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:
     x0: number SDEI event to be delivered
     x1: parameter associated with the SDEI event
     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 <gs...@redhat.com>
---
 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 b2d51c6d055c..30e850257ef4 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -47,6 +47,7 @@
 #define KVM_REQ_VCPU_RESET     KVM_ARCH_REQ(2)
 #define KVM_REQ_RECORD_STEAL   KVM_ARCH_REQ(3)
 #define KVM_REQ_RELOAD_GICv4   KVM_ARCH_REQ(4)
+#define KVM_REQ_SDEI           KVM_ARCH_REQ(5)
 
 #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 a7ae16df3df7..e243bd5ad730 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -668,6 +668,9 @@ 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 */
+       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);
+       }
+
+       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;
-- 
2.23.0

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