Re: [dpdk-dev] [PATCH v10 2/2] eal: support for VFIO-PCI VF token

[Andrew Rybchenko <arybchenko@solarflare.com>]

On 4/26/20 4:55 AM, Haiyue Wang wrote:
> The kernel module vfio-pci introduces the VF token to enable SR-IOV
> support since 5.7.
> 
> The VF token can be set by a vfio-pci based PF driver and must be known
> by the vfio-pci based VF driver in order to gain access to the device.
> 
> Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
> Acked-by: Vamsi Attunuru <vattunuru@marvell.com>
> Tested-by: Vamsi Attunuru <vattunuru@marvell.com>

Few points below, anyway:
Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>

[snip]

> diff --git a/doc/guides/linux_gsg/linux_drivers.rst b/doc/guides/linux_gsg/linux_drivers.rst
> index 238f3e900..b42fd708b 100644
> --- a/doc/guides/linux_gsg/linux_drivers.rst
> +++ b/doc/guides/linux_gsg/linux_drivers.rst
> @@ -72,11 +72,50 @@ Note that in order to use VFIO, your kernel must support it.
>  VFIO kernel modules have been included in the Linux kernel since version 3.6.0 and are usually present by default,
>  however please consult your distributions documentation to make sure that is the case.
>  
> +The ``vfio-pci`` module since Linux version 5.7 supports the creation of virtual
> +functions. After the PF is bound to vfio-pci module, the user can create the VFs
> +by sysfs interface, and these VFs are bound to vfio-pci module automatically.
> +
> +When the PF is bound to vfio-pci, it has initial VF token generated by random. For
> +security reason, this token is write only, the user can't read it from the kernel
> +directly. For accessing the VF, the user needs to start the PF with token parameter
> +to setup a VF token (uuid format), then the VF can be accessed with this new known
> +VF token.

If token is write-only in kernel sysfs, shouldn't we make it
invisible in ps output (procfs)? I.e. substitute with something
like xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
However, it does not look easy. Just a thought.

[snip]

> diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
> index 64cd84a68..efb64e2ba 100644
> --- a/drivers/bus/pci/linux/pci_vfio.c
> +++ b/drivers/bus/pci/linux/pci_vfio.c
> @@ -11,6 +11,7 @@
>  #include <sys/mman.h>
>  #include <stdbool.h>
>  
> +#include <rte_devargs.h>
>  #include <rte_log.h>
>  #include <rte_pci.h>
>  #include <rte_bus_pci.h>
> @@ -644,12 +645,72 @@ pci_vfio_msix_is_mappable(int vfio_dev_fd, int msix_region)
>  	return ret;
>  }
>  
> +static int
> +vfio_pci_vf_token_arg(struct rte_devargs *devargs, rte_uuid_t uuid)
> +{
> +#define VF_TOKEN_ARG "vf_token="
> +	char c, *p, *vf_token;
> +
> +	memset(uuid, 0, sizeof(rte_uuid_t));
> +
> +	if (devargs == NULL)
> +		return 0;
> +
> +	p = strstr(devargs->args, VF_TOKEN_ARG);
> +	if (!p)

Please, p == NULL as you do few lines above.

[snip]