Merge tag 'x86_boot_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 boot updates from Borislav Petkov:
 "Consolidation and cleanup of the early memory reservations, along with
  a couple of gcc11 warning fixes"

* tag 'x86_boot_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/setup: Move trim_snb_memory() later in setup_arch() to fix boot hangs
  x86/setup: Merge several reservations of start of memory
  x86/setup: Consolidate early memory reservations
  x86/boot/compressed: Avoid gcc-11 -Wstringop-overread warning
  x86/boot/tboot: Avoid Wstringop-overread-warning

1 files changed, 58 insertions, 51 deletions

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index ccab6cf91283..0e3175551a56 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -633,11 +633,16 @@ static void __init trim_snb_memory(void)
 	printk(KERN_DEBUG "reserving inaccessible SNB gfx pages\n");
 
 	/*
-	 * Reserve all memory below the 1 MB mark that has not
-	 * already been reserved.
+	 * SandyBridge integrated graphics devices have a bug that prevents
+	 * them from accessing certain memory ranges, namely anything below
+	 * 1M and in the pages listed in bad_pages[] above.
+	 *
+	 * To avoid these pages being ever accessed by SNB gfx devices
+	 * reserve all memory below the 1 MB mark and bad_pages that have
+	 * not already been reserved at boot time.
 	 */
 	memblock_reserve(0, 1<<20);
-	
+
 	for (i = 0; i < ARRAY_SIZE(bad_pages); i++) {
 		if (memblock_reserve(bad_pages[i], PAGE_SIZE))
 			printk(KERN_WARNING "failed to reserve 0x%08lx\n",
@@ -645,18 +650,6 @@ static void __init trim_snb_memory(void)
 	}
 }
 
-/*
- * Here we put platform-specific memory range workarounds, i.e.
- * memory known to be corrupt or otherwise in need to be reserved on
- * specific platforms.
- *
- * If this gets used more widely it could use a real dispatch mechanism.
- */
-static void __init trim_platform_memory_ranges(void)
-{
-	trim_snb_memory();
-}
-
 static void __init trim_bios_range(void)
 {
 	/*
@@ -725,11 +718,41 @@ static int __init parse_reservelow(char *p)
 
 early_param("reservelow", parse_reservelow);
 
-static void __init trim_low_memory_range(void)
+static void __init early_reserve_memory(void)
 {
+	/*
+	 * Reserve the memory occupied by the kernel between _text and
+	 * __end_of_kernel_reserve symbols. Any kernel sections after the
+	 * __end_of_kernel_reserve symbol must be explicitly reserved with a
+	 * separate memblock_reserve() or they will be discarded.
+	 */
+	memblock_reserve(__pa_symbol(_text),
+			 (unsigned long)__end_of_kernel_reserve - (unsigned long)_text);
+
+	/*
+	 * The first 4Kb of memory is a BIOS owned area, but generally it is
+	 * not listed as such in the E820 table.
+	 *
+	 * Reserve the first memory page and typically some additional
+	 * memory (64KiB by default) since some BIOSes are known to corrupt
+	 * low memory. See the Kconfig help text for X86_RESERVE_LOW.
+	 *
+	 * In addition, make sure page 0 is always reserved because on
+	 * systems with L1TF its contents can be leaked to user processes.
+	 */
 	memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE));
+
+	early_reserve_initrd();
+
+	if (efi_enabled(EFI_BOOT))
+		efi_memblock_x86_reserve_range();
+
+	memblock_x86_reserve_range_setup_data();
+
+	reserve_ibft_region();
+	reserve_bios_regions();
 }
-	
+
 /*
  * Dump out kernel offset information on panic.
  */
@@ -764,29 +787,6 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
 
 void __init setup_arch(char **cmdline_p)
 {
-	/*
-	 * Reserve the memory occupied by the kernel between _text and
-	 * __end_of_kernel_reserve symbols. Any kernel sections after the
-	 * __end_of_kernel_reserve symbol must be explicitly reserved with a
-	 * separate memblock_reserve() or they will be discarded.
-	 */
-	memblock_reserve(__pa_symbol(_text),
-			 (unsigned long)__end_of_kernel_reserve - (unsigned long)_text);
-
-	/*
-	 * Make sure page 0 is always reserved because on systems with
-	 * L1TF its contents can be leaked to user processes.
-	 */
-	memblock_reserve(0, PAGE_SIZE);
-
-	early_reserve_initrd();
-
-	/*
-	 * At this point everything still needed from the boot loader
-	 * or BIOS or kernel text should be early reserved or marked not
-	 * RAM in e820. All other memory is free game.
-	 */
-
 #ifdef CONFIG_X86_32
 	memcpy(&boot_cpu_data, &new_cpu_data, sizeof(new_cpu_data));
 
@@ -910,8 +910,18 @@ void __init setup_arch(char **cmdline_p)
 
 	parse_early_param();
 
-	if (efi_enabled(EFI_BOOT))
-		efi_memblock_x86_reserve_range();
+	/*
+	 * Do some memory reservations *before* memory is added to
+	 * memblock, so memblock allocations won't overwrite it.
+	 * Do it after early param, so we could get (unlikely) panic from
+	 * serial.
+	 *
+	 * After this point everything still needed from the boot loader or
+	 * firmware or kernel text should be early reserved or marked not
+	 * RAM in e820. All other memory is free game.
+	 */
+	early_reserve_memory();
+
 #ifdef CONFIG_MEMORY_HOTPLUG
 	/*
 	 * Memory used by the kernel cannot be hot-removed because Linux
@@ -938,9 +948,6 @@ void __init setup_arch(char **cmdline_p)
 
 	x86_report_nx();
 
-	/* after early param, so could get panic from serial */
-	memblock_x86_reserve_range_setup_data();
-
 	if (acpi_mps_check()) {
 #ifdef CONFIG_X86_LOCAL_APIC
 		disable_apic = 1;
@@ -1032,8 +1039,6 @@ void __init setup_arch(char **cmdline_p)
 	 */
 	find_smp_config();
 
-	reserve_ibft_region();
-
 	early_alloc_pgt_buf();
 
 	/*
@@ -1054,8 +1059,6 @@ void __init setup_arch(char **cmdline_p)
 	 */
 	sev_setup_arch();
 
-	reserve_bios_regions();
-
 	efi_fake_memmap();
 	efi_find_mirror();
 	efi_esrt_init();
@@ -1081,8 +1084,12 @@ void __init setup_arch(char **cmdline_p)
 
 	reserve_real_mode();
 
-	trim_platform_memory_ranges();
-	trim_low_memory_range();
+	/*
+	 * Reserving memory causing GPU hangs on Sandy Bridge integrated
+	 * graphics devices should be done after we allocated memory under
+	 * 1M for the real mode trampoline.
+	 */
+	trim_snb_memory();
 
 	init_mem_mapping();