commit 7e0815b3e09986d2fe651199363e135b9358132a upstream.

When a XEN_HVM guest uses the XEN PIRQ/Eventchannel mechanism, then PCI/MSI[-X] masking is solely controlled by the hypervisor, but contrary to XEN_PV guests this does not disable PCI/MSI[-X] masking in the PCI/MSI layer.

This can lead to a situation where the PCI/MSI layer masks an MSI[-X] interrupt and the hypervisor grants the write despite the fact that it already requested the interrupt. As a consequence interrupt delivery on the affected device is not happening ever.

Set pci_msi_ignore_mask to prevent that like it's done for XEN_PV guests already.

Fixes: 809f9267bbab ("xen: map MSIs into pirqs") Reported-by: Jeremi Piotrowski jpiotrowski@linux.microsoft.com Reported-by: Dusty Mabe dustymabe@redhat.com Reported-by: Salvatore Bonaccorso carnil@debian.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Noah Meyerhans noahm@debian.org Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/87tuaduxj5.ffs@tglx [nmeyerha@amazon.com: backported to 4.19] Signed-off-by: Noah Meyerhans nmeyerha@amazon.com --- arch/x86/pci/xen.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c index 22da9bfd8a45..bacf8d988f65 100644 --- a/arch/x86/pci/xen.c +++ b/arch/x86/pci/xen.c @@ -441,6 +441,11 @@ void __init xen_msi_init(void)

x86_msi.setup_msi_irqs = xen_hvm_setup_msi_irqs; x86_msi.teardown_msi_irq = xen_teardown_msi_irq; + /* + * With XEN PIRQ/Eventchannels in use PCI/MSI[-X] masking is solely + * controlled by the hypervisor. + */ + pci_msi_ignore_mask = 1; } #endif