[dpdk-dev] [PATCH v3 2/2] virtio: fix PCI config err handling

[Luca Boccassi]

From: Brian Russell <bruss...@brocade.com>

In virtio_read_caps and vtpci_msix_detect, rte_pci_read_config returns
the number of bytes read from PCI config or < 0 on error.
If less than the expected number of bytes are read then log the
failure and return rather than carrying on with garbage.

Fixes: 6ba1f63b5ab0 ("virtio: support specification 1.0")

Signed-off-by: Brian Russell <bruss...@brocade.com>
Signed-off-by: Luca Boccassi <bl...@debian.org>
---
v2: handle additional rte_pci_read_config incomplete reads
v3: do not handle rte_pci_read_config of virtio cap, added in v2,
    as it's less clear what the right thing to do there is

 drivers/net/virtio/virtio_pci.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/net/virtio/virtio_pci.c b/drivers/net/virtio/virtio_pci.c
index 6bd22e54a6..e1df2c3b4d 100644
--- a/drivers/net/virtio/virtio_pci.c
+++ b/drivers/net/virtio/virtio_pci.c
@@ -567,16 +567,18 @@ virtio_read_caps(struct rte_pci_device *dev, struct 
virtio_hw *hw)
        }
 
        ret = rte_pci_read_config(dev, &pos, 1, PCI_CAPABILITY_LIST);
-       if (ret < 0) {
-               PMD_INIT_LOG(DEBUG, "failed to read pci capability list");
+       if (ret != 1) {
+               PMD_INIT_LOG(DEBUG,
+                            "failed to read pci capability list, ret %d", ret);
                return -1;
        }
 
        while (pos) {
                ret = rte_pci_read_config(dev, &cap, sizeof(cap), pos);
-               if (ret < 0) {
-                       PMD_INIT_LOG(ERR,
-                               "failed to read pci cap at pos: %x", pos);
+               if (ret != sizeof(cap)) {
+                       PMD_INIT_LOG(DEBUG,
+                                    "failed to read pci cap at pos: %x ret %d",
+                                    pos, ret);
                        break;
                }
 
@@ -693,16 +695,18 @@ vtpci_msix_detect(struct rte_pci_device *dev)
        int ret;
 
        ret = rte_pci_read_config(dev, &pos, 1, PCI_CAPABILITY_LIST);
-       if (ret < 0) {
-               PMD_INIT_LOG(DEBUG, "failed to read pci capability list");
+       if (ret != 1) {
+               PMD_INIT_LOG(DEBUG,
+                            "failed to read pci capability list, ret %d", ret);
                return VIRTIO_MSIX_NONE;
        }
 
        while (pos) {
                ret = rte_pci_read_config(dev, &cap, sizeof(cap), pos);
-               if (ret < 0) {
-                       PMD_INIT_LOG(ERR,
-                               "failed to read pci cap at pos: %x", pos);
+               if (ret != sizeof(cap)) {
+                       PMD_INIT_LOG(DEBUG,
+                                    "failed to read pci cap at pos: %x ret %d",
+                                    pos, ret);
                        break;
                }
 
-- 
2.18.0