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>

diff --git a/arch/s390/kernel/swsusp_asm64.S b/arch/s390/kernel/swsusp_asm64.S
index 6b09fdf..ca62946 100644 (file)
--- 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: