On Wed, Aug 21, 2019 at 05:54:27PM +0200, Thomas Hellström (VMware) wrote:
On 8/20/19 4:53 PM, Daniel Vetter wrote:
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.
Cc: Alex Deucher alexander.deucher@amd.com Cc: Christian König christian.koenig@amd.com Cc: Chris Wilson chris@chris-wilson.co.uk Cc: Thomas Zimmermann tzimmermann@suse.de Cc: Rob Herring robh@kernel.org Cc: Tomeu Vizoso tomeu.vizoso@collabora.com Cc: Eric Anholt eric@anholt.net Cc: Dave Airlie airlied@redhat.com Cc: Gerd Hoffmann kraxel@redhat.com Cc: Ben Skeggs bskeggs@redhat.com Cc: "VMware Graphics" linux-graphics-maintainer@vmware.com Cc: Thomas Hellstrom thellstrom@vmware.com Signed-off-by: Daniel Vetter daniel.vetter@intel.com
drivers/dma-buf/dma-resv.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index 42a8f3f11681..3edca10d3faf 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
@@ -107,6 +108,17 @@ void dma_resv_init(struct dma_resv *obj) &reservation_seqcount_class); RCU_INIT_POINTER(obj->fence, NULL); RCU_INIT_POINTER(obj->fence_excl, NULL);
- if (IS_ENABLED(CONFIG_LOCKDEP)) {
if (current->mm)down_read(¤t->mm->mmap_sem);ww_mutex_lock(&obj->lock, NULL);fs_reclaim_acquire(GFP_KERNEL);fs_reclaim_release(GFP_KERNEL);ww_mutex_unlock(&obj->lock);if (current->mm)up_read(¤t->mm->mmap_sem);- } } EXPORT_SYMBOL(dma_resv_init);
I assume if this would have been easily done and maintainable using only lockdep annotation instead of actually acquiring the locks, that would have been done?
There's might_lock(), plus a pile of macros, but they don't map obviuosly, so pretty good chances I accidentally end up with the wrong type of annotation. Easier to just take the locks quickly, and stuff that all into a lockdep-only section to avoid overhead.
Otherwise LGTM.
Reviewed-by: Thomas Hellström thellstrom@vmware.com
Will test this and let you know if it trips on vmwgfx, but it really shouldn't.
Thanks, Daniel