powerpc/pseries: Reject discontiguous/non-zero based MSI-X requests

There's no way for us to express to firmware that we want a
discontiguous, or non-zero based, range of MSI-X entries. So we
must reject such requests.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/pseries/msi.c
index 3e0d6ef3eca..bf2e1ac4130 100644
--- a/arch/powerpc/platforms/pseries/msi.c
+++ b/arch/powerpc/platforms/pseries/msi.c
@@ -356,6 +356,27 @@ static int rtas_msi_check_device(struct pci_dev *pdev, int nvec, int type)
         return 0;
 }
 
+static int check_msix_entries(struct pci_dev *pdev)
+{
+        struct msi_desc *entry;
+        int expected;
+
+        /* There's no way for us to express to firmware that we want
+         * a discontiguous, or non-zero based, range of MSI-X entries.
+         * So we must reject such requests. */
+
+        expected = 0;
+        list_for_each_entry(entry, &pdev->msi_list, list) {
+                if (entry->msi_attrib.entry_nr != expected) {
+                        pr_debug("rtas_msi: bad MSI-X entries.\n");
+                        return -EINVAL;
+                }
+                expected++;
+        }
+
+        return 0;
+}
+
 static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
 {
         struct pci_dn *pdn;
@@ -367,6 +388,9 @@ static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
         if (!pdn)
                 return -ENODEV;
 
+        if (type == PCI_CAP_ID_MSIX && check_msix_entries(pdev))
+                return -EINVAL;
+
         /*
          * Try the new more explicit firmware interface, if that fails fall
          * back to the old interface. The old interface is known to never