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>

4 files changed, 34 insertions, 8 deletions

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 9f746eab333d..19adfd385882 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2671,7 +2671,7 @@ 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 bc738d2b8392..1b693cb2d5b2 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -301,13 +301,6 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
         kvm_arm_set_running_vcpu(NULL);
 }
 
-int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
-                                        struct kvm_guest_debug *dbg)
-{
-        return -EINVAL;
-}
-
-
 int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
                                     struct kvm_mp_state *mp_state)
 {
diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
index d503fbb787d3..96e935bbc38c 100644
--- a/arch/arm/kvm/guest.c
+++ b/arch/arm/kvm/guest.c
@@ -290,3 +290,9 @@ int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
 {
         return -EINVAL;
 }
+
+int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
+                                        struct kvm_guest_debug *dbg)
+{
+        return -EINVAL;
+}
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;
+}