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

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

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,
>   			      &table_offset);
>   	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?


-boris