[dpdk-dev] [PATCH v3 2/2] vhost: enable IOMMU for async vhost

[Xuan Ding <xuan.ding@intel.com>]

The use of IOMMU has many advantages, such as isolation and address
translation. This patch extends the capbility of DMA engine to use
IOMMU if the DMA engine is bound to vfio.

When set memory table, the guest memory will be mapped
into the default container of DPDK.

Signed-off-by: Xuan Ding <xuan.ding@intel.com>
---
 lib/vhost/vhost.h      |   4 ++
 lib/vhost/vhost_user.c | 112 ++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 114 insertions(+), 2 deletions(-)

diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
index 89a31e4ca8..bc5695e899 100644
--- a/lib/vhost/vhost.h
+++ b/lib/vhost/vhost.h
@@ -370,6 +370,10 @@ struct virtio_net {
 	int16_t			broadcast_rarp;
 	uint32_t		nr_vring;
 	int			async_copy;
+
+	/* Record the dma map status for each region. */
+	bool			*async_map_status;
+
 	int			extbuf;
 	int			linearbuf;
 	struct vhost_virtqueue	*virtqueue[VHOST_MAX_QUEUE_PAIRS * 2];
diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index 29a4c9af60..3990e9b057 100644
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c
@@ -45,6 +45,8 @@
 #include <rte_common.h>
 #include <rte_malloc.h>
 #include <rte_log.h>
+#include <rte_vfio.h>
+#include <rte_errno.h>
 
 #include "iotlb.h"
 #include "vhost.h"
@@ -141,6 +143,63 @@ get_blk_size(int fd)
 	return ret == -1 ? (uint64_t)-1 : (uint64_t)stat.st_blksize;
 }
 
+static int
+async_dma_map(struct rte_vhost_mem_region *region, bool *dma_map_success, bool do_map)
+{
+	uint64_t host_iova;
+	int ret = 0;
+
+	host_iova = rte_mem_virt2iova((void *)(uintptr_t)region->host_user_addr);
+	if (do_map) {
+		/* Add mapped region into the default container of DPDK. */
+		ret = rte_vfio_container_dma_map(RTE_VFIO_DEFAULT_CONTAINER_FD,
+						 region->host_user_addr,
+						 host_iova,
+						 region->size);
+		*dma_map_success = ret == 0;
+
+		if (ret) {
+			/*
+			 * DMA device may bind with kernel driver, in this case,
+			 * we don't need to program IOMMU manually. However, if no
+			 * device is bound with vfio/uio in DPDK, and vfio kernel
+			 * module is loaded, the API will still be called and return
+			 * with ENODEV/ENOSUP.
+			 *
+			 * DPDK VFIO only returns ENODEV/ENOSUP in very similar
+			 * situations(VFIO either unsupported, or supported
+			 * but no devices found). Either way, no mappings could be
+			 * performed. We treat it as normal case in async path.
+			 */
+			if (rte_errno == ENODEV && rte_errno == ENOTSUP) {
+				return 0;
+			} else {
+				VHOST_LOG_CONFIG(ERR, "DMA engine map failed\n");
+				return ret;
+			}
+		}
+
+	} else {
+		/* No need to do vfio unmap if the map failed. */
+		if (!*dma_map_success)
+			return 0;
+
+		/* Remove mapped region from the default container of DPDK. */
+		ret = rte_vfio_container_dma_unmap(RTE_VFIO_DEFAULT_CONTAINER_FD,
+						   region->host_user_addr,
+						   host_iova,
+						   region->size);
+		if (ret) {
+			VHOST_LOG_CONFIG(ERR, "DMA engine unmap failed\n");
+			return ret;
+		}
+		/* Clear the flag once the unmap succeeds. */
+		*dma_map_success = 0;
+	}
+
+	return ret;
+}
+
 static void
 free_mem_region(struct virtio_net *dev)
 {
@@ -153,6 +212,9 @@ free_mem_region(struct virtio_net *dev)
 	for (i = 0; i < dev->mem->nregions; i++) {
 		reg = &dev->mem->regions[i];
 		if (reg->host_user_addr) {
+			if (dev->async_copy && rte_vfio_is_enabled("vfio"))
+				async_dma_map(reg, &dev->async_map_status[i], false);
+
 			munmap(reg->mmap_addr, reg->mmap_size);
 			close(reg->fd);
 		}
@@ -203,6 +265,11 @@ vhost_backend_cleanup(struct virtio_net *dev)
 	}
 
 	dev->postcopy_listening = 0;
+
+	if (dev->async_map_status) {
+		rte_free(dev->async_map_status);
+		dev->async_map_status = NULL;
+	}
 }
 
 static void
@@ -621,6 +688,17 @@ numa_realloc(struct virtio_net *dev, int index)
 	}
 	dev->mem = mem;
 
+	if (dev->async_copy && rte_vfio_is_enabled("vfio")) {
+		dev->async_map_status = rte_zmalloc_socket("async-dma-map-status",
+					sizeof(bool) * dev->mem->nregions, 0, node);
+		if (!dev->async_map_status) {
+			VHOST_LOG_CONFIG(ERR,
+				"(%d) failed to realloc dma mapping status on node\n",
+				dev->vid);
+			return dev;
+		}
+	}
+
 	gp = rte_realloc_socket(dev->guest_pages, dev->max_guest_pages * sizeof(*gp),
 			RTE_CACHE_LINE_SIZE, node);
 	if (!gp) {
@@ -1151,12 +1229,14 @@ vhost_user_postcopy_register(struct virtio_net *dev, int main_fd,
 static int
 vhost_user_mmap_region(struct virtio_net *dev,
 		struct rte_vhost_mem_region *region,
+		uint32_t region_index,
 		uint64_t mmap_offset)
 {
 	void *mmap_addr;
 	uint64_t mmap_size;
 	uint64_t alignment;
 	int populate;
+	int ret;
 
 	/* Check for memory_size + mmap_offset overflow */
 	if (mmap_offset >= -region->size) {
@@ -1210,13 +1290,25 @@ vhost_user_mmap_region(struct virtio_net *dev,
 	region->mmap_size = mmap_size;
 	region->host_user_addr = (uint64_t)(uintptr_t)mmap_addr + mmap_offset;
 
-	if (dev->async_copy)
+	if (dev->async_copy) {
 		if (add_guest_pages(dev, region, alignment) < 0) {
 			VHOST_LOG_CONFIG(ERR,
 					"adding guest pages to region failed.\n");
 			return -1;
 		}
 
+		if (rte_vfio_is_enabled("vfio")) {
+			ret = async_dma_map(region, &dev->async_map_status[region_index], true);
+			if (ret) {
+				VHOST_LOG_CONFIG(ERR, "Configure IOMMU for DMA "
+							"engine failed\n");
+				rte_free(dev->async_map_status);
+				dev->async_map_status = NULL;
+				return -1;
+			}
+		}
+	}
+
 	VHOST_LOG_CONFIG(INFO,
 			"guest memory region size: 0x%" PRIx64 "\n"
 			"\t guest physical addr: 0x%" PRIx64 "\n"
@@ -1291,6 +1383,11 @@ vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg *msg,
 		dev->mem = NULL;
 	}
 
+	if (dev->async_map_status) {
+		rte_free(dev->async_map_status);
+		dev->async_map_status = NULL;
+	}
+
 	/* Flush IOTLB cache as previous HVAs are now invalid */
 	if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
 		for (i = 0; i < dev->nr_vring; i++)
@@ -1329,6 +1426,17 @@ vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg *msg,
 		goto free_guest_pages;
 	}
 
+	if (dev->async_copy) {
+		dev->async_map_status = rte_zmalloc_socket("async-dma-map-status",
+					sizeof(bool) * memory->nregions, 0, numa_node);
+		if (!dev->async_map_status) {
+			VHOST_LOG_CONFIG(ERR,
+				"(%d) failed to allocate memory for dma mapping status\n",
+				dev->vid);
+			goto free_guest_pages;
+		}
+	}
+
 	for (i = 0; i < memory->nregions; i++) {
 		reg = &dev->mem->regions[i];
 
@@ -1345,7 +1453,7 @@ vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg *msg,
 
 		mmap_offset = memory->regions[i].mmap_offset;
 
-		if (vhost_user_mmap_region(dev, reg, mmap_offset) < 0) {
+		if (vhost_user_mmap_region(dev, reg, i, mmap_offset) < 0) {
 			VHOST_LOG_CONFIG(ERR, "Failed to mmap region %u\n", i);
 			goto free_mem_table;
 		}
-- 
2.17.1