[PATCH v5 5/9] drm/xe: Update xe_ttm_access_memory to use GPU for non-visible access
Matthew Brost
matthew.brost at intel.com
Mon Oct 21 21:45:11 UTC 2024
On Mon, Oct 21, 2024 at 02:18:31PM -0700, Matthew Brost wrote:
> Add migrate layer functions to access VRAM and update
> xe_ttm_access_memory to use for non-visible access and large (more tahn
> 16k) BO access.
>
> v4:
> - Fix non-page aligned accesses
> - Add support for small / unaligned access
> - Update commit message indicating migrate used for large accesses (Auld)
> - Fix warning in xe_res_cursor for non-zero offset
> v5:
> - Fix 32 bit build (CI)
>
> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> ---
> drivers/gpu/drm/xe/xe_bo.c | 15 +-
> drivers/gpu/drm/xe/xe_migrate.c | 325 ++++++++++++++++++++++++++++++++
> drivers/gpu/drm/xe/xe_migrate.h | 4 +
> 3 files changed, 340 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index 04bc042f3bc7..4e1f54aad5bc 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -1127,6 +1127,7 @@ static int xe_ttm_access_memory(struct ttm_buffer_object *ttm_bo,
> struct xe_res_cursor cursor;
> struct xe_mem_region *vram;
> int bytes_left = len;
> + int err = 0;
>
> xe_bo_assert_held(bo);
> xe_device_assert_mem_access(xe);
> @@ -1134,9 +1135,14 @@ static int xe_ttm_access_memory(struct ttm_buffer_object *ttm_bo,
> if (!mem_type_is_vram(ttm_bo->resource->mem_type))
> return -EIO;
>
> - /* FIXME: Use GPU for non-visible VRAM */
> - if (!xe_ttm_resource_visible(ttm_bo->resource))
> - return -EIO;
> + if (!xe_ttm_resource_visible(ttm_bo->resource) || len >= SZ_16K) {
> + struct xe_migrate *migrate =
> + mem_type_to_migrate(xe, ttm_bo->resource->mem_type);
> +
> + err = xe_migrate_access_memory(migrate, bo, offset, buf, len,
> + write);
> + goto out;
> + }
>
> vram = res_to_mem_region(ttm_bo->resource);
> xe_res_first(ttm_bo->resource, offset & PAGE_MASK,
> @@ -1160,7 +1166,8 @@ static int xe_ttm_access_memory(struct ttm_buffer_object *ttm_bo,
> xe_res_next(&cursor, PAGE_SIZE);
> } while (bytes_left);
>
> - return len;
> +out:
> + return err ?: len;
> }
>
> const struct ttm_device_funcs xe_ttm_funcs = {
> diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
> index cfd31ae49cc1..05ade498f559 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.c
> +++ b/drivers/gpu/drm/xe/xe_migrate.c
> @@ -669,6 +669,7 @@ static void emit_copy(struct xe_gt *gt, struct xe_bb *bb,
> u32 mocs = 0;
> u32 tile_y = 0;
>
> + xe_gt_assert(gt, !(pitch & 3));
> xe_gt_assert(gt, size / pitch <= S16_MAX);
> xe_gt_assert(gt, pitch / 4 <= S16_MAX);
> xe_gt_assert(gt, pitch <= U16_MAX);
> @@ -1542,6 +1543,330 @@ void xe_migrate_wait(struct xe_migrate *m)
> dma_fence_wait(m->fence, false);
> }
>
> +static u32 pte_update_cmd_size(u64 size)
> +{
> + u32 dword;
> + u64 entries = DIV_ROUND_UP(size, XE_PAGE_SIZE);
> +
> + XE_WARN_ON(size > MAX_PREEMPTDISABLE_TRANSFER);
> + /*
> + * MI_STORE_DATA_IMM command is used to update page table. Each
> + * instruction can update maximumly 0x1ff pte entries. To update
> + * n (n <= 0x1ff) pte entries, we need:
> + * 1 dword for the MI_STORE_DATA_IMM command header (opcode etc)
> + * 2 dword for the page table's physical location
> + * 2*n dword for value of pte to fill (each pte entry is 2 dwords)
> + */
> + dword = (1 + 2) * DIV_ROUND_UP(entries, 0x1ff);
> + dword += entries * 2;
> +
> + return dword;
> +}
> +
> +static void build_pt_update_batch_sram(struct xe_migrate *m,
> + struct xe_bb *bb, u32 pt_offset,
> + dma_addr_t *sram_addr, u32 size)
> +{
> + u16 pat_index = tile_to_xe(m->tile)->pat.idx[XE_CACHE_WB];
> + u32 ptes;
> + int i = 0;
> +
> + ptes = DIV_ROUND_UP(size, XE_PAGE_SIZE);
> + while (ptes) {
> + u32 chunk = min(0x1ffU, ptes);
> +
> + bb->cs[bb->len++] = MI_STORE_DATA_IMM | MI_SDI_NUM_QW(chunk);
> + bb->cs[bb->len++] = pt_offset;
> + bb->cs[bb->len++] = 0;
> +
> + pt_offset += chunk * 8;
> + ptes -= chunk;
> +
> + while (chunk--) {
> + u64 addr = sram_addr[i++] & PAGE_MASK;
> +
> + xe_tile_assert(m->tile, addr);
> + addr = m->q->vm->pt_ops->pte_encode_addr(m->tile->xe,
> + addr, pat_index,
> + 0, false, 0);
> + bb->cs[bb->len++] = lower_32_bits(addr);
> + bb->cs[bb->len++] = upper_32_bits(addr);
> + }
> + }
> +}
> +
> +enum xe_migrate_copy_dir {
> + XE_MIGRATE_COPY_TO_VRAM,
> + XE_MIGRATE_COPY_TO_SRAM,
> +};
> +
> +#define CACHELINE_BYTES 64ull
> +#define CACHELINE_MASK (CACHELINE_BYTES - 1)
> +
> +static struct dma_fence *xe_migrate_vram(struct xe_migrate *m,
> + unsigned long len,
> + unsigned long sram_offset,
> + dma_addr_t *sram_addr, u64 vram_addr,
> + const enum xe_migrate_copy_dir dir)
> +{
> + struct xe_gt *gt = m->tile->primary_gt;
> + struct xe_device *xe = gt_to_xe(gt);
> + struct dma_fence *fence = NULL;
> + u32 batch_size = 2;
> + u64 src_L0_ofs, dst_L0_ofs;
> + struct xe_sched_job *job;
> + struct xe_bb *bb;
> + u32 update_idx, pt_slot = 0;
> + unsigned long npages = DIV_ROUND_UP(len + sram_offset, PAGE_SIZE);
> + unsigned int pitch = len >= PAGE_SIZE && !(len & ~PAGE_MASK) ?
> + PAGE_SIZE : 4;
> + int err;
> +
> + if (drm_WARN_ON(&xe->drm, (len & CACHELINE_MASK) ||
> + (sram_offset | vram_addr) & CACHELINE_MASK))
> + return ERR_PTR(-EOPNOTSUPP);
> +
> + xe_assert(xe, npages * PAGE_SIZE <= MAX_PREEMPTDISABLE_TRANSFER);
> +
> + batch_size += pte_update_cmd_size(len);
> + batch_size += EMIT_COPY_DW;
> +
> + bb = xe_bb_new(gt, batch_size, true);
> + if (IS_ERR(bb)) {
> + err = PTR_ERR(bb);
> + return ERR_PTR(err);
> + }
> +
> + build_pt_update_batch_sram(m, bb, pt_slot * XE_PAGE_SIZE,
> + sram_addr, len + sram_offset);
> +
> + if (dir == XE_MIGRATE_COPY_TO_VRAM) {
> + src_L0_ofs = xe_migrate_vm_addr(pt_slot, 0) + sram_offset;
> + dst_L0_ofs = xe_migrate_vram_ofs(xe, vram_addr, false);
> +
> + } else {
> + src_L0_ofs = xe_migrate_vram_ofs(xe, vram_addr, false);
> + dst_L0_ofs = xe_migrate_vm_addr(pt_slot, 0) + sram_offset;
> + }
> +
> + bb->cs[bb->len++] = MI_BATCH_BUFFER_END;
> + update_idx = bb->len;
> +
> + emit_copy(gt, bb, src_L0_ofs, dst_L0_ofs, len, pitch);
> +
> + job = xe_bb_create_migration_job(m->q, bb,
> + xe_migrate_batch_base(m, true),
> + update_idx);
> + if (IS_ERR(job)) {
> + err = PTR_ERR(job);
> + goto err;
> + }
> +
> + xe_sched_job_add_migrate_flush(job, 0);
> +
> + mutex_lock(&m->job_mutex);
> + xe_sched_job_arm(job);
> + fence = dma_fence_get(&job->drm.s_fence->finished);
> + xe_sched_job_push(job);
> +
> + dma_fence_put(m->fence);
> + m->fence = dma_fence_get(fence);
> + mutex_unlock(&m->job_mutex);
> +
> + xe_bb_free(bb, fence);
> +
> + return fence;
> +
> +err:
> + xe_bb_free(bb, NULL);
> +
> + return ERR_PTR(err);
> +}
> +
> +static void xe_migrate_dma_unmap(struct xe_device *xe, dma_addr_t *dma_addr,
> + int len, int write)
> +{
> + unsigned long i, npages = DIV_ROUND_UP(len, PAGE_SIZE);
> +
> + for (i = 0; i < npages; ++i) {
> + if (!dma_addr[i])
> + continue;
> +
> + dma_unmap_page(xe->drm.dev, dma_addr[i], PAGE_SIZE,
> + write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
> + }
> + kfree(dma_addr);
> +}
> +
> +static dma_addr_t *xe_migrate_dma_map(struct xe_device *xe,
> + void *buf, int len, int write)
> +{
> + dma_addr_t *dma_addr;
> + unsigned long i, npages = DIV_ROUND_UP(len, PAGE_SIZE);
> +
> + dma_addr = kcalloc(npages, sizeof(*dma_addr), GFP_KERNEL);
> + if (!dma_addr)
> + return ERR_PTR(-ENOMEM);
> +
> + for (i = 0; i < npages; ++i) {
> + dma_addr_t addr;
> + struct page *page;
> +
> + if (is_vmalloc_addr(buf))
> + page = vmalloc_to_page(buf);
> + else
> + page = virt_to_page(buf);
> +
> + addr = dma_map_page(xe->drm.dev,
> + page, 0, PAGE_SIZE,
> + write ? DMA_TO_DEVICE :
> + DMA_FROM_DEVICE);
> + if (dma_mapping_error(xe->drm.dev, addr))
> + goto err_fault;
> +
> + dma_addr[i] = addr;
> + buf += PAGE_SIZE;
> + }
> +
> + return dma_addr;
> +
> +err_fault:
> + xe_migrate_dma_unmap(xe, dma_addr, len, write);
> + return ERR_PTR(-EFAULT);
> +}
> +
> +/**
> + * xe_migrate_access_memory - Access memory of a BO via GPU
> + *
> + * @m: The migration context.
> + * @bo: buffer object
> + * @offset: access offset into buffer object
> + * @buf: pointer to caller memory to read into or write from
> + * @len: length of access
> + * @write: write access
> + *
> + * Access memory of a BO via GPU either reading in or writing from a passed in
> + * pointer. Pointer is dma mapped for GPU access and GPU commands are issued to
> + * read to or write from pointer.
> + *
> + * Returns:
> + * 0 if successful, negative error code on failure.
> + */
> +int xe_migrate_access_memory(struct xe_migrate *m, struct xe_bo *bo,
> + unsigned long offset, void *buf, int len,
> + int write)
> +{
> + struct xe_tile *tile = m->tile;
> + struct xe_device *xe = tile_to_xe(tile);
> + struct xe_res_cursor cursor;
> + struct dma_fence *fence = NULL;
> + dma_addr_t *dma_addr;
> + unsigned long page_offset = (unsigned long)buf & ~PAGE_MASK;
> + int bytes_left = len, current_page = 0;
> + void *orig_buf = buf;
> +
> + xe_bo_assert_held(bo);
> +
> + /* Use bounce buffer for small access and unaligned access */
> + if (len & CACHELINE_MASK || ((uintptr_t)buf | offset) & CACHELINE_MASK) {
> + int buf_offset = 0;
> +
> + /*
> + * Less than ideal for large unaligned access but this should be
> + * fairly rare, can fixup if this becomes common.
> + */
> + do {
> + u8 bounce[CACHELINE_BYTES];
> + void *ptr = (void *)bounce;
> + int err;
> + int copy_bytes = min_t(int, bytes_left,
> + CACHELINE_BYTES -
> + (offset & CACHELINE_MASK));
> + int ptr_offset = offset & CACHELINE_MASK;
> +
> + err = xe_migrate_access_memory(m, bo,
> + offset & ~CACHELINE_MASK,
> + (void *)ptr,
> + sizeof(bounce), 0);
> + if (err)
> + return err;
> +
> + if (!write) {
> + memcpy(buf + buf_offset, ptr + ptr_offset,
> + copy_bytes);
> + goto next;
> + }
> +
> + memcpy(ptr + ptr_offset, buf + buf_offset, copy_bytes);
> + err = xe_migrate_access_memory(m, bo,
> + offset & ~CACHELINE_MASK,
> + (void *)ptr,
> + sizeof(bounce), 0);
Don't want to spam the list with another rev but this should be 'sizeof(bounce), 1'.
Matt
> + if (err)
> + return err;
> +
> +next:
> + bytes_left -= copy_bytes;
> + buf_offset += copy_bytes;
> + offset += copy_bytes;
> + } while (bytes_left);
> +
> + return 0;
> + }
> +
> + dma_addr = xe_migrate_dma_map(xe, buf, len + page_offset, write);
> + if (IS_ERR(dma_addr))
> + return PTR_ERR(dma_addr);
> +
> + xe_res_first(bo->ttm.resource, offset, bo->size - offset, &cursor);
> +
> + do {
> + struct dma_fence *__fence;
> + u64 vram_addr = vram_region_gpu_offset(bo->ttm.resource) +
> + cursor.start;
> + int current_bytes;
> +
> + if (cursor.size > MAX_PREEMPTDISABLE_TRANSFER)
> + current_bytes = min_t(int, bytes_left,
> + MAX_PREEMPTDISABLE_TRANSFER);
> + else
> + current_bytes = min_t(int, bytes_left, cursor.size);
> +
> + if (fence)
> + dma_fence_put(fence);
> +
> + __fence = xe_migrate_vram(m, current_bytes,
> + (unsigned long)buf & ~PAGE_MASK,
> + dma_addr + current_page,
> + vram_addr, write ?
> + XE_MIGRATE_COPY_TO_VRAM :
> + XE_MIGRATE_COPY_TO_SRAM);
> + if (IS_ERR(__fence)) {
> + if (fence)
> + dma_fence_wait(fence, false);
> + fence = __fence;
> + goto out_err;
> + }
> + fence = __fence;
> +
> + buf += current_bytes;
> + offset += current_bytes;
> + current_page = (int)(buf - orig_buf) / PAGE_SIZE;
> + bytes_left -= current_bytes;
> + if (bytes_left)
> + xe_res_next(&cursor, current_bytes);
> + } while (bytes_left);
> +
> + dma_fence_wait(fence, false);
> + xe_migrate_dma_unmap(xe, dma_addr, len + page_offset, write);
> +
> + return 0;
> +
> +out_err:
> + xe_migrate_dma_unmap(xe, dma_addr, len + page_offset, write);
> + return PTR_ERR(fence);
> +}
> +
> #if IS_ENABLED(CONFIG_DRM_XE_KUNIT_TEST)
> #include "tests/xe_migrate.c"
> #endif
> diff --git a/drivers/gpu/drm/xe/xe_migrate.h b/drivers/gpu/drm/xe/xe_migrate.h
> index 0109866e398a..94197d262178 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.h
> +++ b/drivers/gpu/drm/xe/xe_migrate.h
> @@ -102,6 +102,10 @@ struct dma_fence *xe_migrate_copy(struct xe_migrate *m,
> struct ttm_resource *dst,
> bool copy_only_ccs);
>
> +int xe_migrate_access_memory(struct xe_migrate *m, struct xe_bo *bo,
> + unsigned long offset, void *buf, int len,
> + int write);
> +
> #define XE_MIGRATE_CLEAR_FLAG_BO_DATA BIT(0)
> #define XE_MIGRATE_CLEAR_FLAG_CCS_DATA BIT(1)
> #define XE_MIGRATE_CLEAR_FLAG_FULL (XE_MIGRATE_CLEAR_FLAG_BO_DATA | \
> --
> 2.34.1
>
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