Commit 7ba793ae authored Apr 12, 2019 by Konrad Rzeszutek Wilk Committed by Greg Kroah-Hartman May 14, 2019

x86/speculation/mds: Print SMT vulnerable on MSBDS with mitigations off



commit e2c3c94788b08891dcf3dbe608f9880523ecd71b upstream

This code is only for CPUs which are affected by MSBDS, but are *not*
affected by the other two MDS issues.

For such CPUs, enabling the mds_idle_clear mitigation is enough to
mitigate SMT.

However if user boots with 'mds=off' and still has SMT enabled, we should
not report that SMT is mitigated:

$cat /sys//devices/system/cpu/vulnerabilities/mds
Vulnerable; SMT mitigated

But rather:
Vulnerable; SMT vulnerable

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20190412215118.294906495@localhost.localdomain


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e9ae3226

arch/x86/kernel/cpu/bugs.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1186,7 +1186,8 @@ static ssize_t mds_show_state(char *buf)

		if (boot_cpu_has(X86_BUG_MSBDS_ONLY)) {
		return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],
		sched_smt_active() ? "mitigated" : "disabled");
		(mds_mitigation == MDS_MITIGATION_OFF ? "vulnerable" :
		sched_smt_active() ? "mitigated" : "disabled"));
		}

		return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],