RE: [PATCH] drm/hyperv: Fix double mouse pointers

From: Deepak Rawat <redacted>
Sent: Tuesday, September 14, 2021 8:59 AM
...

quoted

+/* Send mouse pointer info to host */
+int hyperv_send_ptr(struct hv_device *hdev)
+{
+       struct synthvid_msg msg;
+
+       memset(&msg, 0, sizeof(struct synthvid_msg));
+       msg.vid_hdr.type = SYNTHVID_POINTER_POSITION;
+       msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+               sizeof(struct synthvid_pointer_position);
+       msg.ptr_pos.is_visible = 1;

"is_visible" should be 0 since you want to hide the pointer. Maybe
better, accept these from the caller.

According to my test, "is_visible = 0" doesn't work, i.e. can't hide the
unwanted HW mouse poiner. It looks like the field is for some very old
legacy Windows VMs like Windows Vista.

Haiyang also replied in another email, saying "is_visible = 0" doesn't
work.

quoted

+       msg.ptr_pos.video_output = 0;
+       msg.ptr_pos.image_x = 0;
+       msg.ptr_pos.image_y = 0;
+       hyperv_sendpacket(hdev, &msg);
+
+       memset(&msg, 0, sizeof(struct synthvid_msg));
+       msg.vid_hdr.type = SYNTHVID_POINTER_SHAPE;
+       msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+               sizeof(struct synthvid_pointer_shape);
+       msg.ptr_shape.part_idx = SYNTHVID_CURSOR_COMPLETE;
+       msg.ptr_shape.is_argb = 1;
+       msg.ptr_shape.width = 1;
+       msg.ptr_shape.height = 1;
+       msg.ptr_shape.hot_x = 0;
+       msg.ptr_shape.hot_y = 0;
+       msg.ptr_shape.data[0] = 0;
+       msg.ptr_shape.data[1] = 1;
+       msg.ptr_shape.data[2] = 1;
+       msg.ptr_shape.data[3] = 1;
+       hyperv_sendpacket(hdev, &msg);
+

Is it necessary to send SYNTHVID_POINTER_SHAPE here? Perhaps we should

According to my test, yes. If I don't send a SYNTHVID_POINTER_SHAPE message,
the unwanted mouse pointer can't be hidden. As we know, the protocol between
the VSC and the VSP is not well documented to us. I can ask Hyper-V
team for some clarification on this, but it's probably we can just use the current
version of hiding the mouse pointer as-is -- this has been used for 10+ years
in the hyperv_fb driver without any issue. :-)

separate SYNTHVID_POINTER_POSITION and SYNTHVID_POINTER_SHAPE into
different functions.

Since the 2 messages are only used here, I suggest we keep it as-is.

Thanks,
-- Dexuan