Hi Eric,

On 11/10/21 6:58 PM, Eric Auger wrote:
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 <[email protected]>
---
  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?

The guest kernel uses COMPLETE and COMPLETE_AND_RESUME hypercalls to notify the
SDEI event has been acknoledged by it. The difference between them is 
COMPLETE_AND_RESUME
fires the pending interrupts, but COMPLETE doesn't.

+       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 --?

On each SDEI event is queued for delivery, both reference count are increased. 
I guess
it's a bit confusing. I will change in next revision:

ksve->state.refcount: Increased on each SDEI event is queued for delivered
kske->state.refcount: Increased on each @ksve is created


+       if (!ksve->state.refcount) {
why not using a struct kref directly?

The reason is kref isn't friendly to userspace. This field (@refcount) needs to 
be
migrated :)

+               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;


Thanks,
Gavin

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