On Thu, Feb 28, 2013 at 2:08 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote: > Bjorn, > > in the context of dealing with the final part of a long known security > issue on Xen, I'd appreciate if you could help me understand > under what conditions (or at which times) MMIO resources for PCI > devices can get re-assigned in Linux. Or really I'm in need to know > under what conditions there won't be any resource re-assignment > (i.e. we particularly need the BARs to be stable that cover the > MSI-X table and the Pending Bit Array). > > Right now I'm intending to send the hypervisor a respective > notification in the context of xen-pciback's probe function, after > having called pci_enable_device(). Can you confirm that at this > point, and until the driver lets go of the device again, resources > won't get re-assigned? Or if not, can you suggest a better point > in time for sending such a notification, or additional steps we > may need to take in order to ensure resource stability? Hi Jan, There is currently no mechanism for the PCI core to tell a driver that we're changing any device resources (IRQ, MMIO, I/O). Since there's no way to tell a driver to refresh its idea of device resources, the core can not change anything after we call a driver's .probe() method. This could change in the future if we support dynamic resource reassignment, but I think that would require adding some sort of notification infrastructure so we could essentially suspend a driver, reassign device resources, and tell the driver "things might have changed" when we resume it. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
