linux-kernel - [tip: x86/boot] x86/boot: Disregard __supported_pte_mask in __startup

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Message-ID: <174636842907.22196.17764583510375832637.tip-bot2@tip-bot2>
Date: Sun, 04 May 2025 14:20:29 -0000
From: "tip-bot2 for Ard Biesheuvel" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Ard Biesheuvel <ardb@...nel.org>, Ingo Molnar <mingo@...nel.org>,
 Arnd Bergmann <arnd@...db.de>, David Woodhouse <dwmw@...zon.co.uk>,
 Dionna Amalie Glaze <dionnaglaze@...gle.com>,
 "H. Peter Anvin" <hpa@...or.com>, Kees Cook <keescook@...omium.org>,
 Kevin Loughlin <kevinloughlin@...gle.com>, Len Brown <len.brown@...el.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
 Tom Lendacky <thomas.lendacky@....com>, linux-efi@...r.kernel.org,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject:
 [tip: x86/boot] x86/boot: Disregard __supported_pte_mask in __startup_64()

The following commit has been merged into the x86/boot branch of tip:

Commit-ID:     b3464a36f7f2499d517e8334e07ddd6eefcd67c1
Gitweb:        https://git.kernel.org/tip/b3464a36f7f2499d517e8334e07ddd6eefcd67c1
Author:        Ard Biesheuvel <ardb@...nel.org>
AuthorDate:    Sun, 04 May 2025 11:52:32 +02:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Sun, 04 May 2025 15:27:23 +02:00

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@...nel.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: David Woodhouse <dwmw@...zon.co.uk>
Cc: Dionna Amalie Glaze <dionnaglaze@...gle.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Kevin Loughlin <kevinloughlin@...gle.com>
Cc: Len Brown <len.brown@...el.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: linux-efi@...r.kernel.org
Link: https://lore.kernel.org/r/20250504095230.2932860-27-ardb+git@google.com
---
 arch/x86/boot/startup/map_kernel.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/x86/boot/startup/map_kernel.c b/arch/x86/boot/startup/map_kernel.c
index 0eac3f1..099ae25 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;