On Wed, Jul 14, 2021 at 11:01 PM Jason Ekstrand <jason@xxxxxxxxxxxxxx> wrote: > > On Tue, Jul 13, 2021 at 10:23 AM Daniel Vetter <daniel@xxxxxxxx> wrote: > > > > On Tue, Jul 13, 2021 at 04:06:13PM +0100, Matthew Auld wrote: > > > On Tue, 13 Jul 2021 at 15:44, Daniel Vetter <daniel@xxxxxxxx> wrote: > > > > > > > > On Mon, Jul 12, 2021 at 06:12:34PM -0500, Jason Ekstrand wrote: > > > > > From: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> > > > > > > > > > > Until we support p2p dma or as a complement to that, migrate data > > > > > to system memory at dma-buf attach time if possible. > > > > > > > > > > v2: > > > > > - Rebase on dynamic exporter. Update the igt_dmabuf_import_same_driver > > > > > selftest to migrate if we are LMEM capable. > > > > > v3: > > > > > - Migrate also in the pin() callback. > > > > > v4: > > > > > - Migrate in attach > > > > > v5: (jason) > > > > > - Lock around the migration > > > > > > > > > > Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> > > > > > Signed-off-by: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx> > > > > > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > > > > Signed-off-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx> > > > > > Reviewed-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx> > > > > > --- > > > > > drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 25 ++++++++++++++++++- > > > > > .../drm/i915/gem/selftests/i915_gem_dmabuf.c | 4 ++- > > > > > 2 files changed, 27 insertions(+), 2 deletions(-) > > > > > > > > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > > > > > index 9a655f69a0671..3163f00554476 100644 > > > > > --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > > > > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > > > > > @@ -170,8 +170,31 @@ static int i915_gem_dmabuf_attach(struct dma_buf *dmabuf, > > > > > struct dma_buf_attachment *attach) > > > > > { > > > > > struct drm_i915_gem_object *obj = dma_buf_to_obj(dmabuf); > > > > > + struct i915_gem_ww_ctx ww; > > > > > + int err; > > > > > + > > > > > + for_i915_gem_ww(&ww, err, true) { > > > > > + err = i915_gem_object_lock(obj, &ww); > > > > > + if (err) > > > > > + continue; > > > > > + > > > > > + if (!i915_gem_object_can_migrate(obj, INTEL_REGION_SMEM)) { > > > > > + err = -EOPNOTSUPP; > > > > > + continue; > > > > > + } > > > > > + > > > > > + err = i915_gem_object_migrate(obj, &ww, INTEL_REGION_SMEM); > > > > > + if (err) > > > > > + continue; > > > > > > > > > > - return i915_gem_object_pin_pages_unlocked(obj); > > > > > + err = i915_gem_object_wait_migration(obj, 0); > > > > > + if (err) > > > > > + continue; > > > > > + > > > > > + err = i915_gem_object_pin_pages(obj); > > > > > + } > > > > > + > > > > > + return err; > > > > > } > > > > > > > > > > static void i915_gem_dmabuf_detach(struct dma_buf *dmabuf, > > > > > diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c > > > > > index 3dc0f8b3cdab0..4f7e77b1c0152 100644 > > > > > --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c > > > > > +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c > > > > > @@ -106,7 +106,9 @@ static int igt_dmabuf_import_same_driver(void *arg) > > > > > int err; > > > > > > > > > > force_different_devices = true; > > > > > - obj = i915_gem_object_create_shmem(i915, PAGE_SIZE); > > > > > + obj = i915_gem_object_create_lmem(i915, PAGE_SIZE, 0); > > > > > > > > I'm wondering (and couldn't answer) whether this creates an lmem+smem > > > > buffer, since if we create an lmem-only buffer then the migration above > > > > should fail. > > > > > > It's lmem-only, but it's also a kernel internal object, so the > > > migration path will still happily migrate it if asked. On the other > > > hand if it's a userspace object then we always have to respect the > > > placements. > > > > > > I think for now the only usecase for that is in the selftests. > > > > Yeah I've read the kerneldoc, it's all nicely documented but feels a bit > > dangerous. What I proposed on irc: > > - i915_gem_object_migrate does the placement check, i.e. as strict as > > can_migrate. > > - A new __i915_gem_object_migrate is for selftest that do special stuff. > > I just sent out a patch which does this except we don't actually need > the __ version because there are no self-tests that want to do a > dangerous migrate. We could add such a helper later if we needed. > > > - In the import selftest we check that lmem-only fails (because we can't > > pin it into smem) for a non-dynamic importer, but lmem+smem works and > > gets migrated. > > I think we maybe want multiple things here? The test we have right > now is useful because, by creating an internal LMEM buffer we ensure > that the migration actually happens. If we create LMEM+SMEM, then > it's possible it'll start off in SMEM and the migration would be a > no-op. Not sure how likely that is in reality in a self-test > environment, though. lmem+smem is supposed to allocate in lmem first (I guess we could verify this by peeking behind the curtain), so it should migrate. -Daniel > > --Jason > > > - Once we have dynamic dma-buf for p2p pci, then we'll have another > > selftest which checks that things work for lmem only if and only if the > > importer is dynamic and has set the allow_p2p flag. > > > > We could also add the can_migrate check everywhere (including > > dma_buf->attach), but that feels like the less save api. > > -Daniel > > > > > > > > > > > > > > > Which I'm also not sure we have a testcase for that testcase either ... > > > > > > > > I tried to read some code here, but got a bit lost. Ideas? > > > > -Daniel > > > > > > > > > + if (IS_ERR(obj)) > > > > > + obj = i915_gem_object_create_shmem(i915, PAGE_SIZE); > > > > > if (IS_ERR(obj)) > > > > > goto out_ret; > > > > > > > > > > -- > > > > > 2.31.1 > > > > > > > > > > > > > -- > > > > Daniel Vetter > > > > Software Engineer, Intel Corporation > > > > http://blog.ffwll.ch > > > > -- > > Daniel Vetter > > Software Engineer, Intel Corporation > > http://blog.ffwll.ch -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch