From 3b1ce482e2e669fc8093035e9a9fabd7e6ff2289 Mon Sep 17 00:00:00 2001 From: David Kaplan Date: Sun, 21 Apr 2024 21:17:28 +0200 Subject: [PATCH] x86/cpu: Fix check for RDPKRU in __show_regs() 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 Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240421191728.32239-1-bp@kernel.org Signed-off-by: Greg Kroah-Hartman --- 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 33b268747bb7..4989095ab769 100644 --- 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, 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()); }