Full audit of everyone: - i915, radeon, amdgpu should be clean per their maintainers.
- vram helpers should be fine, they don't do command submission, so really no business holding struct_mutex while doing copy_*_user. But I haven't checked them all. - panfrost seems to dma_resv_lock only in panfrost_job_push, which looks clean. - v3d holds dma_resv locks in the tail of its v3d_submit_cl_ioctl(), copying from/to userspace happens all in v3d_lookup_bos which is outside of the critical section. - vmwgfx has a bunch of ioctls that do their own copy_*_user: - vmw_execbuf_process: First this does some copies in vmw_execbuf_cmdbuf() and also in the vmw_execbuf_process() itself. Then comes the usual ttm reserve/validate sequence, then actual submission/fencing, then unreserving, and finally some more copy_to_user in vmw_execbuf_copy_fence_user. Glossing over tons of details, but looks all safe. - vmw_fence_event_ioctl: No ttm_reserve/dma_resv_lock anywhere to be seen, seems to only create a fence and copy it out. - a pile of smaller ioctl in vmwgfx_ioctl.c, no reservations to be found there. Summary: vmwgfx seems to be fine too. - virtio: There's virtio_gpu_execbuffer_ioctl, which does all the copying from userspace before even looking up objects through their handles, so safe. Plus the getparam/getcaps ioctl, also both safe. - qxl only has qxl_execbuffer_ioctl, which calls into qxl_process_single_command. There's a lovely comment before the __copy_from_user_inatomic that the slowpath should be copied from i915, but I guess that never happened. Try not to be unlucky and get your CS data evicted between when it's written and the kernel tries to read it. The only other copy_from_user is for relocs, but those are done before qxl_release_reserve_list(), which seems to be the only thing reserving buffers (in the ttm/dma_resv sense) in that code. So looks safe. - A debugfs file in nouveau_debugfs_pstate_set() and the usif ioctl in usif_ioctl() look safe. nouveau_gem_ioctl_pushbuf() otoh breaks this everywhere and needs to be fixed up. v2: Thomas pointed at that vmwgfx calls dma_resv_init while it holds a dma_resv lock of a different object already. Christian mentioned that ttm core does this too for ghost objects. intel-gfx-ci highlighted that i915 has similar issues. Unfortunately we can't do this in the usual module init functions, because kernel threads don't have an ->mm - we have to wait around for some user thread to do this. Solution is to spawn a worker (but only once). It's horrible, but it works. v3: We can allocate mm! (Chris). Horrible worker hack out, clean initcall solution in. Cc: Alex Deucher <alexander.deuc...@amd.com> Cc: Christian König <christian.koe...@amd.com> Cc: Chris Wilson <ch...@chris-wilson.co.uk> Cc: Thomas Zimmermann <tzimmerm...@suse.de> Cc: Rob Herring <r...@kernel.org> Cc: Tomeu Vizoso <tomeu.viz...@collabora.com> Cc: Eric Anholt <e...@anholt.net> Cc: Dave Airlie <airl...@redhat.com> Cc: Gerd Hoffmann <kra...@redhat.com> Cc: Ben Skeggs <bske...@redhat.com> Cc: "VMware Graphics" <linux-graphics-maintai...@vmware.com> Cc: Thomas Hellstrom <thellst...@vmware.com> Signed-off-by: Daniel Vetter <daniel.vet...@intel.com> --- drivers/dma-buf/dma-resv.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index 42a8f3f11681..d233ef4cf0d7 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -34,6 +34,7 @@ #include <linux/dma-resv.h> #include <linux/export.h> +#include <linux/sched/mm.h> /** * DOC: Reservation Object Overview @@ -95,6 +96,29 @@ static void dma_resv_list_free(struct dma_resv_list *list) kfree_rcu(list, rcu); } +#if IS_ENABLED(CONFIG_LOCKDEP) +static void dma_resv_lockdep(void) +{ + struct mm_struct *mm = mm_alloc(); + struct dma_resv obj; + + if (!mm) + return; + + dma_resv_init(&obj); + + down_read(&mm->mmap_sem); + ww_mutex_lock(&obj.lock, NULL); + fs_reclaim_acquire(GFP_KERNEL); + fs_reclaim_release(GFP_KERNEL); + ww_mutex_unlock(&obj.lock); + up_read(&mm->mmap_sem); + + mmput(mm); +} +subsys_initcall(dma_resv_lockdep); +#endif + /** * dma_resv_init - initialize a reservation object * @obj: the reservation object -- 2.23.0.rc1 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel