[v3,1/2] ui/gtk: flush display pipeline before saving vmstate when blob=true

From: Dongwon Kim <dongwon.kim@intel.com>

If the guest state is paused before it gets a response for the current
scanout frame submission (resource-flush), it won't flush new frames
after being restored as it still waits for the old response, which is
accepted as a scanout render done signal. So it's needed to unblock
the current scanout render pipeline before the run state is changed
to make sure the guest receives the response for the current frame
submission.

v2: Giving some time for the fence to be signaled before flushing
    the pipeline

v3: Prevent redundant call of gd_hw_gl_flushed by checking dmabuf
    and fence_fd >= 0 in it (e.g. during and after eglClientWaitSync
    in gd_change_runstate).

    Destroy sync object later in gd_hw_fl_flushed since it is needed
    by eglClientWaitSync.

Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
---
 ui/egl-helpers.c |  2 --
 ui/gtk.c         | 31 +++++++++++++++++++++++++++----
 2 files changed, 27 insertions(+), 6 deletions(-)

Hi Marc-André,

Can you take a look at this new version and also https://lists.gnu.org/archive/html/qemu-devel/2023-12/msg01828.html?

Thanks!
DW

> -----Original Message-----
> From: qemu-devel-bounces+dongwon.kim=intel.com@nongnu.org <qemu-
> devel-bounces+dongwon.kim=intel.com@nongnu.org> On Behalf Of
> dongwon.kim@intel.com
> Sent: Wednesday, September 20, 2023 4:24 PM
> To: qemu-devel@nongnu.org
> Subject: [PATCH v3 1/2] ui/gtk: flush display pipeline before saving vmstate
> when blob=true
> 
> From: Dongwon Kim <dongwon.kim@intel.com>
> 
> If the guest state is paused before it gets a response for the current scanout
> frame submission (resource-flush), it won't flush new frames after being
> restored as it still waits for the old response, which is accepted as a scanout
> render done signal. So it's needed to unblock the current scanout render pipeline
> before the run state is changed to make sure the guest receives the response for
> the current frame submission.
> 
> v2: Giving some time for the fence to be signaled before flushing
>     the pipeline
> 
> v3: Prevent redundant call of gd_hw_gl_flushed by checking dmabuf
>     and fence_fd >= 0 in it (e.g. during and after eglClientWaitSync
>     in gd_change_runstate).
> 
>     Destroy sync object later in gd_hw_fl_flushed since it is needed
>     by eglClientWaitSync.
> 
> Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
> Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
> Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
> ---
>  ui/egl-helpers.c |  2 --
>  ui/gtk.c         | 31 +++++++++++++++++++++++++++----
>  2 files changed, 27 insertions(+), 6 deletions(-)
> 
> diff --git a/ui/egl-helpers.c b/ui/egl-helpers.c index 3d19dbe382..a77f9e57d9
> 100644
> --- a/ui/egl-helpers.c
> +++ b/ui/egl-helpers.c
> @@ -385,8 +385,6 @@ void egl_dmabuf_create_fence(QemuDmaBuf *dmabuf)
>      if (dmabuf->sync) {
>          dmabuf->fence_fd = eglDupNativeFenceFDANDROID(qemu_egl_display,
>                                                        dmabuf->sync);
> -        eglDestroySyncKHR(qemu_egl_display, dmabuf->sync);
> -        dmabuf->sync = NULL;
>      }
>  }
> 
> diff --git a/ui/gtk.c b/ui/gtk.c
> index 810d7fc796..eaca890cba 100644
> --- a/ui/gtk.c
> +++ b/ui/gtk.c
> @@ -597,10 +597,14 @@ void gd_hw_gl_flushed(void *vcon)
>      VirtualConsole *vc = vcon;
>      QemuDmaBuf *dmabuf = vc->gfx.guest_fb.dmabuf;
> 
> -    qemu_set_fd_handler(dmabuf->fence_fd, NULL, NULL, NULL);
> -    close(dmabuf->fence_fd);
> -    dmabuf->fence_fd = -1;
> -    graphic_hw_gl_block(vc->gfx.dcl.con, false);
> +    if (dmabuf && dmabuf->fence_fd >= 0) {
> +        qemu_set_fd_handler(dmabuf->fence_fd, NULL, NULL, NULL);
> +        close(dmabuf->fence_fd);
> +        dmabuf->fence_fd = -1;
> +        eglDestroySyncKHR(qemu_egl_display, dmabuf->sync);
> +        dmabuf->sync = NULL;
> +        graphic_hw_gl_block(vc->gfx.dcl.con, false);
> +    }
>  }
> 
>  /** DisplayState Callbacks (opengl version) **/ @@ -678,6 +682,25 @@ static
> const DisplayGLCtxOps egl_ctx_ops = {  static void gd_change_runstate(void
> *opaque, bool running, RunState state)  {
>      GtkDisplayState *s = opaque;
> +    int i;
> +
> +    if (state == RUN_STATE_SAVE_VM) {
> +        for (i = 0; i < s->nb_vcs; i++) {
> +            VirtualConsole *vc = &s->vc[i];
> +
> +            if (vc->gfx.guest_fb.dmabuf &&
> +                vc->gfx.guest_fb.dmabuf->fence_fd >= 0) {
> +                eglClientWaitSync(qemu_egl_display,
> +                                  vc->gfx.guest_fb.dmabuf->sync,
> +                                  EGL_SYNC_FLUSH_COMMANDS_BIT_KHR,
> +                                  100000000);
> +
> +                /* force flushing current scanout blob rendering process
> +                 * just in case the fence is still not signaled */
> +                gd_hw_gl_flushed(vc);
> +            }
> +        }
> +    }
> 
>      gd_update_caption(s);
>  }
> --
> 2.34.1
>