The Xen MSI → PIRQ magic does support MSI-X, so advertise it. (In fact it's better off with MSI-X than MSI, because it's actually broken by design for 32-bit MSI, since it puts the high bits of the PIRQ# into the high 32 bits of the MSI message address, instead of the Extended Destination ID field which is in bits 4-11. Strictly speaking, this really fixes a much older commit 2e4386eba0c0 ("x86/xen: Wrap XEN MSI management into irqdomain") which failed to set the flag. But that never really mattered until __pci_enable_msix_range() started to check and bail out early. So in 6.2-rc we see failures e.g. to bring up networking on an Amazon EC2 m4.16xlarge instance: [ 41.498694] ena 0000:00:03.0 (unnamed net_device) (uninitialized): Failed to enable MSI-X. irq_cnt -524 [ 41.498705] ena 0000:00:03.0: Can not reserve msix vectors [ 41.498712] ena 0000:00:03.0: Failed to enable and set the admin interrupts Side note: This is the first bug found, and first patch tested, by running Xen guests under QEMU/KVM instead of running under actual Xen. Fixes: 99f3d2797657 ("PCI/MSI: Reject MSI-X early") Signed-off-by: David Woodhouse --- arch/x86/pci/xen.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c index b94f727251b6..790550479831 100644 --- a/arch/x86/pci/xen.c +++ b/arch/x86/pci/xen.c @@ -433,6 +433,7 @@ static struct msi_domain_ops xen_pci_msi_domain_ops = { }; static struct msi_domain_info xen_pci_msi_domain_info = { + .flags = MSI_FLAG_PCI_MSIX, .ops = &xen_pci_msi_domain_ops, }; -- 2.34.1