x86, pci: Add sanity check for PCI fixed bar probing

While probing for the PCI fixed BAR capability in the extended PCI
configuration space we need to make sure raw_pci_ext_ops is
actually initialized.

Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
LKML-Reference: <43F901BD926A4E43B106BF17856F0755A321E8F7@orsmsx508.amr.corp.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86/pci/mrst.c b/arch/x86/pci/mrst.c
index 6e9e1a35a5d7..8bf2fcb88d04 100644
--- a/arch/x86/pci/mrst.c
+++ b/arch/x86/pci/mrst.c
@@ -57,6 +57,10 @@ static int fixed_bar_cap(struct pci_bus *bus, unsigned int devfn)
         u32 pcie_cap = 0, cap_data;
 
         pos = PCIE_CAP_OFFSET;
+
+        if (!raw_pci_ext_ops)
+                return 0;
+
         while (pos) {
                 if (raw_pci_ext_ops->read(pci_domain_nr(bus), bus->number,
                                           devfn, pos, 4, &pcie_cap))