Linaro-mm-sig

linaro-mm-sig@lists.linaro.org

24 participants
3677 discussions

[PATCH 0/5] Replace the dmabuf custom test framework with kunit

by Jason Gunthorpe

Using kunit to write tests for new work on dmabuf is coming up: https://lore.kernel.org/all/26-v1-b5cab63049c0+191af-dmabuf_map_type_jgg@nv… Replace the custom test framework with kunit to avoid maintaining two concurrent test frameworks. The conversion minimizes code changes and uses simple pattern-oriented reworks to reduce the chance of breaking any tests. Aside from adding the kunit_test_suite() boilerplate, the conversion follows a number of patterns: Test failures without cleanup. For example: if (!ptr) return -ENOMEM; Becomes: KUNIT_ASSERT_NOT_NULL(test, ptr); In kunit ASSERT longjumps out of the test. Check for error, fail and cleanup: if (err) { pr_err("msg\n"); goto cleanup; } Becomes: if (err) { KUNIT_FAIL(test, "msg"); goto cleanup; } Preserve the existing failure messages and cleanup code. Cases where the test returns err but prints no message: if (err) goto cleanup; Becomes: if (err) { KUNIT_FAIL(test, "msg"); goto cleanup; } Use KUNIT_FAIL to retain the 'cleanup on err' behavior. Overall, the conversion is straightforward. The result can be run with kunit.py: $ tools/testing/kunit/kunit.py run --build_dir build_kunit_x86_64 --arch x86_64 --kunitconfig ./drivers/dma-buf/.kunitconfig [20:37:23] Configuring KUnit Kernel ... [20:37:23] Building KUnit Kernel ... Populating config with: $ make ARCH=x86_64 O=build_kunit_x86_64 olddefconfig Building with: $ make all compile_commands.json scripts_gdb ARCH=x86_64 O=build_kunit_x86_64 --jobs=20 [20:37:29] Starting KUnit Kernel (1/1)... [20:37:29] ============================================================ Running tests with: $ qemu-system-x86_64 -nodefaults -m 1024 -kernel build_kunit_x86_64/arch/x86/boot/bzImage -append 'kunit.enable=1 console=ttyS0 kunit_shutdown=reboot' -no-reboot -nographic -accel kvm -accel hvf -accel tcg -serial stdio -bios qboot.rom [20:37:30] ================ dma-buf-resv (5 subtests) ================= [20:37:30] [PASSED] test_sanitycheck [20:37:30] ===================== test_signaling ====================== [20:37:30] [PASSED] kernel [20:37:30] [PASSED] write [20:37:30] [PASSED] read [20:37:30] [PASSED] bookkeep [20:37:30] ================= [PASSED] test_signaling ================== ... [20:37:35] Testing complete. Ran 50 tests: passed: 49, skipped: 1 [20:37:35] Elapsed time: 12.635s total, 0.001s configuring, 6.551s building, 6.017s running One test that requires two CPUs is skipped since the default VM has a single CPU and cannot run the test. All other usual ways to run kunit work as well, and all tests are placed in a module to provide more options for how they are run. AI was used to do the large scale semantic search and replaces described above, then everything was hand checked. AI also deduced the issue with test_race_signal_callback() in a couple of seconds from the kunit crash (!!), again was hand checked though I am not so familiar with this test to be fully certain this is the best answer. Jason Gunthorpe (5): dma-buf: Change st-dma-resv.c to use kunit dma-buf: Change st-dma-fence.c to use kunit dma-buf: Change st-dma-fence-unwrap.c to use kunit dma-buf: Change st-dma-fence-chain.c to use kunit dma-buf: Remove the old selftest drivers/dma-buf/.kunitconfig | 2 + drivers/dma-buf/Kconfig | 11 +- drivers/dma-buf/Makefile | 5 +- drivers/dma-buf/selftest.c | 167 --------------- drivers/dma-buf/selftest.h | 30 --- drivers/dma-buf/selftests.h | 16 -- drivers/dma-buf/st-dma-fence-chain.c | 217 +++++++++---------- drivers/dma-buf/st-dma-fence-unwrap.c | 290 +++++++++++--------------- drivers/dma-buf/st-dma-fence.c | 200 ++++++++---------- drivers/dma-buf/st-dma-resv.c | 145 +++++++------ drivers/gpu/drm/i915/Kconfig.debug | 2 +- 11 files changed, 394 insertions(+), 691 deletions(-) create mode 100644 drivers/dma-buf/.kunitconfig delete mode 100644 drivers/dma-buf/selftest.c delete mode 100644 drivers/dma-buf/selftest.h delete mode 100644 drivers/dma-buf/selftests.h base-commit: 41dae5ac5e157b0bb260f381eb3df2f4a4610205 -- 2.43.0

4 months, 1 week

[PATCH] base: Remove unused DMA_FENCE_TRACE Kconfig symbol

by Geert Uytterhoeven

Commit d72277b6c37db66b ("dma-buf: nuke DMA_FENCE_TRACE macros v2") in v5.16 removed all users of DMA_FENCE_TRACE on the premise that the Kconfig symbol did not exist. Apparently one failed to notice the symbol did exist since almost five years before: it was renamed from FENCE_TRACE to DMA_FENCE_TRACE in commit f54d1867005c3323 ("dma-buf: Rename struct fence to dma_fence") in v4.10. Time passed by, so remove the Kconfig symbol, as no one seems to have missed the functionality. Signed-off-by: Geert Uytterhoeven <geert(a)linux-m68k.org> --- drivers/base/Kconfig | 9 --------- 1 file changed, 9 deletions(-) diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index f7d385cbd3ba4b2b..43f20ca95a2a6ba9 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -222,15 +222,6 @@ config DMA_SHARED_BUFFER APIs extension; the file's descriptor can then be passed on to other driver. -config DMA_FENCE_TRACE - bool "Enable verbose DMA_FENCE_TRACE messages" - depends on DMA_SHARED_BUFFER - help - Enable the DMA_FENCE_TRACE printks. This will add extra - spam to the console log, but will make it easier to diagnose - lockup related problems for dma-buffers shared across multiple - devices. - config GENERIC_ARCH_TOPOLOGY bool help -- 2.43.0

4 months, 1 week

[PATCH v3 0/4] rust / dma_buf: Add abstractions for dma_fence

by Philipp Stanner

Changes since v2: - Don't drop DriverFenceData as a whole, but only the members we really want to drop. Gives more robustness. (Gary). - Break apart large pin_init_from_closure(). (Danilo, Onur) - Remove rcu_barrier() and synchronize_rcu() from FenceCtx::drop(). FenceCtx might drop in atomic context, where you must not perform those operations. With the current way C dma_fence is designed, the driver must wait for a grace period manually until it unloads. - Repair the DriverFenceBorrow implementation, properly injecting a life time into it. (Danilo) - Fix memory layout bug for rcu_head. (Onur) - Drop RCU patches, since this series doesn't need them anymore. Changes since v1: - Remove unnecessary mutable references (Alice) - Split up unsafe comments where possible (Danilo) - Remove PhantomData + implement FenceCtx ops trait (Boris) - Consistently call FenceCtx generic data `T`. FenceDataType is derived from that. (Boris) - Add abstractions for call_rcu() and synchronize_rcu() (Danilo) - Add ECANCELED error code in Rust (Alice) - Remove the rcu_barrier() from FenceCtx::drop() – because we now use call_rcu(), there can be no UAF access to the FenceCtx anymore. In any case, it is illegal to use either call_rcu() or synchronize_rcu() in FenceCtx::drop(), because our new drop_driver_fence_data() can run in atomic context and might put the last fence_ctx reference. So we now only have to guard against module unload, which it seems either the driver or Rust driver-core / module unload infrastructure must solve. - Minor formatting etc. changes - Add C helpers to MAINTAINERS. (Danilo) - Ensure that `Fence::is_signaled()` is fully synchronized, i.e., all callbacks really have run. See [1] and [2]. (Myself, Christian König) Changes since the RFCs: - Include support for ForeignOwnable for ARef, so that a Fence can be stuffed into an XArray et al. (Code by Danilo) - Implement ForeignOwnable (with new borrow type) for DriverFence, so that it can be stuffed into an XArray. - Include the rcu::RcuBox data type to defer dropping data with RCU (Cody by Alice) - Port DmaFence to RcuBox to make UAF bugs through later, new dma_fence callbacks (backend_ops) impossible. - Force users to pass their fence data in an RcuBox (or have it not need drop()) through a Sealed trait. - Document the rules for the user's DriverFence::data's drop implementation very clearly (deadlock danger). - rustfmt, Clippy. - Various style suggestions, safety comments, etc. (Önur) - Add __rust_helper prefix to helper functions. (Önur) Changes in RFC v3: - Omit JobQueue patches for now - Completely redesign the memory layout: Instead of a Fence refcounting a DriverFence, both now live in the same allocation to allow for future support the dma_fence backend_ops callbacks which need to do container_of. (mostly Boris's feedback) - Allow for pre-allocating fences to avoid deadlocks when submitting jobs to a GPU. (Boris) - Simultaneously, allow for pre-preparing fence callback objects, so the driver can allocate them when it sees fit. (code largely stolen and inspired by Daniel). - Signal fences on drop, ensure synchronization. - Force users to set an error code when signalling. - Write more documentation - A ton of minor other changes. [1] https://lore.kernel.org/dri-devel/20260608142436.265820-2-phasta@kernel.org/ [2] https://lore.kernel.org/dri-devel/20260612104251.2264707-2-phasta@kernel.or… Alright, so since the last RFCs did not reveal significant design issues, I decided to transition this series to a v1 and hope that we can get it upstream. This now includes code for more common infrastructure that dma_fence needs, contributed by Danilo and Alice. --- Old cover letter for RFC: So, this is the spiritual successor of the first / second RFC [1]. v2 also contained code for drm::JobQueue, but mostly to show how the fence code would be used. JobQueue is under heavy rework right now, so I don't want to bother your eyes with it. The docstring examples should show how Rust fences are supposed to be used, though. This v3 contains a huge amount of highly valuable feedback from a variety of people, notably Boris, but also from Alice, Gary and Danilo. There are some TODOs open (a better trait for fence backend_ops and RCU support), but my hope is that this effort is now finally approaching its end. I would greatly appreciate feedback and especially more information about what might be missing to make this usable, which is obviously where Daniel's and Boris's feedback will be valuable once more. Please regard this patch just as what it's titled: an RFC, to discuss a bit more and to inform a broader community about what the current state is and where this is heading at. Many regards, Philipp [1] https://lore.kernel.org/rust-for-linux/20260203081403.68733-2-phasta@kernel… Danilo Krummrich (1): rust: types: implement ForeignOwnable for ARef<T> Philipp Stanner (3): rust: error: Add ECANCELED error code rust: Add dma_fence abstractions MAINTAINERS: Add entry for Rust dma-buf MAINTAINERS | 3 + rust/bindings/bindings_helper.h | 1 + rust/helpers/dma_fence.c | 48 ++ rust/helpers/helpers.c | 1 + rust/kernel/dma_buf/dma_fence.rs | 852 +++++++++++++++++++++++++++++++ rust/kernel/dma_buf/mod.rs | 14 + rust/kernel/error.rs | 1 + rust/kernel/lib.rs | 1 + rust/kernel/sync/aref.rs | 39 ++ 9 files changed, 960 insertions(+) create mode 100644 rust/helpers/dma_fence.c create mode 100644 rust/kernel/dma_buf/dma_fence.rs create mode 100644 rust/kernel/dma_buf/mod.rs base-commit: 848bf57e98e1678ce7a49eb4e0bf0502da95dc07 -- 2.54.0

4 months, 1 week

Mental Health Tips Every College Student Should Follow

by smithjohns9696＠gmail.com

College life is often seen as an exciting phase filled with new experiences, independence, friendships, and opportunities. However, behind the social events and academic growth, many students also face stress, anxiety, loneliness, and pressure to perform well. Managing mental health during this time is just as important as achieving good grades, because emotional well-being directly impacts concentration, productivity, and overall success. Learning how to take care of your mental health can help students handle challenges more effectively and enjoy a more balanced college experience. Many students struggle to keep up with assignments, deadlines, and academic expectations, which can sometimes feel overwhelming. In such situations, academic support services like pay for someone to <a href="https://myassignmenthelp.com/ca/do-my-homework.html">do my homework online</a> from MyAssignmentHelp can help reduce academic pressure and allow students to focus on maintaining better mental and emotional well-being alongside their studies. Understanding Mental Health in College Life Mental health refers to a person’s emotional, psychological, and social well-being. In college, students go through major life transitions—moving away from home, adapting to new environments, managing finances, and handling academic responsibilities. All of these changes can affect mental stability. It is normal to feel stressed occasionally, but prolonged stress or emotional exhaustion should not be ignored. Recognizing early signs such as fatigue, loss of motivation, irritability, or difficulty concentrating is important for taking timely action. Maintain a Balanced Routine One of the most effective ways to support mental health is by maintaining a balanced daily routine. A structured lifestyle helps reduce chaos and creates a sense of stability. Students should try to: Follow a consistent sleep schedule Allocate time for study and relaxation Avoid last-minute cramming Include breaks between study sessions Set realistic daily goals A balanced routine helps prevent burnout and ensures that students do not feel overwhelmed by academic pressure. Prioritize Sleep and Rest Sleep plays a crucial role in mental health. Lack of sleep can increase stress levels, reduce concentration, and negatively impact memory. College students often sacrifice sleep to complete assignments or prepare for exams, but this habit can be harmful in the long run. Ideally, students should aim for 7–9 hours of quality sleep each night. Creating a bedtime routine, limiting screen time before sleep, and avoiding caffeine late in the day can significantly improve sleep quality. Stay Physically Active Physical activity is not just good for the body but also essential for mental well-being. Exercise releases endorphins, which are natural mood boosters. Students do not need intense workouts to benefit from physical activity. Simple habits like walking, cycling, yoga, or light stretching can make a big difference. Regular exercise helps: Reduce stress and anxiety Improve focus and concentration Boost energy levels Enhance overall mood Even 20–30 minutes of activity a day can have noticeable positive effects. Build Strong Social Connections Social support is one of the most important factors in maintaining good mental health. College is a great place to build friendships and connections that provide emotional support. Students should try to: Spend time with supportive friends Participate in group activities Join clubs or student organizations Talk openly about feelings when needed Having people to talk to can reduce feelings of loneliness and help students cope better with stress. Learn Stress Management Techniques Stress is unavoidable in college, but it can be managed effectively with the right techniques. Some helpful stress management strategies include: Deep breathing exercises Meditation and mindfulness practices Journaling thoughts and emotions Listening to calming music Taking short breaks during study sessions These techniques help calm the mind and improve emotional balance. Avoid Overloading Yourself Many students try to take on too many responsibilities at once—academics, part-time jobs, extracurricular activities, and social commitments. While involvement is important, overloading can lead to burnout. Learning to say no when necessary is a healthy habit. Students should prioritize tasks based on importance and avoid unnecessary pressure. It is better to do a few things well than to do everything poorly due to exhaustion. Seek Help When Needed One of the most important aspects of mental health is recognizing when help is needed. Unfortunately, many students hesitate to seek support due to stigma or fear of judgment. However, asking for help is a sign of strength, not weakness. Support can come from: Friends and family College counselors Mentors or professors Mental health professionals Talking about problems can provide relief and open up solutions that may not be visible when dealing with stress alone. Limit Social Media Usage While social media helps students stay connected, excessive use can negatively affect mental health. Constant comparison with others, exposure to unrealistic lifestyles, and online pressure can increase anxiety and reduce self-esteem. Students should: Set time limits for social media use Avoid comparing themselves to others Take digital detox breaks Focus on real-life interactions Reducing screen time can improve focus, productivity, and emotional well-being. Practice Self-Care Regularly Self-care is essential for maintaining mental balance. It involves taking time to do activities that bring relaxation and happiness. Self-care can include: Reading a book Watching a favorite show Spending time in nature Pursuing hobbies Taking rest without guilt Prioritizing self-care helps recharge the mind and improves resilience against stress. Develop a Positive Mindset A positive mindset plays a major role in mental health. College life comes with challenges, and setbacks are a normal part of the journey. Instead of focusing on failures, students should: Learn from mistakes Celebrate small achievements Stay hopeful during difficult times Practice gratitude Positive thinking helps build confidence and reduces emotional distress. Maintain Academic Balance Academic pressure is one of the biggest sources of stress for college students. Managing coursework effectively can significantly improve mental health. Students should break tasks into smaller steps, avoid procrastination, and seek academic support when necessary. Staying organized can reduce last-minute stress and improve overall performance. Conclusion Mental health is a vital part of a successful and fulfilling college experience. Students who take care of their emotional well-being are more likely to perform better academically, build stronger relationships, and enjoy their college journey. By maintaining a balanced routine, staying physically active, managing stress, and seeking support when needed, students can create a healthier and more positive lifestyle. Remember, college is not just about academic achievement—it is also about growing as a person, and mental well-being

4 months, 1 week

[PATCH net-next v2 0/4] net: devmem: allow rx-buf-size > PAGE_SIZE per binding

by Bobby Eshleman

Every devmem dmabuf binding hands the page_pool PAGE_SIZE niovs today. On NICs that consume one descriptor per netmem, this caps a single RX descriptor at PAGE_SIZE and burns CPU on buffer churn. In this series, we add a bind-time netlink attribute, NETDEV_A_DMABUF_RX_BUF_SIZE, that lets userspace request a larger niov size (power of two >= PAGE_SIZE). Drivers must opt in via queue_mgmt_ops.QCFG_RX_PAGE_SIZE. Selftests use udmabuf, but udmabuf sgtables were previously hardcoded to PAGE_SIZE. This series modifies udmabuf to respect folio sizes in its exported sgtable. The result is that when backing udmabuf with MFD_HUGETLB 2MB pages, the sgtable is populated with 2MB entries, allowing devmem's gen_pool to carve out large (eg. 64K) niovs. Measurements ------------ Setup: kperf devmem RX/TX cuda, 4 flows, 64 MB messages, 60s, dctcp, num-rx-queues=4, dmabuf-rx/tx-size-mb=2048, 10 runs per niov size, mlx5. niov RX dev Gbps RX flow avg Gbps app sys % ----- ---------------- ----------------- ---------------- 4K 300.63 +/- 53.21 75.16 +/- 13.30 54.15 +/- 10.23 16K 321.35 +/- 28.20 80.34 +/- 7.05 41.05 +/- 8.87 32K 347.63 +/- 2.20 86.91 +/- 0.55 44.54 +/- 3.51 64K 332.11 +/- 14.26 83.03 +/- 3.56 35.47 +/- 3.11 RX app sys % drops ~19% from 4K to 64K. kperf support (not yet merged): https://github.com/facebookexperimental/kperf/commit/8837577f920876bce6986e… Signed-off-by: Bobby Eshleman <bobbyeshleman(a)meta.com> --- Changes in v2: - Use NL_SET_ERR_MSG_FMT for sg alignment failure details (Stan) - Keep -E2BIG (not a direct ask, but seemed preferred, Stan) - Update udmabuf commit message and comments explaining why "one sg ent per folio" is useful (Christian) - Set/restore nr_hugepages in py harness (Stan) - Link to v1: https://lore.kernel.org/r/20260603-tcpdm-large-niovs-v1-0-f37a4ac6726c@meta… --- Bobby Eshleman (4): net: devmem: allow rx-buf-size > PAGE_SIZE per dmabuf binding udmabuf: emit one sg entry per pinned folio selftests/net: ncdevmem: add -b option to set rx-buf-size on bind selftests/net: devmem.py: add check_rx_large_niov Documentation/netlink/specs/netdev.yaml | 8 +++ drivers/dma-buf/udmabuf.c | 52 +++++++++++++++++-- include/uapi/linux/netdev.h | 1 + net/core/devmem.c | 51 +++++++++++-------- net/core/devmem.h | 13 +++-- net/core/netdev-genl-gen.c | 5 +- net/core/netdev-genl.c | 19 ++++++- tools/include/uapi/linux/netdev.h | 1 + tools/testing/selftests/drivers/net/hw/config | 1 + tools/testing/selftests/drivers/net/hw/devmem.py | 12 ++++- .../testing/selftests/drivers/net/hw/devmem_lib.py | 58 +++++++++++++++++++++- tools/testing/selftests/drivers/net/hw/ncdevmem.c | 49 ++++++++++++++++-- .../testing/selftests/drivers/net/hw/nk_devmem.py | 11 +++- 13 files changed, 238 insertions(+), 43 deletions(-) --- base-commit: 518d8d0199538a4d6d5e51064044ece71e0c42e7 change-id: 20260602-tcpdm-large-niovs-56523a3a1077 Best regards, -- Bobby Eshleman <bobbyeshleman(a)meta.com>

4 months, 1 week

[PATCH net-next v3 0/4] net: devmem: allow rx-buf-size > PAGE_SIZE per binding

by Bobby Eshleman

Every devmem dmabuf binding hands the page_pool PAGE_SIZE niovs today. On NICs that consume one descriptor per netmem, this caps a single RX descriptor at PAGE_SIZE and burns CPU on buffer churn. In this series, we add a bind-time netlink attribute, NETDEV_A_DMABUF_RX_BUF_SIZE, that lets userspace request a larger niov size (power of two >= PAGE_SIZE). Drivers must opt in via queue_mgmt_ops.QCFG_RX_PAGE_SIZE. Selftests use udmabuf, but udmabuf sgtables were previously hardcoded to PAGE_SIZE. This series modifies udmabuf to respect folio sizes in its exported sgtable. The result is that when backing udmabuf with MFD_HUGETLB 2MB pages, the sgtable is populated with 2MB entries, allowing devmem's gen_pool to carve out large (eg. 64K) niovs. Measurements ------------ Setup: kperf devmem RX/TX cuda, 4 flows, 64 MB messages, 60s, dctcp, num-rx-queues=4, dmabuf-rx/tx-size-mb=2048, 10 runs per niov size, mlx5. niov RX dev Gbps RX flow avg Gbps app sys % ----- ---------------- ----------------- ---------------- 4K 300.63 +/- 53.21 75.16 +/- 13.30 54.15 +/- 10.23 16K 321.35 +/- 28.20 80.34 +/- 7.05 41.05 +/- 8.87 32K 347.63 +/- 2.20 86.91 +/- 0.55 44.54 +/- 3.51 64K 332.11 +/- 14.26 83.03 +/- 3.56 35.47 +/- 3.11 RX app sys % drops ~19% from 4K to 64K. kperf support (not yet merged): https://github.com/facebookexperimental/kperf/commit/8837577f920876bce6986e… Signed-off-by: Bobby Eshleman <bobbyeshleman(a)meta.com> --- Changes in v3: - fix a bunch of non-reverse christmas tree declarations (Stan) - remove extra uint32 cast for getpagesize() (Stan) - remove overzealous strtoul checking (Stan) - remove value checks that the kernel already performs on rx_buf_size (Stan) - Link to v2: https://lore.kernel.org/r/20260611-tcpdm-large-niovs-v2-0-ee2bf15e7523@meta… Changes in v2: - Use NL_SET_ERR_MSG_FMT for sg alignment failure details (Stan) - Keep -E2BIG (not a direct ask, but seemed preferred, Stan) - Update udmabuf commit message and comments explaining why "one sg ent per folio" is useful (Christian) - Set/restore nr_hugepages in py harness (Stan) - Link to v1: https://lore.kernel.org/r/20260603-tcpdm-large-niovs-v1-0-f37a4ac6726c@meta… --- Bobby Eshleman (4): net: devmem: allow rx-buf-size > PAGE_SIZE per dmabuf binding udmabuf: emit one sg entry per pinned folio selftests/net: ncdevmem: add -b option to set rx-buf-size on bind selftests/net: devmem.py: add check_rx_large_niov Documentation/netlink/specs/netdev.yaml | 8 +++ drivers/dma-buf/udmabuf.c | 52 +++++++++++++++++-- include/uapi/linux/netdev.h | 1 + net/core/devmem.c | 51 +++++++++++-------- net/core/devmem.h | 13 +++-- net/core/netdev-genl-gen.c | 5 +- net/core/netdev-genl.c | 19 ++++++- tools/include/uapi/linux/netdev.h | 1 + tools/testing/selftests/drivers/net/hw/config | 1 + tools/testing/selftests/drivers/net/hw/devmem.py | 12 ++++- .../testing/selftests/drivers/net/hw/devmem_lib.py | 58 +++++++++++++++++++++- tools/testing/selftests/drivers/net/hw/ncdevmem.c | 36 ++++++++++++-- .../testing/selftests/drivers/net/hw/nk_devmem.py | 11 +++- 13 files changed, 225 insertions(+), 43 deletions(-) --- base-commit: 518d8d0199538a4d6d5e51064044ece71e0c42e7 change-id: 20260602-tcpdm-large-niovs-56523a3a1077 Best regards, -- Bobby Eshleman <bobbyeshleman(a)meta.com>

4 months, 1 week

[PATCH v20 0/4] Rust bindings for gem shmem

by Lyude Paul

Most of this patch series has already been pushed upstream, this is just the second half of the patch series that has not been pushed yet + some additional changes which were required to implement changes requested by the mailing list. This patch series is originally from Asahi, previously posted by Daniel Almeida. The previous version of the patch series can be found here: https://patchwork.freedesktop.org/series/164580/ Branch with patches applied available here: https://gitlab.freedesktop.org/lyudess/linux/-/commits/rust/gem-shmem This patch series applies on top of drm-rust-next Patch-series wide changes since V15: * Fix some major rebasing errors I somehow didn't notice :( * Drop the dependency on LazyInit, use the trick that Alice suggested instead. * Fix dependency ordering so that Tyr can get the vmap stuff first without the other bits. Patch-series wide changes since V16: * Fix ordering one more time (SetOnce::reset() doesn't need to come before adding vmap functions) * Rebase against the latest DeviceContext changes from me that got pushed. Patch-series wide changes since V20: * Lots of Sashiko fixes, excluding the comments that I couldn't prove weren't just bogus. Lyude Paul (4): rust: drm: gem: shmem: Add DmaResvGuard helper rust: drm: gem: shmem: Add vmap functions rust: faux: Allow retrieving a bound Device rust: drm: gem: Introduce shmem::Object::sg_table() rust/kernel/drm/gem/shmem.rs | 546 ++++++++++++++++++++++++++++++++++- rust/kernel/faux.rs | 16 +- 2 files changed, 546 insertions(+), 16 deletions(-) base-commit: 848bf57e98e1678ce7a49eb4e0bf0502da95dc07 -- 2.54.0

4 months, 2 weeks

[PATCH v6 1/2] accel/rocket: Fix error path handling in rocket_job_run()

by ZhaoJinming

In rocket_job_run(), after taking an extra fence reference for job->done_fence via dma_fence_get(), the error paths have three bugs: - The dma_fence reference held by job->done_fence is never released, causing a reference leak. - pm_runtime_get_sync() increments the usage counter even on failure, but the error path does not decrement it, leaking the runtime PM reference and preventing the NPU from suspending. - A valid but unsignaled fence is returned to the DRM scheduler, which triggers WARN("Fence ... released with pending signals!") when the scheduler drops its reference. Fix by replacing pm_runtime_get_sync() with pm_runtime_resume_and_get() which auto-balances the usage counter on failure, releasing both fence references on error, and returning ERR_PTR(ret) instead of the unsignaled fence. Cc: stable(a)vger.kernel.org Fixes: 0810d5ad88a1 ("accel/rocket: Add job submission IOCTL") Signed-off-by: ZhaoJinming <zhaojinming(a)uniontech.com> --- drivers/accel/rocket/rocket_job.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/drivers/accel/rocket/rocket_job.c b/drivers/accel/rocket/rocket_job.c index ac51bff39833..e8a073e22ac2 100644 --- a/drivers/accel/rocket/rocket_job.c +++ b/drivers/accel/rocket/rocket_job.c @@ -310,13 +310,22 @@ static struct dma_fence *rocket_job_run(struct drm_sched_job *sched_job) dma_fence_put(job->done_fence); job->done_fence = dma_fence_get(fence); - ret = pm_runtime_get_sync(core->dev); - if (ret < 0) - return fence; + ret = pm_runtime_resume_and_get(core->dev); + if (ret < 0) { + dma_fence_put(job->done_fence); + job->done_fence = NULL; + dma_fence_put(fence); + return ERR_PTR(ret); + } ret = iommu_attach_group(job->domain->domain, core->iommu_group); - if (ret < 0) - return fence; + if (ret < 0) { + pm_runtime_put(core->dev); + dma_fence_put(job->done_fence); + job->done_fence = NULL; + dma_fence_put(fence); + return ERR_PTR(ret); + } scoped_guard(mutex, &core->job_lock) { core->in_flight_job = job; -- 2.20.1

4 months, 2 weeks

[PATCH 00/15] accel/qda: Qualcomm DSP Accelerator driver

by Ekansh Gupta via B4 Relay

This patch series introduces the Qualcomm DSP Accelerator (QDA) driver, a DRM-based accelerator driver for Qualcomm DSPs. The driver provides a standardized interface for offloading computational tasks to DSPs found on Qualcomm SoCs, supporting all DSP domains. The QDA driver implements the FastRPC protocol over the DRM accel subsystem. It uses the same device-tree node structure as the existing fastrpc driver in drivers/misc/. The approach for binding the QDA driver to device-tree nodes while coexisting with the fastrpc driver is an open item described below. RFC thread: https://lore.kernel.org/dri-devel/20260224-qda-firstpost-v1-0-fe46a9c1a046@… User-space staging branch ========================= https://github.com/qualcomm/fastrpc/tree/accel/staging Key Features ============ * Standard DRM accelerator interface via /dev/accel/accelN * GEM-based buffer management with DMA-BUF import/export (PRIME) * IOMMU-based memory isolation using per-process context banks * FastRPC protocol implementation for DSP communication * RPMsg transport layer for reliable message passing * Support for all DSP domains (ADSP, CDSP, SDSP, GDSP) * DRM IOCTL interface for DSP session management, buffer allocation, and remote procedure invocation Architecture ============ 1. DRM Accelerator Framework Integration The driver registers as a DRM accel device, exposing a standard /dev/accel/accelN character device node. This provides established DRM infrastructure for device management, file operations, and IOCTL dispatch. 2. Memory Management Buffers are managed as GEM objects with full PRIME support for DMA-BUF import/export. This enables seamless buffer sharing with other DRM drivers (GPU, camera, video) using standard kernel mechanisms. 3. IOMMU Context Bank Management IOMMU context banks (CBs) are represented as proper struct device instances on a custom virtual bus (qda-compute-cb). Each CB device is registered with the IOMMU subsystem and receives its own IOMMU domain, enabling per-session address space isolation. The custom bus was introduced because IOMMU context banks are synthetic constructs — not real platform devices — and to ensure CB device lifetime is strictly subordinate to the parent QDA device. See also: https://lore.kernel.org/all/245d602f-3037-4ae3-9af9-d98f37258aae@oss.qualco… 4. Memory Manager Architecture A pluggable memory manager coordinates IOMMU device assignment and buffer allocation. The current implementation uses a DMA-coherent backend with SID-prefixed DMA addresses for DSP firmware compatibility. 5. Transport Layer RPMsg communication is handled in a dedicated transport layer (qda_rpmsg.c), separate from the core DRM driver logic. 6. Code Organization The driver is organized across multiple files (~4600 lines total): * qda_drv.c: Core driver and DRM integration * qda_rpmsg.c: RPMsg transport layer * qda_cb.c: Context bank device management * qda_compute_bus.c: Custom virtual bus for CB devices * qda_gem.c: GEM object management * qda_prime.c: DMA-BUF import (PRIME) * qda_memory_manager.c: IOMMU device registry and allocation * qda_memory_dma.c: DMA-coherent allocation backend * qda_fastrpc.c: FastRPC protocol implementation * qda_ioctl.c: IOCTL dispatch 7. UAPI Design The driver exposes DRM-style IOCTLs defined in include/uapi/drm/qda_accel.h, following DRM UAPI conventions (__u32/__u64 types, C++ guard, GPL-2.0-only WITH Linux-syscall-note). Patch Series Organization ========================== Patch 01: MAINTAINERS entry Patch 02: Driver documentation (Documentation/accel/qda/) Patches 03-04: Core driver skeleton and compute bus Patch 05: iommu: Register qda-compute-cb bus with IOMMU subsystem Patches 06-07: CB device enumeration and memory manager Patch 08: QUERY IOCTL and UAPI header Patches 09-11: GEM buffer management and PRIME import Patches 12-15: FastRPC protocol (invoke, session create/release, map/unmap) Open Items =========== 1. Device-Tree Compatible String The QDA driver uses the same device-tree node structure and properties as the existing fastrpc driver in drivers/misc/. A mechanism is needed to allow the QDA driver to bind to its device node independently of the fastrpc driver. The intended coexistence model is: platforms that require the complete fastrpc feature set continue to use "qcom,fastrpc"; new platforms where a feature available only in QDA takes priority, or where QDA's current feature set is sufficient, use a QDA-specific compatible string. New feature development is directed toward QDA rather than the existing fastrpc driver. As QDA matures toward feature parity with fastrpc, platforms can adopt the QDA-specific compatible string exclusively. The options under consideration are: a) Add a new "qcom,qda" compatible string to the existing qcom,fastrpc.yaml binding, since the DT node structure and properties are identical. This avoids a separate binding file but adds a QDA-specific string to a fastrpc binding. b) Introduce a separate qcom,qda.yaml binding that references or inherits the fastrpc binding properties. Seeking guidance from DT binding maintainers on the preferred approach. 2. Privilege Level Management Currently, daemon processes and user processes have the same access level as both use the same accel device node. This needs to be addressed as daemons attach to privileged DSP protection domains and require higher privilege levels for system-level operations. Seeking guidance on the best approach: separate device nodes, capability-based checks, or DRM master/authentication mechanisms. 3. UAPI Compatibility Layer A compatibility layer is needed to facilitate migration of client applications from the existing FastRPC UAPI to the new QDA UAPI, ensuring a smooth transition for existing userspace code. Seeking guidance on the preferred implementation approach: in-kernel translation layer, userspace wrapper library, or hybrid solution. An initial evaluation of an in-kernel translation shim was performed, where legacy FastRPC device nodes (/dev/fastrpc-*) are exposed and requests are internally routed to the QDA accel driver. The goal was to keep the compatibility layer minimal, reuse existing QDA helper paths (attach, buffer allocation, mapping, etc.), and avoid duplication of GEM and buffer management logic. However, the following challenges were identified: a) Dependency on drm_file for QDA helpers QDA relies on GEM-backed allocations and per-client handle namespaces, which require a valid struct drm_file. Since GEM handles are scoped per drm_file, the compatibility layer cannot directly reuse QDA helper paths without establishing a proper drm_file context for each client. b) Lack of public API for drm_file creation Creating a drm_file directly (similar to mock_drm_getfile()-style approaches) is not feasible, as the required helpers (drm_file_alloc(), drm_file_free(), etc.) are internal to the DRM core and not exported. This prevents external drivers from safely constructing and managing drm_file instances. c) VFS-based open is not a viable solution Opening the underlying accel device (/dev/accel/accelN) from the compatibility driver via filp_open() does provide a valid drm_file, but introduces reliance on userspace-visible device paths, lack of stability in containerized or chroot environments, and no clean mapping between legacy device nodes and accel devices. d) Userspace proxy limitations (CUSE) A CUSE-based userspace proxy was evaluated. However, DMA-buf file descriptors passed by legacy applications cannot be directly reused in the CUSE daemon (file descriptors are process-specific), which breaks buffer sharing semantics. e) drm_client-based approaches do not match requirements drm_client APIs (used for fbdev emulation) rely on a shared drm_file and do not provide the per-client isolation required by FastRPC semantics. Due to the above constraints, it is currently unclear how to implement an in-kernel compatibility layer that correctly handles per-client drm_file contexts without relying on VFS paths or non-exported DRM internals. 4. Documentation Improvements Add detailed IOCTL usage examples, document DSP firmware interface requirements, and create a migration guide from the existing FastRPC driver. 5. Per-Session Memory Allocation Develop a userspace API to support memory allocation on a per-session basis, enabling session-specific memory management. 6. Audio and Sensors PD Support The current series does not handle Audio PD and Sensors PD functionalities. These specialized protection domains require additional support for real-time constraints and power management. Interface Compatibility ======================== The QDA driver uses the same device-tree node structure and child node layout (including "qcom,fastrpc-compute-cb" child nodes) as the existing fastrpc driver. The underlying FastRPC protocol and DSP firmware interface are compatible with the existing fastrpc driver, ensuring that DSP firmware and libraries continue to work without modification. References ========== Previous discussions on this migration: - https://lkml.org/lkml/2024/6/24/479 - https://lkml.org/lkml/2024/6/21/1252 Testing ======= The driver has been tested on Qualcomm platforms with: - Basic FastRPC attach/release operations - DSP process creation and initialization - Memory mapping/unmapping operations - Dynamic invocation with various buffer types - GEM buffer allocation and mmap - PRIME buffer import from other subsystems Signed-off-by: Ekansh Gupta <ekansh.gupta(a)oss.qualcomm.com> --- Ekansh Gupta (15): MAINTAINERS: Add entry for Qualcomm DSP Accelerator (QDA) driver accel/qda: Add QDA driver documentation accel/qda: Add initial QDA DRM accelerator driver accel/qda: Add compute bus for QDA context banks iommu: Add QDA compute context bank bus to iommu_buses accel/qda: Create compute context bank devices on QDA compute bus accel/qda: Add memory manager for CB devices accel/qda: Add QUERY IOCTL and QDA UAPI header accel/qda: Add DMA-backed GEM objects and memory manager integration accel/qda: Add GEM_CREATE and GEM_MMAP_OFFSET IOCTLs accel/qda: Add PRIME DMA-BUF import support accel/qda: Add FastRPC invocation support accel/qda: Add DSP process creation and release accel/qda: Add remote memory mapping to DSP address space accel/qda: Add remote memory unmap from DSP address space Documentation/accel/index.rst | 1 + Documentation/accel/qda/index.rst | 13 + Documentation/accel/qda/qda.rst | 146 +++++ MAINTAINERS | 9 + drivers/accel/Kconfig | 1 + drivers/accel/Makefile | 2 + drivers/accel/qda/Kconfig | 34 + drivers/accel/qda/Makefile | 19 + drivers/accel/qda/qda_cb.c | 146 +++++ drivers/accel/qda/qda_cb.h | 32 + drivers/accel/qda/qda_compute_bus.c | 68 ++ drivers/accel/qda/qda_drv.c | 192 ++++++ drivers/accel/qda/qda_drv.h | 91 +++ drivers/accel/qda/qda_fastrpc.c | 1058 ++++++++++++++++++++++++++++++++ drivers/accel/qda/qda_fastrpc.h | 390 ++++++++++++ drivers/accel/qda/qda_gem.c | 177 ++++++ drivers/accel/qda/qda_gem.h | 62 ++ drivers/accel/qda/qda_ioctl.c | 296 +++++++++ drivers/accel/qda/qda_ioctl.h | 19 + drivers/accel/qda/qda_memory_dma.c | 110 ++++ drivers/accel/qda/qda_memory_dma.h | 17 + drivers/accel/qda/qda_memory_manager.c | 380 ++++++++++++ drivers/accel/qda/qda_memory_manager.h | 75 +++ drivers/accel/qda/qda_prime.c | 184 ++++++ drivers/accel/qda/qda_prime.h | 18 + drivers/accel/qda/qda_rpmsg.c | 248 ++++++++ drivers/accel/qda/qda_rpmsg.h | 30 + drivers/iommu/iommu.c | 4 + include/linux/qda_compute_bus.h | 32 + include/uapi/drm/qda_accel.h | 229 +++++++ 30 files changed, 4083 insertions(+) --- base-commit: 80dd246accce631c328ea43294e53b2b2dd2aa32 change-id: 20260519-qda-series-78c2bf0ed78b Best regards, -- Ekansh Gupta <ekansh.gupta(a)oss.qualcomm.com>

4 months, 2 weeks

[PATCH] dma-buf: move system_cc_shared heap under separate Kconfig

by Sumit Semwal

From: Arnd Bergmann <arnd(a)arndb.de> While system heap and system_cc_shared heap share a lot of code and hence the same source file, their users have different needs. system heap users need it to be a loadable module, while system_cc_shared heap users don't. Building as a loadable module breaks system_cc_shared heap on powerpc and s390 due to un-exported set_memory_encrypted / set_memory_decrypted functions. Fix these by reorganising code to put the system_cc_shared heap under a new Kconfig symbol, which allows either building both into the kernel, or leave encryption up to the consumers of the system heap. Fixes: fd55edff8a0a ("dma-buf: heaps: system: Turn the heap into a module") Signed-off-by: Arnd Bergmann <arnd(a)arndb.de> Signed-off-by: Sumit Semwal <sumit.semwal(a)linaro.org> --- drivers/dma-buf/heaps/Kconfig | 8 ++++++++ drivers/dma-buf/heaps/system_heap.c | 16 ++++++++++------ 2 files changed, 18 insertions(+), 6 deletions(-) diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig index e273fb18feca..a39decdcf067 100644 --- a/drivers/dma-buf/heaps/Kconfig +++ b/drivers/dma-buf/heaps/Kconfig @@ -5,6 +5,14 @@ config DMABUF_HEAPS_SYSTEM Choose this option to enable the system dmabuf heap. The system heap is backed by pages from the buddy allocator. If in doubt, say Y. +config DMABUF_HEAPS_CC_SYSTEM + bool "DMA-BUF System Heap for decrypted CoCo VMs" + depends on DMABUF_HEAPS && ARCH_HAS_MEM_ENCRYPT && DMABUF_HEAPS_SYSTEM=y + help + Choose this option to enable the system_cc_shared dmabuf heap. This + allows allocating shared (decrypted) memory for confidential computing + (CoCo) VMs. + config DMABUF_HEAPS_CMA tristate "DMA-BUF CMA Heap" depends on DMABUF_HEAPS && DMA_CMA diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index c92bdec356fc..71d9028cc3df 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -48,6 +48,9 @@ struct dma_heap_attachment { bool cc_shared; }; +#define cc_shared_buffer(b) (IS_ENABLED(CONFIG_DMABUF_HEAPS_CC_SYSTEM) && \ + (b)->cc_shared) + #define LOW_ORDER_GFP (GFP_HIGHUSER | __GFP_ZERO) #define HIGH_ORDER_GFP (((GFP_HIGHUSER | __GFP_ZERO | __GFP_NOWARN \ | __GFP_NORETRY) & ~__GFP_RECLAIM) \ @@ -161,7 +164,7 @@ static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attac unsigned long attrs; int ret; - attrs = a->cc_shared ? DMA_ATTR_CC_SHARED : 0; + attrs = cc_shared_buffer(a) ? DMA_ATTR_CC_SHARED : 0; ret = dma_map_sgtable(attachment->dev, table, direction, attrs); if (ret) return ERR_PTR(ret); @@ -233,7 +236,7 @@ static int system_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma) int i, ret; prot = vma->vm_page_prot; - if (buffer->cc_shared) + if (cc_shared_buffer(buffer)) prot = pgprot_decrypted(prot); for_each_sgtable_sg(table, sg, i) { @@ -282,7 +285,7 @@ static void *system_heap_do_vmap(struct system_heap_buffer *buffer) } prot = PAGE_KERNEL; - if (buffer->cc_shared) + if (cc_shared_buffer(buffer)) prot = pgprot_decrypted(prot); vaddr = vmap(pages, npages, VM_MAP, prot); vfree(pages); @@ -349,7 +352,7 @@ static void system_heap_dma_buf_release(struct dma_buf *dmabuf) * Intentionally leak pages that cannot be re-encrypted * to prevent shared memory from being reused. */ - if (buffer->cc_shared && + if (cc_shared_buffer(buffer) && system_heap_set_page_encrypted(page)) continue; @@ -456,7 +459,7 @@ static struct dma_buf *system_heap_allocate(struct dma_heap *heap, list_del(&page->lru); } - if (cc_shared) { + if (cc_shared_buffer(buffer)) { for_each_sgtable_sg(table, sg, i) { ret = system_heap_set_page_decrypted(sg_page(sg)); if (ret) @@ -485,7 +488,7 @@ static struct dma_buf *system_heap_allocate(struct dma_heap *heap, * Intentionally leak pages that cannot be re-encrypted * to prevent shared memory from being reused. */ - if (buffer->cc_shared && + if (cc_shared_buffer(buffer) && system_heap_set_page_encrypted(p)) continue; __free_pages(p, compound_order(p)); @@ -525,6 +528,7 @@ static int __init system_heap_create(void) return PTR_ERR(sys_heap); if (IS_ENABLED(CONFIG_HIGHMEM) || + !IS_ENABLED(CONFIG_DMABUF_HEAPS_CC_SYSTEM) || !cc_platform_has(CC_ATTR_MEM_ENCRYPT)) return 0; -- 2.43.0

4 months, 2 weeks

Jump to page:

2026

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

Linaro-mm-sig