[PATCH v4 06/21] KVM: arm64: Support SDEI_EVENT_CONTEXT hypercall

[Gavin Shan <gshan@redhat.com>]

This supports SDEI_EVENT_CONTEXT hypercall. It's used by the guest
to retrieved the original registers (R0 - R17) in its SDEI event
handler. Those registers can be corrupted during the SDEI event
delivery.

Signed-off-by: Gavin Shan <gshan@redhat.com>
---
 arch/arm64/kvm/sdei.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
index b022ce0a202b..b4162efda470 100644
--- a/arch/arm64/kvm/sdei.c
+++ b/arch/arm64/kvm/sdei.c
@@ -270,6 +270,44 @@ static unsigned long kvm_sdei_hypercall_enable(struct kvm_vcpu *vcpu,
 	return ret;
 }
 
+static unsigned long kvm_sdei_hypercall_context(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_vcpu_regs *regs;
+	unsigned long index = smccc_get_arg1(vcpu);
+	unsigned long ret = SDEI_SUCCESS;
+
+	/* Sanity check */
+	if (!(ksdei && vsdei)) {
+		ret = SDEI_NOT_SUPPORTED;
+		goto out;
+	}
+
+	if (index > ARRAY_SIZE(vsdei->state.critical_regs.regs)) {
+		ret = SDEI_INVALID_PARAMETERS;
+		goto out;
+	}
+
+	/* Check if the pending event exists */
+	spin_lock(&vsdei->lock);
+	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;
+	ret = regs->regs[index];
+
+unlock:
+	spin_unlock(&vsdei->lock);
+out:
+	return ret;
+}
+
 int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
 {
 	u32 func = smccc_get_function(vcpu);
@@ -290,6 +328,8 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu)
 		ret = kvm_sdei_hypercall_enable(vcpu, false);
 		break;
 	case SDEI_1_0_FN_SDEI_EVENT_CONTEXT:
+		ret = kvm_sdei_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