On Mon, Dec 02, 2024 at 11:13:55AM +0100, Thomas Hellström wrote:
> On Tue, 2024-10-15 at 20:25 -0700, Matthew Brost wrote:
> > Add GPUSVM devic memory copy vfunc functions and connect to migration
>
> s/devic/device
Yes.
> >
>
> > layer.
> >
> > v2:
> > - Allow NULL device pages in xe_svm_copy
> > - Use new drm_gpusvm_devmem_ops
> >
> > Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/xe/xe_svm.c | 150
> > ++++++++++++++++++++++++++++++++++++
> > 1 file changed, 150 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/xe/xe_svm.c
> > b/drivers/gpu/drm/xe/xe_svm.c
> > index 22e6341117bd..b33fd42d035b 100644
> > --- a/drivers/gpu/drm/xe/xe_svm.c
> > +++ b/drivers/gpu/drm/xe/xe_svm.c
> > @@ -6,6 +6,7 @@
> > #include "drm_gpusvm.h"
> >
> > #include "xe_gt_tlb_invalidation.h"
> > +#include "xe_migrate.h"
> > #include "xe_pt.h"
> > #include "xe_svm.h"
> > #include "xe_vm.h"
> > @@ -269,6 +270,155 @@ static void
> > xe_svm_garbage_collector_work_func(struct work_struct *w)
> > up_write(&vm->lock);
> > }
> >
> > +static struct xe_mem_region *page_to_mr(struct page *page)
> > +{
> > + return container_of(page->pgmap, struct xe_mem_region,
> > pagemap);
> > +}
> > +
> > +static struct xe_tile *mr_to_tile(struct xe_mem_region *mr)
> > +{
> > + return container_of(mr, struct xe_tile, mem.vram);
> > +}
> > +
> > +static u64 xe_mem_region_page_to_dpa(struct xe_mem_region *mr,
> > + struct page *page)
> > +{
> > + u64 dpa;
> > + struct xe_tile *tile = mr_to_tile(mr);
> > + u64 pfn = page_to_pfn(page);
> > + u64 offset;
> > +
> > + xe_tile_assert(tile, is_device_private_page(page));
> > + xe_tile_assert(tile, (pfn << PAGE_SHIFT) >= mr->hpa_base);
> > +
> > + offset = (pfn << PAGE_SHIFT) - mr->hpa_base;
> > + dpa = mr->dpa_base + offset;
> > +
> > + return dpa;
> > +}
> > +
> > +enum xe_svm_copy_dir {
> > + XE_SVM_COPY_TO_VRAM,
> > + XE_SVM_COPY_TO_SRAM,
> > +};
> > +
> > +static int xe_svm_copy(struct page **pages, dma_addr_t *dma_addr,
> > + unsigned long npages, const enum
> > xe_svm_copy_dir dir)
> > +{
> > + struct xe_mem_region *mr = NULL;
> > + struct xe_tile *tile;
> > + struct dma_fence *fence = NULL;
> > + unsigned long i;
> > +#define VRAM_ADDR_INVALID ~0x0ull
> > + u64 vram_addr = VRAM_ADDR_INVALID;
> > + int err = 0, pos = 0;
> > + bool sram = dir == XE_SVM_COPY_TO_SRAM;
> > +
> > + for (i = 0; i < npages; ++i) {
> > + struct page *spage = pages[i];
> > + struct dma_fence *__fence;
> > + u64 __vram_addr;
> > + bool match = false, chunk, last;
> > +
> > + chunk = (i - pos) == (SZ_2M / PAGE_SIZE);
> > + last = (i + 1) == npages;
> > +
> > + if (!dma_addr[i] && vram_addr == VRAM_ADDR_INVALID)
> > + continue;
> > +
> > + if (!mr && spage) {
> > + mr = page_to_mr(spage);
> > + tile = mr_to_tile(mr);
> > + }
> > +
> > + if (dma_addr[i] && spage) {
> > + __vram_addr = xe_mem_region_page_to_dpa(mr,
> > spage);
> > + if (vram_addr == VRAM_ADDR_INVALID) {
> > + vram_addr = __vram_addr;
> > + pos = i;
> > + }
> > +
> > + match = vram_addr + PAGE_SIZE * (i - pos) ==
> > __vram_addr;
> > + }
> > +
> > + if (!match || chunk || last) {
> > + int incr = (match && last) ? 1 : 0;
> > +
> > + if (vram_addr != VRAM_ADDR_INVALID) {
> > + if (sram)
> > + __fence =
> > xe_migrate_from_vram(tile->migrate,
> > +
> > i - pos + incr,
> > +
> > vram_addr,
> > +
> > dma_addr + pos);
> > + else
> > + __fence =
> > xe_migrate_to_vram(tile->migrate,
> > +
> > i - pos + incr,
> > +
> > dma_addr + pos,
> > +
> > vram_addr);
> > + if (IS_ERR(__fence)) {
> > + err = PTR_ERR(__fence);
> > + goto err_out;
> > + }
> > +
> > + dma_fence_put(fence);
> > + fence = __fence;
> > + }
> > +
> > + if (dma_addr[i] && spage) {
> > + vram_addr = __vram_addr;
> > + pos = i;
> > + } else {
> > + vram_addr = VRAM_ADDR_INVALID;
> > + }
> > +
> > + if (!match && last && dma_addr[i] && spage)
> > {
> > + if (sram)
> > + __fence =
> > xe_migrate_from_vram(tile->migrate, 1,
> > +
> > vram_addr,
> > +
> > dma_addr + pos);
> > + else
> > + __fence =
> > xe_migrate_to_vram(tile->migrate, 1,
> > +
> > dma_addr + pos,
> > +
> > vram_addr);
> > + if (IS_ERR(__fence)) {
> > + err = PTR_ERR(__fence);
> > + goto err_out;
> > + }
> > +
> > + dma_fence_put(fence);
> > + fence = __fence;
> > + }
>
> I think the flow in this function is a bit hard to follow. Could it
> perhaps be simplified? If not, perhaps add a comment to the function
> what it expects from the input arguments and the possible corner cases
> that complicates it?
>
Maybe? It may need to updated to do clears to in the next rev, so let me
play around with this. At minimum can add comments + kernel doc.
Matt
>
> > + }
> > + }
> > +
> > +err_out:
> > + if (fence) {
> > + dma_fence_wait(fence, false);
> > + dma_fence_put(fence);
> > + }
> > +
> > + return err;
> > +#undef VRAM_ADDR_INVALID
> > +}
> > +
> > +static int xe_svm_copy_to_devmem(struct page **pages, dma_addr_t
> > *dma_addr,
> > + unsigned long npages)
> > +{
> > + return xe_svm_copy(pages, dma_addr, npages,
> > XE_SVM_COPY_TO_VRAM);
> > +}
> > +
> > +static int xe_svm_copy_to_ram(struct page **pages, dma_addr_t
> > *dma_addr,
> > + unsigned long npages)
> > +{
> > + return xe_svm_copy(pages, dma_addr, npages,
> > XE_SVM_COPY_TO_SRAM);
> > +}
> > +
> > +__maybe_unused
>
> Is this __maybe_unused to be removed in a follow-up patch? If so could
> you add a comment stating that?
>
> > +static const struct drm_gpusvm_devmem_ops gpusvm_devmem_ops = {
> > + .copy_to_devmem = xe_svm_copy_to_devmem,
> > + .copy_to_ram = xe_svm_copy_to_ram,
> > +};
> > +
> > static const struct drm_gpusvm_ops gpusvm_ops = {
> > .range_alloc = xe_svm_range_alloc,
> > .range_free = xe_svm_range_free,
>
> Thanks,
> Thomas
>
>
