Re: [PATCH v4] examples/vdpa: support running in nested virtualization environment

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 11/14/22 04:04, Hao Chen wrote:
> When we run dpdk vdpa in the nested virtual machine vm-L1 and ping
> test in vm-L2, the ping is not good. The reason for troubleshooting is
> that the virtio net in vm-L2 sends control information to the vring,
> and the qemu back-end device in vm-L1 cannot obtain correct data
> from the vring. This problem is related to the opening of the vIOMMU.
> 
> This patch add flag RTE_VHOST_USER_IOMMU_SUPPORT to use vhost vIOMMU
> , VIRTIO_F_IOMMU_PLATFORM feature will be negotiated successfully if
> virtio iommu is used in a nested virtualization environment.
> 
> The configuration is as follows:
> The host starts iommu, and the kernel parameter is added with
> 'intel_iommu=on iommu=pt'.
> VM-L1's xml add viommu and virtio device adds iommu='on' ats='on'.
> VM-L2's xml enables viommu, and adds  parameters
> 'intel_iommu=on iommu=pt' to kernel.
> 
> Then the ping test in vm-L2 is OK.
> 
> Signed-off-by: Hao Chen <chenh@yusur.tech>
> ---
> v4:
> *Simplify the patch. Set the flags RTE_VHOST_USER_IOMMU_SUPPORT default.
> 
> v3:
> *Modify mail title.
> 
> v2:
> *fprintf all string including the eal one.
> *remove exit(1).
> 
>   examples/vdpa/main.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/examples/vdpa/main.c b/examples/vdpa/main.c
> index 4c7e81d7b6..4d3203f3a7 100644
> --- a/examples/vdpa/main.c
> +++ b/examples/vdpa/main.c
> @@ -214,6 +214,8 @@ start_vdpa(struct vdpa_port *vport)
>   	if (client_mode)
>   		vport->flags |= RTE_VHOST_USER_CLIENT;
>   
> +	vport->flags |= RTE_VHOST_USER_IOMMU_SUPPORT;
> +
>   	if (access(socket_path, F_OK) != -1 && !client_mode) {
>   		RTE_LOG(ERR, VDPA,
>   			"%s exists, please remove it or specify another file and try again.\n",

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime