KVM: arm: guest debug, add stub KVM_SET_GUEST_DEBUG ioctl

This commit adds a stub function to support the KVM_SET_GUEST_DEBUG
ioctl. Any unsupported flag will return -EINVAL. For now, only
KVM_GUESTDBG_ENABLE is supported, although it won't have any effects.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>.
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 9535bd555d1d..0ba86775235d 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -331,3 +331,30 @@ int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
 {
 	return -EINVAL;
 }
+
+#define KVM_GUESTDBG_VALID_MASK (KVM_GUESTDBG_ENABLE)
+
+/**
+ * kvm_arch_vcpu_ioctl_set_guest_debug - set up guest debugging
+ * @kvm:	pointer to the KVM struct
+ * @kvm_guest_debug: the ioctl data buffer
+ *
+ * This sets up and enables the VM for guest debugging. Userspace
+ * passes in a control flag to enable different debug types and
+ * potentially other architecture specific information in the rest of
+ * the structure.
+ */
+int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
+					struct kvm_guest_debug *dbg)
+{
+	if (dbg->control & ~KVM_GUESTDBG_VALID_MASK)
+		return -EINVAL;
+
+	if (dbg->control & KVM_GUESTDBG_ENABLE) {
+		vcpu->guest_debug = dbg->control;
+	} else {
+		/* If not enabled clear all flags */
+		vcpu->guest_debug = 0;
+	}
+	return 0;
+}