| Message ID | 1397542455-354-12-git-send-email-anup.patel@linaro.org |
|---|---|
| State | New |
| Headers | show |
On Tue, Apr 15 2014 at 7:14:14 am BST, Anup Patel <anup.patel@linaro.org> wrote: > This patch adds emulation of PSCI v0.2 CPU_SUSPEND function call for > KVM ARM/ARM64. This is a CPU-level function call which can suspend > current CPU or current CPU cluster. We don't have VCPU clusters in > KVM so we only suspend the current VCPU. > > The CPU_SUSPEND emulation is not tested much because currently there > is no CPUIDLE driver in Linux kernel that uses PSCI CPU_SUSPEND. The > PSCI CPU_SUSPEND implementation in ARM64 kernel was tested using a > Simple CPUIDLE driver which is not published due to unstable DT-bindings > for PSCI. > (For more info, http://lwn.net/Articles/574950/) > > Even if we had stable DT-bindings for PSCI and CPUIDLE driver that > uses PSCI CPU_SUSPEND then still we need to define SUSPEND states > and WAKEUP events for KVM ARM/ARM64. > > Due to above, we implement CPU_SUSPEND emulation similar to WFI > (Wait-for-interrupt) emulation and we also treat power-down request > to be same as stand-by request. This is consistent with section > 5.4.1 and section 5.4.2 of PSCI v0.2 specification. > > Signed-off-by: Anup Patel <anup.patel@linaro.org> > Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org> > --- > arch/arm/kvm/psci.c | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c > index f59f09d..fdb347a 100644 > --- a/arch/arm/kvm/psci.c > +++ b/arch/arm/kvm/psci.c > @@ -37,6 +37,27 @@ static unsigned long psci_affinity_mask(unsigned long affinity_level) > return 0; > } > > +static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu) > +{ > + /* > + * NOTE: Currently, we don't have any wakeup events defined > + * for KVM so for simplicity we make VCPU suspend emulation > + * to be same-as WFI (Wait-for-interrupt) emulation. Well, in this implementation, any interrupt is a wakeup event, so you can remove the comment about "we don't have any wakeup events". We arguably have too many of them. > + * > + * This means for KVM the wakeup events are interrupts and > + * this is consistent with intended use of StateID as described > + * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A). > + * > + * Further, we also treat power-down request to be same as > + * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2 > + * specification (ARM DEN 0022A). This means all suspend states > + * for KVM will preserve the register state. > + */ > + kvm_vcpu_block(vcpu); > + > + return PSCI_RET_SUCCESS; > +} > + > static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu) > { > vcpu->arch.pause = true; > @@ -183,6 +204,10 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) > */ > val = 2; > break; > + case PSCI_0_2_FN_CPU_SUSPEND: > + case PSCI_0_2_FN64_CPU_SUSPEND: > + val = kvm_psci_vcpu_suspend(vcpu); > + break; > case PSCI_0_2_FN_CPU_OFF: > kvm_psci_vcpu_off(vcpu); > val = PSCI_RET_SUCCESS; > @@ -221,10 +246,6 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) > val = PSCI_RET_SUCCESS; > ret = 0; > break; > - case PSCI_0_2_FN_CPU_SUSPEND: > - case PSCI_0_2_FN64_CPU_SUSPEND: > - val = PSCI_RET_NOT_SUPPORTED; > - break; > default: > return -EINVAL; > }
diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c index f59f09d..fdb347a 100644 --- a/arch/arm/kvm/psci.c +++ b/arch/arm/kvm/psci.c @@ -37,6 +37,27 @@ static unsigned long psci_affinity_mask(unsigned long affinity_level) return 0; } +static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu) +{ + /* + * NOTE: Currently, we don't have any wakeup events defined + * for KVM so for simplicity we make VCPU suspend emulation + * to be same-as WFI (Wait-for-interrupt) emulation. + * + * This means for KVM the wakeup events are interrupts and + * this is consistent with intended use of StateID as described + * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A). + * + * Further, we also treat power-down request to be same as + * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2 + * specification (ARM DEN 0022A). This means all suspend states + * for KVM will preserve the register state. + */ + kvm_vcpu_block(vcpu); + + return PSCI_RET_SUCCESS; +} + static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu) { vcpu->arch.pause = true; @@ -183,6 +204,10 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) */ val = 2; break; + case PSCI_0_2_FN_CPU_SUSPEND: + case PSCI_0_2_FN64_CPU_SUSPEND: + val = kvm_psci_vcpu_suspend(vcpu); + break; case PSCI_0_2_FN_CPU_OFF: kvm_psci_vcpu_off(vcpu); val = PSCI_RET_SUCCESS; @@ -221,10 +246,6 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) val = PSCI_RET_SUCCESS; ret = 0; break; - case PSCI_0_2_FN_CPU_SUSPEND: - case PSCI_0_2_FN64_CPU_SUSPEND: - val = PSCI_RET_NOT_SUPPORTED; - break; default: return -EINVAL; }