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@xxxxxxxxxxxxxxxxxxx>
Reported-by: Dusty Mabe <dustymabe@xxxxxxxxxx>
Reported-by: Salvatore Bonaccorso <carnil@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Noah Meyerhans <noahm@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/87tuaduxj5.ffs@tglx
[nmeyerha@xxxxxxxxxx: backported to 5.4]
Signed-off-by: Noah Meyerhans <nmeyerha@xxxxxxxxxx>
---
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 5c11ae66b5d8..9cf8f5417e7f 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -442,6 +442,11 @@ 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
--
2.25.1
