| Message ID | 20210628144626.76126-5-thomas.hellstrom@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915/gem: Introduce a migrate interface | expand |
>-----Original Message----- >From: Thomas Hellström <thomas.hellstrom@linux.intel.com> >Sent: Monday, June 28, 2021 10:46 AM >To: intel-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org >Cc: Auld, Matthew <matthew.auld@intel.com>; >maarten.lankhorst@linux.intel.com; Thomas Hellström ><thomas.hellstrom@linux.intel.com>; Ruhl; Ruhl, Michael J ><michael.j.ruhl@intel.com> >Subject: [PATCH v3 4/5] drm/i915/gem: Fix same-driver-another-instance >dma-buf export > >If our exported dma-bufs are imported by another instance of our driver, >that instance will typically have the imported dma-bufs locked during >map_attachment(). But the exporter also locks the same reservation >object in the map_dma_buf() callback, which leads to recursive locking. > >Add a live selftest to catch this case, and as a workaround until >we fully support dynamic import and export, declare the exporter dynamic >by providing NOP pin() and unpin() functions. This means our map_dma_buf() >callback will *always* get called locked, and by pinning unconditionally >in i915_gem_map_dma_buf() we make sure we don't need to use the >move_notify() functionality which is not yet implemented. An interesting abuse of the interface, but it seems reasonable (for now) to me. Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com> Mike >Reported-by: Ruhl, Michael J <michael.j.ruhl@intel.com> >Cc: Ruhl, Michael J <michael.j.ruhl@intel.com> >Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> >--- > drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 31 ++++++- > .../drm/i915/gem/selftests/i915_gem_dmabuf.c | 81 >++++++++++++++++++- > 2 files changed, 108 insertions(+), 4 deletions(-) > >diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >index 616c3a2f1baf..1d1eeb167d28 100644 >--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >@@ -12,6 +12,8 @@ > #include "i915_gem_object.h" > #include "i915_scatterlist.h" > >+I915_SELFTEST_DECLARE(static bool force_different_devices;) >+ > static struct drm_i915_gem_object *dma_buf_to_obj(struct dma_buf *buf) > { > return to_intel_bo(buf->priv); >@@ -25,7 +27,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct >dma_buf_attachment *attachme > struct scatterlist *src, *dst; > int ret, i; > >- ret = i915_gem_object_pin_pages_unlocked(obj); >+ assert_object_held(obj); >+ >+ ret = i915_gem_object_pin_pages(obj); > if (ret) > goto err; > >@@ -168,6 +172,26 @@ static int i915_gem_end_cpu_access(struct dma_buf >*dma_buf, enum dma_data_direct > return err; > } > >+/* >+ * As a workaround until we fully support dynamic import and export, >+ * declare the exporter dynamic by providing NOP pin() and unpin() >functions. >+ * This means our i915_gem_map_dma_buf() callback will *always* get >called >+ * locked, and by pinning unconditionally in i915_gem_map_dma_buf() we >make >+ * sure we don't need to use the move_notify() functionality which is >+ * not yet implemented. Typically for the same-driver-another-instance case, >+ * i915_gem_map_dma_buf() will be called at importer attach time and the >+ * mapped sg_list will be cached by the dma-buf core for the >+ * duration of the attachment. >+ */ >+static int i915_gem_dmabuf_pin(struct dma_buf_attachment *attach) >+{ >+ return 0; >+} >+ >+static void i915_gem_dmabuf_unpin(struct dma_buf_attachment *attach) >+{ >+} >+ > static const struct dma_buf_ops i915_dmabuf_ops = { > .map_dma_buf = i915_gem_map_dma_buf, > .unmap_dma_buf = i915_gem_unmap_dma_buf, >@@ -177,6 +201,8 @@ static const struct dma_buf_ops i915_dmabuf_ops = { > .vunmap = i915_gem_dmabuf_vunmap, > .begin_cpu_access = i915_gem_begin_cpu_access, > .end_cpu_access = i915_gem_end_cpu_access, >+ .pin = i915_gem_dmabuf_pin, >+ .unpin = i915_gem_dmabuf_unpin, > }; > > struct dma_buf *i915_gem_prime_export(struct drm_gem_object >*gem_obj, int flags) >@@ -241,7 +267,8 @@ struct drm_gem_object >*i915_gem_prime_import(struct drm_device *dev, > if (dma_buf->ops == &i915_dmabuf_ops) { > obj = dma_buf_to_obj(dma_buf); > /* is it from our device? */ >- if (obj->base.dev == dev) { >+ if (obj->base.dev == dev && >+ !I915_SELFTEST_ONLY(force_different_devices)) { > /* > * Importing dmabuf exported from out own gem >increases > * refcount on gem itself instead of f_count of >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 dd74bc09ec88..24735d6c12a2 100644 >--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c >+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c >@@ -35,7 +35,7 @@ static int igt_dmabuf_export(void *arg) > static int igt_dmabuf_import_self(void *arg) > { > struct drm_i915_private *i915 = arg; >- struct drm_i915_gem_object *obj; >+ struct drm_i915_gem_object *obj, *import_obj; > struct drm_gem_object *import; > struct dma_buf *dmabuf; > int err; >@@ -65,14 +65,90 @@ static int igt_dmabuf_import_self(void *arg) > err = -EINVAL; > goto out_import; > } >+ import_obj = to_intel_bo(import); >+ >+ i915_gem_object_lock(import_obj, NULL); >+ err = ____i915_gem_object_get_pages(import_obj); >+ i915_gem_object_unlock(import_obj); >+ if (err) { >+ pr_err("Same object dma-buf get_pages failed!\n"); >+ goto out_import; >+ } > > err = 0; > out_import: >- i915_gem_object_put(to_intel_bo(import)); >+ i915_gem_object_put(import_obj); >+out_dmabuf: >+ dma_buf_put(dmabuf); >+out: >+ i915_gem_object_put(obj); >+ return err; >+} >+ >+static int igt_dmabuf_import_same_driver(void *arg) >+{ >+ struct drm_i915_private *i915 = arg; >+ struct drm_i915_gem_object *obj, *import_obj; >+ struct drm_gem_object *import; >+ struct dma_buf *dmabuf; >+ int err; >+ >+ force_different_devices = true; >+ obj = i915_gem_object_create_shmem(i915, PAGE_SIZE); >+ if (IS_ERR(obj)) >+ goto out_ret; >+ >+ dmabuf = i915_gem_prime_export(&obj->base, 0); >+ if (IS_ERR(dmabuf)) { >+ pr_err("i915_gem_prime_export failed with err=%d\n", >+ (int)PTR_ERR(dmabuf)); >+ err = PTR_ERR(dmabuf); >+ goto out; >+ } >+ >+ import = i915_gem_prime_import(&i915->drm, dmabuf); >+ if (IS_ERR(import)) { >+ pr_err("i915_gem_prime_import failed with err=%d\n", >+ (int)PTR_ERR(import)); >+ err = PTR_ERR(import); >+ goto out_dmabuf; >+ } >+ >+ if (import == &obj->base) { >+ pr_err("i915_gem_prime_import reused gem object!\n"); >+ err = -EINVAL; >+ goto out_import; >+ } >+ >+ import_obj = to_intel_bo(import); >+ >+ i915_gem_object_lock(import_obj, NULL); >+ err = ____i915_gem_object_get_pages(import_obj); >+ if (err) { >+ pr_err("Different objects dma-buf get_pages failed!\n"); >+ i915_gem_object_unlock(import_obj); >+ goto out_import; >+ } >+ >+ /* >+ * If the exported object is not in system memory, something >+ * weird is going on. TODO: When p2p is supported, this is no >+ * longer considered weird. >+ */ >+ if (obj->mm.region != i915->mm.regions[INTEL_REGION_SMEM]) { >+ pr_err("Exported dma-buf is not in system memory\n"); >+ err = -EINVAL; >+ } >+ i915_gem_object_unlock(import_obj); >+ >+out_import: >+ i915_gem_object_put(import_obj); > out_dmabuf: > dma_buf_put(dmabuf); > out: > i915_gem_object_put(obj); >+out_ret: >+ force_different_devices = false; > return err; > } > >@@ -286,6 +362,7 @@ int i915_gem_dmabuf_live_selftests(struct >drm_i915_private *i915) > { > static const struct i915_subtest tests[] = { > SUBTEST(igt_dmabuf_export), >+ SUBTEST(igt_dmabuf_import_same_driver), > }; > > return i915_subtests(tests, i915); >-- >2.31.1
On Mon, Jun 28, 2021 at 07:45:31PM +0000, Ruhl, Michael J wrote: > >-----Original Message----- > >From: Thomas Hellström <thomas.hellstrom@linux.intel.com> > >Sent: Monday, June 28, 2021 10:46 AM > >To: intel-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org > >Cc: Auld, Matthew <matthew.auld@intel.com>; > >maarten.lankhorst@linux.intel.com; Thomas Hellström > ><thomas.hellstrom@linux.intel.com>; Ruhl; Ruhl, Michael J > ><michael.j.ruhl@intel.com> > >Subject: [PATCH v3 4/5] drm/i915/gem: Fix same-driver-another-instance > >dma-buf export > > > >If our exported dma-bufs are imported by another instance of our driver, > >that instance will typically have the imported dma-bufs locked during > >map_attachment(). But the exporter also locks the same reservation > >object in the map_dma_buf() callback, which leads to recursive locking. > > > >Add a live selftest to catch this case, and as a workaround until > >we fully support dynamic import and export, declare the exporter dynamic > >by providing NOP pin() and unpin() functions. This means our map_dma_buf() > >callback will *always* get called locked, and by pinning unconditionally > >in i915_gem_map_dma_buf() we make sure we don't need to use the > >move_notify() functionality which is not yet implemented. > > An interesting abuse of the interface, but it seems reasonable (for now) to me. Hm I'm not sure this is the best interface abuse, since if we combine this with amdgpu it goes boom. Also I thought the dynamic stuff is optional (or is that only for the importer). What I discussed a bit with Maarten on irc is to essentially emulate the rules of what a dynamic exporter would end up with with a non-dynamic importer: pin/unpin the buffer at attach/detach time. We could fake this in our attach/detach callbacks. At least I don't think it's the locking changes that saves us here, but the caching of the sgt list in attach/detach. As long as we hand-roll that we should be fine. So hand-rolling that feels like the best option to make sure we're not making this worse, as long as we haven't fully validated the true dynamic importer _and_ exporter case. Cheers, Daniel > Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com> > > Mike > > >Reported-by: Ruhl, Michael J <michael.j.ruhl@intel.com> > >Cc: Ruhl, Michael J <michael.j.ruhl@intel.com> > >Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> > >--- > > drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 31 ++++++- > > .../drm/i915/gem/selftests/i915_gem_dmabuf.c | 81 > >++++++++++++++++++- > > 2 files changed, 108 insertions(+), 4 deletions(-) > > > >diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > >b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > >index 616c3a2f1baf..1d1eeb167d28 100644 > >--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > >+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c > >@@ -12,6 +12,8 @@ > > #include "i915_gem_object.h" > > #include "i915_scatterlist.h" > > > >+I915_SELFTEST_DECLARE(static bool force_different_devices;) > >+ > > static struct drm_i915_gem_object *dma_buf_to_obj(struct dma_buf *buf) > > { > > return to_intel_bo(buf->priv); > >@@ -25,7 +27,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct > >dma_buf_attachment *attachme > > struct scatterlist *src, *dst; > > int ret, i; > > > >- ret = i915_gem_object_pin_pages_unlocked(obj); > >+ assert_object_held(obj); > >+ > >+ ret = i915_gem_object_pin_pages(obj); > > if (ret) > > goto err; > > > >@@ -168,6 +172,26 @@ static int i915_gem_end_cpu_access(struct dma_buf > >*dma_buf, enum dma_data_direct > > return err; > > } > > > >+/* > >+ * As a workaround until we fully support dynamic import and export, > >+ * declare the exporter dynamic by providing NOP pin() and unpin() > >functions. > >+ * This means our i915_gem_map_dma_buf() callback will *always* get > >called > >+ * locked, and by pinning unconditionally in i915_gem_map_dma_buf() we > >make > >+ * sure we don't need to use the move_notify() functionality which is > >+ * not yet implemented. Typically for the same-driver-another-instance case, > >+ * i915_gem_map_dma_buf() will be called at importer attach time and the > >+ * mapped sg_list will be cached by the dma-buf core for the > >+ * duration of the attachment. > >+ */ > >+static int i915_gem_dmabuf_pin(struct dma_buf_attachment *attach) > >+{ > >+ return 0; > >+} > >+ > >+static void i915_gem_dmabuf_unpin(struct dma_buf_attachment *attach) > >+{ > >+} > >+ > > static const struct dma_buf_ops i915_dmabuf_ops = { > > .map_dma_buf = i915_gem_map_dma_buf, > > .unmap_dma_buf = i915_gem_unmap_dma_buf, > >@@ -177,6 +201,8 @@ static const struct dma_buf_ops i915_dmabuf_ops = { > > .vunmap = i915_gem_dmabuf_vunmap, > > .begin_cpu_access = i915_gem_begin_cpu_access, > > .end_cpu_access = i915_gem_end_cpu_access, > >+ .pin = i915_gem_dmabuf_pin, > >+ .unpin = i915_gem_dmabuf_unpin, > > }; > > > > struct dma_buf *i915_gem_prime_export(struct drm_gem_object > >*gem_obj, int flags) > >@@ -241,7 +267,8 @@ struct drm_gem_object > >*i915_gem_prime_import(struct drm_device *dev, > > if (dma_buf->ops == &i915_dmabuf_ops) { > > obj = dma_buf_to_obj(dma_buf); > > /* is it from our device? */ > >- if (obj->base.dev == dev) { > >+ if (obj->base.dev == dev && > >+ !I915_SELFTEST_ONLY(force_different_devices)) { > > /* > > * Importing dmabuf exported from out own gem > >increases > > * refcount on gem itself instead of f_count of > >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 dd74bc09ec88..24735d6c12a2 100644 > >--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c > >+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c > >@@ -35,7 +35,7 @@ static int igt_dmabuf_export(void *arg) > > static int igt_dmabuf_import_self(void *arg) > > { > > struct drm_i915_private *i915 = arg; > >- struct drm_i915_gem_object *obj; > >+ struct drm_i915_gem_object *obj, *import_obj; > > struct drm_gem_object *import; > > struct dma_buf *dmabuf; > > int err; > >@@ -65,14 +65,90 @@ static int igt_dmabuf_import_self(void *arg) > > err = -EINVAL; > > goto out_import; > > } > >+ import_obj = to_intel_bo(import); > >+ > >+ i915_gem_object_lock(import_obj, NULL); > >+ err = ____i915_gem_object_get_pages(import_obj); > >+ i915_gem_object_unlock(import_obj); > >+ if (err) { > >+ pr_err("Same object dma-buf get_pages failed!\n"); > >+ goto out_import; > >+ } > > > > err = 0; > > out_import: > >- i915_gem_object_put(to_intel_bo(import)); > >+ i915_gem_object_put(import_obj); > >+out_dmabuf: > >+ dma_buf_put(dmabuf); > >+out: > >+ i915_gem_object_put(obj); > >+ return err; > >+} > >+ > >+static int igt_dmabuf_import_same_driver(void *arg) > >+{ > >+ struct drm_i915_private *i915 = arg; > >+ struct drm_i915_gem_object *obj, *import_obj; > >+ struct drm_gem_object *import; > >+ struct dma_buf *dmabuf; > >+ int err; > >+ > >+ force_different_devices = true; > >+ obj = i915_gem_object_create_shmem(i915, PAGE_SIZE); > >+ if (IS_ERR(obj)) > >+ goto out_ret; > >+ > >+ dmabuf = i915_gem_prime_export(&obj->base, 0); > >+ if (IS_ERR(dmabuf)) { > >+ pr_err("i915_gem_prime_export failed with err=%d\n", > >+ (int)PTR_ERR(dmabuf)); > >+ err = PTR_ERR(dmabuf); > >+ goto out; > >+ } > >+ > >+ import = i915_gem_prime_import(&i915->drm, dmabuf); > >+ if (IS_ERR(import)) { > >+ pr_err("i915_gem_prime_import failed with err=%d\n", > >+ (int)PTR_ERR(import)); > >+ err = PTR_ERR(import); > >+ goto out_dmabuf; > >+ } > >+ > >+ if (import == &obj->base) { > >+ pr_err("i915_gem_prime_import reused gem object!\n"); > >+ err = -EINVAL; > >+ goto out_import; > >+ } > >+ > >+ import_obj = to_intel_bo(import); > >+ > >+ i915_gem_object_lock(import_obj, NULL); > >+ err = ____i915_gem_object_get_pages(import_obj); > >+ if (err) { > >+ pr_err("Different objects dma-buf get_pages failed!\n"); > >+ i915_gem_object_unlock(import_obj); > >+ goto out_import; > >+ } > >+ > >+ /* > >+ * If the exported object is not in system memory, something > >+ * weird is going on. TODO: When p2p is supported, this is no > >+ * longer considered weird. > >+ */ > >+ if (obj->mm.region != i915->mm.regions[INTEL_REGION_SMEM]) { > >+ pr_err("Exported dma-buf is not in system memory\n"); > >+ err = -EINVAL; > >+ } > >+ i915_gem_object_unlock(import_obj); > >+ > >+out_import: > >+ i915_gem_object_put(import_obj); > > out_dmabuf: > > dma_buf_put(dmabuf); > > out: > > i915_gem_object_put(obj); > >+out_ret: > >+ force_different_devices = false; > > return err; > > } > > > >@@ -286,6 +362,7 @@ int i915_gem_dmabuf_live_selftests(struct > >drm_i915_private *i915) > > { > > static const struct i915_subtest tests[] = { > > SUBTEST(igt_dmabuf_export), > >+ SUBTEST(igt_dmabuf_import_same_driver), > > }; > > > > return i915_subtests(tests, i915); > >-- > >2.31.1 >
On 6/29/21 10:43 AM, Daniel Vetter wrote: > On Mon, Jun 28, 2021 at 07:45:31PM +0000, Ruhl, Michael J wrote: >>> -----Original Message----- >>> From: Thomas Hellström <thomas.hellstrom@linux.intel.com> >>> Sent: Monday, June 28, 2021 10:46 AM >>> To: intel-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org >>> Cc: Auld, Matthew <matthew.auld@intel.com>; >>> maarten.lankhorst@linux.intel.com; Thomas Hellström >>> <thomas.hellstrom@linux.intel.com>; Ruhl; Ruhl, Michael J >>> <michael.j.ruhl@intel.com> >>> Subject: [PATCH v3 4/5] drm/i915/gem: Fix same-driver-another-instance >>> dma-buf export >>> >>> If our exported dma-bufs are imported by another instance of our driver, >>> that instance will typically have the imported dma-bufs locked during >>> map_attachment(). But the exporter also locks the same reservation >>> object in the map_dma_buf() callback, which leads to recursive locking. >>> >>> Add a live selftest to catch this case, and as a workaround until >>> we fully support dynamic import and export, declare the exporter dynamic >>> by providing NOP pin() and unpin() functions. This means our map_dma_buf() >>> callback will *always* get called locked, and by pinning unconditionally >>> in i915_gem_map_dma_buf() we make sure we don't need to use the >>> move_notify() functionality which is not yet implemented. >> An interesting abuse of the interface, but it seems reasonable (for now) to me. > Hm I'm not sure this is the best interface abuse, since if we combine this > with amdgpu it goes boom. Also I thought the dynamic stuff is optional (or > is that only for the importer). I'm not sure what would go wrong here when combined with amdgpu? I figure an amdgpu importer being dynamic, would expect to get notified using move_notify() on move, but that never happens since the exported bo is pinned. If it matters for interface abuse then I could add real implementations of pin() and unpin(). But choosing to not evict a mapped dma-buf must remain at the exporter's discretion and is not an interface abuse IMO. Could you point me to a case that would not work with this code? > What I discussed a bit with Maarten on irc is to essentially emulate the > rules of what a dynamic exporter would end up with with a non-dynamic > importer: pin/unpin the buffer at attach/detach time. We could fake this > in our attach/detach callbacks. Yes, but that would only reimplement what's already in the dma-buf core? Since we're about to add a real and correct implementation of this, that sounds like a waste of time IMHO. > > At least I don't think it's the locking changes that saves us here, but > the caching of the sgt list in attach/detach. Yes that saves us for the case of a non-locking non-dynamic importer, but for same-driver-another-instance, it's indeed the locking changes. > As long as we hand-roll that > we should be fine. So hand-rolling that feels like the best option to make > sure we're not making this worse, as long as we haven't fully validated > the true dynamic importer _and_ exporter case. /Thomas > > Cheers, Daniel > >> Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com> >> >> Mike >> >>> Reported-by: Ruhl, Michael J <michael.j.ruhl@intel.com> >>> Cc: Ruhl, Michael J <michael.j.ruhl@intel.com> >>> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> >>> --- >>> drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 31 ++++++- >>> .../drm/i915/gem/selftests/i915_gem_dmabuf.c | 81 >>> ++++++++++++++++++- >>> 2 files changed, 108 insertions(+), 4 deletions(-) >>> >>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >>> b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >>> index 616c3a2f1baf..1d1eeb167d28 100644 >>> --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c >>> @@ -12,6 +12,8 @@ >>> #include "i915_gem_object.h" >>> #include "i915_scatterlist.h" >>> >>> +I915_SELFTEST_DECLARE(static bool force_different_devices;) >>> + >>> static struct drm_i915_gem_object *dma_buf_to_obj(struct dma_buf *buf) >>> { >>> return to_intel_bo(buf->priv); >>> @@ -25,7 +27,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct >>> dma_buf_attachment *attachme >>> struct scatterlist *src, *dst; >>> int ret, i; >>> >>> - ret = i915_gem_object_pin_pages_unlocked(obj); >>> + assert_object_held(obj); >>> + >>> + ret = i915_gem_object_pin_pages(obj); >>> if (ret) >>> goto err; >>> >>> @@ -168,6 +172,26 @@ static int i915_gem_end_cpu_access(struct dma_buf >>> *dma_buf, enum dma_data_direct >>> return err; >>> } >>> >>> +/* >>> + * As a workaround until we fully support dynamic import and export, >>> + * declare the exporter dynamic by providing NOP pin() and unpin() >>> functions. >>> + * This means our i915_gem_map_dma_buf() callback will *always* get >>> called >>> + * locked, and by pinning unconditionally in i915_gem_map_dma_buf() we >>> make >>> + * sure we don't need to use the move_notify() functionality which is >>> + * not yet implemented. Typically for the same-driver-another-instance case, >>> + * i915_gem_map_dma_buf() will be called at importer attach time and the >>> + * mapped sg_list will be cached by the dma-buf core for the >>> + * duration of the attachment. >>> + */ >>> +static int i915_gem_dmabuf_pin(struct dma_buf_attachment *attach) >>> +{ >>> + return 0; >>> +} >>> + >>> +static void i915_gem_dmabuf_unpin(struct dma_buf_attachment *attach) >>> +{ >>> +} >>> + >>> static const struct dma_buf_ops i915_dmabuf_ops = { >>> .map_dma_buf = i915_gem_map_dma_buf, >>> .unmap_dma_buf = i915_gem_unmap_dma_buf, >>> @@ -177,6 +201,8 @@ static const struct dma_buf_ops i915_dmabuf_ops = { >>> .vunmap = i915_gem_dmabuf_vunmap, >>> .begin_cpu_access = i915_gem_begin_cpu_access, >>> .end_cpu_access = i915_gem_end_cpu_access, >>> + .pin = i915_gem_dmabuf_pin, >>> + .unpin = i915_gem_dmabuf_unpin, >>> }; >>> >>> struct dma_buf *i915_gem_prime_export(struct drm_gem_object >>> *gem_obj, int flags) >>> @@ -241,7 +267,8 @@ struct drm_gem_object >>> *i915_gem_prime_import(struct drm_device *dev, >>> if (dma_buf->ops == &i915_dmabuf_ops) { >>> obj = dma_buf_to_obj(dma_buf); >>> /* is it from our device? */ >>> - if (obj->base.dev == dev) { >>> + if (obj->base.dev == dev && >>> + !I915_SELFTEST_ONLY(force_different_devices)) { >>> /* >>> * Importing dmabuf exported from out own gem >>> increases >>> * refcount on gem itself instead of f_count of >>> 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 dd74bc09ec88..24735d6c12a2 100644 >>> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c >>> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c >>> @@ -35,7 +35,7 @@ static int igt_dmabuf_export(void *arg) >>> static int igt_dmabuf_import_self(void *arg) >>> { >>> struct drm_i915_private *i915 = arg; >>> - struct drm_i915_gem_object *obj; >>> + struct drm_i915_gem_object *obj, *import_obj; >>> struct drm_gem_object *import; >>> struct dma_buf *dmabuf; >>> int err; >>> @@ -65,14 +65,90 @@ static int igt_dmabuf_import_self(void *arg) >>> err = -EINVAL; >>> goto out_import; >>> } >>> + import_obj = to_intel_bo(import); >>> + >>> + i915_gem_object_lock(import_obj, NULL); >>> + err = ____i915_gem_object_get_pages(import_obj); >>> + i915_gem_object_unlock(import_obj); >>> + if (err) { >>> + pr_err("Same object dma-buf get_pages failed!\n"); >>> + goto out_import; >>> + } >>> >>> err = 0; >>> out_import: >>> - i915_gem_object_put(to_intel_bo(import)); >>> + i915_gem_object_put(import_obj); >>> +out_dmabuf: >>> + dma_buf_put(dmabuf); >>> +out: >>> + i915_gem_object_put(obj); >>> + return err; >>> +} >>> + >>> +static int igt_dmabuf_import_same_driver(void *arg) >>> +{ >>> + struct drm_i915_private *i915 = arg; >>> + struct drm_i915_gem_object *obj, *import_obj; >>> + struct drm_gem_object *import; >>> + struct dma_buf *dmabuf; >>> + int err; >>> + >>> + force_different_devices = true; >>> + obj = i915_gem_object_create_shmem(i915, PAGE_SIZE); >>> + if (IS_ERR(obj)) >>> + goto out_ret; >>> + >>> + dmabuf = i915_gem_prime_export(&obj->base, 0); >>> + if (IS_ERR(dmabuf)) { >>> + pr_err("i915_gem_prime_export failed with err=%d\n", >>> + (int)PTR_ERR(dmabuf)); >>> + err = PTR_ERR(dmabuf); >>> + goto out; >>> + } >>> + >>> + import = i915_gem_prime_import(&i915->drm, dmabuf); >>> + if (IS_ERR(import)) { >>> + pr_err("i915_gem_prime_import failed with err=%d\n", >>> + (int)PTR_ERR(import)); >>> + err = PTR_ERR(import); >>> + goto out_dmabuf; >>> + } >>> + >>> + if (import == &obj->base) { >>> + pr_err("i915_gem_prime_import reused gem object!\n"); >>> + err = -EINVAL; >>> + goto out_import; >>> + } >>> + >>> + import_obj = to_intel_bo(import); >>> + >>> + i915_gem_object_lock(import_obj, NULL); >>> + err = ____i915_gem_object_get_pages(import_obj); >>> + if (err) { >>> + pr_err("Different objects dma-buf get_pages failed!\n"); >>> + i915_gem_object_unlock(import_obj); >>> + goto out_import; >>> + } >>> + >>> + /* >>> + * If the exported object is not in system memory, something >>> + * weird is going on. TODO: When p2p is supported, this is no >>> + * longer considered weird. >>> + */ >>> + if (obj->mm.region != i915->mm.regions[INTEL_REGION_SMEM]) { >>> + pr_err("Exported dma-buf is not in system memory\n"); >>> + err = -EINVAL; >>> + } >>> + i915_gem_object_unlock(import_obj); >>> + >>> +out_import: >>> + i915_gem_object_put(import_obj); >>> out_dmabuf: >>> dma_buf_put(dmabuf); >>> out: >>> i915_gem_object_put(obj); >>> +out_ret: >>> + force_different_devices = false; >>> return err; >>> } >>> >>> @@ -286,6 +362,7 @@ int i915_gem_dmabuf_live_selftests(struct >>> drm_i915_private *i915) >>> { >>> static const struct i915_subtest tests[] = { >>> SUBTEST(igt_dmabuf_export), >>> + SUBTEST(igt_dmabuf_import_same_driver), >>> }; >>> >>> return i915_subtests(tests, i915); >>> -- >>> 2.31.1
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c index 616c3a2f1baf..1d1eeb167d28 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c @@ -12,6 +12,8 @@ #include "i915_gem_object.h" #include "i915_scatterlist.h" +I915_SELFTEST_DECLARE(static bool force_different_devices;) + static struct drm_i915_gem_object *dma_buf_to_obj(struct dma_buf *buf) { return to_intel_bo(buf->priv); @@ -25,7 +27,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme struct scatterlist *src, *dst; int ret, i; - ret = i915_gem_object_pin_pages_unlocked(obj); + assert_object_held(obj); + + ret = i915_gem_object_pin_pages(obj); if (ret) goto err; @@ -168,6 +172,26 @@ static int i915_gem_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direct return err; } +/* + * As a workaround until we fully support dynamic import and export, + * declare the exporter dynamic by providing NOP pin() and unpin() functions. + * This means our i915_gem_map_dma_buf() callback will *always* get called + * locked, and by pinning unconditionally in i915_gem_map_dma_buf() we make + * sure we don't need to use the move_notify() functionality which is + * not yet implemented. Typically for the same-driver-another-instance case, + * i915_gem_map_dma_buf() will be called at importer attach time and the + * mapped sg_list will be cached by the dma-buf core for the + * duration of the attachment. + */ +static int i915_gem_dmabuf_pin(struct dma_buf_attachment *attach) +{ + return 0; +} + +static void i915_gem_dmabuf_unpin(struct dma_buf_attachment *attach) +{ +} + static const struct dma_buf_ops i915_dmabuf_ops = { .map_dma_buf = i915_gem_map_dma_buf, .unmap_dma_buf = i915_gem_unmap_dma_buf, @@ -177,6 +201,8 @@ static const struct dma_buf_ops i915_dmabuf_ops = { .vunmap = i915_gem_dmabuf_vunmap, .begin_cpu_access = i915_gem_begin_cpu_access, .end_cpu_access = i915_gem_end_cpu_access, + .pin = i915_gem_dmabuf_pin, + .unpin = i915_gem_dmabuf_unpin, }; struct dma_buf *i915_gem_prime_export(struct drm_gem_object *gem_obj, int flags) @@ -241,7 +267,8 @@ struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev, if (dma_buf->ops == &i915_dmabuf_ops) { obj = dma_buf_to_obj(dma_buf); /* is it from our device? */ - if (obj->base.dev == dev) { + if (obj->base.dev == dev && + !I915_SELFTEST_ONLY(force_different_devices)) { /* * Importing dmabuf exported from out own gem increases * refcount on gem itself instead of f_count of 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 dd74bc09ec88..24735d6c12a2 100644 --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c @@ -35,7 +35,7 @@ static int igt_dmabuf_export(void *arg) static int igt_dmabuf_import_self(void *arg) { struct drm_i915_private *i915 = arg; - struct drm_i915_gem_object *obj; + struct drm_i915_gem_object *obj, *import_obj; struct drm_gem_object *import; struct dma_buf *dmabuf; int err; @@ -65,14 +65,90 @@ static int igt_dmabuf_import_self(void *arg) err = -EINVAL; goto out_import; } + import_obj = to_intel_bo(import); + + i915_gem_object_lock(import_obj, NULL); + err = ____i915_gem_object_get_pages(import_obj); + i915_gem_object_unlock(import_obj); + if (err) { + pr_err("Same object dma-buf get_pages failed!\n"); + goto out_import; + } err = 0; out_import: - i915_gem_object_put(to_intel_bo(import)); + i915_gem_object_put(import_obj); +out_dmabuf: + dma_buf_put(dmabuf); +out: + i915_gem_object_put(obj); + return err; +} + +static int igt_dmabuf_import_same_driver(void *arg) +{ + struct drm_i915_private *i915 = arg; + struct drm_i915_gem_object *obj, *import_obj; + struct drm_gem_object *import; + struct dma_buf *dmabuf; + int err; + + force_different_devices = true; + obj = i915_gem_object_create_shmem(i915, PAGE_SIZE); + if (IS_ERR(obj)) + goto out_ret; + + dmabuf = i915_gem_prime_export(&obj->base, 0); + if (IS_ERR(dmabuf)) { + pr_err("i915_gem_prime_export failed with err=%d\n", + (int)PTR_ERR(dmabuf)); + err = PTR_ERR(dmabuf); + goto out; + } + + import = i915_gem_prime_import(&i915->drm, dmabuf); + if (IS_ERR(import)) { + pr_err("i915_gem_prime_import failed with err=%d\n", + (int)PTR_ERR(import)); + err = PTR_ERR(import); + goto out_dmabuf; + } + + if (import == &obj->base) { + pr_err("i915_gem_prime_import reused gem object!\n"); + err = -EINVAL; + goto out_import; + } + + import_obj = to_intel_bo(import); + + i915_gem_object_lock(import_obj, NULL); + err = ____i915_gem_object_get_pages(import_obj); + if (err) { + pr_err("Different objects dma-buf get_pages failed!\n"); + i915_gem_object_unlock(import_obj); + goto out_import; + } + + /* + * If the exported object is not in system memory, something + * weird is going on. TODO: When p2p is supported, this is no + * longer considered weird. + */ + if (obj->mm.region != i915->mm.regions[INTEL_REGION_SMEM]) { + pr_err("Exported dma-buf is not in system memory\n"); + err = -EINVAL; + } + i915_gem_object_unlock(import_obj); + +out_import: + i915_gem_object_put(import_obj); out_dmabuf: dma_buf_put(dmabuf); out: i915_gem_object_put(obj); +out_ret: + force_different_devices = false; return err; } @@ -286,6 +362,7 @@ int i915_gem_dmabuf_live_selftests(struct drm_i915_private *i915) { static const struct i915_subtest tests[] = { SUBTEST(igt_dmabuf_export), + SUBTEST(igt_dmabuf_import_same_driver), }; return i915_subtests(tests, i915);
If our exported dma-bufs are imported by another instance of our driver, that instance will typically have the imported dma-bufs locked during map_attachment(). But the exporter also locks the same reservation object in the map_dma_buf() callback, which leads to recursive locking. Add a live selftest to catch this case, and as a workaround until we fully support dynamic import and export, declare the exporter dynamic by providing NOP pin() and unpin() functions. This means our map_dma_buf() callback will *always* get called locked, and by pinning unconditionally in i915_gem_map_dma_buf() we make sure we don't need to use the move_notify() functionality which is not yet implemented. Reported-by: Ruhl, Michael J <michael.j.ruhl@intel.com> Cc: Ruhl, Michael J <michael.j.ruhl@intel.com> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com> --- drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 31 ++++++- .../drm/i915/gem/selftests/i915_gem_dmabuf.c | 81 ++++++++++++++++++- 2 files changed, 108 insertions(+), 4 deletions(-)