On Fri, Dec 13, 2019 at 01:56:08PM -0800, Niranjana Vishwanathapura wrote:
> @@ -169,6 +170,11 @@ static int i915_range_fault(struct svm_notifier *sn,
> return ret;
> }
>
> + /* For dgfx, ensure the range is in device local memory only */
> + regions = i915_dmem_convert_pfn(vm->i915, &range);
> + if (!regions || (IS_DGFX(vm->i915) && (regions & REGION_SMEM)))
> + return -EINVAL;
> +
This is not OK, as I said before, the driver cannot de-reference pfns
before doing the retry check, under lock.
> +
> +int i915_dmem_convert_pfn(struct drm_i915_private *dev_priv,
> + struct hmm_range *range)
> +{
> + unsigned long i, npages;
> + int regions = 0;
> +
> + npages = (range->end - range->start) >> PAGE_SHIFT;
> + for (i = 0; i < npages; ++i) {
> + struct i915_buddy_block *block;
> + struct intel_memory_region *mem;
> + struct page *page;
> + u64 addr;
> +
> + page = hmm_device_entry_to_page(range, range->pfns[i]);
^^^^^^^^^^^^^^^^^^^^^^
For instance, that cannot be done on a speculatively loaded page.
This also looks like it suffers from the same bug as
> + if (!page)
> + continue;
> +
> + if (!(range->pfns[i] & range->flags[HMM_PFN_DEVICE_PRIVATE])) {
> + regions |= REGION_SMEM;
> + continue;
> + }
> +
> + if (!i915_dmem_page(dev_priv, page)) {
> + WARN(1, "Some unknown device memory !\n");
Why is that a WARN? The user could put other device memory in the
address space. You need to 'segfault' the GPU execution if this happens.
> + range->pfns[i] = 0;
> + continue;
> + }
> +
> + regions |= REGION_LMEM;
> + block = page->zone_device_data;
> + mem = block->private;
> + addr = mem->region.start +
> + i915_buddy_block_offset(block);
> + addr += (page_to_pfn(page) - block->pfn_first) << PAGE_SHIFT;
> +
> + range->pfns[i] &= ~range->flags[HMM_PFN_DEVICE_PRIVATE];
> + range->pfns[i] &= ((1UL << range->pfn_shift) - 1);
> + range->pfns[i] |= (addr >> PAGE_SHIFT) << range->pfn_shift;
This makes more sense as a direct manipulation of the sgl, not sure
why this routine is split out from the sgl builder?
Jason
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