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

[Gavin Shan <gshan@redhat.com>]

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;
+	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--;
+	if (!ksve->state.refcount) {
+		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;
-- 
2.23.0