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Hi, Keir, This patch is a bugfix for saving and restoring MSI/MSI-X across S3. Currently, Dom0''s PCI layer unmaps MSI when S3 and maps them back when resuming. However, this triggers unexpected behaviors. For example, if the drivers still holds that irq at the point of unmapping MSI, Xen will force unbind that pirq. But after resume, we have no mechanism to rebind that pirq. The device