vfio: fix DMA mapping granularity for IOVA as VA

[ upstream commit c13ca4e ]

Partial unmapping is not supported for VFIO IOMMU type1
by kernel. Though kernel gives return as zero, the unmapped size
returned will not be same as expected. So check for
returned unmap size and return error.

For IOVA as PA, DMA mapping is already at memseg size
granularity. Do the same even for IOVA as VA mode as
DMA map/unmap triggered by heap allocations,
maintain granularity of memseg page size so that heap
expansion and contraction does not have this issue.

For user requested DMA map/unmap disallow partial unmapping
for VFIO type1.

Fixes: 73a6390 ("vfio: allow to map other memory regions")

Signed-off-by: Nithin Dabilpuram <ndabilpuram@marvell.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: David Christensen <drc@linux.vnet.ibm.com>

lib/librte_eal/linux/eal_vfio.c

@@ -70,20 +70,23 @@ static const struct vfio_iommu_type iommu_types[] = {
 	{
 		.type_id = RTE_VFIO_TYPE1,
 		.name = "Type 1",
+		.partial_unmap = false,
 		.dma_map_func = &vfio_type1_dma_map,
 		.dma_user_map_func = &vfio_type1_dma_mem_map
 	},
 	/* ppc64 IOMMU, otherwise known as spapr */
 	{
 		.type_id = RTE_VFIO_SPAPR,
 		.name = "sPAPR",
+		.partial_unmap = true,
 		.dma_map_func = &vfio_spapr_dma_map,
 		.dma_user_map_func = &vfio_spapr_dma_mem_map
 	},
 	/* IOMMU-less mode */
 	{
 		.type_id = RTE_VFIO_NOIOMMU,
 		.name = "No-IOMMU",
+		.partial_unmap = true,
 		.dma_map_func = &vfio_noiommu_dma_map,
 		.dma_user_map_func = &vfio_noiommu_dma_mem_map
 	},
@@ -526,12 +529,19 @@ vfio_mem_event_callback(enum rte_mem_event type, const void *addr, size_t len,
 	/* for IOVA as VA mode, no need to care for IOVA addresses */
 	if (rte_eal_iova_mode() == RTE_IOVA_VA && msl->external == 0) {
 		uint64_t vfio_va = (uint64_t)(uintptr_t)addr;
-		if (type == RTE_MEM_EVENT_ALLOC)
-			vfio_dma_mem_map(default_vfio_cfg, vfio_va, vfio_va,
-					len, 1);
-		else
-			vfio_dma_mem_map(default_vfio_cfg, vfio_va, vfio_va,
-					len, 0);
+		uint64_t page_sz = msl->page_sz;
+
+		/* Maintain granularity of DMA map/unmap to memseg size */
+		for (; cur_len < len; cur_len += page_sz) {
+			if (type == RTE_MEM_EVENT_ALLOC)
+				vfio_dma_mem_map(default_vfio_cfg, vfio_va,
+						 vfio_va, page_sz, 1);
+			else
+				vfio_dma_mem_map(default_vfio_cfg, vfio_va,
+						 vfio_va, page_sz, 0);
+			vfio_va += page_sz;
+		}
+
 		return;
 	}
 
@@ -1348,6 +1358,12 @@ vfio_type1_dma_mem_map(int vfio_container_fd, uint64_t vaddr, uint64_t iova,
 			RTE_LOG(ERR, EAL, "  cannot clear DMA remapping, error %i (%s)\n",
 					errno, strerror(errno));
 			return -1;
+		} else if (dma_unmap.size != len) {
+			RTE_LOG(ERR, EAL, "  unexpected size %"PRIu64" of DMA "
+				"remapping cleared instead of %"PRIu64"\n",
+				(uint64_t)dma_unmap.size, len);
+			rte_errno = EIO;
+			return -1;
 		}
 	}
 
@@ -1823,6 +1839,12 @@ container_dma_unmap(struct vfio_config *vfio_cfg, uint64_t vaddr, uint64_t iova,
 		/* we're partially unmapping a previously mapped region, so we
 		 * need to split entry into two.
 		 */
+		if (!vfio_cfg->vfio_iommu_type->partial_unmap) {
+			RTE_LOG(DEBUG, EAL, "DMA partial unmap unsupported\n");
+			rte_errno = ENOTSUP;
+			ret = -1;
+			goto out;
+		}
 		if (user_mem_maps->n_maps == VFIO_MAX_USER_MEM_MAPS) {
 			RTE_LOG(ERR, EAL, "Not enough space to store partial mapping\n");
 			rte_errno = ENOMEM;

lib/librte_eal/linux/eal_vfio.h

@@ -113,6 +113,7 @@ typedef int (*vfio_dma_user_func_t)(int fd, uint64_t vaddr, uint64_t iova,
 struct vfio_iommu_type {
 	int type_id;
 	const char *name;
+	bool partial_unmap;
 	vfio_dma_user_func_t dma_user_map_func;
 	vfio_dma_func_t dma_map_func;
 };