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To: X86 ML <>
Cc: LKML <>,
	David Kaplan <>,
	Borislav Petkov <>
Subject: [PATCH] x86/cpu: Fix check for RDPKRU in __show_regs()
Date: Sun, 21 Apr 2024 21:17:28 +0200	[thread overview]
Message-ID: <> (raw)

From: David Kaplan <>

cpu_feature_enabled(X86_FEATURE_OSPKE) does not necessarily reflect
whether CR4.PKE is set on the CPU.  In particular, they may differ on
non-BSP CPUs before setup_pku() is executed.  In this scenario, RDPKRU
will #UD causing the system to hang.

Fix by checking CR4 for PKE enablement which is always correct for the
current CPU.

The scenario happens by inserting a WARN* before setup_pku() in
identiy_cpu() or some other diagnostic which would lead to calling

  [ bp: Massage commit message. ]

Signed-off-by: David Kaplan <>
Signed-off-by: Borislav Petkov (AMD) <>
 arch/x86/kernel/process_64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 7062b84dd467..6d3d20e3e43a 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -139,7 +139,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode,
 		       log_lvl, d3, d6, d7);
-	if (cpu_feature_enabled(X86_FEATURE_OSPKE))
+	if (cr4 & X86_CR4_PKE)
 		printk("%sPKRU: %08x\n", log_lvl, read_pkru());

             reply	other threads:[~2024-04-21 19:17 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-21 19:17 bp [this message]
2024-04-24 12:43 ` [tip: x86/urgent] x86/cpu: Fix check for RDPKRU in __show_regs() tip-bot2 for David Kaplan

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