xen-pcifront: Sanity check the MSI/MSI-X values

Check the returned vector values for any values that are
odd or plain incorrect (say vector value zero), and if so
print a warning. Also fixup the return values.

This patch was precipiated by the Xen PCIBack returning the
incorrect values due to how it was retrieving PIRQ values.
This has been fixed in the xen-pciback by
"xen/pciback: Utilize 'xen_pirq_from_irq' to get PIRQ value"
patch.

Reviewed-by: Ian Campbell <Ian.Campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 16 insertions, 4 deletions

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 030ce3743439..5c7b6ad68056 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -277,18 +277,24 @@ static int pci_frontend_enable_msix(struct pci_dev *dev,
         if (likely(!err)) {
                 if (likely(!op.value)) {
                         /* we get the result */
-                        for (i = 0; i < nvec; i++)
+                        for (i = 0; i < nvec; i++) {
+                                if (op.msix_entries[i].vector <= 0) {
+                                        dev_warn(&dev->dev, "MSI-X entry %d is invalid: %d!\n",
+                                                i, op.msix_entries[i].vector);
+                                        err = -EINVAL;
+                                        *(*vector+i) = -1;
+                                        continue;
+                                }
                                 *(*vector+i) = op.msix_entries[i].vector;
-                        return 0;
+                        }
                 } else {
                         printk(KERN_DEBUG "enable msix get value %x\n",
                                 op.value);
-                        return op.value;
                 }
         } else {
                 dev_err(&dev->dev, "enable msix get err %x\n", err);
-                return err;
         }
+        return err;
 }
 
 static void pci_frontend_disable_msix(struct pci_dev *dev)
@@ -325,6 +331,12 @@ static int pci_frontend_enable_msi(struct pci_dev *dev, int **vector)
         err = do_pci_op(pdev, &op);
         if (likely(!err)) {
                 *(*vector) = op.value;
+                if (op.value <= 0) {
+                        dev_warn(&dev->dev, "MSI entry is invalid: %d!\n",
+                                op.value);
+                        err = -EINVAL;
+                        *(*vector) = -1;        
+                }
         } else {
                 dev_err(&dev->dev, "pci frontend enable msi failed for dev "
                                     "%x:%x\n", op.bus, op.devfn);