s390/smp: reenable smt after resume

After a suspend/resume cycle we missed to enable smt again, which leads
to all sorts of bugs, since the kernel assumes smt is enabled, while the
hardware thinks it is not.

Reported-and-tested-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reported-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/s390/kernel/swsusp_asm64.S b/arch/s390/kernel/swsusp_asm64.S
index 6b09fdffbd2f..ca6294645dd3 100644
--- a/arch/s390/kernel/swsusp_asm64.S
+++ b/arch/s390/kernel/swsusp_asm64.S
@@ -177,6 +177,17 @@ restart_entry:
         lhi     %r1,1
         sigp    %r1,%r0,SIGP_SET_ARCHITECTURE
         sam64
+#ifdef CONFIG_SMP
+        larl    %r1,smp_cpu_mt_shift
+        icm     %r1,15,0(%r1)
+        jz      smt_done
+        llgfr   %r1,%r1
+smt_loop:
+        sigp    %r1,%r0,SIGP_SET_MULTI_THREADING
+        brc     8,smt_done                      /* accepted */
+        brc     2,smt_loop                      /* busy, try again */
+smt_done:
+#endif
         larl    %r1,.Lnew_pgm_check_psw
         lpswe   0(%r1)
 pgm_check_entry: