Commit b187fae6 authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Greg Kroah-Hartman

cpu/speculation: Warn on unsupported mitigations= parameter

commit 1bf72720 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: 98af8452 ("cpu/speculation: Add 'mitigations=' cmdline option")
Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190516070935.22546-1-geert@linux-m68k.orgSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 82d0f7b6
......@@ -2315,6 +2315,9 @@ 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;
}
......
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