Re: [PATCH v4 13/21] KVM: arm64: Impment SDEI event delivery

From: Eric Auger
Date: Wed Nov 10 2021 - 05:59:05 EST

s/Impment/Implement in the commit title

On 8/15/21 2:13 AM, Gavin Shan wrote:
> This implement kvm_sdei_deliver() to support SDEI event delivery.
> The function is called when the request (KVM_REQ_SDEI) is raised.
> The following rules are taken according to the SDEI specification:
>
> * x0 - x17 are saved. All of them are cleared except the following
> registered:
s/registered/registers
> x0: number SDEI event to be delivered
s/number SDEI event/SDEI event number
> x1: parameter associated with the SDEI event
user arg?
> x2: PC of the interrupted context
> x3: PState of the interrupted context
>
> * PC is set to the handler of the SDEI event, which was provided
> during its registration. PState is modified accordingly.
>
> * SDEI event with critical priority can preempt those with normal
> priority.
>
> Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/kvm_host.h | 1 +
> arch/arm64/include/asm/kvm_sdei.h | 1 +
> arch/arm64/kvm/arm.c | 3 ++
> arch/arm64/kvm/sdei.c | 84 +++++++++++++++++++++++++++++++
> 4 files changed, 89 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index aedf901e1ec7..46f363aa6524 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -47,6 +47,7 @@
> #define KVM_REQ_RECORD_STEAL KVM_ARCH_REQ(3)
> #define KVM_REQ_RELOAD_GICv4 KVM_ARCH_REQ(4)
> #define KVM_REQ_RELOAD_PMU KVM_ARCH_REQ(5)
> +#define KVM_REQ_SDEI KVM_ARCH_REQ(6)
>
> #define KVM_DIRTY_LOG_MANUAL_CAPS (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE | \
> KVM_DIRTY_LOG_INITIALLY_SET)
> diff --git a/arch/arm64/include/asm/kvm_sdei.h b/arch/arm64/include/asm/kvm_sdei.h
> index b0abc13a0256..7f5f5ad689e6 100644
> --- a/arch/arm64/include/asm/kvm_sdei.h
> +++ b/arch/arm64/include/asm/kvm_sdei.h
> @@ -112,6 +112,7 @@ KVM_SDEI_FLAG_FUNC(enabled)
> void kvm_sdei_init_vm(struct kvm *kvm);
> void kvm_sdei_create_vcpu(struct kvm_vcpu *vcpu);
> int kvm_sdei_hypercall(struct kvm_vcpu *vcpu);
> +void kvm_sdei_deliver(struct kvm_vcpu *vcpu);
> void kvm_sdei_destroy_vcpu(struct kvm_vcpu *vcpu);
> void kvm_sdei_destroy_vm(struct kvm *kvm);
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 2f021aa41632..0c3db1ef1ba9 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -689,6 +689,9 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu)
> if (kvm_check_request(KVM_REQ_VCPU_RESET, vcpu))
> kvm_reset_vcpu(vcpu);
>
> + if (kvm_check_request(KVM_REQ_SDEI, vcpu))
> + kvm_sdei_deliver(vcpu);
> +
> /*
> * Clear IRQ_PENDING requests that were made to guarantee
> * that a VCPU sees new virtual interrupts.
> diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> index 62efee2b67b8..b5d6d1ed3858 100644
> --- a/arch/arm64/kvm/sdei.c
> +++ b/arch/arm64/kvm/sdei.c
> @@ -671,6 +671,90 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> return 1;
> }
>
> +void kvm_sdei_deliver(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_event *kse = NULL;
> + struct kvm_sdei_kvm_event *kske = NULL;
> + struct kvm_sdei_vcpu_event *ksve = NULL;
> + struct kvm_sdei_vcpu_regs *regs = NULL;
> + unsigned long pstate;
> + int index = 0;
> +
> + /* Sanity check */
> + if (!(ksdei && vsdei))
> + return;
> +
> + /* The critical event can't be preempted */
move the comment after the spin_lock
> + spin_lock(&vsdei->lock);
> + if (vsdei->critical_event)
> + goto unlock;
> +
> + /*
> + * The normal event can be preempted by the critical event.
> + * However, the normal event can't be preempted by another
> + * normal event.
> + */
> + ksve = list_first_entry_or_null(&vsdei->critical_events,
> + struct kvm_sdei_vcpu_event, link);
> + if (!ksve && !vsdei->normal_event) {
> + ksve = list_first_entry_or_null(&vsdei->normal_events,
> + struct kvm_sdei_vcpu_event, link);
> + }
At this stage of the review the struct kvm_sdei_vcpu_event lifecycle is
not known.

>From the dispatcher pseudocode I understand you check

((IsCriticalEvent(E) and !CriticalEventRunning(P, C)) ||
(!IsCriticalEvent(E) and !EventRunning(P, C)))

but I can't check you take care of
IsEnabled(E) and
IsEventTarget(E, P)
IsUnmasked(P)

Either you should shash with 18/21 or at least you should add comments.
> +
> + if (!ksve)
> + goto unlock;
> +
> + kske = ksve->kske;
> + kse = kske->kse;
> + if (kse->state.priority == SDEI_EVENT_PRIORITY_CRITICAL) {
> + vsdei->critical_event = ksve;
> + vsdei->state.critical_num = ksve->state.num;
> + regs = &vsdei->state.critical_regs;
> + } else {
> + vsdei->normal_event = ksve;
> + vsdei->state.normal_num = ksve->state.num;
> + regs = &vsdei->state.normal_regs;
> + }
> +
> + /* Save registers: x0 -> x17, PC, PState */
> + for (index = 0; index < ARRAY_SIZE(regs->regs); index++)
> + regs->regs[index] = vcpu_get_reg(vcpu, index);
> +
> + regs->pc = *vcpu_pc(vcpu);
> + regs->pstate = *vcpu_cpsr(vcpu);
> +
> + /*
> + * Inject SDEI event: x0 -> x3, PC, PState. We needn't take lock
> + * for the KVM event as it can't be destroyed because of its
> + * reference count.
> + */
> + for (index = 0; index < ARRAY_SIZE(regs->regs); index++)
> + vcpu_set_reg(vcpu, index, 0);
> +
> + index = (kse->state.type == SDEI_EVENT_TYPE_PRIVATE) ?
> + vcpu->vcpu_idx : 0;
> + vcpu_set_reg(vcpu, 0, kske->state.num);
> + vcpu_set_reg(vcpu, 1, kske->state.params[index]);
> + vcpu_set_reg(vcpu, 2, regs->pc);
> + vcpu_set_reg(vcpu, 3, regs->pstate);
> +
> + pstate = regs->pstate;
> + pstate |= (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT);
> + pstate &= ~PSR_MODE_MASK;
> + pstate |= PSR_MODE_EL1h;
> + pstate &= ~PSR_MODE32_BIT;
> +
> + vcpu_write_sys_reg(vcpu, regs->pstate, SPSR_EL1);
> + *vcpu_cpsr(vcpu) = pstate;
> + *vcpu_pc(vcpu) = kske->state.entries[index];
> +
> +unlock:
> + spin_unlock(&vsdei->lock);
> +}
> +
> void kvm_sdei_init_vm(struct kvm *kvm)
> {
> struct kvm_sdei_kvm *ksdei;
>
Eric