* Re: [PATCH] KVM: PPC: e500: Emulate power management control SPR
@ 2014-06-30 18:20 ` Scott Wood
0 siblings, 0 replies; 9+ messages in thread
From: Scott Wood @ 2014-06-30 18:20 UTC (permalink / raw)
To: Mihai Caraman; +Cc: kvm-ppc, kvm, linuxppc-dev
On Mon, 2014-06-30 at 15:55 +0300, Mihai Caraman wrote:
> For FSL e6500 core the kernel uses power management SPR register (PWRMGTCR0)
> to enable idle power down for cores and devices by setting up the idle count
> period at boot time. With the host already controlling the power management
> configuration the guest could simply benefit from it, so emulate guest request
> as nop.
>
> Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
> ---
> arch/powerpc/kvm/e500_emulate.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/arch/powerpc/kvm/e500_emulate.c b/arch/powerpc/kvm/e500_emulate.c
> index 002d517..98a22e5 100644
> --- a/arch/powerpc/kvm/e500_emulate.c
> +++ b/arch/powerpc/kvm/e500_emulate.c
> @@ -250,6 +250,10 @@ int kvmppc_core_emulate_mtspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong spr_va
> spr_val);
> break;
>
> + case SPRN_PWRMGTCR0:
> + /* Guest relies on host power management configurations */
> + break;
> +
> /* extra exceptions */
> case SPRN_IVOR32:
> vcpu->arch.ivor[BOOKE_IRQPRIO_SPE_UNAVAIL] = spr_val;
> @@ -355,6 +359,10 @@ int kvmppc_core_emulate_mfspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong *spr_v
> *spr_val = 0;
> break;
>
> + case SPRN_PWRMGTCR0:
> + *spr_val = 0;
> + break;
> +
> case SPRN_MMUCFG:
> *spr_val = vcpu->arch.mmucfg;
> break;
When reading, is it better to return zero, or the current host value, or
the value last written by the guest (even though it wasn't written to
hardware)?
-Scott
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] KVM: PPC: e500: Emulate power management control SPR
@ 2014-06-30 18:20 ` Scott Wood
0 siblings, 0 replies; 9+ messages in thread
From: Scott Wood @ 2014-06-30 18:20 UTC (permalink / raw)
To: Mihai Caraman; +Cc: linuxppc-dev, kvm, kvm-ppc
On Mon, 2014-06-30 at 15:55 +0300, Mihai Caraman wrote:
> For FSL e6500 core the kernel uses power management SPR register (PWRMGTCR0)
> to enable idle power down for cores and devices by setting up the idle count
> period at boot time. With the host already controlling the power management
> configuration the guest could simply benefit from it, so emulate guest request
> as nop.
>
> Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
> ---
> arch/powerpc/kvm/e500_emulate.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/arch/powerpc/kvm/e500_emulate.c b/arch/powerpc/kvm/e500_emulate.c
> index 002d517..98a22e5 100644
> --- a/arch/powerpc/kvm/e500_emulate.c
> +++ b/arch/powerpc/kvm/e500_emulate.c
> @@ -250,6 +250,10 @@ int kvmppc_core_emulate_mtspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong spr_va
> spr_val);
> break;
>
> + case SPRN_PWRMGTCR0:
> + /* Guest relies on host power management configurations */
> + break;
> +
> /* extra exceptions */
> case SPRN_IVOR32:
> vcpu->arch.ivor[BOOKE_IRQPRIO_SPE_UNAVAIL] = spr_val;
> @@ -355,6 +359,10 @@ int kvmppc_core_emulate_mfspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong *spr_v
> *spr_val = 0;
> break;
>
> + case SPRN_PWRMGTCR0:
> + *spr_val = 0;
> + break;
> +
> case SPRN_MMUCFG:
> *spr_val = vcpu->arch.mmucfg;
> break;
When reading, is it better to return zero, or the current host value, or
the value last written by the guest (even though it wasn't written to
hardware)?
-Scott
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] KVM: PPC: e500: Emulate power management control SPR
2014-06-30 18:20 ` Scott Wood
(?)
@ 2014-07-03 12:03 ` Alexander Graf
-1 siblings, 0 replies; 9+ messages in thread
From: Alexander Graf @ 2014-07-03 12:03 UTC (permalink / raw)
To: Scott Wood, Mihai Caraman; +Cc: kvm-ppc, kvm, linuxppc-dev
On 30.06.14 20:20, Scott Wood wrote:
> On Mon, 2014-06-30 at 15:55 +0300, Mihai Caraman wrote:
>> For FSL e6500 core the kernel uses power management SPR register (PWRMGTCR0)
>> to enable idle power down for cores and devices by setting up the idle count
>> period at boot time. With the host already controlling the power management
>> configuration the guest could simply benefit from it, so emulate guest request
>> as nop.
>>
>> Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
>> ---
>> arch/powerpc/kvm/e500_emulate.c | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> diff --git a/arch/powerpc/kvm/e500_emulate.c b/arch/powerpc/kvm/e500_emulate.c
>> index 002d517..98a22e5 100644
>> --- a/arch/powerpc/kvm/e500_emulate.c
>> +++ b/arch/powerpc/kvm/e500_emulate.c
>> @@ -250,6 +250,10 @@ int kvmppc_core_emulate_mtspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong spr_va
>> spr_val);
>> break;
>>
>> + case SPRN_PWRMGTCR0:
>> + /* Guest relies on host power management configurations */
>> + break;
>> +
>> /* extra exceptions */
>> case SPRN_IVOR32:
>> vcpu->arch.ivor[BOOKE_IRQPRIO_SPE_UNAVAIL] = spr_val;
>> @@ -355,6 +359,10 @@ int kvmppc_core_emulate_mfspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong *spr_v
>> *spr_val = 0;
>> break;
>>
>> + case SPRN_PWRMGTCR0:
>> + *spr_val = 0;
>> + break;
>> +
>> case SPRN_MMUCFG:
>> *spr_val = vcpu->arch.mmucfg;
>> break;
> When reading, is it better to return zero, or the current host value, or
> the value last written by the guest (even though it wasn't written to
> hardware)?
I think it makes sense to treat it as general storage. I don't think
leaking the host value into the guest is useful. And while zero works,
the spec does say that the value gets retained, so I think we should do
the same.
Alex
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] KVM: PPC: e500: Emulate power management control SPR
@ 2014-07-03 12:03 ` Alexander Graf
0 siblings, 0 replies; 9+ messages in thread
From: Alexander Graf @ 2014-07-03 12:03 UTC (permalink / raw)
To: Scott Wood, Mihai Caraman; +Cc: kvm-ppc, kvm, linuxppc-dev
On 30.06.14 20:20, Scott Wood wrote:
> On Mon, 2014-06-30 at 15:55 +0300, Mihai Caraman wrote:
>> For FSL e6500 core the kernel uses power management SPR register (PWRMGTCR0)
>> to enable idle power down for cores and devices by setting up the idle count
>> period at boot time. With the host already controlling the power management
>> configuration the guest could simply benefit from it, so emulate guest request
>> as nop.
>>
>> Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
>> ---
>> arch/powerpc/kvm/e500_emulate.c | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> diff --git a/arch/powerpc/kvm/e500_emulate.c b/arch/powerpc/kvm/e500_emulate.c
>> index 002d517..98a22e5 100644
>> --- a/arch/powerpc/kvm/e500_emulate.c
>> +++ b/arch/powerpc/kvm/e500_emulate.c
>> @@ -250,6 +250,10 @@ int kvmppc_core_emulate_mtspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong spr_va
>> spr_val);
>> break;
>>
>> + case SPRN_PWRMGTCR0:
>> + /* Guest relies on host power management configurations */
>> + break;
>> +
>> /* extra exceptions */
>> case SPRN_IVOR32:
>> vcpu->arch.ivor[BOOKE_IRQPRIO_SPE_UNAVAIL] = spr_val;
>> @@ -355,6 +359,10 @@ int kvmppc_core_emulate_mfspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong *spr_v
>> *spr_val = 0;
>> break;
>>
>> + case SPRN_PWRMGTCR0:
>> + *spr_val = 0;
>> + break;
>> +
>> case SPRN_MMUCFG:
>> *spr_val = vcpu->arch.mmucfg;
>> break;
> When reading, is it better to return zero, or the current host value, or
> the value last written by the guest (even though it wasn't written to
> hardware)?
I think it makes sense to treat it as general storage. I don't think
leaking the host value into the guest is useful. And while zero works,
the spec does say that the value gets retained, so I think we should do
the same.
Alex
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] KVM: PPC: e500: Emulate power management control SPR
@ 2014-07-03 12:03 ` Alexander Graf
0 siblings, 0 replies; 9+ messages in thread
From: Alexander Graf @ 2014-07-03 12:03 UTC (permalink / raw)
To: Scott Wood, Mihai Caraman; +Cc: linuxppc-dev, kvm, kvm-ppc
On 30.06.14 20:20, Scott Wood wrote:
> On Mon, 2014-06-30 at 15:55 +0300, Mihai Caraman wrote:
>> For FSL e6500 core the kernel uses power management SPR register (PWRMGTCR0)
>> to enable idle power down for cores and devices by setting up the idle count
>> period at boot time. With the host already controlling the power management
>> configuration the guest could simply benefit from it, so emulate guest request
>> as nop.
>>
>> Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
>> ---
>> arch/powerpc/kvm/e500_emulate.c | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> diff --git a/arch/powerpc/kvm/e500_emulate.c b/arch/powerpc/kvm/e500_emulate.c
>> index 002d517..98a22e5 100644
>> --- a/arch/powerpc/kvm/e500_emulate.c
>> +++ b/arch/powerpc/kvm/e500_emulate.c
>> @@ -250,6 +250,10 @@ int kvmppc_core_emulate_mtspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong spr_va
>> spr_val);
>> break;
>>
>> + case SPRN_PWRMGTCR0:
>> + /* Guest relies on host power management configurations */
>> + break;
>> +
>> /* extra exceptions */
>> case SPRN_IVOR32:
>> vcpu->arch.ivor[BOOKE_IRQPRIO_SPE_UNAVAIL] = spr_val;
>> @@ -355,6 +359,10 @@ int kvmppc_core_emulate_mfspr_e500(struct kvm_vcpu *vcpu, int sprn, ulong *spr_v
>> *spr_val = 0;
>> break;
>>
>> + case SPRN_PWRMGTCR0:
>> + *spr_val = 0;
>> + break;
>> +
>> case SPRN_MMUCFG:
>> *spr_val = vcpu->arch.mmucfg;
>> break;
> When reading, is it better to return zero, or the current host value, or
> the value last written by the guest (even though it wasn't written to
> hardware)?
I think it makes sense to treat it as general storage. I don't think
leaking the host value into the guest is useful. And while zero works,
the spec does say that the value gets retained, so I think we should do
the same.
Alex
^ permalink raw reply [flat|nested] 9+ messages in thread