On Wed, Oct 28, 2015 at 10:27:28AM -0600, Alex Williamson wrote: > On Wed, 2015-10-28 at 13:12 +0000, Eric Auger wrote: > > diff --git a/drivers/vfio/vfio_iommu_type1.c > > b/drivers/vfio/vfio_iommu_type1.c > > index 57d8c37..13fb974 100644 > > --- a/drivers/vfio/vfio_iommu_type1.c > > +++ b/drivers/vfio/vfio_iommu_type1.c > > @@ -403,7 +403,7 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, > > struct vfio_dma *dma) > > static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu) > > { > > struct vfio_domain *domain; > > - unsigned long bitmap = PAGE_MASK; > > + unsigned long bitmap = ULONG_MAX; > > Isn't this and removing the WARN_ON()s the only real change in this > patch? The rest looks like conversion to use IS_ALIGNED and the > following test, that I don't really understand... > > > > > mutex_lock(&iommu->lock); > > list_for_each_entry(domain, &iommu->domain_list, next) > > @@ -416,20 +416,18 @@ static unsigned long vfio_pgsize_bitmap(struct > > vfio_iommu *iommu) > > static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > > struct vfio_iommu_type1_dma_unmap *unmap) > > { > > - uint64_t mask; > > struct vfio_dma *dma; > > size_t unmapped = 0; > > int ret = 0; > > + unsigned int min_pagesz = __ffs(vfio_pgsize_bitmap(iommu)); > > + unsigned int requested_alignment = (min_pagesz < PAGE_SIZE) ? > > + PAGE_SIZE : min_pagesz; > > This one. If we're going to support sub-PAGE_SIZE mappings, why do we > care to cap alignment at PAGE_SIZE?
Eric can clarify, but I think the intention here is to have VFIO continue doing things in PAGE_SIZE chunks precisely so that we don't have to rework all of the pinning code etc. The IOMMU API can then deal with the smaller page size. > > - mask = ((uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu))) - 1; > > - > > - if (unmap->iova & mask) > > + if (!IS_ALIGNED(unmap->iova, requested_alignment)) > > return -EINVAL; > > - if (!unmap->size || unmap->size & mask) > > + if (!unmap->size || !IS_ALIGNED(unmap->size, requested_alignment)) > > return -EINVAL; > > > > - WARN_ON(mask & PAGE_MASK); > > - > > mutex_lock(&iommu->lock); > > > > /* > > @@ -553,25 +551,24 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu, > > size_t size = map->size; > > long npage; > > int ret = 0, prot = 0; > > - uint64_t mask; > > struct vfio_dma *dma; > > unsigned long pfn; > > + unsigned int min_pagesz = __ffs(vfio_pgsize_bitmap(iommu)); > > + unsigned int requested_alignment = (min_pagesz < PAGE_SIZE) ? > > + PAGE_SIZE : min_pagesz; > > > > /* Verify that none of our __u64 fields overflow */ > > if (map->size != size || map->vaddr != vaddr || map->iova != iova) > > return -EINVAL; > > > > - mask = ((uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu))) - 1; > > - > > - WARN_ON(mask & PAGE_MASK); > > - > > /* READ/WRITE from device perspective */ > > if (map->flags & VFIO_DMA_MAP_FLAG_WRITE) > > prot |= IOMMU_WRITE; > > if (map->flags & VFIO_DMA_MAP_FLAG_READ) > > prot |= IOMMU_READ; > > > > - if (!prot || !size || (size | iova | vaddr) & mask) > > + if (!prot || !size || > > + !IS_ALIGNED(size | iova | vaddr, requested_alignment)) > > return -EINVAL; > > > > /* Don't allow IOVA or virtual address wrap */ > > This is mostly ignoring the problems with sub-PAGE_SIZE mappings. For > instance, we can only pin on PAGE_SIZE and therefore we only do > accounting on PAGE_SIZE, so if the user does 4K mappings across your 64K > page, that page gets pinned and accounted 16 times. Are we going to > tell users that their locked memory limit needs to be 16x now? The rest > of the code would need an audit as well to see what other sub-page bugs > might be hiding. Thanks, I don't see that. The pinning all happens the same in VFIO, which can then happily pass a 64k region to iommu_map. iommu_map will then call ->map in 4k chunks on the IOMMU driver ops. Will -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html