[PATCH v6 2/8] drm/ttm: Add ttm_bo_access
Rodrigo Vivi
rodrigo.vivi at intel.com
Mon Nov 4 22:26:44 UTC 2024
On Mon, Nov 04, 2024 at 01:30:41PM -0800, Matthew Brost wrote:
> On Mon, Nov 04, 2024 at 08:47:01PM +0100, Christian König wrote:
> > Am 01.11.24 um 00:43 schrieb Matthew Brost:
> > > On Thu, Oct 31, 2024 at 11:10:42AM -0700, Matthew Brost wrote:
> > > > Non-contiguous VRAM cannot easily be mapped in TTM nor can non-visible
> > > > VRAM easily be accessed. Add ttm_bo_access, which is similar to
> > > > ttm_bo_vm_access, to access such memory.
> > > >
> > > > v4:
> > > > - Fix checkpatch warnings (CI)
> > > > v5:
> > > > - Fix checkpatch warnings (CI)
> > > > v6:
> > > > - Fix kernel doc (Auld)
> > > >
> > > Christian - Do you mind if I merge patch along with the rest of the
> > > series to drm-xe-next?
> >
> > I don't see the original patch anywhere in my inbox, please make sure to CC
> > me while sending things out.
> >
>
> I think I had you on an earlier revision but used the wrong alias to send out
> this latest one. I will be sure to include you on future patches.
>
> Would you like to continue the discussion here, or should I send out a fresh
> revision with you included and an updated commit message?
please send over a refreshed version with updated commit message and also
cc'ing dri-devel
>
> > Apart from that I absolutely don't see any justification for this patch. You
> > move stuff into ttm_bo_util.c which not even remotely belongs in there.
> >
>
> The justification is that EuDebugger requires essentially the same functionality
> as ptrace -> vm_access. This patch simply adds a helper to achieve this. There
> is no functional change to the existing code.
>
> Regarding the statement about ttm_bo_util.c, that seems quite aggressive. It is
> a TTM BO helper function, so it could logically belong in either ttm_bo.c or
> ttm_bo_util.c. A BO helper definitely shouldn't call into ttm_bo_vm.c, nor
> should it reside there. Perhaps I chose the wrong ttm_bo* file? I apologize for
> that. It would be helpful to know why you think this is the wrong place so I can
> better understand your expectations for TTM.
I also believe that the ttm_bo_util seems a good place for that, but
perhaps someone else has some other better ideas or suggestions there
>
> Matt
>
> > Regards,
> > Christian.
> >
> > >
> > > Matt
> > >
> > > > Reported-by: Christoph Manszewski <christoph.manszewski at intel.com>
> > > > Suggested-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> > > > Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> > > > Tested-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> > > > Reviewed-by: Matthew Auld <matthew.auld at intel.com>
> > > > ---
> > > > drivers/gpu/drm/ttm/ttm_bo_util.c | 86 +++++++++++++++++++++++++++++++
> > > > drivers/gpu/drm/ttm/ttm_bo_vm.c | 65 +----------------------
> > > > include/drm/ttm/ttm_bo.h | 2 +
> > > > 3 files changed, 89 insertions(+), 64 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> > > > index d939925efa81..77e760ea7193 100644
> > > > --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> > > > +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> > > > @@ -919,3 +919,89 @@ s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct ttm_device *bdev,
> > > > return progress;
> > > > }
> > > > +
> > > > +static int ttm_bo_access_kmap(struct ttm_buffer_object *bo,
> > > > + unsigned long offset,
> > > > + void *buf, int len, int write)
> > > > +{
> > > > + unsigned long page = offset >> PAGE_SHIFT;
> > > > + unsigned long bytes_left = len;
> > > > + int ret;
> > > > +
> > > > + /* Copy a page at a time, that way no extra virtual address
> > > > + * mapping is needed
> > > > + */
> > > > + offset -= page << PAGE_SHIFT;
> > > > + do {
> > > > + unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
> > > > + struct ttm_bo_kmap_obj map;
> > > > + void *ptr;
> > > > + bool is_iomem;
> > > > +
> > > > + ret = ttm_bo_kmap(bo, page, 1, &map);
> > > > + if (ret)
> > > > + return ret;
> > > > +
> > > > + ptr = (void *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;
> > > > + WARN_ON_ONCE(is_iomem);
> > > > + if (write)
> > > > + memcpy(ptr, buf, bytes);
> > > > + else
> > > > + memcpy(buf, ptr, bytes);
> > > > + ttm_bo_kunmap(&map);
> > > > +
> > > > + page++;
> > > > + buf += bytes;
> > > > + bytes_left -= bytes;
> > > > + offset = 0;
> > > > + } while (bytes_left);
> > > > +
> > > > + return len;
> > > > +}
> > > > +
> > > > +/**
> > > > + * ttm_bo_access - Helper to access a buffer object
> > > > + *
> > > > + * @bo: ttm 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
> > > > + *
> > > > + * Utility function to access a buffer object. Useful when buffer object cannot
> > > > + * be easily mapped (non-contiguous, non-visible, etc...).
> > > > + *
> > > > + * Returns:
> > > > + * @len if successful, negative error code on failure.
> > > > + */
> > > > +int ttm_bo_access(struct ttm_buffer_object *bo, unsigned long offset,
> > > > + void *buf, int len, int write)
> > > > +{
> > > > + int ret;
> > > > +
> > > > + if (len < 1 || (offset + len) > bo->base.size)
> > > > + return -EIO;
> > > > +
> > > > + ret = ttm_bo_reserve(bo, true, false, NULL);
> > > > + if (ret)
> > > > + return ret;
> > > > +
> > > > + switch (bo->resource->mem_type) {
> > > > + case TTM_PL_SYSTEM:
> > > > + fallthrough;
> > > > + case TTM_PL_TT:
> > > > + ret = ttm_bo_access_kmap(bo, offset, buf, len, write);
> > > > + break;
> > > > + default:
> > > > + if (bo->bdev->funcs->access_memory)
> > > > + ret = bo->bdev->funcs->access_memory
> > > > + (bo, offset, buf, len, write);
> > > > + else
> > > > + ret = -EIO;
> > > > + }
> > > > +
> > > > + ttm_bo_unreserve(bo);
> > > > +
> > > > + return ret;
> > > > +}
> > > > +EXPORT_SYMBOL(ttm_bo_access);
> > > > diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > > > index 2c699ed1963a..20b1e5f78684 100644
> > > > --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > > > +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> > > > @@ -366,45 +366,6 @@ void ttm_bo_vm_close(struct vm_area_struct *vma)
> > > > }
> > > > EXPORT_SYMBOL(ttm_bo_vm_close);
> > > > -static int ttm_bo_vm_access_kmap(struct ttm_buffer_object *bo,
> > > > - unsigned long offset,
> > > > - uint8_t *buf, int len, int write)
> > > > -{
> > > > - unsigned long page = offset >> PAGE_SHIFT;
> > > > - unsigned long bytes_left = len;
> > > > - int ret;
> > > > -
> > > > - /* Copy a page at a time, that way no extra virtual address
> > > > - * mapping is needed
> > > > - */
> > > > - offset -= page << PAGE_SHIFT;
> > > > - do {
> > > > - unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
> > > > - struct ttm_bo_kmap_obj map;
> > > > - void *ptr;
> > > > - bool is_iomem;
> > > > -
> > > > - ret = ttm_bo_kmap(bo, page, 1, &map);
> > > > - if (ret)
> > > > - return ret;
> > > > -
> > > > - ptr = (uint8_t *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;
> > > > - WARN_ON_ONCE(is_iomem);
> > > > - if (write)
> > > > - memcpy(ptr, buf, bytes);
> > > > - else
> > > > - memcpy(buf, ptr, bytes);
> > > > - ttm_bo_kunmap(&map);
> > > > -
> > > > - page++;
> > > > - buf += bytes;
> > > > - bytes_left -= bytes;
> > > > - offset = 0;
> > > > - } while (bytes_left);
> > > > -
> > > > - return len;
> > > > -}
> > > > -
> > > > int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> > > > void *buf, int len, int write)
> > > > {
> > > > @@ -412,32 +373,8 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> > > > unsigned long offset = (addr) - vma->vm_start +
> > > > ((vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node))
> > > > << PAGE_SHIFT);
> > > > - int ret;
> > > > -
> > > > - if (len < 1 || (offset + len) > bo->base.size)
> > > > - return -EIO;
> > > > - ret = ttm_bo_reserve(bo, true, false, NULL);
> > > > - if (ret)
> > > > - return ret;
> > > > -
> > > > - switch (bo->resource->mem_type) {
> > > > - case TTM_PL_SYSTEM:
> > > > - fallthrough;
> > > > - case TTM_PL_TT:
> > > > - ret = ttm_bo_vm_access_kmap(bo, offset, buf, len, write);
> > > > - break;
> > > > - default:
> > > > - if (bo->bdev->funcs->access_memory)
> > > > - ret = bo->bdev->funcs->access_memory(
> > > > - bo, offset, buf, len, write);
> > > > - else
> > > > - ret = -EIO;
> > > > - }
> > > > -
> > > > - ttm_bo_unreserve(bo);
> > > > -
> > > > - return ret;
> > > > + return ttm_bo_access(bo, offset, buf, len, write);
> > > > }
> > > > EXPORT_SYMBOL(ttm_bo_vm_access);
> > > > diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h
> > > > index 5804408815be..8ea11cd8df39 100644
> > > > --- a/include/drm/ttm/ttm_bo.h
> > > > +++ b/include/drm/ttm/ttm_bo.h
> > > > @@ -421,6 +421,8 @@ void ttm_bo_unpin(struct ttm_buffer_object *bo);
> > > > int ttm_bo_evict_first(struct ttm_device *bdev,
> > > > struct ttm_resource_manager *man,
> > > > struct ttm_operation_ctx *ctx);
> > > > +int ttm_bo_access(struct ttm_buffer_object *bo, unsigned long offset,
> > > > + void *buf, int len, int write);
> > > > vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
> > > > struct vm_fault *vmf);
> > > > vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
> > > > --
> > > > 2.34.1
> > > >
> >
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