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[34.68.225.194]) by smtp.gmail.com with ESMTPSA id y3-20020a92c983000000b002c7dce8329fsm10292511iln.72.2022.03.22.16.06.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Mar 2022 16:06:07 -0700 (PDT) Date: Tue, 22 Mar 2022 23:06:04 +0000 From: Oliver Upton To: Gavin Shan Cc: kvmarm@lists.cs.columbia.edu, maz@kernel.org, linux-kernel@vger.kernel.org, eauger@redhat.com, shan.gavin@gmail.com, Jonathan.Cameron@huawei.com, pbonzini@redhat.com, vkuznets@redhat.com, will@kernel.org Subject: Re: [PATCH v5 15/22] KVM: arm64: Support SDEI_EVENT_SIGNAL hypercall Message-ID: References: <20220322080710.51727-1-gshan@redhat.com> <20220322080710.51727-16-gshan@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220322080710.51727-16-gshan@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Gavin, On Tue, Mar 22, 2022 at 04:07:03PM +0800, Gavin Shan wrote: > This supports SDEI_EVENT_SIGNAL hypercall. It's used by the guest > to inject SDEI event, whose number must be zero to the specified > vCPU. As the routing mode and affinity isn't supported yet, the > calling vCPU is assumed to be the target. > > The SDEI event 0x0 is a private one, with normal priority. It's > usually used for testing. I don't know if that is actually the case. One real use that immediately comes to mind is doing an NMI on a wedged CPU. KVM probably shouldn't glean at how the guest may use a particular call, so at most we should just point at the spec and state that event 0 is for software signaled events. > Signed-off-by: Gavin Shan > --- > arch/arm64/kvm/sdei.c | 64 ++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 63 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c > index a24270378305..ba2ca65c871b 100644 > --- a/arch/arm64/kvm/sdei.c > +++ b/arch/arm64/kvm/sdei.c > @@ -726,6 +726,66 @@ static int do_inject_event(struct kvm_vcpu *vcpu, > return 0; > } > > +static unsigned long hypercall_signal(struct kvm_vcpu *vcpu) > +{ > + struct kvm *kvm = vcpu->kvm; > + struct kvm_sdei_kvm *ksdei = kvm->arch.sdei; > + struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei; > + struct kvm_sdei_exposed_event *exposed_event; > + struct kvm_sdei_registered_event *registered_event; > + unsigned long event_num = smccc_get_arg1(vcpu); > + int index; > + unsigned long ret = SDEI_SUCCESS; > + > + /* @event_num must be zero */ > + if (!kvm_sdei_is_default(event_num)) { 0 isn't KVM's default event. I'd argue KVM doesn't have a default event to begin with. This has a precise definition coming from the spec. In fact, 'KVM_SDEI_DEFAULT_EVENT' should probably be eliminated, and any missing SDEI definitions should be added to include/uapi/linux/arm_sdei.h. That goes for any values coming from the specification. KVM's implementation details belong in a KVM header :) -- Thanks, Oliver