| Message ID | 20210311182957.486939-5-berrange@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | ui: improve precision of VNC desktop resizing | expand |
On Thu, Mar 11, 2021 at 10:38 PM Daniel P. Berrangé <berrange@redhat.com> wrote: > A long time ago the VNC server code had some memory corruption > fixes done in: > > commit bea60dd7679364493a0d7f5b54316c767cf894ef > Author: Peter Lieven <pl@kamp.de> > Date: Mon Jun 30 10:57:51 2014 +0200 > > ui/vnc: fix potential memory corruption issues > > One of the implications of the fix was that the VNC server would have a > thin black bad down the right hand side if the guest desktop width was > not a multiple of 16. In practice this was a non-issue since the VNC > server was always honouring a guest specified resolution and guests > essentially always pick from a small set of sane resolutions likely in > real world hardware. > > We recently introduced support for the extended desktop resize extension > and as a result the VNC client has ability to specify an arbitrary > desktop size and the guest OS may well honour it exactly. As a result we > no longer have any guarantee that the width will be a multiple of 16, > and so when resizing the desktop we have a 93% chance of getting the > black bar on the right hand size. > > The VNC server maintains three different desktop dimensions > > 1. The guest surface > 2. The server surface > 3. The client desktop > > The requirement for the width to be a multiple of 16 only applies to > item 2, the server surface, for the purpose of doing dirty bitmap > tracking. > > Normally we will set the client desktop size to always match the server > surface size, but that's not a strict requirement. In order to cope with > clients that don't support the desktop size encoding, we already allow > for the client desktop to be a different size that the server surface. > > Thus we can trivially eliminate the black bar, but setting the client > desktop size to be the un-rounded server surface size - the so called > "true width". > > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> > --- > ui/trace-events | 2 ++ > ui/vnc.c | 23 +++++++++++++++++++---- > ui/vnc.h | 1 + > 3 files changed, 22 insertions(+), 4 deletions(-) > > diff --git a/ui/trace-events b/ui/trace-events > index 3838ae2d84..5d1da6f236 100644 > --- a/ui/trace-events > +++ b/ui/trace-events > @@ -59,6 +59,8 @@ vnc_client_throttle_audio(void *state, void *ioc, size_t > offset) "VNC client thr > vnc_client_unthrottle_forced(void *state, void *ioc) "VNC client > unthrottle forced offset state=%p ioc=%p" > vnc_client_unthrottle_incremental(void *state, void *ioc, size_t offset) > "VNC client unthrottle incremental state=%p ioc=%p offset=%zu" > vnc_client_output_limit(void *state, void *ioc, size_t offset, size_t > threshold) "VNC client output limit state=%p ioc=%p offset=%zu > threshold=%zu" > +vnc_server_dpy_pageflip(void *dpy, int w, int h, int fmt) "VNC server dpy > pageflip dpy=%p size=%dx%d fmt=%d" > +vnc_server_dpy_recreate(void *dpy, int w, int h, int fmt) "VNC server dpy > recreate dpy=%p size=%dx%d fmt=%d" > vnc_job_add_rect(void *state, void *job, int x, int y, int w, int h) "VNC > add rect state=%p job=%p offset=%d,%d size=%dx%d" > vnc_job_discard_rect(void *state, void *job, int x, int y, int w, int h) > "VNC job discard rect state=%p job=%p offset=%d,%d size=%dx%d" > vnc_job_clamp_rect(void *state, void *job, int x, int y, int w, int h) > "VNC job clamp rect state=%p job=%p offset=%d,%d size=%dx%d" > diff --git a/ui/vnc.c b/ui/vnc.c > index 8c9890b3cd..9c004a11f4 100644 > --- a/ui/vnc.c > +++ b/ui/vnc.c > @@ -608,6 +608,11 @@ static int vnc_width(VncDisplay *vd) > VNC_DIRTY_PIXELS_PER_BIT)); > } > > +static int vnc_true_width(VncDisplay *vd) > +{ > + return MIN(VNC_MAX_WIDTH, surface_width(vd->ds)); > +} > + > static int vnc_height(VncDisplay *vd) > { > return MIN(VNC_MAX_HEIGHT, surface_height(vd->ds)); > @@ -691,16 +696,16 @@ static void vnc_desktop_resize(VncState *vs) > !vnc_has_feature(vs, > VNC_FEATURE_RESIZE_EXT))) { > return; > } > - if (vs->client_width == pixman_image_get_width(vs->vd->server) && > + if (vs->client_width == vs->vd->true_width && > vs->client_height == pixman_image_get_height(vs->vd->server)) { > return; > } > > - assert(pixman_image_get_width(vs->vd->server) < 65536 && > - pixman_image_get_width(vs->vd->server) >= 0); > + assert(vs->vd->true_width < 65536 && > + vs->vd->true_width >= 0); > assert(pixman_image_get_height(vs->vd->server) < 65536 && > pixman_image_get_height(vs->vd->server) >= 0); > - vs->client_width = pixman_image_get_width(vs->vd->server); > + vs->client_width = vs->vd->true_width; > vs->client_height = pixman_image_get_height(vs->vd->server); > > if (vnc_has_feature(vs, VNC_FEATURE_RESIZE_EXT)) { > @@ -774,6 +779,7 @@ static void vnc_update_server_surface(VncDisplay *vd) > > width = vnc_width(vd); > height = vnc_height(vd); > + vd->true_width = vnc_true_width(vd); > vd->server = pixman_image_create_bits(VNC_SERVER_FB_FORMAT, > width, height, > NULL, 0); > @@ -809,13 +815,22 @@ static void vnc_dpy_switch(DisplayChangeListener > *dcl, > vd->guest.fb = pixman_image_ref(surface->image); > vd->guest.format = surface->format; > > + > if (pageflip) { > + trace_vnc_server_dpy_pageflip(vd, > + surface_width(surface), > + surface_height(surface), > + surface_format(surface)); > vnc_set_area_dirty(vd->guest.dirty, vd, 0, 0, > surface_width(surface), > surface_height(surface)); > return; > } > > + trace_vnc_server_dpy_recreate(vd, > + surface_width(surface), > + surface_height(surface), > + surface_format(surface)); > /* server surface */ > vnc_update_server_surface(vd); > > diff --git a/ui/vnc.h b/ui/vnc.h > index 116463d5f0..d4f3e15558 100644 > --- a/ui/vnc.h > +++ b/ui/vnc.h > @@ -164,6 +164,7 @@ struct VncDisplay > > struct VncSurface guest; /* guest visible surface (aka ds->surface) > */ > pixman_image_t *server; /* vnc server surface */ > + int true_width; /* server surface width before rounding up */ > > const char *id; > QTAILQ_ENTRY(VncDisplay) next; > -- > 2.29.2 > > > Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
diff --git a/ui/trace-events b/ui/trace-events index 3838ae2d84..5d1da6f236 100644 --- a/ui/trace-events +++ b/ui/trace-events @@ -59,6 +59,8 @@ vnc_client_throttle_audio(void *state, void *ioc, size_t offset) "VNC client thr vnc_client_unthrottle_forced(void *state, void *ioc) "VNC client unthrottle forced offset state=%p ioc=%p" vnc_client_unthrottle_incremental(void *state, void *ioc, size_t offset) "VNC client unthrottle incremental state=%p ioc=%p offset=%zu" vnc_client_output_limit(void *state, void *ioc, size_t offset, size_t threshold) "VNC client output limit state=%p ioc=%p offset=%zu threshold=%zu" +vnc_server_dpy_pageflip(void *dpy, int w, int h, int fmt) "VNC server dpy pageflip dpy=%p size=%dx%d fmt=%d" +vnc_server_dpy_recreate(void *dpy, int w, int h, int fmt) "VNC server dpy recreate dpy=%p size=%dx%d fmt=%d" vnc_job_add_rect(void *state, void *job, int x, int y, int w, int h) "VNC add rect state=%p job=%p offset=%d,%d size=%dx%d" vnc_job_discard_rect(void *state, void *job, int x, int y, int w, int h) "VNC job discard rect state=%p job=%p offset=%d,%d size=%dx%d" vnc_job_clamp_rect(void *state, void *job, int x, int y, int w, int h) "VNC job clamp rect state=%p job=%p offset=%d,%d size=%dx%d" diff --git a/ui/vnc.c b/ui/vnc.c index 8c9890b3cd..9c004a11f4 100644 --- a/ui/vnc.c +++ b/ui/vnc.c @@ -608,6 +608,11 @@ static int vnc_width(VncDisplay *vd) VNC_DIRTY_PIXELS_PER_BIT)); } +static int vnc_true_width(VncDisplay *vd) +{ + return MIN(VNC_MAX_WIDTH, surface_width(vd->ds)); +} + static int vnc_height(VncDisplay *vd) { return MIN(VNC_MAX_HEIGHT, surface_height(vd->ds)); @@ -691,16 +696,16 @@ static void vnc_desktop_resize(VncState *vs) !vnc_has_feature(vs, VNC_FEATURE_RESIZE_EXT))) { return; } - if (vs->client_width == pixman_image_get_width(vs->vd->server) && + if (vs->client_width == vs->vd->true_width && vs->client_height == pixman_image_get_height(vs->vd->server)) { return; } - assert(pixman_image_get_width(vs->vd->server) < 65536 && - pixman_image_get_width(vs->vd->server) >= 0); + assert(vs->vd->true_width < 65536 && + vs->vd->true_width >= 0); assert(pixman_image_get_height(vs->vd->server) < 65536 && pixman_image_get_height(vs->vd->server) >= 0); - vs->client_width = pixman_image_get_width(vs->vd->server); + vs->client_width = vs->vd->true_width; vs->client_height = pixman_image_get_height(vs->vd->server); if (vnc_has_feature(vs, VNC_FEATURE_RESIZE_EXT)) { @@ -774,6 +779,7 @@ static void vnc_update_server_surface(VncDisplay *vd) width = vnc_width(vd); height = vnc_height(vd); + vd->true_width = vnc_true_width(vd); vd->server = pixman_image_create_bits(VNC_SERVER_FB_FORMAT, width, height, NULL, 0); @@ -809,13 +815,22 @@ static void vnc_dpy_switch(DisplayChangeListener *dcl, vd->guest.fb = pixman_image_ref(surface->image); vd->guest.format = surface->format; + if (pageflip) { + trace_vnc_server_dpy_pageflip(vd, + surface_width(surface), + surface_height(surface), + surface_format(surface)); vnc_set_area_dirty(vd->guest.dirty, vd, 0, 0, surface_width(surface), surface_height(surface)); return; } + trace_vnc_server_dpy_recreate(vd, + surface_width(surface), + surface_height(surface), + surface_format(surface)); /* server surface */ vnc_update_server_surface(vd); diff --git a/ui/vnc.h b/ui/vnc.h index 116463d5f0..d4f3e15558 100644 --- a/ui/vnc.h +++ b/ui/vnc.h @@ -164,6 +164,7 @@ struct VncDisplay struct VncSurface guest; /* guest visible surface (aka ds->surface) */ pixman_image_t *server; /* vnc server surface */ + int true_width; /* server surface width before rounding up */ const char *id; QTAILQ_ENTRY(VncDisplay) next;
A long time ago the VNC server code had some memory corruption fixes done in: commit bea60dd7679364493a0d7f5b54316c767cf894ef Author: Peter Lieven <pl@kamp.de> Date: Mon Jun 30 10:57:51 2014 +0200 ui/vnc: fix potential memory corruption issues One of the implications of the fix was that the VNC server would have a thin black bad down the right hand side if the guest desktop width was not a multiple of 16. In practice this was a non-issue since the VNC server was always honouring a guest specified resolution and guests essentially always pick from a small set of sane resolutions likely in real world hardware. We recently introduced support for the extended desktop resize extension and as a result the VNC client has ability to specify an arbitrary desktop size and the guest OS may well honour it exactly. As a result we no longer have any guarantee that the width will be a multiple of 16, and so when resizing the desktop we have a 93% chance of getting the black bar on the right hand size. The VNC server maintains three different desktop dimensions 1. The guest surface 2. The server surface 3. The client desktop The requirement for the width to be a multiple of 16 only applies to item 2, the server surface, for the purpose of doing dirty bitmap tracking. Normally we will set the client desktop size to always match the server surface size, but that's not a strict requirement. In order to cope with clients that don't support the desktop size encoding, we already allow for the client desktop to be a different size that the server surface. Thus we can trivially eliminate the black bar, but setting the client desktop size to be the un-rounded server surface size - the so called "true width". Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> --- ui/trace-events | 2 ++ ui/vnc.c | 23 +++++++++++++++++++---- ui/vnc.h | 1 + 3 files changed, 22 insertions(+), 4 deletions(-)