Jerome,
I think this could and should be accomplished in the following way (like
the old ttm did).
1: For kernel maps:
a) reserve the bo.
b) validate the bo into a mappable segment of vram, perhaps using range
validation.
c) idle any accelerated move.
d) call ttm_bo_kmap.
2: For fault:
a) in bo_driver::fault_reserve_notify, validate the bo into a mappable
segment of vram, perhaps using range validation.
b) The fault method will automatically idle any accelerated move.
Is there something that could not be accomplished with this approach?
However, in any case to avoid lock inversion between mmap_sem and
bo::reserve, one must ensure that any bo::reserve called during the
validation process (for example during eviction) is called with the
no_wait argument set to true, and if the call returns -EBUSY, call
set_need_resched() and return VM_FAULT_NOPAGE from fault. If the error
code is -ERESTARTSYS, we should also call VM_FAULT_NOPAGE, but without
the set_need_resched().
This requires a return value from bo:driver::fault_reserve_notify and an
extra argument to ttm_bo_validate. Note that waiting for the GPU while
holding the mmap_sem is still OK from a lock inversion point of view,
which means that the @no_wait argument to ttm_bo_validate could still be
false. There might be other aspects to this, though.
Note that this last section would have applied to your patch as well.
/Thomas
Jerome Glisse wrote:
> On fault the driver is given the opportunity to perform any operation
> it sees fit in order to place the buffer into a CPU visible area of
> memory. This patch doesn't break TTM users, nouveau, vmwgfx and radeon
> should keep working properly. Future patch will take advantage of this
> infrastructure and remove the old path from TTM once driver are
> converted.
>
> Signed-off-by: Jerome Glisse <jgli...@redhat.com>
> ---
> drivers/gpu/drm/ttm/ttm_bo.c | 3 +-
> drivers/gpu/drm/ttm/ttm_bo_util.c | 92
> +++++++++++++++++--------------------
> drivers/gpu/drm/ttm/ttm_bo_vm.c | 48 +++++++++----------
> include/drm/ttm/ttm_bo_api.h | 1 +
> include/drm/ttm/ttm_bo_driver.h | 30 ++++++++++++
> 5 files changed, 97 insertions(+), 77 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index c7320ce..28f3fcf 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -1581,7 +1581,8 @@ void ttm_bo_unmap_virtual(struct ttm_buffer_object *bo)
>
> if (!bdev->dev_mapping)
> return;
> -
> + if (bdev->driver->io_mem_free)
> + bdev->driver->io_mem_free(bdev, &bo->mem);
> unmap_mapping_range(bdev->dev_mapping, offset, holelen, 1);
> }
> EXPORT_SYMBOL(ttm_bo_unmap_virtual);
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c
> b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index 3f72fe1..10c5fc6 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -84,26 +84,36 @@ int ttm_mem_reg_ioremap(struct ttm_bo_device *bdev,
> struct ttm_mem_reg *mem,
> void **virtual)
> {
> struct ttm_mem_type_manager *man = &bdev->man[mem->mem_type];
> - unsigned long bus_offset;
> - unsigned long bus_size;
> - unsigned long bus_base;
> + struct ttm_bus_placement pl;
> int ret;
> void *addr;
>
> *virtual = NULL;
> - ret = ttm_bo_pci_offset(bdev, mem, &bus_base, &bus_offset, &bus_size);
> - if (ret || bus_size == 0)
> - return ret;
> + if (bdev->driver->io_mem_reserve) {
> + ret = bdev->driver->io_mem_reserve(bdev, mem, &pl);
> + if (unlikely(ret != 0)) {
> + return ret;
> + }
> + } else {
> + ret = ttm_bo_pci_offset(bdev, mem, &pl.base, &pl.offset,
> &pl.size);
> + if (unlikely(ret != 0) || pl.size == 0) {
> + return ret;
> + }
> + pl.is_iomem = (pl.size != 0);
> + }
>
> if (!(man->flags & TTM_MEMTYPE_FLAG_NEEDS_IOREMAP))
> - addr = (void *)(((u8 *) man->io_addr) + bus_offset);
> + addr = (void *)(pl.base + pl.offset);
> else {
> if (mem->placement & TTM_PL_FLAG_WC)
> - addr = ioremap_wc(bus_base + bus_offset, bus_size);
> + addr = ioremap_wc(pl.base + pl.offset, pl.size);
> else
> - addr = ioremap_nocache(bus_base + bus_offset,
> bus_size);
> - if (!addr)
> + addr = ioremap_nocache(pl.base + pl.offset, pl.size);
> + if (!addr) {
> + if (bdev->driver->io_mem_free)
> + bdev->driver->io_mem_free(bdev, mem);
> return -ENOMEM;
> + }
> }
> *virtual = addr;
> return 0;
> @@ -118,6 +128,8 @@ void ttm_mem_reg_iounmap(struct ttm_bo_device *bdev,
> struct ttm_mem_reg *mem,
>
> if (virtual && (man->flags & TTM_MEMTYPE_FLAG_NEEDS_IOREMAP))
> iounmap(virtual);
> + if (bdev->driver->io_mem_free)
> + bdev->driver->io_mem_free(bdev, mem);
> }
>
> static int ttm_copy_io_page(void *dst, void *src, unsigned long page)
> @@ -440,13 +452,12 @@ int ttm_bo_kmap(struct ttm_buffer_object *bo,
> unsigned long start_page, unsigned long num_pages,
> struct ttm_bo_kmap_obj *map)
> {
> + struct ttm_bus_placement pl;
> int ret;
> - unsigned long bus_base;
> - unsigned long bus_offset;
> - unsigned long bus_size;
>
> BUG_ON(!list_empty(&bo->swap));
> map->virtual = NULL;
> + map->bo = bo;
> if (num_pages > bo->num_pages)
> return -EINVAL;
> if (start_page > bo->num_pages)
> @@ -455,16 +466,24 @@ int ttm_bo_kmap(struct ttm_buffer_object *bo,
> if (num_pages > 1 && !DRM_SUSER(DRM_CURPROC))
> return -EPERM;
> #endif
> - ret = ttm_bo_pci_offset(bo->bdev, &bo->mem, &bus_base,
> - &bus_offset, &bus_size);
> - if (ret)
> - return ret;
> - if (bus_size == 0) {
> + if (bo->bdev->driver->io_mem_reserve) {
> + ret = bo->bdev->driver->io_mem_reserve(bo->bdev, &bo->mem,
> &pl);
> + if (unlikely(ret != 0)) {
> + return ret;
> + }
> + } else {
> + ret = ttm_bo_pci_offset(bo->bdev, &bo->mem, &pl.base,
> &pl.offset, &pl.size);
> + if (unlikely(ret != 0)) {
> + return ret;
> + }
> + pl.is_iomem = (pl.size != 0);
> + }
> + if (!pl.is_iomem) {
> return ttm_bo_kmap_ttm(bo, start_page, num_pages, map);
> } else {
> - bus_offset += start_page << PAGE_SHIFT;
> - bus_size = num_pages << PAGE_SHIFT;
> - return ttm_bo_ioremap(bo, bus_base, bus_offset, bus_size,
> map);
> + pl.offset += start_page << PAGE_SHIFT;
> + pl.size = num_pages << PAGE_SHIFT;
> + return ttm_bo_ioremap(bo, pl.base, pl.offset, pl.size, map);
> }
> }
> EXPORT_SYMBOL(ttm_bo_kmap);
> @@ -476,6 +495,8 @@ void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
> switch (map->bo_kmap_type) {
> case ttm_bo_map_iomap:
> iounmap(map->virtual);
> + if (map->bo->bdev->driver->io_mem_free)
> + map->bo->bdev->driver->io_mem_free(map->bo->bdev,
> &map->bo->mem);
> break;
> case ttm_bo_map_vmap:
> vunmap(map->virtual);
> @@ -493,35 +514,6 @@ void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
> }
> EXPORT_SYMBOL(ttm_bo_kunmap);
>
> -int ttm_bo_pfn_prot(struct ttm_buffer_object *bo,
> - unsigned long dst_offset,
> - unsigned long *pfn, pgprot_t *prot)
> -{
> - struct ttm_mem_reg *mem = &bo->mem;
> - struct ttm_bo_device *bdev = bo->bdev;
> - unsigned long bus_offset;
> - unsigned long bus_size;
> - unsigned long bus_base;
> - int ret;
> - ret = ttm_bo_pci_offset(bdev, mem, &bus_base, &bus_offset,
> - &bus_size);
> - if (ret)
> - return -EINVAL;
> - if (bus_size != 0)
> - *pfn = (bus_base + bus_offset + dst_offset) >> PAGE_SHIFT;
> - else
> - if (!bo->ttm)
> - return -EINVAL;
> - else
> - *pfn = page_to_pfn(ttm_tt_get_page(bo->ttm,
> - dst_offset >>
> - PAGE_SHIFT));
> - *prot = (mem->placement & TTM_PL_FLAG_CACHED) ?
> - PAGE_KERNEL : ttm_io_prot(mem->placement, PAGE_KERNEL);
> -
> - return 0;
> -}
> -
> int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
> void *sync_obj,
> void *sync_obj_arg,
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 668dbe8..9446b26 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -74,9 +74,7 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma,
> struct vm_fault *vmf)
> struct ttm_buffer_object *bo = (struct ttm_buffer_object *)
> vma->vm_private_data;
> struct ttm_bo_device *bdev = bo->bdev;
> - unsigned long bus_base;
> - unsigned long bus_offset;
> - unsigned long bus_size;
> + struct ttm_bus_placement pl;
> unsigned long page_offset;
> unsigned long page_last;
> unsigned long pfn;
> @@ -84,7 +82,6 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma,
> struct vm_fault *vmf)
> struct page *page;
> int ret;
> int i;
> - bool is_iomem;
> unsigned long address = (unsigned long)vmf->virtual_address;
> int retval = VM_FAULT_NOPAGE;
>
> @@ -104,11 +101,25 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma,
> struct vm_fault *vmf)
> if (bdev->driver->fault_reserve_notify)
> bdev->driver->fault_reserve_notify(bo);
>
> + if (bdev->driver->fault_reserve) {
> + ret = bdev->driver->fault_reserve(bo, &pl);
> + if (unlikely(ret != 0)) {
> + retval = VM_FAULT_SIGBUS;
> + goto out_unlock;
> + }
> + } else {
> + ret = ttm_bo_pci_offset(bdev, &bo->mem, &pl.base, &pl.offset,
> &pl.size);
> + if (unlikely(ret != 0)) {
> + retval = VM_FAULT_SIGBUS;
> + goto out_unlock;
> + }
> + pl.is_iomem = (pl.size != 0);
> + }
> +
> /*
> * Wait for buffer data in transit, due to a pipelined
> * move.
> */
> -
> spin_lock(&bo->lock);
> if (test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)) {
> ret = ttm_bo_wait(bo, false, true, false);
> @@ -122,20 +133,10 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma,
> struct vm_fault *vmf)
> spin_unlock(&bo->lock);
>
>
> - ret = ttm_bo_pci_offset(bdev, &bo->mem, &bus_base, &bus_offset,
> - &bus_size);
> - if (unlikely(ret != 0)) {
> - retval = VM_FAULT_SIGBUS;
> - goto out_unlock;
> - }
> -
> - is_iomem = (bus_size != 0);
> -
> page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
> bo->vm_node->start - vma->vm_pgoff;
> page_last = ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) +
> bo->vm_node->start - vma->vm_pgoff;
> -
> if (unlikely(page_offset >= bo->num_pages)) {
> retval = VM_FAULT_SIGBUS;
> goto out_unlock;
> @@ -154,8 +155,7 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma,
> struct vm_fault *vmf)
> * vma->vm_page_prot when the object changes caching policy, with
> * the correct locks held.
> */
> -
> - if (is_iomem) {
> + if (pl.is_iomem) {
> vma->vm_page_prot = ttm_io_prot(bo->mem.placement,
> vma->vm_page_prot);
> } else {
> @@ -169,12 +169,9 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma,
> struct vm_fault *vmf)
> * Speculatively prefault a number of pages. Only error on
> * first page.
> */
> -
> for (i = 0; i < TTM_BO_VM_NUM_PREFAULT; ++i) {
> -
> - if (is_iomem)
> - pfn = ((bus_base + bus_offset) >> PAGE_SHIFT) +
> - page_offset;
> + if (pl.is_iomem)
> + pfn = ((pl.base + pl.offset) >> PAGE_SHIFT) +
> page_offset;
> else {
> page = ttm_tt_get_page(ttm, page_offset);
> if (unlikely(!page && i == 0)) {
> @@ -191,14 +188,12 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma,
> struct vm_fault *vmf)
> * Somebody beat us to this PTE or prefaulting to
> * an already populated PTE, or prefaulting error.
> */
> -
> if (unlikely((ret == -EBUSY) || (ret != 0 && i > 0)))
> break;
> else if (unlikely(ret != 0)) {
> retval =
> (ret == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
> goto out_unlock;
> -
> }
>
> address += PAGE_SIZE;
> @@ -221,9 +216,10 @@ static void ttm_bo_vm_open(struct vm_area_struct *vma)
>
> static void ttm_bo_vm_close(struct vm_area_struct *vma)
> {
> - struct ttm_buffer_object *bo =
> - (struct ttm_buffer_object *)vma->vm_private_data;
> + struct ttm_buffer_object *bo = (struct ttm_buffer_object
> *)vma->vm_private_data;
>
> + if (bo->bdev->driver->io_mem_free)
> + bo->bdev->driver->io_mem_free(bo->bdev, &bo->mem);
> ttm_bo_unref(&bo);
> vma->vm_private_data = NULL;
> }
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 81eb9f4..1b38c67 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -274,6 +274,7 @@ struct ttm_bo_kmap_obj {
> ttm_bo_map_kmap = 3,
> ttm_bo_map_premapped = 4 | TTM_BO_MAP_IOMEM_MASK,
> } bo_kmap_type;
> + struct ttm_buffer_object *bo;
> };
>
> /**
> diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
> index 4c4e0f8..923fecf 100644
> --- a/include/drm/ttm/ttm_bo_driver.h
> +++ b/include/drm/ttm/ttm_bo_driver.h
> @@ -240,6 +240,23 @@ struct ttm_mem_type_manager {
> };
>
> /**
> + * struct ttm_bus_placement
> + *
> + * @base: bus base address
> + * @is_iomem: is this io memory ?
> + * @size: size in byte
> + * @offset: offset from the base address
> + *
> + * Structure indicating the bus placement of an object.
> + */
> +struct ttm_bus_placement {
> + unsigned long base;
> + unsigned long size;
> + unsigned long offset;
> + bool is_iomem;
> +};
> +
> +/**
> * struct ttm_bo_driver
> *
> * @create_ttm_backend_entry: Callback to create a struct ttm_backend.
> @@ -358,6 +375,19 @@ struct ttm_bo_driver {
> * notify the driver that we're about to swap out this bo
> */
> void (*swap_notify) (struct ttm_buffer_object *bo);
> +
> + /**
> + * Driver callback on bo fault, driver is responsible to fill the
> + * bus placement and has the opportunity to move the buffer into
> + * visible space.
> + */
> + int (*fault_reserve)(struct ttm_buffer_object *bo, struct
> ttm_bus_placement *pl);
> + /**
> + * Driver callback on when mapping io memory (for bo_move_memcpy for
> instance).
> + * TTM will take care to call io_mem_free whenever the mapping is not
> use anymore.
> + */
> + int (*io_mem_reserve)(struct ttm_bo_device *bdev, struct ttm_mem_reg
> *mem, struct ttm_bus_placement *pl);
> + void (*io_mem_free)(struct ttm_bo_device *bdev, struct ttm_mem_reg
> *mem);
> };
>
> /**
> --
> 1.6.6
>
>
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