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SubjectRe: [PATCH v3 1/6] iommu/core: split mapping to page sizes as supported by the hardware
On Mon, Oct 10, 2011 at 06:49:32PM -0400, Ohad Ben-Cohen wrote:
> -int iommu_unmap(struct iommu_domain *domain, unsigned long iova, int gfp_order)
> +int iommu_unmap(struct iommu_domain *domain, unsigned long iova, int size)
> {
> - size_t size;
> + int order, unmapped_size, unmapped_order, total_unmapped = 0;
>
> if (unlikely(domain->ops->unmap == NULL))
> return -ENODEV;
>
> - size = PAGE_SIZE << gfp_order;
> + /*
> + * The virtual address, as well as the size of the mapping, must be
> + * aligned (at least) to the size of the smallest page supported
> + * by the hardware
> + */
> + if (!IS_ALIGNED(iova | size, domain->ops->min_pagesz)) {
> + pr_err("unaligned: iova 0x%lx size 0x%x min_pagesz 0x%x\n",
> + iova, size, domain->ops->min_pagesz);
> + return -EINVAL;
> + }
> +
> + pr_debug("unmap this: iova 0x%lx size 0x%x\n", iova, size);
> +
> + while (size > total_unmapped) {
> + order = get_order(size - total_unmapped);

Hmm, this actually unmaps more than requested, even in the symetric
case. Imgine the user wants to unmap a 12kb region, then order
will be 4 and this code will tell the iommu-driver to unmap 16kb.

You need to make sure that you don;t pass larger regions then requested
to the low-level driver. Some logic like in the iommu_map function
should do it.

> +
> + unmapped_order = domain->ops->unmap(domain, iova, order);
> + if (unmapped_order < 0)
> + break;
> +
> + pr_debug("unmapped: iova 0x%lx order %d\n", iova,
> + unmapped_order);
> +
> + unmapped_size = 0x1000UL << unmapped_order;

Please use PAGE_SIZE instead of 0x1000UL.

>
> - BUG_ON(!IS_ALIGNED(iova, size));
> + iova += unmapped_size;
> + total_unmapped += unmapped_size;
> + }
>
> - return domain->ops->unmap(domain, iova, gfp_order);
> + return total_unmapped;
> }
> EXPORT_SYMBOL_GPL(iommu_unmap);
>
> diff --git a/drivers/iommu/omap-iovmm.c b/drivers/iommu/omap-iovmm.c
> index e8fdb88..4a8f761 100644
> --- a/drivers/iommu/omap-iovmm.c
> +++ b/drivers/iommu/omap-iovmm.c
> @@ -409,7 +409,6 @@ static int map_iovm_area(struct iommu_domain
> *domain, struct iovm_struct *new,
> unsigned int i, j;
> struct scatterlist *sg;
> u32 da = new->da_start;
> - int order;
>
> if (!domain || !sgt)
> return -EINVAL;
> @@ -428,12 +427,10 @@ static int map_iovm_area(struct iommu_domain
> *domain, struct iovm_struct *new,
> if (bytes_to_iopgsz(bytes) < 0)
> goto err_out;
>
> - order = get_order(bytes);
> -
> pr_debug("%s: [%d] %08x %08x(%x)\n", __func__,
> i, da, pa, bytes);
>
> - err = iommu_map(domain, da, pa, order, flags);
> + err = iommu_map(domain, da, pa, bytes, flags);
> if (err)
> goto err_out;
>
> @@ -448,10 +445,9 @@ err_out:
> size_t bytes;
>
> bytes = sg->length + sg->offset;
> - order = get_order(bytes);
>
> /* ignore failures.. we're already handling one */
> - iommu_unmap(domain, da, order);
> + iommu_unmap(domain, da, bytes);
>
> da += bytes;
> }
> @@ -474,13 +470,11 @@ static void unmap_iovm_area(struct iommu_domain
> *domain, struct omap_iommu *obj,
> start = area->da_start;
> for_each_sg(sgt->sgl, sg, sgt->nents, i) {
> size_t bytes;
> - int order;
>
> bytes = sg->length + sg->offset;
> - order = get_order(bytes);
>
> - err = iommu_unmap(domain, start, order);
> - if (err < 0)
> + err = iommu_unmap(domain, start, bytes);
> + if (err < bytes)
> break;
>
> dev_dbg(obj->dev, "%s: unmap %08x(%x) %08x\n",
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 710291f..a10a86c 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -48,6 +48,22 @@ struct iommu_domain {
>
> #ifdef CONFIG_IOMMU_API
>
> +/**
> + * struct iommu_ops - iommu ops and capabilities
> + * @domain_init: init iommu domain
> + * @domain_destroy: destroy iommu domain
> + * @attach_dev: attach device to an iommu domain
> + * @detach_dev: detach device from an iommu domain
> + * @map: map a physically contiguous memory region to an iommu domain
> + * @unmap: unmap a physically contiguous memory region from an iommu domain
> + * @iova_to_phys: translate iova to physical address
> + * @domain_has_cap: domain capabilities query
> + * @commit: commit iommu domain
> + * @pgsize_bitmap: bitmap of supported page sizes
> + * @min_pagesz: smallest page size supported. note: this member is private
> + * to the IOMMU core, and maintained only for efficiency sake;
> + * drivers don't need to set it.
> + */
> struct iommu_ops {
> int (*domain_init)(struct iommu_domain *domain);
> void (*domain_destroy)(struct iommu_domain *domain);
> @@ -62,6 +78,8 @@ struct iommu_ops {
> int (*domain_has_cap)(struct iommu_domain *domain,
> unsigned long cap);
> void (*commit)(struct iommu_domain *domain);
> + unsigned long pgsize_bitmap;
> + unsigned int min_pagesz;
> };
>
> extern int bus_set_iommu(struct bus_type *bus, struct iommu_ops *ops);
> @@ -73,9 +91,9 @@ extern int iommu_attach_device(struct iommu_domain *domain,
> extern void iommu_detach_device(struct iommu_domain *domain,
> struct device *dev);
> extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
> - phys_addr_t paddr, int gfp_order, int prot);
> + phys_addr_t paddr, int size, int prot);
> extern int iommu_unmap(struct iommu_domain *domain, unsigned long iova,
> - int gfp_order);
> + int size);
> extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain,
> unsigned long iova);
> extern int iommu_domain_has_cap(struct iommu_domain *domain,
> diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
> index ca409be..26b3199 100644
> --- a/virt/kvm/iommu.c
> +++ b/virt/kvm/iommu.c
> @@ -111,7 +111,7 @@ int kvm_iommu_map_pages(struct kvm *kvm, struct
> kvm_memory_slot *slot)
>
> /* Map into IO address space */
> r = iommu_map(domain, gfn_to_gpa(gfn), pfn_to_hpa(pfn),
> - get_order(page_size), flags);
> + page_size, flags);
> if (r) {
> printk(KERN_ERR "kvm_iommu_map_address:"
> "iommu failed to map pfn=%llx\n", pfn);
> @@ -292,15 +292,15 @@ static void kvm_iommu_put_pages(struct kvm *kvm,
>
> while (gfn < end_gfn) {
> unsigned long unmap_pages;
> - int order;
> + int size;
>
> /* Get physical address */
> phys = iommu_iova_to_phys(domain, gfn_to_gpa(gfn));
> pfn = phys >> PAGE_SHIFT;
>
> /* Unmap address from IO address space */
> - order = iommu_unmap(domain, gfn_to_gpa(gfn), 0);
> - unmap_pages = 1ULL << order;
> + size = iommu_unmap(domain, gfn_to_gpa(gfn), PAGE_SIZE);
> + unmap_pages = 1ULL << get_order(size);
>
> /* Unpin all pages we just unmapped to not leak any memory */
> kvm_unpin_pages(kvm, pfn, unmap_pages);

--
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