[dpdk-stable] [PATCH 18.08] vfio: don't needlessly setup devices in secondary process

[Darek Stojaczyk]

Setting up a device that wasn't setup in the primary
process will possibly break the primary process. That's
because the IPC message to retrieve the group fd in the
primary will also *open* that group if it wasn't opened
before. Even though the secondary process closes that fd
soon after as a part of its error handling path, the
primary process leaks it.

What's worse, opening that fd on the primary will
increment the process-local counter of opened groups.
If it was 0 before, then the group will never be added
to the vfio container, nor dpdk memory will be ever
mapped.

This patch moves the proper error checks earlier in the
code to fuly prevent setting up devices in secondary
processes that weren't setup in the primary process.

Fixes: 2f4adfad0a69 ("vfio: add multiprocess support")

Change-Id: I9ea4dfa7522fd6cf144f40db4492645c7e8c8a65
Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk at intel.com>
Acked-by: Anatoly Burakov <anatoly.burakov at intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
 drivers/bus/pci/linux/pci_vfio.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
index 686386d6a..569953666 100644
--- a/drivers/bus/pci/linux/pci_vfio.c
+++ b/drivers/bus/pci/linux/pci_vfio.c
@@ -551,11 +551,6 @@ pci_vfio_map_resource_secondary(struct rte_pci_device *dev)
 	snprintf(pci_addr, sizeof(pci_addr), PCI_PRI_FMT,
 			loc->domain, loc->bus, loc->devid, loc->function);
 
-	ret = rte_vfio_setup_device(rte_pci_get_sysfs_path(), pci_addr,
-					&vfio_dev_fd, &device_info);
-	if (ret)
-		return ret;
-
 	/* if we're in a secondary process, just find our tailq entry */
 	TAILQ_FOREACH(vfio_res, vfio_res_list, next) {
 		if (rte_pci_addr_cmp(&vfio_res->pci_addr,
@@ -567,9 +562,14 @@ pci_vfio_map_resource_secondary(struct rte_pci_device *dev)
 	if (vfio_res == NULL) {
 		RTE_LOG(ERR, EAL, "  %s cannot find TAILQ entry for PCI device!\n",
 				pci_addr);
-		goto err_vfio_dev_fd;
+		return -1;
 	}
 
+	ret = rte_vfio_setup_device(rte_pci_get_sysfs_path(), pci_addr,
+					&vfio_dev_fd, &device_info);
+	if (ret)
+		return ret;
+
 	/* map BARs */
 	maps = vfio_res->maps;
 
-- 
2.17.1