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

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

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
>>
>
>