[PATCH v2 04/10] KVM: arm: guest debug, add stub KVM_SET_GUEST_DEBUG ioctl

["Alex Bennée" <alex.bennee@linaro.org>]

This commit adds a stub function to support the KVM_SET_GUEST_DEBUG
ioctl. Currently any operation flag will return EINVAL. Actual
functionality will be added with further patches.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>.

---
v2
  - simplified form of the ioctl (stuff will go into setup_debug)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index b112efc..06c5064 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2604,7 +2604,7 @@ handled.
 4.87 KVM_SET_GUEST_DEBUG
 
 Capability: KVM_CAP_SET_GUEST_DEBUG
-Architectures: x86, s390, ppc
+Architectures: x86, s390, ppc, arm64
 Type: vcpu ioctl
 Parameters: struct kvm_guest_debug (in)
 Returns: 0 on success; -1 on error
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 5560f74..445933d 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -183,6 +183,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_ARM_PSCI:
 	case KVM_CAP_ARM_PSCI_0_2:
 	case KVM_CAP_READONLY_MEM:
+	case KVM_CAP_SET_GUEST_DEBUG:
 		r = 1;
 		break;
 	case KVM_CAP_COALESCED_MMIO:
@@ -303,10 +304,21 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 	kvm_arm_set_running_vcpu(NULL);
 }
 
+#define KVM_GUESTDBG_VALID (KVM_GUESTDBG_ENABLE)
+
 int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 					struct kvm_guest_debug *dbg)
 {
-	return -EINVAL;
+	if (dbg->control & KVM_GUESTDBG_ENABLE) {
+		if (dbg->control & ~KVM_GUESTDBG_VALID)
+			return -EINVAL;
+
+		vcpu->guest_debug = dbg->control;
+	} else {
+		/* If not enabled clear all flags */
+		vcpu->guest_debug = 0;
+	}
+	return 0;
 }
 
 
-- 
2.3.4