[dpdk-dev] [PATCH] bus/pci: fix mmap PCI resource

[alvinx.zhang at intel.com]

From: Alvin Zhang <alvinx.zhang at intel.com>

When mapping a PCI BAR containing an MSI-X table, some devices do not
need to actually map this BAR or only need to map part of them, which
may cause the mapping to fail. Now some checks are added and a non-NULL
initial value is set to the variable to avoid this situation.

Fixes: 2fd3567e5425 ("pci: use OS generic memory mapping functions")
Cc: talshn at mellanox.com

Signed-off-by: Alvin Zhang <alvinx.zhang at intel.com>
---
 drivers/bus/pci/linux/pci_vfio.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
index fdeb9a8..9143bfc 100644
--- a/drivers/bus/pci/linux/pci_vfio.c
+++ b/drivers/bus/pci/linux/pci_vfio.c
@@ -547,6 +547,14 @@
 			bar_index,
 			memreg[0].offset, memreg[0].size,
 			memreg[1].offset, memreg[1].size);
+
+		if (memreg[0].size == 0 && memreg[1].size == 0) {
+			/* No need to map this BAR */
+			RTE_LOG(DEBUG, EAL, "Skipping BAR%d\n", bar_index);
+			bar->size = 0;
+			bar->addr = 0;
+			return 0;
+		}
 	} else {
 		memreg[0].offset = bar->offset;
 		memreg[0].size = bar->size;
@@ -556,7 +564,9 @@
 	bar_addr = mmap(bar->addr, bar->size, 0, MAP_PRIVATE |
 			MAP_ANONYMOUS | additional_flags, -1, 0);
 	if (bar_addr != MAP_FAILED) {
-		void *map_addr = NULL;
+		/* Set non NULL initial value for in case of no PCI mapping */
+		void *map_addr = bar_addr;
+
 		if (memreg[0].size) {
 			/* actual map of first part */
 			map_addr = pci_map_resource(bar_addr, vfio_dev_fd,
-- 
1.8.3.1