On Wed, Jul 06, 2022 at 10:02:07AM +0300, Dmitry Osipenko wrote: > On 7/6/22 00:48, Rob Clark wrote: > > On Tue, Jul 5, 2022 at 4:51 AM Christian König <christian.koenig@xxxxxxx> wrote: > >> > >> Am 01.07.22 um 11:02 schrieb Dmitry Osipenko: > >>> Drivers that use drm_gem_mmap() and drm_gem_mmap_obj() helpers don't > >>> handle imported dma-bufs properly, which results in mapping of something > >>> else than the imported dma-buf. On NVIDIA Tegra we get a hard lockup when > >>> userspace writes to the memory mapping of a dma-buf that was imported into > >>> Tegra's DRM GEM. > >>> > >>> Majority of DRM drivers prohibit mapping of the imported GEM objects. > >>> Mapping of imported GEMs require special care from userspace since it > >>> should sync dma-buf because mapping coherency of the exporter device may > >>> not match the DRM device. Let's prohibit the mapping for all DRM drivers > >>> for consistency. > >>> > >>> Suggested-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> > >>> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx> > >> > >> I'm pretty sure that this is the right approach, but it's certainly more > >> than possible that somebody abused this already. > > > > I suspect that this is abused if you run deqp cts on android.. ie. all > > winsys buffers are dma-buf imports from gralloc. And then when you > > hit readpix... > > > > You might only hit this in scenarios with separate gpu and display (or > > dGPU+iGPU) because self-imports are handled differently in > > drm_gem_prime_import_dev().. and maybe not in cases where you end up > > with a blit from tiled/compressed to linear.. maybe that narrows the > > scope enough to just fix it in userspace? > > Given that that only drivers which use DRM-SHMEM potentially could've > map imported dma-bufs (Panfrost, Lima) and they already don't allow to > do that, I think we're good. So can I have an ack from Rob here or are there still questions that this might go boom? Dmitry, since you have a bunch of patches merged now I think would also be good to get commit rights so you can drive this more yourself. I've asked Daniel Stone to help you out with getting that. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
