For gfxV9, due to a hardware bug ("based on the comments in the code
here [1]"), the control stack of a user-mode compute queue must be
allocated immediately after the page boundary of its regular MQD buffer.
To handle this, we allocate an enlarged MQD buffer where the first page
is used as the MQD and the remaining pages store the control stack.
Although these regions share the same BO, they require different memory
types: the MQD must be UC (uncached), while the control stack must be
NC (non-coherent), matching the behavior when the control stack is
allocated in user space.This logic works correctly on systems where the CPU page size matches the GPU page size (4K). However, the current implementation aligns both the MQD and the control stack to the CPU PAGE_SIZE. On systems with a larger CPU page size, the entire first CPU page is marked UC—even though that page may contain multiple GPU pages. The GPU treats the second 4K GPU page inside that CPU page as part of the control stack, but it is incorrectly mapped as UC. This misalignment leads to queue preemption and eviction failures. This patch fixes the issue by aligning both the MQD and control stack sizes to the GPU page size (4K). The first 4K page is correctly marked as UC for the MQD, and the remaining GPU pages are marked NC for the control stack. This ensures proper memory type assignment on systems with larger CPU page sizes and prevents incorrect behavior in queue preemption and eviction. [1]: https://elixir.bootlin.com/linux/v6.18/source/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c#L118 Signed-off-by: Donet Tom <[email protected]> --- drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c | 29 +++++++++++++++++++ drivers/gpu/drm/amd/amdgpu/amdgpu_gart.h | 2 ++ drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 16 ++-------- .../gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c | 15 +++++----- 4 files changed, 41 insertions(+), 21 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c index b2033f8352f5..0e1c017d10dc 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c @@ -368,6 +368,35 @@ void amdgpu_gart_map(struct amdgpu_device *adev, uint64_t offset, } drm_dev_exit(idx); } +void amdgpu_gart_map_gfx9_mqd(struct amdgpu_device *adev, uint64_t offset, + int pages, dma_addr_t *dma_addr, uint64_t flags) +{ + uint64_t page_base; + unsigned int i, j, t; + int idx; + uint64_t ctrl_flags = AMDGPU_PTE_MTYPE_VG10(flags, AMDGPU_MTYPE_NC); + void *dst; + + if (!adev->gart.ptr) + return; + + if (!drm_dev_enter(adev_to_drm(adev), &idx)) + return; + + t = offset / AMDGPU_GPU_PAGE_SIZE; + dst = adev->gart.ptr; + for (i = 0; i < pages; i++) { + page_base = dma_addr[i]; + for (j = 0; j < AMDGPU_GPU_PAGES_IN_CPU_PAGE; j++, t++) { + if ((i == 0) && (j == 0)) + amdgpu_gmc_set_pte_pde(adev, dst, t, page_base, flags); + else + amdgpu_gmc_set_pte_pde(adev, dst, t, page_base, ctrl_flags); + page_base += AMDGPU_GPU_PAGE_SIZE; + } + } + drm_dev_exit(idx); +} /** * amdgpu_gart_bind - bind pages into the gart page table diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.h index 7cc980bf4725..1beef780936d 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.h +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.h @@ -62,6 +62,8 @@ void amdgpu_gart_unbind(struct amdgpu_device *adev, uint64_t offset, void amdgpu_gart_map(struct amdgpu_device *adev, uint64_t offset, int pages, dma_addr_t *dma_addr, uint64_t flags, void *dst); +void amdgpu_gart_map_gfx9_mqd(struct amdgpu_device *adev, uint64_t offset, + int pages, dma_addr_t *dma_addr, uint64_t flags); void amdgpu_gart_bind(struct amdgpu_device *adev, uint64_t offset, int pages, dma_addr_t *dma_addr, uint64_t flags); void amdgpu_gart_invalidate_tlb(struct amdgpu_device *adev); diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c index 9d568c16beb1..c2e0d2518345 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c @@ -882,25 +882,15 @@ static void amdgpu_ttm_gart_bind_gfx9_mqd(struct amdgpu_device *adev, int num_xcc = max(1U, adev->gfx.num_xcc_per_xcp); uint64_t page_idx, pages_per_xcc; int i; - uint64_t ctrl_flags = AMDGPU_PTE_MTYPE_VG10(flags, AMDGPU_MTYPE_NC); pages_per_xcc = total_pages; do_div(pages_per_xcc, num_xcc); for (i = 0, page_idx = 0; i < num_xcc; i++, page_idx += pages_per_xcc) { - /* MQD page: use default flags */ - amdgpu_gart_bind(adev, + amdgpu_gart_map_gfx9_mqd(adev, gtt->offset + (page_idx << PAGE_SHIFT), - 1, >t->ttm.dma_address[page_idx], flags); - /* - * Ctrl pages - modify the memory type to NC (ctrl_flags) from - * the second page of the BO onward. - */ - amdgpu_gart_bind(adev, - gtt->offset + ((page_idx + 1) << PAGE_SHIFT), - pages_per_xcc - 1, - >t->ttm.dma_address[page_idx + 1], - ctrl_flags); + pages_per_xcc, >t->ttm.dma_address[page_idx], + flags); } } diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c index f2dee320fada..e45e39cd65fe 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_v9.c @@ -43,8 +43,8 @@ static uint64_t mqd_stride_v9(struct mqd_manager *mm, { if (mm->dev->kfd->cwsr_enabled && q->type == KFD_QUEUE_TYPE_COMPUTE) - return ALIGN(q->ctl_stack_size, PAGE_SIZE) + - ALIGN(sizeof(struct v9_mqd), PAGE_SIZE); + return ALIGN(ALIGN(q->ctl_stack_size, AMDGPU_GPU_PAGE_SIZE) + + ALIGN(sizeof(struct v9_mqd), AMDGPU_GPU_PAGE_SIZE), PAGE_SIZE); return mm->mqd_size; } @@ -136,13 +136,12 @@ static struct kfd_mem_obj *allocate_mqd(struct kfd_node *node, if (!mqd_mem_obj) return NULL; retval = amdgpu_amdkfd_alloc_gtt_mem(node->adev, - (ALIGN(q->ctl_stack_size, PAGE_SIZE) + - ALIGN(sizeof(struct v9_mqd), PAGE_SIZE)) * + (ALIGN(ALIGN(q->ctl_stack_size, AMDGPU_GPU_PAGE_SIZE) + + ALIGN(sizeof(struct v9_mqd), AMDGPU_GPU_PAGE_SIZE), PAGE_SIZE)) * NUM_XCC(node->xcc_mask), &(mqd_mem_obj->gtt_mem), &(mqd_mem_obj->gpu_addr), (void *)&(mqd_mem_obj->cpu_ptr), true); - if (retval) { kfree(mqd_mem_obj); return NULL; @@ -343,7 +342,7 @@ static int get_wave_state(struct mqd_manager *mm, void *mqd, struct kfd_context_save_area_header header; /* Control stack is located one page after MQD. */ - void *mqd_ctl_stack = (void *)((uintptr_t)mqd + PAGE_SIZE); + void *mqd_ctl_stack = (void *)((uintptr_t)mqd + AMDGPU_GPU_PAGE_SIZE); m = get_mqd(mqd); @@ -380,7 +379,7 @@ static void checkpoint_mqd(struct mqd_manager *mm, void *mqd, void *mqd_dst, voi { struct v9_mqd *m; /* Control stack is located one page after MQD. */ - void *ctl_stack = (void *)((uintptr_t)mqd + PAGE_SIZE); + void *ctl_stack = (void *)((uintptr_t)mqd + AMDGPU_GPU_PAGE_SIZE); m = get_mqd(mqd); @@ -426,7 +425,7 @@ static void restore_mqd(struct mqd_manager *mm, void **mqd, *gart_addr = addr; /* Control stack is located one page after MQD. */ - ctl_stack = (void *)((uintptr_t)*mqd + PAGE_SIZE); + ctl_stack = (void *)((uintptr_t)*mqd + AMDGPU_GPU_PAGE_SIZE); memcpy(ctl_stack, ctl_stack_src, ctl_stack_size); m->cp_hqd_pq_doorbell_control = -- 2.52.0
