> + * Turns out AMD IOMMU has a page table bug where it won't map large pages
> + * to a region that previously mapped smaller pages. This should be fixed
> + * soon, so this is just a temporary workaround to break mappings down into
> + * PAGE_SIZE. Better to map smaller pages than nothing.
> + */
> +static int map_try_harder(struct vfio_iommu *iommu, dma_addr_t iova,
> + unsigned long pfn, long npage, int prot)
> +{
> + long i;
> + int ret;
> +
> + for (i = 0; i < npage; i++, pfn++, iova += PAGE_SIZE) {
> + ret = iommu_map(iommu->domain, iova,
> + (phys_addr_t)pfn << PAGE_SHIFT,
> + PAGE_SIZE, prot);
> + if (ret)
> + break;
> + }
> +
> + for (; i < npage && i > 0; i--, iova -= PAGE_SIZE)
> + iommu_unmap(iommu->domain, iova, PAGE_SIZE);
> +
> return ret;
> }
This looks to belong to a vfio-quirk file (a something else) that deals with
various IOMMU's quirks.
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