From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: [kvm-unit-tests PATCH v1] s390x: try multiple times to stop CPU Date: Wed, 20 Sep 2017 18:25:48 +0200 Message-ID: <20170920162548.7233-1-david@redhat.com> Cc: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Thomas Huth , Christian Borntraeger , Cornelia Huck , David Hildenbrand To: kvm@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:59834 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751650AbdITQZw (ORCPT ); Wed, 20 Sep 2017 12:25:52 -0400 Sender: kvm-owner@vger.kernel.org List-ID: In theory, we could get a CC == 3, meaning the SIGP facility is busy and we have to retry. So let's retry quite a number of times and at least print a message about the problem before going into a safe loop. Signed-off-by: David Hildenbrand --- While working on TCG SMP support, I had a BUG whereby the CPU would not directly stop but cotinue running for some instructions. This should no properly detect such scenarios where the CPU keeps running after the SIGP without indicating CC=3. lib/s390x/io.c | 31 +++++++++++++++++++++++++++---- 1 file changed, 27 insertions(+), 4 deletions(-) diff --git a/lib/s390x/io.c b/lib/s390x/io.c index 12f9d26..c48d6b1 100644 --- a/lib/s390x/io.c +++ b/lib/s390x/io.c @@ -14,6 +14,7 @@ #include #include #include +#include #include "sclp.h" extern char ipl_args[]; @@ -28,14 +29,36 @@ void puts(const char *s) spin_unlock(&lock); } -static void sigp_stop() +static int sigp_stop(void) { register unsigned long status asm ("1") = 0; register unsigned long cpu asm ("2") = 0; + int cc; asm volatile( - " sigp %0,%1,0(%2)\n" - : "+d" (status) : "d" (cpu), "d" (5) : "cc"); + " sigp %1,%2,0(%3)\n" + " ipm %0\n" + " srl %0,28\n" + : "=d" (cc), "+d" (status) : "d" (cpu), "d" (5) : "cc"); + return cc; +} + +static void machine_stop(void) +{ + int retry = 999999; + int cc; + + /* for now we only have 1 CPU to stop */ + do { + cc = sigp_stop(); + retry--; + } while (cc == 3 && retry); + + printf("\nERROR: Could not stop CPU(s)\n"); + printf("\nEXIT: STATUS=-1\n"); + while (true) { + mb(); + } } void setup() @@ -48,5 +71,5 @@ void setup() void exit(int code) { printf("\nEXIT: STATUS=%d\n", ((code) << 1) | 1); - sigp_stop(); + machine_stop(); } -- 2.13.5