ifdef CONFIG_BOOKE
>   	u32 decar;
> +#endif
>   	u32 tbl;
>   	u32 tbu;
>   	u32 tcr;
> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> index 72f13f4..86681ee 100644
> --- a/arch/powerpc/kvm/booke.c
> +++ b/arch/powerpc/kvm/booke.c
> @@ -1267,6 +1267,11 @@ void kvmppc_decrementer_func(unsigned long data)
>   {
>   	struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
>
> +	if (vcpu->arch.tcr&  TCR_ARE) {
> +		vcpu->arch.dec = vcpu->arch.decar;
> +		kvmppc_emulate_dec(vcpu);
> +	}
> +
>   	kvmppc_set_tsr_bits(vcpu, TSR_DIS);
>   }
>
> diff --git a/arch/powerpc/kvm/booke_emulate.c b/arch/powerpc/kvm/booke_emulate.c
> index 6c76397..83c3796 100644
> --- a/arch/powerpc/kvm/booke_emulate.c
> +++ b/arch/powerpc/kvm/booke_emulate.c
> @@ -129,6 +129,9 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
>   		kvmppc_set_tcr(vcpu, spr_val);
>   		break;
>
> +	case SPRN_DECAR:
> +		vcpu->arch.decar = spr_val;
> +		break;
>   	/*
>   	 * Note: SPRG4-7 are user-readable.
>   	 * These values are loaded into the real SPRGs when resuming the
> @@ -244,7 +247,9 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val)
>   	case SPRN_TCR:
>   		*spr_val = vcpu->arch.tcr;
>   		break;
> -
> +	case SPRN_DECAR:
> +		*spr_val = vcpu->arch.decar;
> +		break;

DECAR can't be read. Otherwise looks good to me.

Alex

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Bharat Bhushan - May 16, 2012, 6:57 a.m.
> -----Original Message-----
> From: Alexander Graf [mailto:agraf@suse.de]
> Sent: Tuesday, May 15, 2012 7:59 PM
> To: Bhushan Bharat-R65777
> Cc: kvm-ppc@vger.kernel.org; Bhushan Bharat-R65777
> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
> 
> On 05/15/2012 09:33 AM, Bharat Bhushan wrote:
> > Added the decrementer auto-reload support.
> >
> > Signed-off-by: Bharat Bhushan<bharat.bhushan@freescale.com>
> > ---
> >   arch/powerpc/include/asm/kvm_host.h |    2 ++
> >   arch/powerpc/kvm/booke.c            |    5 +++++
> >   arch/powerpc/kvm/booke_emulate.c    |    7 ++++++-
> >   3 files changed, 13 insertions(+), 1 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/kvm_host.h
> > b/arch/powerpc/include/asm/kvm_host.h
> > index d848cdc..1d6f89e 100644
> > --- a/arch/powerpc/include/asm/kvm_host.h
> > +++ b/arch/powerpc/include/asm/kvm_host.h
> > @@ -414,7 +414,9 @@ struct kvm_vcpu_arch {
> >   	ulong mcsrr1;
> >   	ulong mcsr;
> >   	u32 dec;
> > +#ifdef CONFIG_BOOKE
> >   	u32 decar;
> > +#endif
> >   	u32 tbl;
> >   	u32 tbu;
> >   	u32 tcr;
> > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index
> > 72f13f4..86681ee 100644
> > --- a/arch/powerpc/kvm/booke.c
> > +++ b/arch/powerpc/kvm/booke.c
> > @@ -1267,6 +1267,11 @@ void kvmppc_decrementer_func(unsigned long data)
> >   {
> >   	struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
> >
> > +	if (vcpu->arch.tcr&  TCR_ARE) {
> > +		vcpu->arch.dec = vcpu->arch.decar;
> > +		kvmppc_emulate_dec(vcpu);
> > +	}
> > +
> >   	kvmppc_set_tsr_bits(vcpu, TSR_DIS);
> >   }
> >
> > diff --git a/arch/powerpc/kvm/booke_emulate.c
> > b/arch/powerpc/kvm/booke_emulate.c
> > index 6c76397..83c3796 100644
> > --- a/arch/powerpc/kvm/booke_emulate.c
> > +++ b/arch/powerpc/kvm/booke_emulate.c
> > @@ -129,6 +129,9 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int
> sprn, ulong spr_val)
> >   		kvmppc_set_tcr(vcpu, spr_val);
> >   		break;
> >
> > +	case SPRN_DECAR:
> > +		vcpu->arch.decar = spr_val;
> > +		break;
> >   	/*
> >   	 * Note: SPRG4-7 are user-readable.
> >   	 * These values are loaded into the real SPRGs when resuming the @@
> > -244,7 +247,9 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu *vcpu, int
> sprn, ulong *spr_val)
> >   	case SPRN_TCR:
> >   		*spr_val = vcpu->arch.tcr;
> >   		break;
> > -
> > +	case SPRN_DECAR:
> > +		*spr_val = vcpu->arch.decar;
> > +		break;
> 
> DECAR can't be read. Otherwise looks good to me.

DECAR can be read on e500mc cores. So I will make this under CONFIG_KVM_E500MC.

What happens if DECAR is read on non e500mc? Is it treated as NOP or illegal instruction exception?

Thanks
-Bharat

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Alexander Graf - May 16, 2012, 9:06 a.m.
On 05/16/2012 08:57 AM, Bhushan Bharat-R65777 wrote:
>
>> -----Original Message-----
>> From: Alexander Graf [mailto:agraf@suse.de]
>> Sent: Tuesday, May 15, 2012 7:59 PM
>> To: Bhushan Bharat-R65777
>> Cc: kvm-ppc@vger.kernel.org; Bhushan Bharat-R65777
>> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
>>
>> On 05/15/2012 09:33 AM, Bharat Bhushan wrote:
>>> Added the decrementer auto-reload support.
>>>
>>> Signed-off-by: Bharat Bhushan<bharat.bhushan@freescale.com>
>>> ---
>>>    arch/powerpc/include/asm/kvm_host.h |    2 ++
>>>    arch/powerpc/kvm/booke.c            |    5 +++++
>>>    arch/powerpc/kvm/booke_emulate.c    |    7 ++++++-
>>>    3 files changed, 13 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/arch/powerpc/include/asm/kvm_host.h
>>> b/arch/powerpc/include/asm/kvm_host.h
>>> index d848cdc..1d6f89e 100644
>>> --- a/arch/powerpc/include/asm/kvm_host.h
>>> +++ b/arch/powerpc/include/asm/kvm_host.h
>>> @@ -414,7 +414,9 @@ struct kvm_vcpu_arch {
>>>    	ulong mcsrr1;
>>>    	ulong mcsr;
>>>    	u32 dec;
>>> +#ifdef CONFIG_BOOKE
>>>    	u32 decar;
>>> +#endif
>>>    	u32 tbl;
>>>    	u32 tbu;
>>>    	u32 tcr;
>>> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index
>>> 72f13f4..86681ee 100644
>>> --- a/arch/powerpc/kvm/booke.c
>>> +++ b/arch/powerpc/kvm/booke.c
>>> @@ -1267,6 +1267,11 @@ void kvmppc_decrementer_func(unsigned long data)
>>>    {
>>>    	struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
>>>
>>> +	if (vcpu->arch.tcr&   TCR_ARE) {
>>> +		vcpu->arch.dec = vcpu->arch.decar;
>>> +		kvmppc_emulate_dec(vcpu);
>>> +	}
>>> +
>>>    	kvmppc_set_tsr_bits(vcpu, TSR_DIS);
>>>    }
>>>
>>> diff --git a/arch/powerpc/kvm/booke_emulate.c
>>> b/arch/powerpc/kvm/booke_emulate.c
>>> index 6c76397..83c3796 100644
>>> --- a/arch/powerpc/kvm/booke_emulate.c
>>> +++ b/arch/powerpc/kvm/booke_emulate.c
>>> @@ -129,6 +129,9 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int
>> sprn, ulong spr_val)
>>>    		kvmppc_set_tcr(vcpu, spr_val);
>>>    		break;
>>>
>>> +	case SPRN_DECAR:
>>> +		vcpu->arch.decar = spr_val;
>>> +		break;
>>>    	/*
>>>    	 * Note: SPRG4-7 are user-readable.
>>>    	 * These values are loaded into the real SPRGs when resuming the @@
>>> -244,7 +247,9 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu *vcpu, int
>> sprn, ulong *spr_val)
>>>    	case SPRN_TCR:
>>>    		*spr_val = vcpu->arch.tcr;
>>>    		break;
>>> -
>>> +	case SPRN_DECAR:
>>> +		*spr_val = vcpu->arch.decar;
>>> +		break;
>> DECAR can't be read. Otherwise looks good to me.
> DECAR can be read on e500mc cores. So I will make this under CONFIG_KVM_E500MC.
>
> What happens if DECAR is read on non e500mc? Is it treated as NOP or illegal instruction exception?

I would assume the latter. NOPs usually don't happen. If anything, it 
would return 0.

See section 9.4 in the PowerISA:

The contents of the Decrementer Auto-Reload Register
cannot be read. The contents of bits 32:63 of register
RS can be written to the Decrementer Auto-Reload
Register using the mtspr instruction.

Could you please paste the respective passage of the e500mc manual that 
declares DECAR as readable?


Alex

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Bharat Bhushan - May 16, 2012, 9:21 a.m.
> -----Original Message-----
> From: Alexander Graf [mailto:agraf@suse.de]
> Sent: Wednesday, May 16, 2012 2:36 PM
> To: Bhushan Bharat-R65777
> Cc: kvm-ppc@vger.kernel.org
> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
> 
> On 05/16/2012 08:57 AM, Bhushan Bharat-R65777 wrote:
> >
> >> -----Original Message-----
> >> From: Alexander Graf [mailto:agraf@suse.de]
> >> Sent: Tuesday, May 15, 2012 7:59 PM
> >> To: Bhushan Bharat-R65777
> >> Cc: kvm-ppc@vger.kernel.org; Bhushan Bharat-R65777
> >> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
> >>
> >> On 05/15/2012 09:33 AM, Bharat Bhushan wrote:
> >>> Added the decrementer auto-reload support.
> >>>
> >>> Signed-off-by: Bharat Bhushan<bharat.bhushan@freescale.com>
> >>> ---
> >>>    arch/powerpc/include/asm/kvm_host.h |    2 ++
> >>>    arch/powerpc/kvm/booke.c            |    5 +++++
> >>>    arch/powerpc/kvm/booke_emulate.c    |    7 ++++++-
> >>>    3 files changed, 13 insertions(+), 1 deletions(-)
> >>>
> >>> diff --git a/arch/powerpc/include/asm/kvm_host.h
> >>> b/arch/powerpc/include/asm/kvm_host.h
> >>> index d848cdc..1d6f89e 100644
> >>> --- a/arch/powerpc/include/asm/kvm_host.h
> >>> +++ b/arch/powerpc/include/asm/kvm_host.h
> >>> @@ -414,7 +414,9 @@ struct kvm_vcpu_arch {
> >>>    	ulong mcsrr1;
> >>>    	ulong mcsr;
> >>>    	u32 dec;
> >>> +#ifdef CONFIG_BOOKE
> >>>    	u32 decar;
> >>> +#endif
> >>>    	u32 tbl;
> >>>    	u32 tbu;
> >>>    	u32 tcr;
> >>> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> >>> index 72f13f4..86681ee 100644
> >>> --- a/arch/powerpc/kvm/booke.c
> >>> +++ b/arch/powerpc/kvm/booke.c
> >>> @@ -1267,6 +1267,11 @@ void kvmppc_decrementer_func(unsigned long data)
> >>>    {
> >>>    	struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
> >>>
> >>> +	if (vcpu->arch.tcr&   TCR_ARE) {
> >>> +		vcpu->arch.dec = vcpu->arch.decar;
> >>> +		kvmppc_emulate_dec(vcpu);
> >>> +	}
> >>> +
> >>>    	kvmppc_set_tsr_bits(vcpu, TSR_DIS);
> >>>    }
> >>>
> >>> diff --git a/arch/powerpc/kvm/booke_emulate.c
> >>> b/arch/powerpc/kvm/booke_emulate.c
> >>> index 6c76397..83c3796 100644
> >>> --- a/arch/powerpc/kvm/booke_emulate.c
> >>> +++ b/arch/powerpc/kvm/booke_emulate.c
> >>> @@ -129,6 +129,9 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu
> >>> *vcpu, int
> >> sprn, ulong spr_val)
> >>>    		kvmppc_set_tcr(vcpu, spr_val);
> >>>    		break;
> >>>
> >>> +	case SPRN_DECAR:
> >>> +		vcpu->arch.decar = spr_val;
> >>> +		break;
> >>>    	/*
> >>>    	 * Note: SPRG4-7 are user-readable.
> >>>    	 * These values are loaded into the real SPRGs when resuming the
> >>> @@
> >>> -244,7 +247,9 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu
> >>> *vcpu, int
> >> sprn, ulong *spr_val)
> >>>    	case SPRN_TCR:
> >>>    		*spr_val = vcpu->arch.tcr;
> >>>    		break;
> >>> -
> >>> +	case SPRN_DECAR:
> >>> +		*spr_val = vcpu->arch.decar;
> >>> +		break;
> >> DECAR can't be read. Otherwise looks good to me.
> > DECAR can be read on e500mc cores. So I will make this under
> CONFIG_KVM_E500MC.
> >
> > What happens if DECAR is read on non e500mc? Is it treated as NOP or illegal
> instruction exception?
> 
> I would assume the latter. NOPs usually don't happen. If anything, it would
> return 0.
> 
> See section 9.4 in the PowerISA:
> 
> The contents of the Decrementer Auto-Reload Register cannot be read. The
> contents of bits 32:63 of register RS can be written to the Decrementer Auto-
> Reload Register using the mtspr instruction.
> 
> Could you please paste the respective passage of the e500mc manual that declares
> DECAR as readable?

I have booke -4 version 1.05.
There are remarks at 3 place

1)
Table 2-1: 
There is remark " DECAR is defined by the architecture to be write-only, however the e500mc allows it to be read."
------------

2)
2.8.5 Decrementer Auto-Reload Register (DECAR)

"For e500V4, the DECAR can be read in hypervisor state, although the architecture defines it as a
write-only register."
--------------

3)
Table 4.37

Hypervisor Privilege on Read  - Yes
Hypervisor Privilege on Write - Yes

Remark: e500mc allows reading of DECAR although Power ISA does not define it.
----------------

I verified with my unit test that reading DECAR traps in KVM on e500mc.

Thanks
-Bharat

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Alexander Graf - May 16, 2012, 9:23 a.m.
On 05/16/2012 11:21 AM, Bhushan Bharat-R65777 wrote:
>
>> -----Original Message-----
>> From: Alexander Graf [mailto:agraf@suse.de]
>> Sent: Wednesday, May 16, 2012 2:36 PM
>> To: Bhushan Bharat-R65777
>> Cc: kvm-ppc@vger.kernel.org
>> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
>>
>> On 05/16/2012 08:57 AM, Bhushan Bharat-R65777 wrote:
>>>> -----Original Message-----
>>>> From: Alexander Graf [mailto:agraf@suse.de]
>>>> Sent: Tuesday, May 15, 2012 7:59 PM
>>>> To: Bhushan Bharat-R65777
>>>> Cc: kvm-ppc@vger.kernel.org; Bhushan Bharat-R65777
>>>> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
>>>>
>>>> On 05/15/2012 09:33 AM, Bharat Bhushan wrote:
>>>>> Added the decrementer auto-reload support.
>>>>>
>>>>> Signed-off-by: Bharat Bhushan<bharat.bhushan@freescale.com>
>>>>> ---
>>>>>     arch/powerpc/include/asm/kvm_host.h |    2 ++
>>>>>     arch/powerpc/kvm/booke.c            |    5 +++++
>>>>>     arch/powerpc/kvm/booke_emulate.c    |    7 ++++++-
>>>>>     3 files changed, 13 insertions(+), 1 deletions(-)
>>>>>
>>>>> diff --git a/arch/powerpc/include/asm/kvm_host.h
>>>>> b/arch/powerpc/include/asm/kvm_host.h
>>>>> index d848cdc..1d6f89e 100644
>>>>> --- a/arch/powerpc/include/asm/kvm_host.h
>>>>> +++ b/arch/powerpc/include/asm/kvm_host.h
>>>>> @@ -414,7 +414,9 @@ struct kvm_vcpu_arch {
>>>>>     	ulong mcsrr1;
>>>>>     	ulong mcsr;
>>>>>     	u32 dec;
>>>>> +#ifdef CONFIG_BOOKE
>>>>>     	u32 decar;
>>>>> +#endif
>>>>>     	u32 tbl;
>>>>>     	u32 tbu;
>>>>>     	u32 tcr;
>>>>> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
>>>>> index 72f13f4..86681ee 100644
>>>>> --- a/arch/powerpc/kvm/booke.c
>>>>> +++ b/arch/powerpc/kvm/booke.c
>>>>> @@ -1267,6 +1267,11 @@ void kvmppc_decrementer_func(unsigned long data)
>>>>>     {
>>>>>     	struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
>>>>>
>>>>> +	if (vcpu->arch.tcr&    TCR_ARE) {
>>>>> +		vcpu->arch.dec = vcpu->arch.decar;
>>>>> +		kvmppc_emulate_dec(vcpu);
>>>>> +	}
>>>>> +
>>>>>     	kvmppc_set_tsr_bits(vcpu, TSR_DIS);
>>>>>     }
>>>>>
>>>>> diff --git a/arch/powerpc/kvm/booke_emulate.c
>>>>> b/arch/powerpc/kvm/booke_emulate.c
>>>>> index 6c76397..83c3796 100644
>>>>> --- a/arch/powerpc/kvm/booke_emulate.c
>>>>> +++ b/arch/powerpc/kvm/booke_emulate.c
>>>>> @@ -129,6 +129,9 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu
>>>>> *vcpu, int
>>>> sprn, ulong spr_val)
>>>>>     		kvmppc_set_tcr(vcpu, spr_val);
>>>>>     		break;
>>>>>
>>>>> +	case SPRN_DECAR:
>>>>> +		vcpu->arch.decar = spr_val;
>>>>> +		break;
>>>>>     	/*
>>>>>     	 * Note: SPRG4-7 are user-readable.
>>>>>     	 * These values are loaded into the real SPRGs when resuming the
>>>>> @@
>>>>> -244,7 +247,9 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu
>>>>> *vcpu, int
>>>> sprn, ulong *spr_val)
>>>>>     	case SPRN_TCR:
>>>>>     		*spr_val = vcpu->arch.tcr;
>>>>>     		break;
>>>>> -
>>>>> +	case SPRN_DECAR:
>>>>> +		*spr_val = vcpu->arch.decar;
>>>>> +		break;
>>>> DECAR can't be read. Otherwise looks good to me.
>>> DECAR can be read on e500mc cores. So I will make this under
>> CONFIG_KVM_E500MC.
>>> What happens if DECAR is read on non e500mc? Is it treated as NOP or illegal
>> instruction exception?
>>
>> I would assume the latter. NOPs usually don't happen. If anything, it would
>> return 0.
>>
>> See section 9.4 in the PowerISA:
>>
>> The contents of the Decrementer Auto-Reload Register cannot be read. The
>> contents of bits 32:63 of register RS can be written to the Decrementer Auto-
>> Reload Register using the mtspr instruction.
>>
>> Could you please paste the respective passage of the e500mc manual that declares
>> DECAR as readable?
> I have booke -4 version 1.05.
> There are remarks at 3 place
>
> 1)
> Table 2-1:
> There is remark " DECAR is defined by the architecture to be write-only, however the e500mc allows it to be read."
> ------------
>
> 2)
> 2.8.5 Decrementer Auto-Reload Register (DECAR)
>
> "For e500V4, the DECAR can be read in hypervisor state, although the architecture defines it as a
> write-only register."
> --------------
>
> 3)
> Table 4.37
>
> Hypervisor Privilege on Read  - Yes
> Hypervisor Privilege on Write - Yes
>
> Remark: e500mc allows reading of DECAR although Power ISA does not define it.
> ----------------
>
> I verified with my unit test that reading DECAR traps in KVM on e500mc.

Alrighty, so how about putting the read into e500_emulate.c then? What 
does e500v2 do here?


Alex

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Bharat Bhushan - May 21, 2012, 4:28 a.m.
> -----Original Message-----
> From: Alexander Graf [mailto:agraf@suse.de]
> Sent: Wednesday, May 16, 2012 2:54 PM
> To: Bhushan Bharat-R65777
> Cc: kvm-ppc@vger.kernel.org
> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
> 
> On 05/16/2012 11:21 AM, Bhushan Bharat-R65777 wrote:
> >
> >> -----Original Message-----
> >> From: Alexander Graf [mailto:agraf@suse.de]
> >> Sent: Wednesday, May 16, 2012 2:36 PM
> >> To: Bhushan Bharat-R65777
> >> Cc: kvm-ppc@vger.kernel.org
> >> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
> >>
> >> On 05/16/2012 08:57 AM, Bhushan Bharat-R65777 wrote:
> >>>> -----Original Message-----
> >>>> From: Alexander Graf [mailto:agraf@suse.de]
> >>>> Sent: Tuesday, May 15, 2012 7:59 PM
> >>>> To: Bhushan Bharat-R65777
> >>>> Cc: kvm-ppc@vger.kernel.org; Bhushan Bharat-R65777
> >>>> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
> >>>>
> >>>> On 05/15/2012 09:33 AM, Bharat Bhushan wrote:
> >>>>> Added the decrementer auto-reload support.
> >>>>>
> >>>>> Signed-off-by: Bharat Bhushan<bharat.bhushan@freescale.com>
> >>>>> ---
> >>>>>     arch/powerpc/include/asm/kvm_host.h |    2 ++
> >>>>>     arch/powerpc/kvm/booke.c            |    5 +++++
> >>>>>     arch/powerpc/kvm/booke_emulate.c    |    7 ++++++-
> >>>>>     3 files changed, 13 insertions(+), 1 deletions(-)
> >>>>>
> >>>>> diff --git a/arch/powerpc/include/asm/kvm_host.h
> >>>>> b/arch/powerpc/include/asm/kvm_host.h
> >>>>> index d848cdc..1d6f89e 100644
> >>>>> --- a/arch/powerpc/include/asm/kvm_host.h
> >>>>> +++ b/arch/powerpc/include/asm/kvm_host.h
> >>>>> @@ -414,7 +414,9 @@ struct kvm_vcpu_arch {
> >>>>>     	ulong mcsrr1;
> >>>>>     	ulong mcsr;
> >>>>>     	u32 dec;
> >>>>> +#ifdef CONFIG_BOOKE
> >>>>>     	u32 decar;
> >>>>> +#endif
> >>>>>     	u32 tbl;
> >>>>>     	u32 tbu;
> >>>>>     	u32 tcr;
> >>>>> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> >>>>> index 72f13f4..86681ee 100644
> >>>>> --- a/arch/powerpc/kvm/booke.c
> >>>>> +++ b/arch/powerpc/kvm/booke.c
> >>>>> @@ -1267,6 +1267,11 @@ void kvmppc_decrementer_func(unsigned long data)
> >>>>>     {
> >>>>>     	struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
> >>>>>
> >>>>> +	if (vcpu->arch.tcr&    TCR_ARE) {
> >>>>> +		vcpu->arch.dec = vcpu->arch.decar;
> >>>>> +		kvmppc_emulate_dec(vcpu);
> >>>>> +	}
> >>>>> +
> >>>>>     	kvmppc_set_tsr_bits(vcpu, TSR_DIS);
> >>>>>     }
> >>>>>
> >>>>> diff --git a/arch/powerpc/kvm/booke_emulate.c
> >>>>> b/arch/powerpc/kvm/booke_emulate.c
> >>>>> index 6c76397..83c3796 100644
> >>>>> --- a/arch/powerpc/kvm/booke_emulate.c
> >>>>> +++ b/arch/powerpc/kvm/booke_emulate.c
> >>>>> @@ -129,6 +129,9 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu
> >>>>> *vcpu, int
> >>>> sprn, ulong spr_val)
> >>>>>     		kvmppc_set_tcr(vcpu, spr_val);
> >>>>>     		break;
> >>>>>
> >>>>> +	case SPRN_DECAR:
> >>>>> +		vcpu->arch.decar = spr_val;
> >>>>> +		break;
> >>>>>     	/*
> >>>>>     	 * Note: SPRG4-7 are user-readable.
> >>>>>     	 * These values are loaded into the real SPRGs when resuming
> >>>>> the @@
> >>>>> -244,7 +247,9 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu
> >>>>> *vcpu, int
> >>>> sprn, ulong *spr_val)
> >>>>>     	case SPRN_TCR:
> >>>>>     		*spr_val = vcpu->arch.tcr;
> >>>>>     		break;
> >>>>> -
> >>>>> +	case SPRN_DECAR:
> >>>>> +		*spr_val = vcpu->arch.decar;
> >>>>> +		break;
> >>>> DECAR can't be read. Otherwise looks good to me.
> >>> DECAR can be read on e500mc cores. So I will make this under
> >> CONFIG_KVM_E500MC.
> >>> What happens if DECAR is read on non e500mc? Is it treated as NOP or
> >>> illegal
> >> instruction exception?
> >>
> >> I would assume the latter. NOPs usually don't happen. If anything, it
> >> would return 0.
> >>
> >> See section 9.4 in the PowerISA:
> >>
> >> The contents of the Decrementer Auto-Reload Register cannot be read.
> >> The contents of bits 32:63 of register RS can be written to the
> >> Decrementer Auto- Reload Register using the mtspr instruction.
> >>
> >> Could you please paste the respective passage of the e500mc manual
> >> that declares DECAR as readable?
> > I have booke -4 version 1.05.
> > There are remarks at 3 place
> >
> > 1)
> > Table 2-1:
> > There is remark " DECAR is defined by the architecture to be write-only,
> however the e500mc allows it to be read."
> > ------------
> >
> > 2)
> > 2.8.5 Decrementer Auto-Reload Register (DECAR)
> >
> > "For e500V4, the DECAR can be read in hypervisor state, although the
> > architecture defines it as a write-only register."
> > --------------
> >
> > 3)
> > Table 4.37
> >
> > Hypervisor Privilege on Read  - Yes
> > Hypervisor Privilege on Write - Yes
> >
> > Remark: e500mc allows reading of DECAR although Power ISA does not define it.
> > ----------------
> >
> > I verified with my unit test that reading DECAR traps in KVM on e500mc.
> 
> Alrighty, so how about putting the read into e500_emulate.c then?

Ok

> What does e500v2 do here?

mfspr(DECAR) works ok e500v2 :), while spec says it is write-only.

We should emulate DECAR as per specifications documented . Right? So we will not support trap and emulate for e500v2.

Thanks
-Bharat


> 
> 
> Alex
> 


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Alexander Graf - May 21, 2012, 6:18 a.m.
On 21.05.2012, at 06:28, Bhushan Bharat-R65777 <R65777@freescale.com> wrote:

> 
> 
>> -----Original Message-----
>> From: Alexander Graf [mailto:agraf@suse.de]
>> Sent: Wednesday, May 16, 2012 2:54 PM
>> To: Bhushan Bharat-R65777
>> Cc: kvm-ppc@vger.kernel.org
>> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
>> 
>> On 05/16/2012 11:21 AM, Bhushan Bharat-R65777 wrote:
>>> 
>>>> -----Original Message-----
>>>> From: Alexander Graf [mailto:agraf@suse.de]
>>>> Sent: Wednesday, May 16, 2012 2:36 PM
>>>> To: Bhushan Bharat-R65777
>>>> Cc: kvm-ppc@vger.kernel.org
>>>> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
>>>> 
>>>> On 05/16/2012 08:57 AM, Bhushan Bharat-R65777 wrote:
>>>>>> -----Original Message-----
>>>>>> From: Alexander Graf [mailto:agraf@suse.de]
>>>>>> Sent: Tuesday, May 15, 2012 7:59 PM
>>>>>> To: Bhushan Bharat-R65777
>>>>>> Cc: kvm-ppc@vger.kernel.org; Bhushan Bharat-R65777
>>>>>> Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
>>>>>> 
>>>>>> On 05/15/2012 09:33 AM, Bharat Bhushan wrote:
>>>>>>> Added the decrementer auto-reload support.
>>>>>>> 
>>>>>>> Signed-off-by: Bharat Bhushan<bharat.bhushan@freescale.com>
>>>>>>> ---
>>>>>>>    arch/powerpc/include/asm/kvm_host.h |    2 ++
>>>>>>>    arch/powerpc/kvm/booke.c            |    5 +++++
>>>>>>>    arch/powerpc/kvm/booke_emulate.c    |    7 ++++++-
>>>>>>>    3 files changed, 13 insertions(+), 1 deletions(-)
>>>>>>> 
>>>>>>> diff --git a/arch/powerpc/include/asm/kvm_host.h
>>>>>>> b/arch/powerpc/include/asm/kvm_host.h
>>>>>>> index d848cdc..1d6f89e 100644
>>>>>>> --- a/arch/powerpc/include/asm/kvm_host.h
>>>>>>> +++ b/arch/powerpc/include/asm/kvm_host.h
>>>>>>> @@ -414,7 +414,9 @@ struct kvm_vcpu_arch {
>>>>>>>        ulong mcsrr1;
>>>>>>>        ulong mcsr;
>>>>>>>        u32 dec;
>>>>>>> +#ifdef CONFIG_BOOKE
>>>>>>>        u32 decar;
>>>>>>> +#endif
>>>>>>>        u32 tbl;
>>>>>>>        u32 tbu;
>>>>>>>        u32 tcr;
>>>>>>> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
>>>>>>> index 72f13f4..86681ee 100644
>>>>>>> --- a/arch/powerpc/kvm/booke.c
>>>>>>> +++ b/arch/powerpc/kvm/booke.c
>>>>>>> @@ -1267,6 +1267,11 @@ void kvmppc_decrementer_func(unsigned long data)
>>>>>>>    {
>>>>>>>        struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
>>>>>>> 
>>>>>>> +    if (vcpu->arch.tcr&    TCR_ARE) {
>>>>>>> +        vcpu->arch.dec = vcpu->arch.decar;
>>>>>>> +        kvmppc_emulate_dec(vcpu);
>>>>>>> +    }
>>>>>>> +
>>>>>>>        kvmppc_set_tsr_bits(vcpu, TSR_DIS);
>>>>>>>    }
>>>>>>> 
>>>>>>> diff --git a/arch/powerpc/kvm/booke_emulate.c
>>>>>>> b/arch/powerpc/kvm/booke_emulate.c
>>>>>>> index 6c76397..83c3796 100644
>>>>>>> --- a/arch/powerpc/kvm/booke_emulate.c
>>>>>>> +++ b/arch/powerpc/kvm/booke_emulate.c
>>>>>>> @@ -129,6 +129,9 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu
>>>>>>> *vcpu, int
>>>>>> sprn, ulong spr_val)
>>>>>>>            kvmppc_set_tcr(vcpu, spr_val);
>>>>>>>            break;
>>>>>>> 
>>>>>>> +    case SPRN_DECAR:
>>>>>>> +        vcpu->arch.decar = spr_val;
>>>>>>> +        break;
>>>>>>>        /*
>>>>>>>         * Note: SPRG4-7 are user-readable.
>>>>>>>         * These values are loaded into the real SPRGs when resuming
>>>>>>> the @@
>>>>>>> -244,7 +247,9 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu
>>>>>>> *vcpu, int
>>>>>> sprn, ulong *spr_val)
>>>>>>>        case SPRN_TCR:
>>>>>>>            *spr_val = vcpu->arch.tcr;
>>>>>>>            break;
>>>>>>> -
>>>>>>> +    case SPRN_DECAR:
>>>>>>> +        *spr_val = vcpu->arch.decar;
>>>>>>> +        break;
>>>>>> DECAR can't be read. Otherwise looks good to me.
>>>>> DECAR can be read on e500mc cores. So I will make this under
>>>> CONFIG_KVM_E500MC.
>>>>> What happens if DECAR is read on non e500mc? Is it treated as NOP or
>>>>> illegal
>>>> instruction exception?
>>>> 
>>>> I would assume the latter. NOPs usually don't happen. If anything, it
>>>> would return 0.
>>>> 
>>>> See section 9.4 in the PowerISA:
>>>> 
>>>> The contents of the Decrementer Auto-Reload Register cannot be read.
>>>> The contents of bits 32:63 of register RS can be written to the
>>>> Decrementer Auto- Reload Register using the mtspr instruction.
>>>> 
>>>> Could you please paste the respective passage of the e500mc manual
>>>> that declares DECAR as readable?
>>> I have booke -4 version 1.05.
>>> There are remarks at 3 place
>>> 
>>> 1)
>>> Table 2-1:
>>> There is remark " DECAR is defined by the architecture to be write-only,
>> however the e500mc allows it to be read."
>>> ------------
>>> 
>>> 2)
>>> 2.8.5 Decrementer Auto-Reload Register (DECAR)
>>> 
>>> "For e500V4, the DECAR can be read in hypervisor state, although the
>>> architecture defines it as a write-only register."
>>> --------------
>>> 
>>> 3)
>>> Table 4.37
>>> 
>>> Hypervisor Privilege on Read  - Yes
>>> Hypervisor Privilege on Write - Yes
>>> 
>>> Remark: e500mc allows reading of DECAR although Power ISA does not define it.
>>> ----------------
>>> 
>>> I verified with my unit test that reading DECAR traps in KVM on e500mc.
>> 
>> Alrighty, so how about putting the read into e500_emulate.c then?
> 
> Ok
> 
>> What does e500v2 do here?
> 
> mfspr(DECAR) works ok e500v2 :), while spec says it is write-only.
> 
> We should emulate DECAR as per specifications documented . Right? So we will not support trap and emulate for e500v2.

Usually yes, but IMHO hardware always wins over specs, so I would enable it for v2 as well if it really does work properly there ;).


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 d848cdc..1d6f89e 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -414,7 +414,9 @@  struct kvm_vcpu_arch {
 	ulong mcsrr1;
 	ulong mcsr;
 	u32 dec;
+#ifdef CONFIG_BOOKE
 	u32 decar;
+#endif
 	u32 tbl;
 	u32 tbu;
 	u32 tcr;
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 72f13f4..86681ee 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -1267,6 +1267,11 @@  void kvmppc_decrementer_func(unsigned long data)
 {
 	struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
 
+	if (vcpu->arch.tcr & TCR_ARE) {
+		vcpu->arch.dec = vcpu->arch.decar;
+		kvmppc_emulate_dec(vcpu);
+	}
+
 	kvmppc_set_tsr_bits(vcpu, TSR_DIS);
 }
 
diff --git a/arch/powerpc/kvm/booke_emulate.c b/arch/powerpc/kvm/booke_emulate.c
index 6c76397..83c3796 100644
--- a/arch/powerpc/kvm/booke_emulate.c
+++ b/arch/powerpc/kvm/booke_emulate.c
@@ -129,6 +129,9 @@  int kvmppc_booke_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 		kvmppc_set_tcr(vcpu, spr_val);
 		break;
 
+	case SPRN_DECAR:
+		vcpu->arch.decar = spr_val;
+		break;
 	/*
 	 * Note: SPRG4-7 are user-readable.
 	 * These values are loaded into the real SPRGs when resuming the
@@ -244,7 +247,9 @@  int kvmppc_booke_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val)
 	case SPRN_TCR:
 		*spr_val = vcpu->arch.tcr;
 		break;
-
+	case SPRN_DECAR:
+		*spr_val = vcpu->arch.decar;
+		break;
 	case SPRN_IVOR0:
 		*spr_val = vcpu->arch.ivor[BOOKE_IRQPRIO_CRITICAL];
 		break;