[PATCH] example: vdpa: support run in nested virtualization environment

[Xia, Chenbo]

> -----Original Message-----
> From: Hao Chen <chenh at yusur.tech>
> Sent: Tuesday, October 11, 2022 10:56 AM
> To: maxime.coquelin at redhat.com; Xia, Chenbo <chenbo.xia at intel.com>
> Cc: dev at dpdk.org; houyl at yusur.tech; zy at yusur.tech
> Subject: [PATCH] example: vdpa: support run in nested virtualization
> environment

Title should be:

examples/vdpa: support running in nested virtualization environment

> 
> When we run dpdk vdpa in the nested virtual machine vm-L1 and ping
> test in vm-L2, the ping is NG. 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 option '--iommu-support' to use guest vIOMMU to
> protect vhost, then the ping test in vm-L2 is OK.
> This option is required in a nested virtualization environment.
> 
> Signed-off-by: Hao Chen <chenh at yusur.tech>
> ---
>  examples/vdpa/main.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/examples/vdpa/main.c b/examples/vdpa/main.c
> index 4c7e81d7b6..a24c78d7a4 100644
> --- a/examples/vdpa/main.c
> +++ b/examples/vdpa/main.c
> @@ -43,16 +43,20 @@ static char iface[MAX_PATH_LEN];
>  static int devcnt;
>  static int interactive;
>  static int client_mode;
> +static int iommu_support;
> 
>  /* display usage */
>  static void
>  vdpa_usage(const char *prgname)
>  {
> -	printf("Usage: %s [EAL options] -- "
> -				 "	--interactive|-i: run in interactive
> mode.\n"
> -				 "	--iface <path>: specify the path prefix of
> the socket files, e.g. /tmp/vhost-user-.\n"
> -				 "	--client: register a vhost-user socket as
> client mode.\n",
> -				 prgname);
> +	printf("Usage: %s [EAL options] --\n", prgname);
> +	const char *usage_str = "	--interactive|-i: run in interactive
> mode.\n"
> +				"	--iface <path>: specify the path prefix of
> the socket files, e.g. /tmp/vhost-user-.\n"
> +				"	--client: register a vhost-user socket as
> client mode.\n"
> +				"	--iommu-support: use guest vIOMMU to protect
> vhost.\n";
> +
> +	fprintf(stderr, "%s", usage_str);

Why not use fprintf all string including the eal one?

> +	exit(1);

I believe the exit should happen outside of the function.

Thanks,
Chenbo

>  }
> 
>  static int
> @@ -63,6 +67,7 @@ parse_args(int argc, char **argv)
>  		{"iface", required_argument, NULL, 0},
>  		{"interactive", no_argument, &interactive, 1},
>  		{"client", no_argument, &client_mode, 1},
> +		{"iommu-support", no_argument, &iommu_support, 1},
>  		{NULL, 0, 0, 0},
>  	};
>  	int opt, idx;
> @@ -220,6 +225,10 @@ start_vdpa(struct vdpa_port *vport)
>  			socket_path);
>  		return -1;
>  	}
> +
> +	if (iommu_support)
> +		vport->flags |= RTE_VHOST_USER_IOMMU_SUPPORT;
> +
>  	ret = rte_vhost_driver_register(socket_path, vport->flags);
>  	if (ret != 0)
>  		rte_exit(EXIT_FAILURE,
> --
> 2.27.0