[PATCH 2/2] mm: remove device private page support from hmm_range_fault
Ralph Campbell
rcampbell at nvidia.com
Mon Mar 16 18:42:19 UTC 2020
On 3/16/20 10:52 AM, Christoph Hellwig wrote:
> No driver has actually used properly wire up and support this feature.
> There is various code related to it in nouveau, but as far as I can tell
> it never actually got turned on, and the only changes since the initial
> commit are global cleanups.
This is not actually true. OpenCL 2.x does support SVM with nouveau and
device private memory via clEnqueueSVMMigrateMem().
Also, Ben Skeggs has accepted a set of patches to map GPU memory after being
migrated and this change would conflict with that.
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 1 -
> drivers/gpu/drm/nouveau/nouveau_dmem.c | 37 -------------------------
> drivers/gpu/drm/nouveau/nouveau_dmem.h | 2 --
> drivers/gpu/drm/nouveau/nouveau_svm.c | 3 --
> include/linux/hmm.h | 2 --
> mm/hmm.c | 28 -------------------
> 6 files changed, 73 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index dee446278417..90821ce5e6ca 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -776,7 +776,6 @@ struct amdgpu_ttm_tt {
> static const uint64_t hmm_range_flags[HMM_PFN_FLAG_MAX] = {
> (1 << 0), /* HMM_PFN_VALID */
> (1 << 1), /* HMM_PFN_WRITE */
> - 0 /* HMM_PFN_DEVICE_PRIVATE */
> };
>
> static const uint64_t hmm_range_values[HMM_PFN_VALUE_MAX] = {
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
> index 7605c4c48985..42808efceaf2 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
> @@ -671,40 +671,3 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
> out:
> return ret;
> }
> -
> -static inline bool
> -nouveau_dmem_page(struct nouveau_drm *drm, struct page *page)
> -{
> - return is_device_private_page(page) && drm->dmem == page_to_dmem(page);
> -}
> -
> -void
> -nouveau_dmem_convert_pfn(struct nouveau_drm *drm,
> - struct hmm_range *range)
> -{
> - unsigned long i, npages;
> -
> - npages = (range->end - range->start) >> PAGE_SHIFT;
> - for (i = 0; i < npages; ++i) {
> - struct page *page;
> - uint64_t addr;
> -
> - page = hmm_device_entry_to_page(range, range->pfns[i]);
> - if (page == NULL)
> - continue;
> -
> - if (!(range->pfns[i] & range->flags[HMM_PFN_DEVICE_PRIVATE])) {
> - continue;
> - }
> -
> - if (!nouveau_dmem_page(drm, page)) {
> - WARN(1, "Some unknown device memory !\n");
> - range->pfns[i] = 0;
> - continue;
> - }
> -
> - addr = nouveau_dmem_page_addr(page);
> - range->pfns[i] &= ((1UL << range->pfn_shift) - 1);
> - range->pfns[i] |= (addr >> PAGE_SHIFT) << range->pfn_shift;
> - }
> -}
> diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.h b/drivers/gpu/drm/nouveau/nouveau_dmem.h
> index 92394be5d649..1ac620b3d4fb 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_dmem.h
> +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.h
> @@ -38,8 +38,6 @@ int nouveau_dmem_migrate_vma(struct nouveau_drm *drm,
> unsigned long start,
> unsigned long end);
>
> -void nouveau_dmem_convert_pfn(struct nouveau_drm *drm,
> - struct hmm_range *range);
> #else /* IS_ENABLED(CONFIG_DRM_NOUVEAU_SVM) */
> static inline void nouveau_dmem_init(struct nouveau_drm *drm) {}
> static inline void nouveau_dmem_fini(struct nouveau_drm *drm) {}
> diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c
> index df9bf1fd1bc0..7e0376dca137 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_svm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
> @@ -367,7 +367,6 @@ static const u64
> nouveau_svm_pfn_flags[HMM_PFN_FLAG_MAX] = {
> [HMM_PFN_VALID ] = NVIF_VMM_PFNMAP_V0_V,
> [HMM_PFN_WRITE ] = NVIF_VMM_PFNMAP_V0_W,
> - [HMM_PFN_DEVICE_PRIVATE] = NVIF_VMM_PFNMAP_V0_VRAM,
> };
>
> static const u64
> @@ -558,8 +557,6 @@ static int nouveau_range_fault(struct nouveau_svmm *svmm,
> break;
> }
>
> - nouveau_dmem_convert_pfn(drm, &range);
> -
> svmm->vmm->vmm.object.client->super = true;
> ret = nvif_object_ioctl(&svmm->vmm->vmm.object, data, size, NULL);
> svmm->vmm->vmm.object.client->super = false;
> diff --git a/include/linux/hmm.h b/include/linux/hmm.h
> index 4bf8d6997b12..5e6034f105c3 100644
> --- a/include/linux/hmm.h
> +++ b/include/linux/hmm.h
> @@ -74,7 +74,6 @@
> * Flags:
> * HMM_PFN_VALID: pfn is valid. It has, at least, read permission.
> * HMM_PFN_WRITE: CPU page table has write permission set
> - * HMM_PFN_DEVICE_PRIVATE: private device memory (ZONE_DEVICE)
> *
> * The driver provides a flags array for mapping page protections to device
> * PTE bits. If the driver valid bit for an entry is bit 3,
> @@ -86,7 +85,6 @@
> enum hmm_pfn_flag_e {
> HMM_PFN_VALID = 0,
> HMM_PFN_WRITE,
> - HMM_PFN_DEVICE_PRIVATE,
> HMM_PFN_FLAG_MAX
> };
>
> diff --git a/mm/hmm.c b/mm/hmm.c
> index 180e398170b0..3d10485bf323 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -118,15 +118,6 @@ static inline void hmm_pte_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
> /* We aren't ask to do anything ... */
> if (!(pfns & range->flags[HMM_PFN_VALID]))
> return;
> - /* If this is device memory then only fault if explicitly requested */
> - if ((cpu_flags & range->flags[HMM_PFN_DEVICE_PRIVATE])) {
> - /* Do we fault on device memory ? */
> - if (pfns & range->flags[HMM_PFN_DEVICE_PRIVATE]) {
> - *write_fault = pfns & range->flags[HMM_PFN_WRITE];
> - *fault = true;
> - }
> - return;
> - }
>
> /* If CPU page table is not valid then we need to fault */
> *fault = !(cpu_flags & range->flags[HMM_PFN_VALID]);
> @@ -259,25 +250,6 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
> if (!pte_present(pte)) {
> swp_entry_t entry = pte_to_swp_entry(pte);
>
> - /*
> - * This is a special swap entry, ignore migration, use
> - * device and report anything else as error.
> - */
> - if (is_device_private_entry(entry)) {
> - cpu_flags = range->flags[HMM_PFN_VALID] |
> - range->flags[HMM_PFN_DEVICE_PRIVATE];
> - cpu_flags |= is_write_device_private_entry(entry) ?
> - range->flags[HMM_PFN_WRITE] : 0;
> - hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
> - &fault, &write_fault);
> - if (fault || write_fault)
> - goto fault;
> - *pfn = hmm_device_entry_from_pfn(range,
> - swp_offset(entry));
> - *pfn |= cpu_flags;
> - return 0;
> - }
> -
> hmm_pte_need_fault(hmm_vma_walk, orig_pfn, 0, &fault,
> &write_fault);
> if (!fault && !write_fault)
>
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