6.6-stable review patch. If anyone has any objections, please let me know. ------------------ 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()); }
