virgl/vtest: add support to vtest for new cap getting.

The vtest protocol is pretty simple but also pretty dumb, and
the v1 caps query was fixed size, with no nice way to expand it,
however the server also ignores any command it doesn't understand.

So we can query v2 caps by sending a v2 followed by a v1, if the
v2 is ignored we know it's an old vtest server, and the we get
a v2 answer then we can just read the v1 answer and discard it.

Acked-by: Jakob Bornecrantz <jakob@collabora.com> (sounds good)

2 files changed, 28 insertions, 4 deletions

diff --git a/src/gallium/winsys/virgl/vtest/virgl_vtest_socket.c b/src/gallium/winsys/virgl/vtest/virgl_vtest_socket.c
index adec26b66b8..d25f9a3bd9e 100644
--- a/src/gallium/winsys/virgl/vtest/virgl_vtest_socket.c
+++ b/src/gallium/winsys/virgl/vtest/virgl_vtest_socket.c
@@ -129,12 +129,14 @@ int virgl_vtest_connect(struct virgl_vtest_winsys *vws)
 int virgl_vtest_send_get_caps(struct virgl_vtest_winsys *vws,
                               struct virgl_drm_caps *caps)
 {
-   uint32_t get_caps_buf[VTEST_HDR_SIZE];
+   uint32_t get_caps_buf[VTEST_HDR_SIZE * 2];
    uint32_t resp_buf[VTEST_HDR_SIZE];
-
+   uint32_t caps_size = sizeof(struct virgl_caps_v2);
    int ret;
    get_caps_buf[VTEST_CMD_LEN] = 0;
-   get_caps_buf[VTEST_CMD_ID] = VCMD_GET_CAPS;
+   get_caps_buf[VTEST_CMD_ID] = VCMD_GET_CAPS2;
+   get_caps_buf[VTEST_CMD_LEN + 2] = 0;
+   get_caps_buf[VTEST_CMD_ID + 2] = VCMD_GET_CAPS;
 
    virgl_block_write(vws->sock_fd, &get_caps_buf, sizeof(get_caps_buf));
 
@@ -142,7 +144,27 @@ int virgl_vtest_send_get_caps(struct virgl_vtest_winsys *vws,
    if (ret <= 0)
       return 0;
 
-   ret = virgl_block_read(vws->sock_fd, &caps->caps, sizeof(struct virgl_caps_v1));
+   if (resp_buf[1] == 2) {
+       struct virgl_caps_v1 dummy;
+       uint32_t resp_size = resp_buf[0] - 1;
+       uint32_t dummy_size = 0;
+       if (resp_size > caps_size) {
+	   dummy_size = resp_size - caps_size;
+	   resp_size = caps_size;
+       }
+
+       ret = virgl_block_read(vws->sock_fd, &caps->caps, resp_size);
+
+       if (dummy_size)
+	   ret = virgl_block_read(vws->sock_fd, &dummy, dummy_size);
+
+       /* now read back the pointless caps v1 we requested */
+       ret = virgl_block_read(vws->sock_fd, resp_buf, sizeof(resp_buf));
+       if (ret <= 0)
+	   return 0;
+       ret = virgl_block_read(vws->sock_fd, &dummy, sizeof(struct virgl_caps_v1));
+   } else
+       ret = virgl_block_read(vws->sock_fd, &caps->caps, sizeof(struct virgl_caps_v1));
 
    return 0;
 }
diff --git a/src/gallium/winsys/virgl/vtest/vtest_protocol.h b/src/gallium/winsys/virgl/vtest/vtest_protocol.h
index 86d197f006c..95bd8c1d0bd 100644
--- a/src/gallium/winsys/virgl/vtest/vtest_protocol.h
+++ b/src/gallium/winsys/virgl/vtest/vtest_protocol.h
@@ -47,6 +47,8 @@
 
 /* pass the process cmd line for debugging */
 #define VCMD_CREATE_RENDERER 8
+
+#define VCMD_GET_CAPS2 9
 /* get caps */
 /* 0 length cmd */
 /* resp VCMD_GET_CAPS + caps */