Migration is implemented with range granularity, with VRAM backing being
a VM private TTM BO (i.e., shares dma-resv with VM). The lifetime of the
TTM BO is limited to when the SVM range is in VRAM (i.e., when a VRAM
SVM range is migrated to SRAM, the TTM BO is destroyed).
The design choice for using TTM BO for VRAM backing store, as opposed to
direct buddy allocation, is as follows:
- DRM buddy allocations are not at page granularity, offering no
advantage over a BO.
- Unified eviction is required (SVM VRAM and TTM BOs need to be able to
evict each other).
- For exhaustive eviction [1], SVM VRAM allocations will almost certainly
require a dma-resv.
- Likely allocation size is 2M which makes of size of BO (872)
acceptable per allocation (872 / 2M == .0004158).
With this, using TTM BO for VRAM backing store seems to be an obvious
choice as it allows leveraging of the TTM eviction code.
Current migration policy is migrate any SVM range greater than or equal
to 64k once.
[1] https://patchwork.freedesktop.org/series/133643/
v2:
- Rebase on latest GPU SVM
- Retry page fault on get pages returning mixed allocation
- Use drm_gpusvm_devmem
v3:
- Use new BO flags
- New range structure (Thomas)
- Hide migration behind Kconfig
- Kernel doc (Thomas)
- Use check_pages_threshold
v4:
- Don't evict partial unmaps in garbage collector (Thomas)
- Use %pe to print errors (Thomas)
- Use %p to print pointers (Thomas)
v5:
- Use range size helper (Thomas)
- Make BO external (Thomas)
- Set tile to NULL for BO creation (Thomas)
- Drop BO mirror flag (Thomas)
- Hold BO dma-resv lock across migration (Auld, Thomas)
v6:
- s/drm_info/drm_dbg (Thomas)
- s/migrated/skip_migrate (Himal)
- Better debug message on VRAM migration failure (Himal)
- Drop return BO from VRAM allocation function (Thomas)
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306012657.3505757-28-matthew.brost@intel.com
uAPI is designed with the use case that only mapping a BO to a malloc'd
address will unbind a CPU-address mirror VMA. Therefore, allowing a
CPU-address mirror VMA to unbind when the GPU has bindings in the range
being unbound does not make much sense. This behavior is not supported,
as it simplifies the code. This decision can always be revisited if a
use case arises.
v3:
- s/arrises/arises (Thomas)
- s/system allocator/GPU address mirror (Thomas)
- Kernel doc (Thomas)
- Newline between function defs (Thomas)
v5:
- Kernel doc (Thomas)
v6:
- Only compile if CONFIG_DRM_GPUSVM selected (CI, Lucas)
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306012657.3505757-18-matthew.brost@intel.com
Add basic SVM garbage collector which destroy a SVM range upon a MMU
UNMAP event. The garbage collector runs on worker or in GPU fault
handler and is required as locks in the path of reclaim are required and
cannot be taken the notifier.
v2:
- Flush garbage collector in xe_svm_close
v3:
- Better commit message (Thomas)
- Kernel doc (Thomas)
- Use list_first_entry_or_null for garbage collector loop (Thomas)
- Don't add to garbage collector if VM is closed (Thomas)
v4:
- Use %pe to print error (Thomas)
v5:
- s/visable/visible (Thomas)
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306012657.3505757-16-matthew.brost@intel.com
Add (re)bind to SVM page fault handler. To facilitate add support
function to VM layer which (re)binds a SVM range. Also teach PT layer to
understand (re)binds of SVM ranges.
v2:
- Don't assert BO lock held for range binds
- Use xe_svm_notifier_lock/unlock helper in xe_svm_close
- Use drm_pagemap dma cursor
- Take notifier lock in bind code to check range state
v3:
- Use new GPU SVM range structure (Thomas)
- Kernel doc (Thomas)
- s/DRM_GPUVA_OP_USER/DRM_GPUVA_OP_DRIVER (Thomas)
v5:
- Kernel doc (Thomas)
v6:
- Only compile if CONFIG_DRM_GPUSVM selected (CI, Lucas)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Tested-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306012657.3505757-15-matthew.brost@intel.com
Add SVM range invalidation vfunc which invalidates PTEs. A new PT layer
function which accepts a SVM range is added to support this. In
addition, add the basic page fault handler which allocates a SVM range
which is used by SVM range invalidation vfunc.
v2:
- Don't run invalidation if VM is closed
- Cycle notifier lock in xe_svm_close
- Drop xe_gt_tlb_invalidation_fence_fini
v3:
- Better commit message (Thomas)
- Add lockdep asserts (Thomas)
- Add kernel doc (Thomas)
- s/change/changed (Thomas)
- Use new GPU SVM range / notifier structures
- Ensure PTEs are zapped / dma mappings are unmapped on VM close (Thomas)
v4:
- Fix macro (Checkpatch)
v5:
- Use range start/end helpers (Thomas)
- Use notifier start/end helpers (Thomas)
v6:
- Use min/max helpers (Himal)
- Only compile if CONFIG_DRM_GPUSVM selected (CI, Lucas)
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306012657.3505757-13-matthew.brost@intel.com
Add SVM init / close / fini to faulting VMs. Minimual implementation
acting as a placeholder for follow on patches.
v2:
- Add close function
v3:
- Better commit message (Thomas)
- Kernel doc (Thomas)
- Update chunk array to be unsigned long (Thomas)
- Use new drm_gpusvm.h header location (Thomas)
- Newlines between functions in xe_svm.h (Thomas)
- Call drm_gpusvm_driver_set_lock in init (Thomas)
v6:
- Only compile if CONFIG_DRM_GPUSVM selected (CI, Lucas)
v7:
- Only select CONFIG_DRM_GPUSVM if DEVICE_PRIVATE (CI)
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250306012657.3505757-10-matthew.brost@intel.com
