[dpdk-dev] [PATCH v2 2/2] vhost: enable IOMMU for async vhost

[Xuan Ding]

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 at intel.com>
---
 lib/vhost/rte_vhost.h  |  1 +
 lib/vhost/vhost_user.c | 57 +++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/lib/vhost/rte_vhost.h b/lib/vhost/rte_vhost.h
index 8d875e9322..e0537249f3 100644
--- a/lib/vhost/rte_vhost.h
+++ b/lib/vhost/rte_vhost.h
@@ -127,6 +127,7 @@ struct rte_vhost_mem_region {
 	void	 *mmap_addr;
 	uint64_t mmap_size;
 	int fd;
+	uint64_t dma_map_success;
 };
 
 /**
diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index 29a4c9af60..7d1d592b86 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 +143,46 @@ 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 do_map)
+{
+	int ret = 0;
+	uint64_t host_iova;
+	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);
+		region->dma_map_success = ret == 0;
+		if (ret) {
+			if (rte_errno != ENODEV && rte_errno != ENOTSUP) {
+				VHOST_LOG_CONFIG(ERR, "DMA engine map failed\n");
+				return ret;
+			}
+			return 0;
+		}
+		return ret;
+	} else {
+		/* No need to do vfio unmap if the map failed. */
+		if (!region->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;
+		}
+		region->dma_map_success = 0;
+	}
+	return ret;
+}
+
 static void
 free_mem_region(struct virtio_net *dev)
 {
@@ -153,6 +195,9 @@ 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, false);
+
 			munmap(reg->mmap_addr, reg->mmap_size);
 			close(reg->fd);
 		}
@@ -1157,6 +1202,7 @@ vhost_user_mmap_region(struct virtio_net *dev,
 	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 +1256,22 @@ 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, true);
+			if (ret < 0) {
+				VHOST_LOG_CONFIG(ERR, "Configure IOMMU for DMA engine failed\n");
+				return -1;
+			}
+		}
+	}
+
 	VHOST_LOG_CONFIG(INFO,
 			"guest memory region size: 0x%" PRIx64 "\n"
 			"\t guest physical addr: 0x%" PRIx64 "\n"
-- 
2.17.1