[PATCH 2/5] xen-pcifront: Sanity check the MSI/MSI-X values

[Konrad Rzeszutek Wilk]

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.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 drivers/pci/xen-pcifront.c |   21 +++++++++++++++++----
 1 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 030ce37..d9fd1e0 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -277,18 +277,25 @@ 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 +332,12 @@ 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);
-- 
1.7.1

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