From 39b3b3c9cac1b4a64a6e546c9faf0c1011d775d4 Mon Sep 17 00:00:00 2001 From: Jean-Philippe Brucker Date: Thu, 26 Mar 2020 10:35:58 +0100 Subject: iommu/virtio: Reject IOMMU page granule larger than PAGE_SIZE We don't currently support IOMMUs with a page granule larger than the system page size. The IOVA allocator has a BUG_ON() in this case, and VFIO has a WARN_ON(). Removing these obstacles ranges doesn't seem possible without major changes to the DMA API and VFIO. Some callers of iommu_map(), for example, want to map multiple page-aligned regions adjacent to each others for scatter-gather purposes. Even in simple DMA API uses, a call to dma_map_page() would let the endpoint access neighbouring memory. And VFIO users cannot ensure that their virtual address buffer is physically contiguous at the IOMMU granule. Rather than triggering the IOVA BUG_ON() on mismatched page sizes, abort the vdomain finalise() with an error message. We could simply abort the viommu probe(), but an upcoming extension to virtio-iommu will allow setting different page masks for each endpoint. Reported-by: Bharat Bhushan Signed-off-by: Jean-Philippe Brucker Reviewed-by: Bharat Bhushan Reviewed-by: Eric Auger Reviewed-by: Robin Murphy Link: https://lore.kernel.org/r/20200326093558.2641019-4-jean-philippe@linaro.org Signed-off-by: Joerg Roedel --- drivers/iommu/virtio-iommu.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'drivers/iommu') diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c index 9d5d4c941874..1adc73d1f90a 100644 --- a/drivers/iommu/virtio-iommu.c +++ b/drivers/iommu/virtio-iommu.c @@ -607,12 +607,22 @@ static struct iommu_domain *viommu_domain_alloc(unsigned type) return &vdomain->domain; } -static int viommu_domain_finalise(struct viommu_dev *viommu, +static int viommu_domain_finalise(struct viommu_endpoint *vdev, struct iommu_domain *domain) { int ret; + unsigned long viommu_page_size; + struct viommu_dev *viommu = vdev->viommu; struct viommu_domain *vdomain = to_viommu_domain(domain); + viommu_page_size = 1UL << __ffs(viommu->pgsize_bitmap); + if (viommu_page_size > PAGE_SIZE) { + dev_err(vdev->dev, + "granule 0x%lx larger than system page size 0x%lx\n", + viommu_page_size, PAGE_SIZE); + return -EINVAL; + } + ret = ida_alloc_range(&viommu->domain_ids, viommu->first_domain, viommu->last_domain, GFP_KERNEL); if (ret < 0) @@ -659,7 +669,7 @@ static int viommu_attach_dev(struct iommu_domain *domain, struct device *dev) * Properly initialize the domain now that we know which viommu * owns it. */ - ret = viommu_domain_finalise(vdev->viommu, domain); + ret = viommu_domain_finalise(vdev, domain); } else if (vdomain->viommu != vdev->viommu) { dev_err(dev, "cannot attach to foreign vIOMMU\n"); ret = -EXDEV; -- cgit v1.2.3