[PATCH] KVM: PPC: e500: Emulate power management control SPR
Scott Wood
scottwood at freescale.com
Tue Jul 1 04:20:04 EST 2014
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 at 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
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