[PATCH v2 15/21] KVM: arm64: Support SDEI event notifier

[Gavin Shan]

The owner of the SDEI event, like asynchronous page fault, need
know the state of injected SDEI event. This supports SDEI event
state updating by introducing notifier mechanism. It's notable
the notifier (handler) should be capable of migration.

Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
---
 arch/arm64/include/asm/kvm_sdei.h      | 12 +++++++
 arch/arm64/include/uapi/asm/kvm_sdei.h |  1 +
 arch/arm64/kvm/sdei.c                  | 45 +++++++++++++++++++++++++-
 3 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_sdei.h b/arch/arm64/include/asm/kvm_sdei.h
index 7f5f5ad689e6..19f2d9b91f85 100644
--- a/arch/arm64/include/asm/kvm_sdei.h
+++ b/arch/arm64/include/asm/kvm_sdei.h
@@ -16,6 +16,16 @@
 #include <linux/list.h>
 #include <linux/spinlock.h>
 
+struct kvm_vcpu;
+
+typedef void (*kvm_sdei_notifier)(struct kvm_vcpu *vcpu,
+				  unsigned long num,
+				  unsigned int state);
+enum {
+	KVM_SDEI_NOTIFY_DELIVERED,
+	KVM_SDEI_NOTIFY_COMPLETED,
+};
+
 struct kvm_sdei_event {
 	struct kvm_sdei_event_state		state;
 	struct kvm				*kvm;
@@ -112,6 +122,8 @@ 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);
+int kvm_sdei_register_notifier(struct kvm *kvm, unsigned long num,
+			       kvm_sdei_notifier notifier);
 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/include/uapi/asm/kvm_sdei.h b/arch/arm64/include/uapi/asm/kvm_sdei.h
index 9dbda2fb457e..20ad724f63c8 100644
--- a/arch/arm64/include/uapi/asm/kvm_sdei.h
+++ b/arch/arm64/include/uapi/asm/kvm_sdei.h
@@ -20,6 +20,7 @@ struct kvm_sdei_event_state {
 	uint8_t		type;
 	uint8_t		signaled;
 	uint8_t		priority;
+	uint64_t	notifier;
 };
 
 struct kvm_sdei_kvm_event_state {
diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
index 1e8e213c9d70..5f7a37dcaa77 100644
--- a/arch/arm64/kvm/sdei.c
+++ b/arch/arm64/kvm/sdei.c
@@ -314,9 +314,11 @@ static unsigned long kvm_sdei_hypercall_complete(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;
+	kvm_sdei_notifier notifier;
 	unsigned long ret = SDEI_SUCCESS;
 	int index;
 
@@ -349,6 +351,13 @@ static unsigned long kvm_sdei_hypercall_complete(struct kvm_vcpu *vcpu,
 	*vcpu_cpsr(vcpu) = regs->pstate;
 	*vcpu_pc(vcpu) = regs->pc;
 
+	/* Notifier */
+	kske = ksve->kske;
+	kse = kske->kse;
+	notifier = (kvm_sdei_notifier)(kse->state.notifier);
+	if (notifier)
+		notifier(vcpu, kse->state.num, KVM_SDEI_NOTIFY_COMPLETED);
+
 	/* Inject interrupt if needed */
 	if (resume)
 		kvm_inject_irq(vcpu);
@@ -358,7 +367,6 @@ static unsigned long kvm_sdei_hypercall_complete(struct kvm_vcpu *vcpu,
 	 * event state as it's not destroyed because of the reference
 	 * count.
 	 */
-	kske = ksve->kske;
 	ksve->state.refcount--;
 	kske->state.refcount--;
 	if (!ksve->state.refcount) {
@@ -746,6 +754,35 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
+int kvm_sdei_register_notifier(struct kvm *kvm,
+			       unsigned long num,
+			       kvm_sdei_notifier notifier)
+{
+	struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
+	struct kvm_sdei_event *kse = NULL;
+	int ret = 0;
+
+	if (!ksdei) {
+		ret = -EPERM;
+		goto out;
+	}
+
+	spin_lock(&ksdei->lock);
+
+	kse = kvm_sdei_find_event(kvm, num);
+	if (!kse) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+
+	kse->state.notifier = (unsigned long)notifier;
+
+unlock:
+	spin_unlock(&ksdei->lock);
+out:
+	return ret;
+}
+
 void kvm_sdei_deliver(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -755,6 +792,7 @@ void kvm_sdei_deliver(struct kvm_vcpu *vcpu)
 	struct kvm_sdei_kvm_event *kske = NULL;
 	struct kvm_sdei_vcpu_event *ksve = NULL;
 	struct kvm_sdei_vcpu_regs *regs = NULL;
+	kvm_sdei_notifier notifier;
 	unsigned long pstate;
 	int index = 0;
 
@@ -826,6 +864,11 @@ void kvm_sdei_deliver(struct kvm_vcpu *vcpu)
 	*vcpu_cpsr(vcpu) = pstate;
 	*vcpu_pc(vcpu) = kske->state.entries[index];
 
+	/* Notifier */
+	notifier = (kvm_sdei_notifier)(kse->state.notifier);
+	if (notifier)
+		notifier(vcpu, kse->state.num, KVM_SDEI_NOTIFY_DELIVERED);
+
 unlock:
 	spin_unlock(&vsdei->lock);
 }
-- 
2.23.0