On Thu, Jan 29, 2015 at 7:15 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote: >>>> On 29.01.15 at 04:54, <wangyijing@xxxxxxxxxx> wrote: >> --- 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; > > Mind explaining what relevance the checking of flags against zero has > (also in the Xen counterpart)? The patch description says nothing in > this regard... It's buried in there: > reset_resource() -->res->start/end/flags = 0 If we fail to assign resources to a BAR, in some cases we set res->flags = 0. There are other cases where we set IORESOURCE_UNSET, and that's the direction I want to go for all situations where we don't assign resources. But right now, we have a mix where flags is zero in some cases (including the one Zhang found), and has IORESOURCE_UNSET in others. I'll try to wordsmith this in the changelog when I apply this. Bjorn -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html