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

["Hu, Jiayu" <jiayu.hu@intel.com>]

Hi Xuan,

> -----Original Message-----
> From: Ding, Xuan <xuan.ding@intel.com>
> Sent: Friday, September 17, 2021 1:26 PM
> To: dev@dpdk.org; Burakov, Anatoly <anatoly.burakov@intel.com>;
> maxime.coquelin@redhat.com; Xia, Chenbo <chenbo.xia@intel.com>
> Cc: Hu, Jiayu <jiayu.hu@intel.com>; Jiang, Cheng1 <cheng1.jiang@intel.com>;
> Richardson, Bruce <bruce.richardson@intel.com>; Pai G, Sunil
> <sunil.pai.g@intel.com>; Wang, Yinan <yinan.wang@intel.com>; Yang,
> YvonneX <yvonnex.yang@intel.com>; Ding, Xuan <xuan.ding@intel.com>
> Subject: [PATCH v2 2/2] vhost: enable IOMMU for async vhost
> 
> 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/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;

How about using bool for 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;

Why return 0, if ret is -1 here?

Thanks,
Jiayu

> +		}
> +		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