Merge branch 'acpi-x86'

Merge a revert of a problematic commit for 5.17-rc4.

* acpi-x86:
  x86/PCI: revert "Ignore E820 reservations for bridge windows on newer systems"

Author: rafaeljw

arch/x86/kernel/resource.c

@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#include <linux/dmi.h>
 #include <linux/ioport.h>
 #include <asm/e820/api.h>
 
@@ -24,31 +23,11 @@ static void resource_clip(struct resource *res, resource_size_t start,
 		res->start = end + 1;
 }
 
-/*
- * Some BIOS-es contain a bug where they add addresses which map to
- * system RAM in the PCI host bridge window returned by the ACPI _CRS
- * method, see commit 4dc2287c1805 ("x86: avoid E820 regions when
- * allocating address space"). To avoid this Linux by default excludes
- * E820 reservations when allocating addresses since 2010.
- * In 2019 some systems have shown-up with E820 reservations which cover
- * the entire _CRS returned PCI host bridge window, causing all attempts
- * to assign memory to PCI BARs to fail if Linux uses E820 reservations.
- *
- * Ideally Linux would fully stop using E820 reservations, but then
- * the old systems this was added for will regress.
- * Instead keep the old behavior for old systems, while ignoring the
- * E820 reservations for any systems from now on.
- */
 static void remove_e820_regions(struct resource *avail)
 {
-	int i, year = dmi_get_bios_year();
+	int i;
 	struct e820_entry *entry;
 
-	if (year >= 2018)
-		return;
-
-	pr_info_once("PCI: Removing E820 reservations from host bridge windows\n");
-
 	for (i = 0; i < e820_table->nr_entries; i++) {
 		entry = &e820_table->entries[i];