From: Ingo Molnar <mingo@kernel.org>
Date: Thu, 15 May 2025 12:05:19 +0000 (+0200)
Subject: x86/boot/e820: Simplify the PPro Erratum #50 workaround
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3814bf08452ecfc6db0de53a2e4f977e9661c1f4;p=thirdparty%2Fkernel%2Flinux.git

x86/boot/e820: Simplify the PPro Erratum #50 workaround

No need to print out the table - users won't really be able
to tell much from it anyway and the messages around this
erratum are unnecessarily obtuse.

Instead clearly inform the user that a 256 kB hole is being
punched in their memory map at the 1.75 GB physical address.

Not that there are many PPro users left. :-)

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H . Peter Anvin <hpa@zytor.com>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paul Menzel <pmenzel@molgen.mpg.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20250515120549.2820541-4-mingo@kernel.org
---

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 1b2edd07a3e17..a231b249d23b2 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1015,11 +1015,9 @@ void __init setup_arch(char **cmdline_p)
 	trim_bios_range();
 #ifdef CONFIG_X86_32
 	if (ppro_with_ram_bug()) {
-		e820__range_update(0x70000000ULL, 0x40000ULL, E820_TYPE_RAM,
-				  E820_TYPE_RESERVED);
+		pr_info("Applying PPro RAM bug workaround: punching 256 kB hole at 1.75 GB physical.\n");
+		e820__range_update(0x70000000ULL, SZ_256K, E820_TYPE_RAM, E820_TYPE_RESERVED);
 		e820__update_table(e820_table);
-		printk(KERN_INFO "fixed physical RAM map:\n");
-		e820__print_table("bad_ppro");
 	}
 #else
 	early_gart_iommu_check();