vfio: fix group descriptor check

The issue is that a file descriptor at 0 is a valid one. Currently
the file not found, the return value will be set to 0. As a result,
it is impossible to distinguish between a correct descriptor and a
failed return value. Fix it to return -ENOENT instead of 0.

Fixes: b758423bc4fe ("vfio: fix race condition with sysfs")
Fixes: ff0b67d1c868 ("vfio: DMA mapping")
Cc: stable@dpdk.org
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>

diff --git a/lib/librte_eal/linux/eal_vfio.c b/lib/librte_eal/linux/eal_vfio.c
index e079799..380f2f4 100644 (file)
--- a/lib/librte_eal/linux/eal_vfio.c
+++ b/lib/librte_eal/linux/eal_vfio.c
@@ -295,7 +295,7 @@ vfio_open_group_fd(int iommu_group_num)
                                                        strerror(errno));
                                        return -1;
                                }
-                               return 0;
+                               return -ENOENT;
                        }
                        /* noiommu group found */
                }
@@ -320,12 +320,12 @@ vfio_open_group_fd(int iommu_group_num)
                        vfio_group_fd = mp_rep->fds[0];
                } else if (p->result == SOCKET_NO_FD) {
                        RTE_LOG(ERR, EAL, "  bad VFIO group fd\n");
-                       vfio_group_fd = 0;
+                       vfio_group_fd = -ENOENT;
                }
        }
 
        free(mp_reply.msgs);
-       if (vfio_group_fd < 0)
+       if (vfio_group_fd < 0 && vfio_group_fd != -ENOENT)
                RTE_LOG(ERR, EAL, "  cannot request group fd\n");
        return vfio_group_fd;
 }
@@ -381,9 +381,9 @@ vfio_get_group_fd(struct vfio_config *vfio_cfg,
        }
 
        vfio_group_fd = vfio_open_group_fd(iommu_group_num);
-       if (vfio_group_fd <= 0) {
+       if (vfio_group_fd < 0) {
                RTE_LOG(ERR, EAL, "Failed to open group %d\n", iommu_group_num);
-               return -1;
+               return vfio_group_fd;
        }
 
        cur_grp->group_num = iommu_group_num;
@@ -733,11 +733,14 @@ rte_vfio_setup_device(const char *sysfs_base, const char *dev_addr,
 
        /* get the actual group fd */
        vfio_group_fd = rte_vfio_get_group_fd(iommu_group_num);
-       if (vfio_group_fd < 0)
+       if (vfio_group_fd < 0 && vfio_group_fd != -ENOENT)
                return -1;
 
-       /* if group_fd == 0, that means the device isn't managed by VFIO */
-       if (vfio_group_fd == 0) {
+       /*
+        * if vfio_group_fd == -ENOENT, that means the device
+        * isn't managed by VFIO
+        */
+       if (vfio_group_fd == -ENOENT) {
                RTE_LOG(WARNING, EAL, " %s not managed by VFIO driver, skipping\n",
                                dev_addr);
                return 1;
@@ -975,10 +978,10 @@ rte_vfio_release_device(const char *sysfs_base, const char *dev_addr,
 
        /* get the actual group fd */
        vfio_group_fd = rte_vfio_get_group_fd(iommu_group_num);
-       if (vfio_group_fd <= 0) {
+       if (vfio_group_fd < 0) {
                RTE_LOG(INFO, EAL, "rte_vfio_get_group_fd failed for %s\n",
                                   dev_addr);
-               ret = -1;
+               ret = vfio_group_fd;
                goto out;
        }
 

diff --git a/lib/librte_eal/linux/eal_vfio_mp_sync.c b/lib/librte_eal/linux/eal_vfio_mp_sync.c
index 5f2a5fc..6254696 100644 (file)
--- a/lib/librte_eal/linux/eal_vfio_mp_sync.c
+++ b/lib/librte_eal/linux/eal_vfio_mp_sync.c
@@ -44,9 +44,9 @@ vfio_mp_primary(const struct rte_mp_msg *msg, const void *peer)
                r->req = SOCKET_REQ_GROUP;
                r->group_num = m->group_num;
                fd = rte_vfio_get_group_fd(m->group_num);
-               if (fd < 0)
+               if (fd < 0 && fd != -ENOENT)
                        r->result = SOCKET_ERR;
-               else if (fd == 0)
+               else if (fd == -ENOENT)
                        /* if VFIO group exists but isn't bound to VFIO driver */
                        r->result = SOCKET_NO_FD;
                else {