From: Ard Biesheuvel <ardb@kernel.org>
Date: Sun, 4 May 2025 09:52:32 +0000 (+0200)
Subject: x86/boot: Disregard __supported_pte_mask in __startup_64()
X-Git-Tag: v6.16-rc1~195^2~30^2~6
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b3464a36f7f2499d517e8334e07ddd6eefcd67c1;p=thirdparty%2Fkernel%2Flinux.git

x86/boot: Disregard __supported_pte_mask in __startup_64()

__supported_pte_mask is statically initialized to U64_MAX and never
assigned until long after the startup code executes that creates the
initial page tables. So applying the mask is unnecessary, and can be
avoided.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Dionna Amalie Glaze <dionnaglaze@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kevin Loughlin <kevinloughlin@google.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: linux-efi@vger.kernel.org
Link: https://lore.kernel.org/r/20250504095230.2932860-27-ardb+git@google.com
---

diff --git a/arch/x86/boot/startup/map_kernel.c b/arch/x86/boot/startup/map_kernel.c
index 0eac3f17dbd3f..099ae25593361 100644
--- a/arch/x86/boot/startup/map_kernel.c
+++ b/arch/x86/boot/startup/map_kernel.c
@@ -179,8 +179,6 @@ unsigned long __head __startup_64(unsigned long p2v_offset,
 	pud[(i + 1) % PTRS_PER_PUD] = (pudval_t)pmd + pgtable_flags;
 
 	pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
-	/* Filter out unsupported __PAGE_KERNEL_* bits: */
-	pmd_entry &= __supported_pte_mask;
 	pmd_entry += sme_get_me_mask();
 	pmd_entry +=  physaddr;