This is a note to let you know that I've just added the patch titled
x86/cpu: Fix check for RDPKRU in __show_regs()
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-cpu-fix-check-for-rdpkru-in-__show_regs.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b53c6bd5d271d023857174b8fd3e32f98ae51372 Mon Sep 17 00:00:00 2001
From: David Kaplan <david.kaplan@xxxxxxx>
Date: Sun, 21 Apr 2024 21:17:28 +0200
Subject: x86/cpu: Fix check for RDPKRU in __show_regs()
From: David Kaplan <david.kaplan@xxxxxxx>
commit b53c6bd5d271d023857174b8fd3e32f98ae51372 upstream.
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
__show_regs().
[ bp: Massage commit message. ]
Signed-off-by: David Kaplan <david.kaplan@xxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Link: https://lore.kernel.org/r/20240421191728.32239-1-bp@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/process_64.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -138,7 +138,7 @@ void __show_regs(struct pt_regs *regs, e
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());
}
Patches currently in stable-queue which might be from david.kaplan@xxxxxxx are
queue-6.6/x86-cpu-fix-check-for-rdpkru-in-__show_regs.patch
