linux-kernel - [PATCH 3/4] x86/fpu: Prepare AMX state for CPU idle

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

Date:   Thu,  4 Nov 2021 15:52:25 -0700
From:   "Chang S. Bae" <chang.seok.bae@...el.com>
To:     linux-kernel@...r.kernel.org
Cc:     x86@...nel.org, tglx@...utronix.de, dave.hansen@...ux.intel.com,
        peterz@...radead.org, bp@...en8.de, mingo@...hat.com,
        chang.seok.bae@...el.com
Subject: [PATCH 3/4] x86/fpu: Prepare AMX state for CPU idle

Before entering CPU idle, make sure large registers such as AMX TILE are
initialized. Otherwise, non-initialized register states may prevent a CPU
from entering a deeper low-power state.

Suggested-by: Dave Hansen <dave.hansen@...ux.intel.com>
Signed-off-by: Chang S. Bae <chang.seok.bae@...el.com>
Cc: x86@...nel.org
Cc: linux-kernel@...r.kernel.org
---
 arch/x86/kernel/process.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index eb470be0e5ae..7044ba276064 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -707,6 +707,7 @@ static inline void play_dead(void)
 
 void arch_cpu_idle_enter(void)
 {
+	fpu_idle_fpregs();
 	tsc_verify_tsc_adjust(false);
 	local_touch_nmi();
 }
-- 
2.17.1