Hi Xuan,
> -----Original Message-----
> From: Ding, Xuan <xuan.d...@intel.com>
> Sent: Wednesday, September 29, 2021 10:41 AM
> To: dev@dpdk.org; Burakov, Anatoly <anatoly.bura...@intel.com>;
> maxime.coque...@redhat.com; Xia, Chenbo <chenbo....@intel.com>
> Cc: Hu, Jiayu <jiayu...@intel.com>; Jiang, Cheng1 <cheng1.ji...@intel.com>;
> Richardson, Bruce <bruce.richard...@intel.com>; Pai G, Sunil
> <sunil.pa...@intel.com>; Wang, Yinan <yinan.w...@intel.com>; Yang,
> YvonneX <yvonnex.y...@intel.com>; Ding, Xuan <xuan.d...@intel.com>
> Subject: [PATCH v6 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.d...@intel.com>
> ---
> +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.
> + */
What do you mean by saying "vfio either unsupported"? Does it mean platform
doesn't support iommu?
Thanks,
Jiayu
