From 0579feb48fea8879046fd589c4d3bd4a7b33e760 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Thu, 4 Jul 2019 11:39:45 +0800 Subject: [PATCH] cpu/speculation: Warn on unsupported mitigations= parameter commit 1bf72720281770162c87990697eae1ba2f1d917a upstream. Currently, if the user specifies an unsupported mitigation strategy on the kernel command line, it will be ignored silently. The code will fall back to the default strategy, possibly leaving the system more vulnerable than expected. This may happen due to e.g. a simple typo, or, for a stable kernel release, because not all mitigation strategies have been backported. Inform the user by printing a message. Fixes: 98af8452945c5565 ("cpu/speculation: Add 'mitigations=' cmdline option") Signed-off-by: Geert Uytterhoeven Signed-off-by: Thomas Gleixner Acked-by: Josh Poimboeuf Cc: Peter Zijlstra Cc: Jiri Kosina Cc: Greg Kroah-Hartman Cc: Ben Hutchings Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20190516070935.22546-1-geert@linux-m68k.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yang Yingliang --- kernel/cpu.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/cpu.c b/kernel/cpu.c index 5d65eae893bd..46aefe5c0e35 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -2289,6 +2289,9 @@ static int __init mitigations_parse_cmdline(char *arg) cpu_mitigations = CPU_MITIGATIONS_AUTO; else if (!strcmp(arg, "auto,nosmt")) cpu_mitigations = CPU_MITIGATIONS_AUTO_NOSMT; + else + pr_crit("Unsupported mitigations=%s, system may still be vulnerable\n", + arg); return 0; } -- GitLab