| Message ID | 1404132929-27308-1-git-send-email-mihai.caraman@freescale.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
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
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
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;
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(+)