| Message ID | 20230606223130.6132-1-dakr@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | DRM GPUVA Manager & Nouveau VM_BIND UAPI | expand |
On Wed, 2023-06-07 at 00:31 +0200, Danilo Krummrich wrote: > > Christian König (1): > drm: execution context for GEM buffers v4 > > Danilo Krummrich (13): > maple_tree: split up MA_STATE() macro > drm: manager to keep track of GPUs VA mappings I have tested the drm GPUVA manager as part of using it with our new driver. The link below shows use of the drm_gpuva_sm_[un]map() functions. I think this is based on the v3 patches, but I have also tried it locally using v4 patches. We will be submitting this driver for review soon. https://gitlab.freedesktop.org/sarah-walker-imgtec/powervr/-/blob/dev/v3/drivers/gpu/drm/imagination/pvr_vm.c In a previous incarnation, I used the drm_gpuva_insert() and drm_gpuva_remove() functions directly. In some now abandoned work I used the drm_gpuva_sm_[un]map_ops_create() route. The only problem I encountered along the way was the maple tree init issue already reported by Boris and fixed in v4. One caveat - as our driver is a work in progress our testing is limited to certain Sascha Willem tests. I did find it quite difficult to get the prealloc route with drm_gpuva_sm_[un]map() working. I'm not sure to what degree this reflects me being a novice on matters DRM, but I did find myself wishing for more direction, even with Boris's help. Tested-by: Donald Robson <donald.robson@imgtec.com> > drm: debugfs: provide infrastructure to dump a DRM GPU VA space > drm/nouveau: new VM_BIND uapi interfaces > drm/nouveau: get vmm via nouveau_cli_vmm() > drm/nouveau: bo: initialize GEM GPU VA interface > drm/nouveau: move usercopy helpers to nouveau_drv.h > drm/nouveau: fence: separate fence alloc and emit > drm/nouveau: fence: fail to emit when fence context is killed > drm/nouveau: chan: provide nouveau_channel_kill() > drm/nouveau: nvkm/vmm: implement raw ops to manage uvmm > drm/nouveau: implement new VM_BIND uAPI > drm/nouveau: debugfs: implement DRM GPU VA debugfs >
Hi Donald, On 6/9/23 13:56, Donald Robson wrote: > On Wed, 2023-06-07 at 00:31 +0200, Danilo Krummrich wrote: >> >> Christian König (1): >> drm: execution context for GEM buffers v4 >> >> Danilo Krummrich (13): >> maple_tree: split up MA_STATE() macro >> drm: manager to keep track of GPUs VA mappings > > I have tested the drm GPUVA manager as part of using it with our new > driver. The link below shows use of the drm_gpuva_sm_[un]map() > functions. I think this is based on the v3 patches, but I have also > tried it locally using v4 patches. We will be submitting this > driver for review soon. That's awesome - thank your for taking the effort! > > https://gitlab.freedesktop.org/sarah-walker-imgtec/powervr/-/blob/dev/v3/drivers/gpu/drm/imagination/pvr_vm.c > > In a previous incarnation, I used the drm_gpuva_insert() and > drm_gpuva_remove() functions directly. In some now abandoned work I > used the drm_gpuva_sm_[un]map_ops_create() route. > > The only problem I encountered along the way was the maple tree init > issue already reported by Boris and fixed in v4. One caveat - as > our driver is a work in progress our testing is limited to certain > Sascha Willem tests. > > I did find it quite difficult to get the prealloc route with > drm_gpuva_sm_[un]map() working. I'm not sure to what degree this > reflects me being a novice on matters DRM, but I did find myself > wishing for more direction, even with Boris's help. I'm definitely up improving the existing documentation. Anything in particular you think should be described in more detail? - Danilo > > Tested-by: Donald Robson <donald.robson@imgtec.com> > >> drm: debugfs: provide infrastructure to dump a DRM GPU VA space >> drm/nouveau: new VM_BIND uapi interfaces >> drm/nouveau: get vmm via nouveau_cli_vmm() >> drm/nouveau: bo: initialize GEM GPU VA interface >> drm/nouveau: move usercopy helpers to nouveau_drv.h >> drm/nouveau: fence: separate fence alloc and emit >> drm/nouveau: fence: fail to emit when fence context is killed >> drm/nouveau: chan: provide nouveau_channel_kill() >> drm/nouveau: nvkm/vmm: implement raw ops to manage uvmm >> drm/nouveau: implement new VM_BIND uAPI >> drm/nouveau: debugfs: implement DRM GPU VA debugfs >>
On Tue, 2023-06-13 at 16:20 +0200, Danilo Krummrich wrote: > I'm definitely up improving the existing documentation. Anything in > particular you think should be described in more detail? > > - Danilo Hi Danilo, As I said, with inexperience it's possible I missed what I was looking for in the existing documentation, which is highly detailed in regard to how it deals with operations, but usage was where I fell down. If I understand there are three ways to use this, which are: 1) Using drm_gpuva_insert() and drm_gpuva_remove() directly using stack va objects. 2) Using drm_gpuva_insert() and drm_gpuva_remove() in a callback context, after having created ops lists using drm_gpuva_sm_[un]map_ops_create(). 3) Using drm_gpuva_[un]map() in callback context after having prealloced a node and va objects for map/remap function use, which must be forwarded in as the 'priv' argument to drm_gpuva_sm_[un]map(). The first of these is pretty self-explanatory. The second was also fairly easy to understand, it has an example in your own driver, and since it takes care of allocs in drm_gpuva_sm_map_ops_create() it leads to pretty clean code too. The third case, which I am using in the new PowerVR driver did not have an example of usage and the approach is quite different to 2) in that you have to prealloc everything explicitly. I didn't realise this, so it led to a fair amount of frustration. I think if you're willing, it would help inexperienced implementers a lot if there were some brief 'how to' snippets for each of the three use cases. Thanks, Donald
On 6/14/23 09:58, Donald Robson wrote: > On Tue, 2023-06-13 at 16:20 +0200, Danilo Krummrich wrote: > >> I'm definitely up improving the existing documentation. Anything in >> particular you think should be described in more detail? >> >> - Danilo > > Hi Danilo, > > As I said, with inexperience it's possible I missed what I was > looking for in the existing documentation, which is highly detailed > in regard to how it deals with operations, but usage was where I fell > down. > > If I understand there are three ways to use this, which are: > 1) Using drm_gpuva_insert() and drm_gpuva_remove() directly using > stack va objects. What do you mean with stack va objects? > 2) Using drm_gpuva_insert() and drm_gpuva_remove() in a callback > context, after having created ops lists using > drm_gpuva_sm_[un]map_ops_create(). > 3) Using drm_gpuva_[un]map() in callback context after having > prealloced a node and va objects for map/remap function use, > which must be forwarded in as the 'priv' argument to > drm_gpuva_sm_[un]map(). Right, and I think it might be worth concretely mentioning this in the documentation. > > The first of these is pretty self-explanatory. The second was also > fairly easy to understand, it has an example in your own driver, and > since it takes care of allocs in drm_gpuva_sm_map_ops_create() it > leads to pretty clean code too. > > The third case, which I am using in the new PowerVR driver did not > have an example of usage and the approach is quite different to 2) > in that you have to prealloc everything explicitly. I didn't realise > this, so it led to a fair amount of frustration. Yeah, I think this is not entirely obvious why this is the case. I should maybe add a comment on how the callback way of using this interface is motivated. The requirement of pre-allocation arises out of two circumstances. First, having a single callback for every drm_gpuva_op on the GPUVA space implies that we're not allowed to fail the operation, because processing the drm_gpuva_ops directly implies that we can't unwind them on failure. I know that the API functions the documentation guides you to use in this case actually can return error codes, but those are just range checks. If they fail, it's clearly a bug. However, I did not use WARN() for those cases, since the driver could still decide to use the callbacks to keep track of the operations in a driver specific way, although I would not recommend doing this and rather like to try to cover the drivers use case within the regular way of creating a list of operations. Second, most (other) drivers when using the callback way of this interface would need to execute the GPUVA space updates asynchronously in a dma_fence signalling critical path, where no memory allocations are permitted. > > I think if you're willing, it would help inexperienced implementers a > lot if there were some brief 'how to' snippets for each of the three > use cases. Yes, I can definitely add some. > > Thanks, > Donald
On 6/7/23 00:31, Danilo Krummrich wrote: > Maple Tree: > - Maple tree uses the 'unsinged long' type for node entries. While this > works for 64bit, it's incompatible with the DRM GPUVA Manager on 32bit, > since the DRM GPUVA Manager uses the u64 type and so do drivers using it. > While it's questionable whether a 32bit kernel and a > 32bit GPU address > space make any sense, it creates tons of compiler warnings when compiling > for 32bit. Maybe it makes sense to expand the maple tree API to let users > decide which size to pick - other ideas / proposals are welcome. I remember you told me that the filesystem folks had some interest in a 64-bit maple tree for a 32-bit kernel as well. Are there any news or plans for such a feature? For the short term I'd probably add a feature flag to the GPUVA manager, where drivers explicitly need to promise not to pass in addresses exceeding 32-bit on a 32-bit kernel, and if they don't refuse to initialize the GPUVA manager on 32-bit kernels - or something similar...
Furthermore, with the DRM GPUVA manager it provides a new DRM core feature to keep track of GPU virtual address (VA) mappings in a more generic way. The DRM GPUVA manager is indented to help drivers implement userspace-manageable GPU VA spaces in reference to the Vulkan API. In order to achieve this goal it serves the following purposes in this context. 1) Provide infrastructure to track GPU VA allocations and mappings, making use of the maple_tree. 2) Generically connect GPU VA mappings to their backing buffers, in particular DRM GEM objects. 3) Provide a common implementation to perform more complex mapping operations on the GPU VA space. In particular splitting and merging of GPU VA mappings, e.g. for intersecting mapping requests or partial unmap requests. The new VM_BIND Nouveau UAPI build on top of the DRM GPUVA manager, itself providing the following new interfaces. 1) Initialize a GPU VA space via the new DRM_IOCTL_NOUVEAU_VM_INIT ioctl for UMDs to specify the portion of VA space managed by the kernel and userspace, respectively. 2) Allocate and free a VA space region as well as bind and unbind memory to the GPUs VA space via the new DRM_IOCTL_NOUVEAU_VM_BIND ioctl. 3) Execute push buffers with the new DRM_IOCTL_NOUVEAU_EXEC ioctl. Both, DRM_IOCTL_NOUVEAU_VM_BIND and DRM_IOCTL_NOUVEAU_EXEC, make use of the DRM scheduler to queue jobs and support asynchronous processing with DRM syncobjs as synchronization mechanism. By default DRM_IOCTL_NOUVEAU_VM_BIND does synchronous processing, DRM_IOCTL_NOUVEAU_EXEC supports asynchronous processing only. The new VM_BIND UAPI for Nouveau makes also use of drm_exec (execution context for GEM buffers) by Christian König. Since the patch implementing drm_exec was not yet merged into drm-next it is part of this series, as well as a small fix for this patch, which was found while testing this series. This patch series is also available at [1]. There is a Mesa NVK merge request by Dave Airlie [2] implementing the corresponding userspace parts for this series. The Vulkan CTS test suite passes the sparse binding and sparse residency test cases for the new UAPI together with Dave's Mesa work. There are also some test cases in the igt-gpu-tools project [3] for the new UAPI and hence the DRM GPU VA manager. However, most of them are testing the DRM GPU VA manager's logic through Nouveau's new UAPI and should be considered just as helper for implementation. However, I absolutely intend to change those test cases to proper kunit test cases for the DRM GPUVA manager, once and if we agree on it's usefulness and design. [1] https://gitlab.freedesktop.org/nouvelles/kernel/-/tree/new-uapi-drm-next / https://gitlab.freedesktop.org/nouvelles/kernel/-/merge_requests/1 [2] https://gitlab.freedesktop.org/nouveau/mesa/-/merge_requests/150/ [3] https://gitlab.freedesktop.org/dakr/igt-gpu-tools/-/tree/wip_nouveau_vm_bind Changes in V2: ============== Nouveau: - Reworked the Nouveau VM_BIND UAPI to avoid memory allocations in fence signalling critical sections. Updates to the VA space are split up in three separate stages, where only the 2. stage executes in a fence signalling critical section: 1. update the VA space, allocate new structures and page tables 2. (un-)map the requested memory bindings 3. free structures and page tables - Separated generic job scheduler code from specific job implementations. - Separated the EXEC and VM_BIND implementation of the UAPI. - Reworked the locking parts of the nvkm/vmm RAW interface, such that (un-)map operations can be executed in fence signalling critical sections. GPUVA Manager: - made drm_gpuva_regions optional for users of the GPUVA manager - allow NULL GEMs for drm_gpuva entries - swichted from drm_mm to maple_tree for track drm_gpuva / drm_gpuva_region entries - provide callbacks for users to allocate custom drm_gpuva_op structures to allow inheritance - added user bits to drm_gpuva_flags - added a prefetch operation type in order to support generating prefetch operations in the same way other operations generated - hand the responsibility for mutual exclusion for a GEM's drm_gpuva list to the user; simplified corresponding (un-)link functions Maple Tree: - I added two maple tree patches to the series, one to support custom tree walk macros and one to hand the locking responsibility to the user of the GPUVA manager without pre-defined lockdep checks. Changes in V3: ============== Nouveau: - Reworked the Nouveau VM_BIND UAPI to do the job cleanup (including page table cleanup) within a workqueue rather than the job_free() callback of the scheduler itself. A job_free() callback can stall the execution (run() callback) of the next job in the queue. Since the page table cleanup requires to take the same locks as need to be taken for page table allocation, doing it directly in the job_free() callback would still violate the fence signalling critical path. - Separated Nouveau fence allocation and emit, such that we do not violate the fence signalling critical path in EXEC jobs. - Implement "regions" (for handling sparse mappings through PDEs and dual page tables) within Nouveau. - Drop the requirement for every mapping to be contained within a region. - Add necassary synchronization of VM_BIND job operation sequences in order to work around limitations in page table handling. This will be addressed in a future re-work of Nouveau's page table handling. - Fixed a couple of race conditions found through more testing. Thanks to Dave for consitently trying to break it. :-) GPUVA Manager: - Implement pre-allocation capabilities for tree modifications within fence signalling critical sections. - Implement accessors to to apply tree modification while walking the GPUVA tree in order to actually support processing of drm_gpuva_ops through callbacks in fence signalling critical sections rather than through pre-allocated operation lists. - Remove merging of GPUVAs; the kernel has limited to none knowlege about the semantics of mapping sequences. Hence, merging is purely speculative. It seems that gaining a significant (or at least a measurable) performance increase through merging is way more likely to happen when userspace is responsible for merging mappings up to the next larger page size if possible. - Since merging was removed, regions pretty much loose their right to exist. They might still be useful for handling dual page tables or similar mechanisms, but since Nouveau seems to be the only driver having a need for this for now, regions were removed from the GPUVA manager. - Fixed a couple of maple_tree related issues; thanks to Liam for helping me out. Changes in V4: ============== Nouveau: - Refactored how specific VM_BIND and EXEC jobs are created and how their arguments are passed to the generic job implementation. - Fixed a UAF race condition where bind job ops could have been freed already while still waiting for a job cleanup to finish. This is due to in certain cases we need to wait for mappings actually being unmapped before creating sparse regions in the same area. - Re-based the code onto drm_exec v4 patch. GPUVA Manager: - Fixed a maple tree related bug when pre-allocating MA states. (Boris Brezillion) - Made struct drm_gpuva_fn_ops a const object in all occurrences. (Boris Brezillion) TODO ==== Maple Tree: - Maple tree uses the 'unsinged long' type for node entries. While this works for 64bit, it's incompatible with the DRM GPUVA Manager on 32bit, since the DRM GPUVA Manager uses the u64 type and so do drivers using it. While it's questionable whether a 32bit kernel and a > 32bit GPU address space make any sense, it creates tons of compiler warnings when compiling for 32bit. Maybe it makes sense to expand the maple tree API to let users decide which size to pick - other ideas / proposals are welcome. Christian König (1): drm: execution context for GEM buffers v4 Danilo Krummrich (13): maple_tree: split up MA_STATE() macro drm: manager to keep track of GPUs VA mappings drm: debugfs: provide infrastructure to dump a DRM GPU VA space drm/nouveau: new VM_BIND uapi interfaces drm/nouveau: get vmm via nouveau_cli_vmm() drm/nouveau: bo: initialize GEM GPU VA interface drm/nouveau: move usercopy helpers to nouveau_drv.h drm/nouveau: fence: separate fence alloc and emit drm/nouveau: fence: fail to emit when fence context is killed drm/nouveau: chan: provide nouveau_channel_kill() drm/nouveau: nvkm/vmm: implement raw ops to manage uvmm drm/nouveau: implement new VM_BIND uAPI drm/nouveau: debugfs: implement DRM GPU VA debugfs Documentation/gpu/driver-uapi.rst | 11 + Documentation/gpu/drm-mm.rst | 43 + drivers/gpu/drm/Kconfig | 6 + drivers/gpu/drm/Makefile | 3 + drivers/gpu/drm/drm_debugfs.c | 41 + drivers/gpu/drm/drm_exec.c | 278 +++ drivers/gpu/drm/drm_gem.c | 3 + drivers/gpu/drm/drm_gpuva_mgr.c | 1687 +++++++++++++++ drivers/gpu/drm/nouveau/Kbuild | 3 + drivers/gpu/drm/nouveau/Kconfig | 2 + drivers/gpu/drm/nouveau/dispnv04/crtc.c | 9 +- drivers/gpu/drm/nouveau/include/nvif/if000c.h | 26 +- drivers/gpu/drm/nouveau/include/nvif/vmm.h | 19 +- .../gpu/drm/nouveau/include/nvkm/subdev/mmu.h | 20 +- drivers/gpu/drm/nouveau/nouveau_abi16.c | 24 + drivers/gpu/drm/nouveau/nouveau_abi16.h | 1 + drivers/gpu/drm/nouveau/nouveau_bo.c | 204 +- drivers/gpu/drm/nouveau/nouveau_bo.h | 2 +- drivers/gpu/drm/nouveau/nouveau_chan.c | 22 +- drivers/gpu/drm/nouveau/nouveau_chan.h | 1 + drivers/gpu/drm/nouveau/nouveau_debugfs.c | 39 + drivers/gpu/drm/nouveau/nouveau_dmem.c | 9 +- drivers/gpu/drm/nouveau/nouveau_drm.c | 27 +- drivers/gpu/drm/nouveau/nouveau_drv.h | 94 +- drivers/gpu/drm/nouveau/nouveau_exec.c | 418 ++++ drivers/gpu/drm/nouveau/nouveau_exec.h | 54 + drivers/gpu/drm/nouveau/nouveau_fence.c | 23 +- drivers/gpu/drm/nouveau/nouveau_fence.h | 5 +- drivers/gpu/drm/nouveau/nouveau_gem.c | 62 +- drivers/gpu/drm/nouveau/nouveau_mem.h | 5 + drivers/gpu/drm/nouveau/nouveau_prime.c | 2 +- drivers/gpu/drm/nouveau/nouveau_sched.c | 461 ++++ drivers/gpu/drm/nouveau/nouveau_sched.h | 123 ++ drivers/gpu/drm/nouveau/nouveau_svm.c | 2 +- drivers/gpu/drm/nouveau/nouveau_uvmm.c | 1898 +++++++++++++++++ drivers/gpu/drm/nouveau/nouveau_uvmm.h | 107 + drivers/gpu/drm/nouveau/nouveau_vmm.c | 4 +- drivers/gpu/drm/nouveau/nvif/vmm.c | 100 +- .../gpu/drm/nouveau/nvkm/subdev/mmu/uvmm.c | 213 +- drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 197 +- drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.h | 25 + .../drm/nouveau/nvkm/subdev/mmu/vmmgf100.c | 16 +- .../drm/nouveau/nvkm/subdev/mmu/vmmgp100.c | 16 +- .../gpu/drm/nouveau/nvkm/subdev/mmu/vmmnv50.c | 27 +- include/drm/drm_debugfs.h | 25 + include/drm/drm_drv.h | 6 + include/drm/drm_exec.h | 119 ++ include/drm/drm_gem.h | 75 + include/drm/drm_gpuva_mgr.h | 681 ++++++ include/linux/maple_tree.h | 7 +- include/uapi/drm/nouveau_drm.h | 209 ++ 51 files changed, 7212 insertions(+), 242 deletions(-) create mode 100644 drivers/gpu/drm/drm_exec.c create mode 100644 drivers/gpu/drm/drm_gpuva_mgr.c create mode 100644 drivers/gpu/drm/nouveau/nouveau_exec.c create mode 100644 drivers/gpu/drm/nouveau/nouveau_exec.h create mode 100644 drivers/gpu/drm/nouveau/nouveau_sched.c create mode 100644 drivers/gpu/drm/nouveau/nouveau_sched.h create mode 100644 drivers/gpu/drm/nouveau/nouveau_uvmm.c create mode 100644 drivers/gpu/drm/nouveau/nouveau_uvmm.h create mode 100644 include/drm/drm_exec.h create mode 100644 include/drm/drm_gpuva_mgr.h base-commit: 33a86170888b7e4aa0cea94ebb9c67180139cea9