Re: [dpdk-dev] [RFC 2/2] nfp: allow for non-root user

[Alejandro Lucero <alejandro.lucero@netronome.com>]

On Tue, Apr 17, 2018 at 8:19 PM, Aaron Conole <aconole@redhat.com> wrote:

> Alejandro Lucero <alejandro.lucero@netronome.com> writes:
>
> > I was just wondering, if device device PCI sysfs resource files or VFIO
> group /dev files require to change
> > permissions for non-root users, does it not make sense to adjust also
> /var/lock in the system?
>
> For the /dev, we use udev rules - so the correct individual vfio device
> files get assigned the correct permissions.  No such mechanism exists
> for /var/lock as far as I can tell.
>
> Ex. see:
>
> https://github.com/openvswitch/ovs/blob/master/
> rhel/usr_lib_udev_rules.d_91-vfio.rules
>
> Maybe something similar exists that we could use to generate the lock
> file automatically?
>

What about /sysfs/bus/pci/device/$PCI_DEV/resource file?

Is RH forcing OVS DPDK to only work if the host has IOMMU support?


>
> > On Tue, Apr 17, 2018 at 4:44 PM, Alejandro Lucero <
> alejandro.lucero@netronome.com> wrote:
> >
> >  I have seen that VFIO also requires explicitly to set the right
> permissions for non-root users to VFIO
> >  groups under /dev/vfio.
> >
> >  I assume then that running OVS or other DPDK apps as non-root is
> possible, although requiring
> >  those explicit permissions changes, and therefore this patch is
> necessary.
> >
> >  Adding stable@ and Thomas for discussing how can this be added to
> stable DPDK versions even if
> >  this is not going to be a patch for current DPDK version.
> >
> >  Acked-by: Alejandro Lucero <alejandro.lucero@netronome.com>
> >
> >  On Fri, Apr 13, 2018 at 4:31 PM, Alejandro Lucero <
> alejandro.lucero@netronome.com> wrote:
> >
> >  On Fri, Apr 13, 2018 at 2:31 PM, Aaron Conole <aconole@redhat.com>
> wrote:
> >
> >  Alejandro Lucero <alejandro.lucero@netronome.com> writes:
> >
> >  > Again, this patch is correct, but because NFP PMD needs to access
> >  > /sys/bus/pci/devices/$DEVICE_PCI_STRING/resource$RESOURCE_ID, and
> these files have
> >  just
> >  > read/write accesses for root, I do not know if this is really
> necessary.
> >  >
> >  > Being honest, I have not used a DPDK app with NFP PMD and not being
> root. Does it
> >  work
> >  > with non-root users and other PMDs with same requirements regarding
> sysfs resource
> >  files?
> >
> >  We do run as non-root user definitely with Intel PMDs.
> >
> >  I'm not very sure about other vendors, but I think mlx pmd runs as
> >  non-root user (and it was modified to move off of sysfs for that
> >  reason[1]).
> >
> >  It is possible to not rely on sysfs resource files if device is
> attached to VFIO, but I think that is a
> >  must with UIO.
> >
> >
> >  I'll continue to push for more information from the testing side to find
> >  out though.
> >
> >  [1]: http://dpdk.org/ml/archives/dev/2018-February/090586.html
> >
> >  > On Fri, Apr 13, 2018 at 12:22 AM, Aaron Conole <aconole@redhat.com>
> wrote:
> >  >
> >  >  Currently, the nfp lock files are taken from the global lock file
> >  >  location, which will work when the user is running as root.  However,
> >  >  some distributions and applications (notably ovs 2.8+ on RHEL/Fedora)
> >  >  run as a non-root user.
> >  >
> >  >  Signed-off-by: Aaron Conole <aconole@redhat.com>
> >  >  ---
> >  >   drivers/net/nfp/nfp_nfpu.c | 23 ++++++++++++++++++-----
> >  >   1 file changed, 18 insertions(+), 5 deletions(-)
> >  >
> >  >  diff --git a/drivers/net/nfp/nfp_nfpu.c b/drivers/net/nfp/nfp_nfpu.c
> >  >  index 2ed985ff4..ae2e07220 100644
> >  >  --- a/drivers/net/nfp/nfp_nfpu.c
> >  >  +++ b/drivers/net/nfp/nfp_nfpu.c
> >  >  @@ -18,6 +18,22 @@
> >  >   #define NFP_CFG_EXP_BAR         7
> >  >
> >  >   #define NFP_CFG_EXP_BAR_CFG_BASE       0x30000
> >  >  +#define NFP_LOCKFILE_PATH_FMT "%s/nfp%d"
> >  >  +
> >  >  +/* get nfp lock file path (/var/lock if root, $HOME otherwise) */
> >  >  +static void
> >  >  +nspu_get_lockfile_path(char *buffer, int bufsz, nfpu_desc_t *desc)
> >  >  +{
> >  >  +       const char *dir = "/var/lock";
> >  >  +       const char *home_dir = getenv("HOME");
> >  >  +
> >  >  +       if (getuid() != 0 && home_dir != NULL)
> >  >  +               dir = home_dir;
> >  >  +
> >  >  +       /* use current prefix as file path */
> >  >  +       snprintf(buffer, bufsz, NFP_LOCKFILE_PATH_FMT, dir,
> >  >  +                       desc->nfp);
> >  >  +}
> >  >
> >  >   /* There could be other NFP userspace tools using the NSP interface.
> >  >    * Make sure there is no other process using it and locking the
> access for
> >  >  @@ -30,9 +46,7 @@ nspv_aquire_process_lock(nfpu_desc_t *desc)
> >  >          struct flock lock;
> >  >          char lockname[30];
> >  >
> >  >  -       memset(&lock, 0, sizeof(lock));
> >  >  -
> >  >  -       snprintf(lockname, sizeof(lockname), "/var/lock/nfp%d",
> desc->nfp);
> >  >  +       nspu_get_lockfile_path(lockname, sizeof(lockname), desc);
> >  >
> >  >          /* Using S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH |
> S_IWOTH */
> >  >          desc->lock = open(lockname, O_RDWR | O_CREAT, 0666);
> >  >  @@ -106,7 +120,6 @@ nfpu_close(nfpu_desc_t *desc)
> >  >          rte_free(desc->nspu);
> >  >          close(desc->lock);
> >  >
> >  >  -       snprintf(lockname, sizeof(lockname), "/var/lock/nfp%d",
> desc->nfp);
> >  >  -       unlink(lockname);
> >  >  +       nspu_get_lockfile_path(lockname, sizeof(lockname), desc);
> >  >          return 0;
> >  >   }
> >  >  --
> >  >  2.14.3
>