linux-kernel - [tip: x86/urgent] x86/cpu: Add Lunar Lake to list of CPUs with a broken MONITOR implementation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <173334477712.412.14806732426864874461.tip-bot2@tip-bot2>
Date: Wed, 04 Dec 2024 20:39:37 -0000
From: "tip-bot2 for Len Brown" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Len Brown <len.brown@...el.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
 "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>, stable@...r.kernel.org,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/cpu: Add Lunar Lake to list of CPUs with a
 broken MONITOR implementation

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

Commit-ID:     c9a4b55431e5220347881e148725bed69c84e037
Gitweb:        https://git.kernel.org/tip/c9a4b55431e5220347881e148725bed69c84e037
Author:        Len Brown <len.brown@...el.com>
AuthorDate:    Tue, 12 Nov 2024 21:07:00 -05:00
Committer:     Dave Hansen <dave.hansen@...ux.intel.com>
CommitterDate: Wed, 04 Dec 2024 12:30:14 -08:00

x86/cpu: Add Lunar Lake to list of CPUs with a broken MONITOR implementation

Under some conditions, MONITOR wakeups on Lunar Lake processors
can be lost, resulting in significant user-visible delays.

Add Lunar Lake to X86_BUG_MONITOR so that wake_up_idle_cpu()
always sends an IPI, avoiding this potential delay.

Reported originally here:

	https://bugzilla.kernel.org/show_bug.cgi?id=219364

[ dhansen: tweak subject ]

Signed-off-by: Len Brown <len.brown@...el.com>
Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Cc:stable@...r.kernel.org
Link: https://lore.kernel.org/all/a4aa8842a3c3bfdb7fe9807710eef159cbf0e705.1731463305.git.len.brown%40intel.com
---
 arch/x86/kernel/cpu/intel.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index d1de300..8ded9f8 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -555,7 +555,9 @@ static void init_intel(struct cpuinfo_x86 *c)
 	     c->x86_vfm == INTEL_WESTMERE_EX))
 		set_cpu_bug(c, X86_BUG_CLFLUSH_MONITOR);

-	if (boot_cpu_has(X86_FEATURE_MWAIT) && c->x86_vfm == INTEL_ATOM_GOLDMONT)
+	if (boot_cpu_has(X86_FEATURE_MWAIT) &&
+	    (c->x86_vfm == INTEL_ATOM_GOLDMONT ||
+	     c->x86_vfm == INTEL_LUNARLAKE_M))
 		set_cpu_bug(c, X86_BUG_MONITOR);

 #ifdef CONFIG_X86_64