xen: Utilize the restore_msi_irqs hook.

to make a hypercall to restore the vectors in the MSI/MSI-X
configuration space.
Signed-off-by: Tang Liang <liang.tang@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/pci/xen.c

@@ -324,6 +324,32 @@ static int xen_initdom_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 out:
 	return ret;
 }
+
+static void xen_initdom_restore_msi_irqs(struct pci_dev *dev, int irq)
+{
+	int ret = 0;
+
+	if (pci_seg_supported) {
+		struct physdev_pci_device restore_ext;
+
+		restore_ext.seg = pci_domain_nr(dev->bus);
+		restore_ext.bus = dev->bus->number;
+		restore_ext.devfn = dev->devfn;
+		ret = HYPERVISOR_physdev_op(PHYSDEVOP_restore_msi_ext,
+					&restore_ext);
+		if (ret == -ENOSYS)
+			pci_seg_supported = false;
+		WARN(ret && ret != -ENOSYS, "restore_msi_ext -> %d\n", ret);
+	}
+	if (!pci_seg_supported) {
+		struct physdev_restore_msi restore;
+
+		restore.bus = dev->bus->number;
+		restore.devfn = dev->devfn;
+		ret = HYPERVISOR_physdev_op(PHYSDEVOP_restore_msi, &restore);
+		WARN(ret && ret != -ENOSYS, "restore_msi -> %d\n", ret);
+	}
+}
 #endif
 
 static void xen_teardown_msi_irqs(struct pci_dev *dev)
@@ -446,6 +472,7 @@ int __init pci_xen_initial_domain(void)
 #ifdef CONFIG_PCI_MSI
 	x86_msi.setup_msi_irqs = xen_initdom_setup_msi_irqs;
 	x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
+	x86_msi.restore_msi_irqs = xen_initdom_restore_msi_irqs;
 #endif
 	xen_setup_acpi_sci();
 	__acpi_register_gsi = acpi_register_gsi_xen;

include/xen/interface/physdev.h

@@ -145,6 +145,13 @@ struct physdev_manage_pci {
 	uint8_t devfn;
 };
 
+#define PHYSDEVOP_restore_msi            19
+struct physdev_restore_msi {
+	/* IN */
+	uint8_t bus;
+	uint8_t devfn;
+};
+
 #define PHYSDEVOP_manage_pci_add_ext	20
 struct physdev_manage_pci_ext {
 	/* IN */