linux-kernel - [tip: x86/mm] x86_64: Show CR4.PSE on auxiliaries like on BSP

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Message-ID: <169555520691.27769.2960713930630159681.tip-bot2@tip-bot2>
Date:   Sun, 24 Sep 2023 11:33:26 -0000
From:   "tip-bot2 for Hugh Dickins" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Hugh Dickins <hughd@...gle.com>, Ingo Molnar <mingo@...nel.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/mm] x86_64: Show CR4.PSE on auxiliaries like on BSP

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

Commit-ID:     f4c5ca9850124fb5715eff06cffb1beed837500c
Gitweb:        https://git.kernel.org/tip/f4c5ca9850124fb5715eff06cffb1beed837500c
Author:        Hugh Dickins <hughd@...gle.com>
AuthorDate:    Mon, 14 Aug 2023 19:53:18 -07:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Sun, 24 Sep 2023 13:23:54 +02:00

x86_64: Show CR4.PSE on auxiliaries like on BSP

Set CR4.PSE in secondary_startup_64: the Intel SDM is clear that it does
not matter whether it's 0 or 1 when 4-level-pts are enabled, but it's
distracting to find CR4 different on BSP and auxiliaries - on x86_64,
BSP alone got to add the PSE bit, in probe_page_size_mask().

Peter Zijlstra adds:

   "I think the point is that PSE bit is completely without
    meaning in long mode.

    But yes, having the same CR4 bits set across BSP and APs is
    definitely sane."

Signed-off-by: Hugh Dickins <hughd@...gle.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lore.kernel.org/r/103ad03a-8c93-c3e2-4226-f79af4d9a074@google.com
---
 arch/x86/kernel/head_64.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index ea69959..3ddce02 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -180,8 +180,8 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
 	movl	$0, %ecx
 #endif
 
-	/* Enable PAE mode, PGE and LA57 */
-	orl	$(X86_CR4_PAE | X86_CR4_PGE), %ecx
+	/* Enable PAE mode, PSE, PGE and LA57 */
+	orl	$(X86_CR4_PAE | X86_CR4_PSE | X86_CR4_PGE), %ecx
 #ifdef CONFIG_X86_5LEVEL
 	testl	$1, __pgtable_l5_enabled(%rip)
 	jz	1f