FAILED: patch "[PATCH] x86/pci/xen: Disable PCI/MSI[-X] masking for XEN_HVM guests" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7e0815b3e09986d2fe651199363e135b9358132a Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <[email protected]>
Date: Thu, 28 Apr 2022 15:50:54 +0200
Subject: [PATCH] x86/pci/xen: Disable PCI/MSI[-X] masking for XEN_HVM guests

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.

index 9bb1e2941179..b94f727251b6 100644
@@ -467,7 +467,6 @@ static __init void xen_setup_pci_msi(void)
 		else
 			xen_msi_ops.setup_msi_irqs = xen_setup_msi_irqs;
 		xen_msi_ops.teardown_msi_irqs = xen_pv_teardown_msi_irqs;
-		pci_msi_ignore_mask = 1;
 	} else if (xen_hvm_domain()) {
 		xen_msi_ops.setup_msi_irqs = xen_hvm_setup_msi_irqs;
 		xen_msi_ops.teardown_msi_irqs = xen_teardown_msi_irqs;

@@ -481,6 +480,11 @@ static __init void xen_setup_pci_msi(void)
 	 * in allocating the native domain and never use it.
 	 */
 	x86_init.irqs.create_pci_msi_domain = xen_create_pci_msi_domain;
+	/*
+	 * With XEN PIRQ/Eventchannels in use PCI/MSI[-X] masking is solely
+	 * controlled by the hypervisor.
+	 */
+	pci_msi_ignore_mask = 1;
 }
 
 #else /* CONFIG_PCI_MSI */