Re: [PATCH v4 14/21] KVM: arm64: Support SDEI_EVENT_{COMPLETE, COMPLETE_AND_RESUME} hypercall

Eric Auger
2021-11-10T10:58:27Z

Hi Gavin,

On 8/15/21 2:13 AM, Gavin Shan wrote:
> This supports SDEI_EVENT_{COMPLETE, COMPLETE_AND_RESUME} hypercall.
> They are used by the guest to notify the completion of the SDEI
> event in the handler. The registers are changed according to the
> SDEI specification as below:
>
> * x0 - x17, PC and PState are restored to what values we had in
> the interrupted context.
>
> * If it's SDEI_EVENT_COMPLETE_AND_RESUME hypercall, IRQ exception
> is injected.
>
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> ---
> arch/arm64/include/asm/kvm_emulate.h | 1 +
> arch/arm64/include/asm/kvm_host.h | 1 +
> arch/arm64/kvm/hyp/exception.c | 7 +++
> arch/arm64/kvm/inject_fault.c | 27 ++++++++++
> arch/arm64/kvm/sdei.c | 75 ++++++++++++++++++++++++++++
> 5 files changed, 111 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
> index fd418955e31e..923b4d08ea9a 100644
> --- a/arch/arm64/include/asm/kvm_emulate.h
> +++ b/arch/arm64/include/asm/kvm_emulate.h
> @@ -37,6 +37,7 @@ bool kvm_condition_valid32(const struct kvm_vcpu *vcpu);
> void kvm_skip_instr32(struct kvm_vcpu *vcpu);
>
> void kvm_inject_undefined(struct kvm_vcpu *vcpu);
> +void kvm_inject_irq(struct kvm_vcpu *vcpu);
> void kvm_inject_vabt(struct kvm_vcpu *vcpu);
> void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr);
> void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 46f363aa6524..1824f7e1f9ab 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -437,6 +437,7 @@ struct kvm_vcpu_arch {
> #define KVM_ARM64_EXCEPT_AA32_UND (0 << 9)
> #define KVM_ARM64_EXCEPT_AA32_IABT (1 << 9)
> #define KVM_ARM64_EXCEPT_AA32_DABT (2 << 9)
> +#define KVM_ARM64_EXCEPT_AA32_IRQ (3 << 9)
> /* For AArch64: */
> #define KVM_ARM64_EXCEPT_AA64_ELx_SYNC (0 << 9)
> #define KVM_ARM64_EXCEPT_AA64_ELx_IRQ (1 << 9)
> diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c
> index 0418399e0a20..ef458207d152 100644
> --- a/arch/arm64/kvm/hyp/exception.c
> +++ b/arch/arm64/kvm/hyp/exception.c
> @@ -310,6 +310,9 @@ static void kvm_inject_exception(struct kvm_vcpu *vcpu)
> case KVM_ARM64_EXCEPT_AA32_DABT:
> enter_exception32(vcpu, PSR_AA32_MODE_ABT, 16);
> break;
> + case KVM_ARM64_EXCEPT_AA32_IRQ:
> + enter_exception32(vcpu, PSR_AA32_MODE_IRQ, 4);
> + break;
> default:
> /* Err... */
> break;
> @@ -320,6 +323,10 @@ static void kvm_inject_exception(struct kvm_vcpu *vcpu)
> KVM_ARM64_EXCEPT_AA64_EL1):
> enter_exception64(vcpu, PSR_MODE_EL1h, except_type_sync);
> break;
> + case (KVM_ARM64_EXCEPT_AA64_ELx_IRQ |
> + KVM_ARM64_EXCEPT_AA64_EL1):
> + enter_exception64(vcpu, PSR_MODE_EL1h, except_type_irq);
> + break;
> default:
> /*
> * Only EL1_SYNC makes sense so far, EL2_{SYNC,IRQ}
> diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
> index b47df73e98d7..3a8c55867d2f 100644
> --- a/arch/arm64/kvm/inject_fault.c
> +++ b/arch/arm64/kvm/inject_fault.c
> @@ -66,6 +66,13 @@ static void inject_undef64(struct kvm_vcpu *vcpu)
> vcpu_write_sys_reg(vcpu, esr, ESR_EL1);
> }
>
> +static void inject_irq64(struct kvm_vcpu *vcpu)
> +{
> + vcpu->arch.flags |= (KVM_ARM64_EXCEPT_AA64_EL1 |
> + KVM_ARM64_EXCEPT_AA64_ELx_IRQ |
> + KVM_ARM64_PENDING_EXCEPTION);
> +}
> +
> #define DFSR_FSC_EXTABT_LPAE 0x10
> #define DFSR_FSC_EXTABT_nLPAE 0x08
> #define DFSR_LPAE BIT(9)
> @@ -77,6 +84,12 @@ static void inject_undef32(struct kvm_vcpu *vcpu)
> KVM_ARM64_PENDING_EXCEPTION);
> }
>
> +static void inject_irq32(struct kvm_vcpu *vcpu)
> +{
> + vcpu->arch.flags |= (KVM_ARM64_EXCEPT_AA32_IRQ |
> + KVM_ARM64_PENDING_EXCEPTION);
> +}
> +
> /*
> * Modelled after TakeDataAbortException() and TakePrefetchAbortException
> * pseudocode.
> @@ -160,6 +173,20 @@ void kvm_inject_undefined(struct kvm_vcpu *vcpu)
> inject_undef64(vcpu);
> }
>
> +/**
> + * kvm_inject_irq - inject an IRQ into the guest
> + *
> + * It is assumed that this code is called from the VCPU thread and that the
> + * VCPU therefore is not currently executing guest code.
> + */
> +void kvm_inject_irq(struct kvm_vcpu *vcpu)
> +{
> + if (vcpu_el1_is_32bit(vcpu))
> + inject_irq32(vcpu);
> + else
> + inject_irq64(vcpu);
> +}
> +
> void kvm_set_sei_esr(struct kvm_vcpu *vcpu, u64 esr)
> {
> vcpu_set_vsesr(vcpu, esr & ESR_ELx_ISS_MASK);
> diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> index b5d6d1ed3858..1e8e213c9d70 100644
> --- a/arch/arm64/kvm/sdei.c
> +++ b/arch/arm64/kvm/sdei.c
> @@ -308,6 +308,75 @@ static unsigned long kvm_sdei_hypercall_context(struct kvm_vcpu *vcpu)
> return ret;
> }
>
> +static unsigned long kvm_sdei_hypercall_complete(struct kvm_vcpu *vcpu,
> + bool resume)
> +{
> + struct kvm *kvm = vcpu->kvm;
> + struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
> + struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
> + struct kvm_sdei_kvm_event *kske = NULL;
> + struct kvm_sdei_vcpu_event *ksve = NULL;
> + struct kvm_sdei_vcpu_regs *regs;
> + unsigned long ret = SDEI_SUCCESS;
for the RESUME you never seem to read resume_addr arg? How does it work?
I don't get the irq injection path. Please could you explain?
> + int index;
> +
> + /* Sanity check */
> + if (!(ksdei && vsdei)) {
> + ret = SDEI_NOT_SUPPORTED;
> + goto out;
> + }
> +
> + spin_lock(&vsdei->lock);
> + if (vsdei->critical_event) {
> + ksve = vsdei->critical_event;
> + regs = &vsdei->state.critical_regs;
> + vsdei->critical_event = NULL;
> + vsdei->state.critical_num = KVM_SDEI_INVALID_NUM;
> + } else if (vsdei->normal_event) {
> + ksve = vsdei->normal_event;
> + regs = &vsdei->state.normal_regs;
> + vsdei->normal_event = NULL;
> + vsdei->state.normal_num = KVM_SDEI_INVALID_NUM;
> + } else {
> + ret = SDEI_DENIED;
> + goto unlock;
> + }
> +
> + /* Restore registers: x0 -> x17, PC, PState */
> + for (index = 0; index < ARRAY_SIZE(regs->regs); index++)
> + vcpu_set_reg(vcpu, index, regs->regs[index]);
> +
> + *vcpu_cpsr(vcpu) = regs->pstate;
> + *vcpu_pc(vcpu) = regs->pc;
> +
> + /* Inject interrupt if needed */
> + if (resume)
> + kvm_inject_irq(vcpu);
> +
> + /*
> + * Update state. We needn't take lock in order to update the KVM
> + * event state as it's not destroyed because of the reference
> + * count.
> + */
> + kske = ksve->kske;
> + ksve->state.refcount--;
> + kske->state.refcount--;
why double --?
> + if (!ksve->state.refcount) {
why not using a struct kref directly?
> + list_del(&ksve->link);
> + kfree(ksve);
> + }
> +
> + /* Make another request if there is pending event */
> + if (!(list_empty(&vsdei->critical_events) &&
> + list_empty(&vsdei->normal_events)))
> + kvm_make_request(KVM_REQ_SDEI, vcpu);
> +
> +unlock:
> + spin_unlock(&vsdei->lock);
> +out:
> + return ret;
> +}
> +
> static unsigned long kvm_sdei_hypercall_unregister(struct kvm_vcpu *vcpu)
> {
> struct kvm *kvm = vcpu->kvm;
> @@ -628,7 +697,13 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
> ret = kvm_sdei_hypercall_context(vcpu);
> break;
> case SDEI_1_0_FN_SDEI_EVENT_COMPLETE:
> + has_result = false;
> + ret = kvm_sdei_hypercall_complete(vcpu, false);
> + break;
> case SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME:
> + has_result = false;
> + ret = kvm_sdei_hypercall_complete(vcpu, true);
> + break;
> case SDEI_1_0_FN_SDEI_EVENT_UNREGISTER:
> ret = kvm_sdei_hypercall_unregister(vcpu);
> break;
>
Eric