[kvm-unit-tests PATCH] s390x: Fix uv_call() exception behavior

[Janosch Frank <frankja@linux.ibm.com>]

On a program exception we usually skip the instruction that caused the
exception and continue. That won't work for UV calls since a "brc 3,0b"
will retry the instruction if the CC is > 1.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---

I know this isn't very pretty.
I'm open for suggestions.

---
 lib/s390x/asm/uv.h | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/lib/s390x/asm/uv.h b/lib/s390x/asm/uv.h
index 4c2fc48..252f1a3 100644
--- a/lib/s390x/asm/uv.h
+++ b/lib/s390x/asm/uv.h
@@ -53,21 +53,23 @@ struct uv_cb_share {
 static inline int uv_call(unsigned long r1, unsigned long r2)
 {
 	int cc;
+	struct lowcore *lc = 0x0;
 
 	/*
-	 * The brc instruction will take care of the cc 2/3 case where
-	 * we need to continue the execution because we were
-	 * interrupted. The inline assembly will only return on
-	 * success/error i.e. cc 0/1.
-	*/
+	 * CC 2 and 3 tell us to re-execute because the instruction
+	 * hasn't yet finished.
+	 */
+	lc->pgm_int_code = 0;
+retry:
 	asm volatile(
 		"0:	.insn rrf,0xB9A40000,%[r1],%[r2],0,0\n"
-		"		brc	3,0b\n"
 		"		ipm	%[cc]\n"
 		"		srl	%[cc],28\n"
 		: [cc] "=d" (cc)
 		: [r1] "a" (r1), [r2] "a" (r2)
 		: "memory", "cc");
+	if (!lc->pgm_int_code && cc > 1)
+		goto retry;
 	return cc;
 }
 
-- 
2.25.1