Consolidation and cleanup of the early memory reservations, along with a

couple of gcc11 warning fixes.
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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

arch/x86/boot/compressed/misc.c

@@ -430,8 +430,6 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
 		error("Destination address too large");
 #endif
 #ifndef CONFIG_RELOCATABLE
-	if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
-		error("Destination address does not match LOAD_PHYSICAL_ADDR");
 	if (virt_addr != LOAD_PHYSICAL_ADDR)
 		error("Destination virtual address changed when not relocatable");
 #endif

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
+	 * SandyBridge integrated graphics devices have a bug that prevents
-	 * already been reserved.
+	 * 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();
 

arch/x86/kernel/tboot.c

@@ -49,6 +49,30 @@ bool tboot_enabled(void)
 	return tboot != NULL;
 }
 
+/* noinline to prevent gcc from warning about dereferencing constant fixaddr */
+static noinline __init bool check_tboot_version(void)
+{
+	if (memcmp(&tboot_uuid, &tboot->uuid, sizeof(tboot->uuid))) {
+		pr_warn("tboot at 0x%llx is invalid\n", boot_params.tboot_addr);
+		return false;
+	}
+
+	if (tboot->version < 5) {
+		pr_warn("tboot version is invalid: %u\n", tboot->version);
+		return false;
+	}
+
+	pr_info("found shared page at phys addr 0x%llx:\n",
+		boot_params.tboot_addr);
+	pr_debug("version: %d\n", tboot->version);
+	pr_debug("log_addr: 0x%08x\n", tboot->log_addr);
+	pr_debug("shutdown_entry: 0x%x\n", tboot->shutdown_entry);
+	pr_debug("tboot_base: 0x%08x\n", tboot->tboot_base);
+	pr_debug("tboot_size: 0x%x\n", tboot->tboot_size);
+
+	return true;
+}
+
 void __init tboot_probe(void)
 {
 	/* Look for valid page-aligned address for shared page. */
@@ -66,25 +90,9 @@ void __init tboot_probe(void)
 
 	/* Map and check for tboot UUID. */
 	set_fixmap(FIX_TBOOT_BASE, boot_params.tboot_addr);
-	tboot = (struct tboot *)fix_to_virt(FIX_TBOOT_BASE);
+	tboot = (void *)fix_to_virt(FIX_TBOOT_BASE);
-	if (memcmp(&tboot_uuid, &tboot->uuid, sizeof(tboot->uuid))) {
+	if (!check_tboot_version())
-		pr_warn("tboot at 0x%llx is invalid\n", boot_params.tboot_addr);
 		tboot = NULL;
-		return;
-	}
-	if (tboot->version < 5) {
-		pr_warn("tboot version is invalid: %u\n", tboot->version);
-		tboot = NULL;
-		return;
-	}
-
-	pr_info("found shared page at phys addr 0x%llx:\n",
-		boot_params.tboot_addr);
-	pr_debug("version: %d\n", tboot->version);
-	pr_debug("log_addr: 0x%08x\n", tboot->log_addr);
-	pr_debug("shutdown_entry: 0x%x\n", tboot->shutdown_entry);
-	pr_debug("tboot_base: 0x%08x\n", tboot->tboot_base);
-	pr_debug("tboot_size: 0x%x\n", tboot->tboot_size);
 }
 
 static pgd_t *tboot_pg_dir;