[PATCH v5 06/22] KVM: arm64: Support SDEI_EVENT_CONTEXT hypercall

[Gavin Shan]

This supports SDEI_EVENT_CONTEXT hypercall. It's used by the guest
to retrieve the registers (R0 - R17) in the preempted context
in the SDEI event handler. The preempted context is saved prior to
servicing or handling the SDEI event and restored after that.

Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
---
 arch/arm64/kvm/sdei.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
index 4ab58f264992..4488d3f044f2 100644
--- a/arch/arm64/kvm/sdei.c
+++ b/arch/arm64/kvm/sdei.c
@@ -297,6 +297,34 @@ static unsigned long hypercall_enable(struct kvm_vcpu *vcpu, bool enable)
 	return ret;
 }
 
+static unsigned long hypercall_context(struct kvm_vcpu *vcpu)
+{
+	struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
+	struct kvm_sdei_vcpu_regs_state *regs;
+	unsigned long param_id = smccc_get_arg1(vcpu);
+	unsigned long ret = SDEI_SUCCESS;
+
+	spin_lock(&vsdei->lock);
+
+	/* Check if the pending event exists */
+	if (!vsdei->critical_event && !vsdei->normal_event) {
+		ret = SDEI_DENIED;
+		goto unlock;
+	}
+
+	/* Fetch the requested register */
+	regs = vsdei->critical_event ? &vsdei->state.critical_regs :
+				       &vsdei->state.normal_regs;
+	if (param_id < ARRAY_SIZE(regs->regs))
+		ret = regs->regs[param_id];
+	else
+		ret = SDEI_INVALID_PARAMETERS;
+
+unlock:
+	spin_unlock(&vsdei->lock);
+	return ret;
+}
+
 int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;
@@ -333,6 +361,8 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
 		ret = hypercall_enable(vcpu, false);
 		break;
 	case SDEI_1_0_FN_SDEI_EVENT_CONTEXT:
+		ret = hypercall_context(vcpu);
+		break;
 	case SDEI_1_0_FN_SDEI_EVENT_COMPLETE:
 	case SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME:
 	case SDEI_1_0_FN_SDEI_EVENT_UNREGISTER:
-- 
2.23.0