| Message ID | 1396435347-20056-12-git-send-email-anup.patel@linaro.org |
|---|---|
| State | New |
| Headers | show |
On Wed, Apr 02, 2014 at 04:12:26PM +0530, Anup Patel 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 also 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 | 27 +++++++++++++++++++++++---- > 1 file changed, 23 insertions(+), 4 deletions(-) > > diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c > index fdbd829..74fa4ad 100644 > --- a/arch/arm/kvm/psci.c > +++ b/arch/arm/kvm/psci.c > @@ -52,6 +52,25 @@ static unsigned long psci_affinity_mask(unsigned long affinity_level) > return affinity_mask; > } > > +static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu) > +{ > + /* > + * NOTE: Currently, we don't have any wakeup events for KVM > + * so for simplicity we make VCPU suspend emulation to be > + * same-as WFI (Wait-for-interrupt) emulation. This is also > + * consistent with intended use of StateID as described in > + * section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A). The WFI implementation wakes up on interrupts, so we are inherently defining that as a wakeup event for KVM with this patch, so the comment should be adjusted accordingly. -Christoffer > + * > + * 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 PSCI emulation 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; > @@ -195,6 +214,10 @@ 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; > @@ -232,10 +255,6 @@ 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; > } > -- > 1.7.9.5 >
On 3 April 2014 02:33, Christoffer Dall <christoffer.dall@linaro.org> wrote: > On Wed, Apr 02, 2014 at 04:12:26PM +0530, Anup Patel 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 also 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 | 27 +++++++++++++++++++++++---- >> 1 file changed, 23 insertions(+), 4 deletions(-) >> >> diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c >> index fdbd829..74fa4ad 100644 >> --- a/arch/arm/kvm/psci.c >> +++ b/arch/arm/kvm/psci.c >> @@ -52,6 +52,25 @@ static unsigned long psci_affinity_mask(unsigned long affinity_level) >> return affinity_mask; >> } >> >> +static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu) >> +{ >> + /* >> + * NOTE: Currently, we don't have any wakeup events for KVM >> + * so for simplicity we make VCPU suspend emulation to be >> + * same-as WFI (Wait-for-interrupt) emulation. This is also >> + * consistent with intended use of StateID as described in >> + * section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A). > > The WFI implementation wakes up on interrupts, so we are inherently > defining that as a wakeup event for KVM with this patch, so the comment > should be adjusted accordingly. Sure, I will update the comment. -- Anup > > -Christoffer > >> + * >> + * 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 PSCI emulation 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; >> @@ -195,6 +214,10 @@ 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; >> @@ -232,10 +255,6 @@ 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; >> } >> -- >> 1.7.9.5 >>
diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c index fdbd829..74fa4ad 100644 --- a/arch/arm/kvm/psci.c +++ b/arch/arm/kvm/psci.c @@ -52,6 +52,25 @@ static unsigned long psci_affinity_mask(unsigned long affinity_level) return affinity_mask; } +static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu) +{ + /* + * NOTE: Currently, we don't have any wakeup events for KVM + * so for simplicity we make VCPU suspend emulation to be + * same-as WFI (Wait-for-interrupt) emulation. This is also + * 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 PSCI emulation 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; @@ -195,6 +214,10 @@ 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; @@ -232,10 +255,6 @@ 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; }