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Re: [Xen-devel] [PATCH v2] PCI: Add guard to avoid mapping a invalid msix base address

On 01/28/2015 01:13 PM, Bjorn Helgaas wrote:

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index fd60806..c3e7dfc 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -694,11 +694,16 @@ static void __iomem *msix_map_region(struct pci_dev *dev, 
unsigned nr_entries)
        resource_size_t phys_addr;
        u32 table_offset;
+       unsigned long flags;
        u8 bir;
pci_read_config_dword(dev, dev->msix_cap + PCI_MSIX_TABLE,
        bir = (u8)(table_offset & PCI_MSIX_TABLE_BIR);
+       flags = pci_resource_flags(dev, bir);
+       if (!flags || (flags & IORESOURCE_UNSET))
+               return NULL;
Thanks, this looks better.

There's similar code in xen_initdom_setup_msi_irqs() that looks like it
might require a similar fix.

Right, I think it does.

One question: do we need to check flags for IORESOURCE_DISABLED as well? Currently IORESOURCE_DISABLED and IORESOURCE_UNSET are set together for PCI so it probably doesn't matter right now but if this changes we won't want to use BAR that's disabled, will we?


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