From a48ce36e2786f8bb33e9f42ea2d0c23ea4af3e0d Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Wed, 9 Aug 2023 20:48:02 +0800 Subject: [PATCH] iommu: Prevent RESV_DIRECT devices from blocking domains The IOMMU_RESV_DIRECT flag indicates that a memory region must be mapped 1:1 at all times. This means that the region must always be accessible to the device, even if the device is attached to a blocking domain. This is equal to saying that IOMMU_RESV_DIRECT flag prevents devices from being attached to blocking domains. This also implies that devices that implement RESV_DIRECT regions will be prevented from being assigned to user space since taking the DMA ownership immediately switches to a blocking domain. The rule of preventing devices with the IOMMU_RESV_DIRECT regions from being assigned to user space has existed in the Intel IOMMU driver for a long time. Now, this rule is being lifted up to a general core rule, as other architectures like AMD and ARM also have RMRR-like reserved regions. This has been discussed in the community mailing list and refer to below link for more details. Other places using unmanaged domains for kernel DMA must follow the iommu_get_resv_regions() and setup IOMMU_RESV_DIRECT - we do not restrict them in the core code. Cc: Robin Murphy Cc: Alex Williamson Cc: Kevin Tian Signed-off-by: Jason Gunthorpe Link: https://lore.kernel.org/linux-iommu/BN9PR11MB5276E84229B5BD952D78E9598C639@BN9PR11MB5276.namprd11.prod.outlook.com Signed-off-by: Lu Baolu Reviewed-by: Jason Gunthorpe Acked-by: Joerg Roedel Link: https://lore.kernel.org/r/20230724060352.113458-2-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/iommu/iommu.c | 37 +++++++++++++++++++++++++++---------- include/linux/iommu.h | 2 ++ 2 files changed, 29 insertions(+), 10 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index d199d144460c..e385a99e25e1 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -960,14 +960,12 @@ static int iommu_create_device_direct_mappings(struct iommu_domain *domain, unsigned long pg_size; int ret = 0; - if (!iommu_is_dma_domain(domain)) - return 0; - - BUG_ON(!domain->pgsize_bitmap); - - pg_size = 1UL << __ffs(domain->pgsize_bitmap); + pg_size = domain->pgsize_bitmap ? 1UL << __ffs(domain->pgsize_bitmap) : 0; INIT_LIST_HEAD(&mappings); + if (WARN_ON_ONCE(iommu_is_dma_domain(domain) && !pg_size)) + return -EINVAL; + iommu_get_resv_regions(dev, &mappings); /* We need to consider overlapping regions for different devices */ @@ -975,13 +973,17 @@ static int iommu_create_device_direct_mappings(struct iommu_domain *domain, dma_addr_t start, end, addr; size_t map_size = 0; + if (entry->type == IOMMU_RESV_DIRECT) + dev->iommu->require_direct = 1; + + if ((entry->type != IOMMU_RESV_DIRECT && + entry->type != IOMMU_RESV_DIRECT_RELAXABLE) || + !iommu_is_dma_domain(domain)) + continue; + start = ALIGN(entry->start, pg_size); end = ALIGN(entry->start + entry->length, pg_size); - if (entry->type != IOMMU_RESV_DIRECT && - entry->type != IOMMU_RESV_DIRECT_RELAXABLE) - continue; - for (addr = start; addr <= end; addr += pg_size) { phys_addr_t phys_addr; @@ -2122,6 +2124,21 @@ static int __iommu_device_set_domain(struct iommu_group *group, { int ret; + /* + * If the device requires IOMMU_RESV_DIRECT then we cannot allow + * the blocking domain to be attached as it does not contain the + * required 1:1 mapping. This test effectively excludes the device + * being used with iommu_group_claim_dma_owner() which will block + * vfio and iommufd as well. + */ + if (dev->iommu->require_direct && + (new_domain->type == IOMMU_DOMAIN_BLOCKED || + new_domain == group->blocking_domain)) { + dev_warn(dev, + "Firmware has requested this device have a 1:1 IOMMU mapping, rejecting configuring the device without a 1:1 mapping. Contact your platform vendor.\n"); + return -EINVAL; + } + if (dev->iommu->attach_deferred) { if (new_domain == group->default_domain) return 0; diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 6b821cb715d5..54bae452975f 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -411,6 +411,7 @@ struct iommu_fault_param { * @priv: IOMMU Driver private data * @max_pasids: number of PASIDs this device can consume * @attach_deferred: the dma domain attachment is deferred + * @require_direct: device requires IOMMU_RESV_DIRECT regions * * TODO: migrate other per device data pointers under iommu_dev_data, e.g. * struct iommu_group *iommu_group; @@ -424,6 +425,7 @@ struct dev_iommu { void *priv; u32 max_pasids; u32 attach_deferred:1; + u32 require_direct:1; }; int iommu_device_register(struct iommu_device *iommu,