Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/xen/pci.c b/drivers/xen/pci.c
index 7494dbe..224df03 100644
--- a/drivers/xen/pci.c
+++ b/drivers/xen/pci.c
@@ -1,19 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (c) 2009, Intel Corporation.
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
- * Place - Suite 330, Boston, MA 02111-1307 USA.
- *
  * Author: Weidong Han <weidong.han@intel.com>
  */
 
@@ -29,6 +17,8 @@
 #include "../pci/pci.h"
 #ifdef CONFIG_PCI_MMCONFIG
 #include <asm/pci_x86.h>
+
+static int xen_mcfg_late(void);
 #endif
 
 static bool __read_mostly pci_seg_supported = true;
@@ -40,7 +30,18 @@
 #ifdef CONFIG_PCI_IOV
 	struct pci_dev *physfn = pci_dev->physfn;
 #endif
-
+#ifdef CONFIG_PCI_MMCONFIG
+	static bool pci_mcfg_reserved = false;
+	/*
+	 * Reserve MCFG areas in Xen on first invocation due to this being
+	 * potentially called from inside of acpi_init immediately after
+	 * MCFG table has been finally parsed.
+	 */
+	if (!pci_mcfg_reserved) {
+		xen_mcfg_late();
+		pci_mcfg_reserved = true;
+	}
+#endif
 	if (pci_seg_supported) {
 		struct {
 			struct physdev_pci_device_add add;
@@ -213,7 +214,7 @@
 arch_initcall(register_xen_pci_notifier);
 
 #ifdef CONFIG_PCI_MMCONFIG
-static int __init xen_mcfg_late(void)
+static int xen_mcfg_late(void)
 {
 	struct pci_mmcfg_region *cfg;
 	int rc;
@@ -252,8 +253,4 @@
 	}
 	return 0;
 }
-/*
- * Needs to be done after acpi_init which are subsys_initcall.
- */
-subsys_initcall_sync(xen_mcfg_late);
 #endif