Joerg,
Any comments on this? I need this for vfio hugepage support, otherwise
we risk getting a map failure that results in a BUG_ON from
iommu_unmap_page in amd_iommu. I can take it in through my vfio tree to
keep the dependencies together if you want to provide an ack. Thanks,
Alex
On Fri, 2013-05-24 at 11:14 -0600, Alex Williamson wrote:
> iommu_map splits requests into pages that the iommu driver reports
> that it can handle. The iommu_unmap path does not do the same. This
> can cause problems not only from callers that might expect the same
> behavior as the map path, but even from the failure path of iommu_map,
> should it fail at a point where it has mapped and needs to unwind a
> set of pages that the iommu driver cannot handle directly. amd_iommu,
> for example, will BUG_ON if asked to unmap a non power of 2 size.
>
> Fix this by extracting and generalizing the sizing code from the
> iommu_map path and use it for both map and unmap.
>
> Signed-off-by: Alex Williamson <alex.william...@redhat.com>
> ---
> drivers/iommu/iommu.c | 63
> +++++++++++++++++++++++++++----------------------
> 1 file changed, 35 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index d8f98b1..4b0b56b 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -754,6 +754,38 @@ int iommu_domain_has_cap(struct iommu_domain *domain,
> }
> EXPORT_SYMBOL_GPL(iommu_domain_has_cap);
>
> +static size_t iommu_pgsize(struct iommu_domain *domain,
> + unsigned long addr_merge, size_t size)
> +{
> + unsigned int pgsize_idx;
> + size_t pgsize;
> +
> + /* Max page size that still fits into 'size' */
> + pgsize_idx = __fls(size);
> +
> + /* need to consider alignment requirements ? */
> + if (likely(addr_merge)) {
> + /* Max page size allowed by address */
> + unsigned int align_pgsize_idx = __ffs(addr_merge);
> + pgsize_idx = min(pgsize_idx, align_pgsize_idx);
> + }
> +
> + /* build a mask of acceptable page sizes */
> + pgsize = (1UL << (pgsize_idx + 1)) - 1;
> +
> + /* throw away page sizes not supported by the hardware */
> + pgsize &= domain->ops->pgsize_bitmap;
> +
> + /* make sure we're still sane */
> + BUG_ON(!pgsize);
> +
> + /* pick the biggest page */
> + pgsize_idx = __fls(pgsize);
> + pgsize = 1UL << pgsize_idx;
> +
> + return pgsize;
> +}
> +
> int iommu_map(struct iommu_domain *domain, unsigned long iova,
> phys_addr_t paddr, size_t size, int prot)
> {
> @@ -785,32 +817,7 @@ int iommu_map(struct iommu_domain *domain, unsigned long
> iova,
> (unsigned long)paddr, (unsigned long)size);
>
> while (size) {
> - unsigned long pgsize, addr_merge = iova | paddr;
> - unsigned int pgsize_idx;
> -
> - /* Max page size that still fits into 'size' */
> - pgsize_idx = __fls(size);
> -
> - /* need to consider alignment requirements ? */
> - if (likely(addr_merge)) {
> - /* Max page size allowed by both iova and paddr */
> - unsigned int align_pgsize_idx = __ffs(addr_merge);
> -
> - pgsize_idx = min(pgsize_idx, align_pgsize_idx);
> - }
> -
> - /* build a mask of acceptable page sizes */
> - pgsize = (1UL << (pgsize_idx + 1)) - 1;
> -
> - /* throw away page sizes not supported by the hardware */
> - pgsize &= domain->ops->pgsize_bitmap;
> -
> - /* make sure we're still sane */
> - BUG_ON(!pgsize);
> -
> - /* pick the biggest page */
> - pgsize_idx = __fls(pgsize);
> - pgsize = 1UL << pgsize_idx;
> + size_t pgsize = iommu_pgsize(domain, iova | paddr, size);
>
> pr_debug("mapping: iova 0x%lx pa 0x%lx pgsize %lu\n", iova,
> (unsigned long)paddr, pgsize);
> @@ -863,9 +870,9 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned
> long iova, size_t size)
> * or we hit an area that isn't mapped.
> */
> while (unmapped < size) {
> - size_t left = size - unmapped;
> + size_t pgsize = iommu_pgsize(domain, iova, size - unmapped);
>
> - unmapped_page = domain->ops->unmap(domain, iova, left);
> + unmapped_page = domain->ops->unmap(domain, iova, pgsize);
> if (!unmapped_page)
> break;
>
>
--
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