From: Konrad Rzeszutek Wilk konrad.wilk@oracle.com
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: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/bugs.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1091,7 +1091,8 @@ 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],