From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Subject: Re: [PATCH v10 11/12] ARM/ARM64: KVM: Emulate PSCI v0.2 CPU_SUSPEND Date: Mon, 28 Apr 2014 15:40:37 +0100 Message-ID: <874n1dtt3u.fsf@approximate.cambridge.arm.com> References: <1398085206-30555-1-git-send-email-anup.patel@linaro.org> <1398085206-30555-12-git-send-email-anup.patel@linaro.org> Mime-Version: 1.0 Content-Type: text/plain Cc: "kvmarm\@lists.cs.columbia.edu" , "kvm\@vger.kernel.org" , "linux-arm-kernel\@lists.infradead.org" , "linaro-kernel\@lists.linaro.org" , "patches\@apm.com" , Christoffer Dall , "rob.herring\@linaro.org" , Pranavkumar Sawargaonkar , Ashwin Chaugule To: Anup Patel Return-path: Received: from fw-tnat.austin.arm.com ([217.140.110.23]:39845 "EHLO collaborate-mta1.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932437AbaD1Oku (ORCPT ); Mon, 28 Apr 2014 10:40:50 -0400 In-Reply-To: <1398085206-30555-12-git-send-email-anup.patel@linaro.org> (Anup Patel's message of "Mon, 21 Apr 2014 14:00:05 +0100") Sender: kvm-owner@vger.kernel.org List-ID: On Mon, Apr 21 2014 at 2:00:05 pm BST, 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/) > > For simplicity, 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 > Signed-off-by: Pranavkumar Sawargaonkar > --- > arch/arm/kvm/psci.c | 28 ++++++++++++++++++++++++---- > 1 file changed, 24 insertions(+), 4 deletions(-) > > diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c > index b582e99..757e506 100644 > --- a/arch/arm/kvm/psci.c > +++ b/arch/arm/kvm/psci.c > @@ -37,6 +37,26 @@ static unsigned long psci_affinity_mask(unsigned long affinity_level) > return 0; > } > > +static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu) > +{ > + /* > + * NOTE: 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 +203,10 @@ 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 +245,6 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) > val = PSCI_RET_INTERNAL_FAILURE; > 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; > } Acked-by: Marc Zyngier M. -- Jazz is not dead. It just smells funny.