drm/vmwgfx: add ioctl for messaging from/to guest userspace to/from host

Up to now, guest userspace does logging directly to host using essentially
the same rather complex port assembly stuff as the kernel.
We'd rather use the same mechanism than duplicate it (it may also change in
the future), hence add a new ioctl for relaying guest/host messaging
(logging is just one application of it).

Signed-off-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>

1 files changed, 83 insertions, 0 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
index d63441194249..e9f448a5ebb3 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
@@ -57,6 +57,8 @@
 
 #define HIGH_WORD(X) ((X & 0xFFFF0000) >> 16)
 
+#define MAX_USER_MSG_LENGTH	PAGE_SIZE
+
 static u32 vmw_msg_enabled = 1;
 
 enum rpc_msg_type {
@@ -517,3 +519,84 @@ out_open:
 
 	return -EINVAL;
 }
+
+
+/**
+ * vmw_msg_ioctl: Sends and receveives a message to/from host from/to user-space
+ *
+ * Sends a message from user-space to host.
+ * Can also receive a result from host and return that to user-space.
+ *
+ * @dev: Identifies the drm device.
+ * @data: Pointer to the ioctl argument.
+ * @file_priv: Identifies the caller.
+ * Return: Zero on success, negative error code on error.
+ */
+
+int vmw_msg_ioctl(struct drm_device *dev, void *data,
+		  struct drm_file *file_priv)
+{
+	struct drm_vmw_msg_arg *arg =
+		(struct drm_vmw_msg_arg *) data;
+	struct rpc_channel channel;
+	char *msg;
+	int length;
+
+	msg = kmalloc(MAX_USER_MSG_LENGTH, GFP_KERNEL);
+	if (!msg) {
+		DRM_ERROR("Cannot allocate memory for log message.\n");
+		return -ENOMEM;
+	}
+
+	length = strncpy_from_user(msg, (void __user *)((unsigned long)arg->send),
+				   MAX_USER_MSG_LENGTH);
+	if (length < 0 || length >= MAX_USER_MSG_LENGTH) {
+		DRM_ERROR("Userspace message access failure.\n");
+		kfree(msg);
+		return -EINVAL;
+	}
+
+
+	if (vmw_open_channel(&channel, RPCI_PROTOCOL_NUM)) {
+		DRM_ERROR("Failed to open channel.\n");
+		goto out_open;
+	}
+
+	if (vmw_send_msg(&channel, msg)) {
+		DRM_ERROR("Failed to send message to host.\n");
+		goto out_msg;
+	}
+
+	if (!arg->send_only) {
+		char *reply = NULL;
+		size_t reply_len = 0;
+
+		if (vmw_recv_msg(&channel, (void *) &reply, &reply_len)) {
+			DRM_ERROR("Failed to receive message from host.\n");
+			goto out_msg;
+		}
+		if (reply && reply_len > 0) {
+			if (copy_to_user((void __user *)((unsigned long)arg->receive),
+							 reply, reply_len)) {
+				DRM_ERROR("Failed to copy message to userspace.\n");
+				kfree(reply);
+				goto out_msg;
+			}
+			arg->receive_len = (__u32)reply_len;
+		}
+		kfree(reply);
+	}
+
+	vmw_close_channel(&channel);
+	kfree(msg);
+
+	return 0;
+
+out_msg:
+	vmw_close_channel(&channel);
+out_open:
+	kfree(msg);
+
+	return -EINVAL;
+}
+