From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:18480 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388488AbhATLoY (ORCPT ); Wed, 20 Jan 2021 06:44:24 -0500 From: Janosch Frank Subject: [kvm-unit-tests GIT PULL 11/11] s390x: Fix uv_call() exception behavior Date: Wed, 20 Jan 2021 06:41:58 -0500 Message-Id: <20210120114158.104559-12-frankja@linux.ibm.com> In-Reply-To: <20210120114158.104559-1-frankja@linux.ibm.com> References: <20210120114158.104559-1-frankja@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit List-ID: To: pbonzini@redhat.com Cc: kvm@vger.kernel.org, frankja@linux.ibm.com, david@redhat.com, borntraeger@de.ibm.com, cohuck@redhat.com, linux-s390@vger.kernel.org, imbrenda@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. Let's forgo the brc when checking for privilege exceptions and use a uv_call_once(). Signed-off-by: Janosch Frank Suggested-by: Claudio Imbrenda Reviewed-by: Thomas Huth Reviewed-by: Cornelia Huck --- lib/s390x/asm/uv.h | 24 ++++++++++++++++-------- s390x/uv-guest.c | 6 +++--- 2 files changed, 19 insertions(+), 11 deletions(-) diff --git a/lib/s390x/asm/uv.h b/lib/s390x/asm/uv.h index 4c2fc48..39d2dc0 100644 --- a/lib/s390x/asm/uv.h +++ b/lib/s390x/asm/uv.h @@ -50,19 +50,12 @@ struct uv_cb_share { u64 reserved28; } __attribute__((packed)) __attribute__((aligned(8))); -static inline int uv_call(unsigned long r1, unsigned long r2) +static inline int uv_call_once(unsigned long r1, unsigned long r2) { int cc; - /* - * 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. - */ 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) @@ -71,4 +64,19 @@ static inline int uv_call(unsigned long r1, unsigned long r2) return cc; } +static inline int uv_call(unsigned long r1, unsigned long r2) +{ + int cc; + + /* + * CC 2 and 3 tell us to re-execute because the instruction + * hasn't yet finished. + */ + do { + cc = uv_call_once(r1, r2); + } while (cc > 1); + + return cc; +} + #endif diff --git a/s390x/uv-guest.c b/s390x/uv-guest.c index e51b85e..9954444 100644 --- a/s390x/uv-guest.c +++ b/s390x/uv-guest.c @@ -29,7 +29,7 @@ static void test_priv(void) uvcb.len = sizeof(struct uv_cb_qui); expect_pgm_int(); enter_pstate(); - uv_call(0, (u64)&uvcb); + uv_call_once(0, (u64)&uvcb); check_pgm_int_code(PGM_INT_CODE_PRIVILEGED_OPERATION); report_prefix_pop(); @@ -38,7 +38,7 @@ static void test_priv(void) uvcb.len = sizeof(struct uv_cb_share); expect_pgm_int(); enter_pstate(); - uv_call(0, (u64)&uvcb); + uv_call_once(0, (u64)&uvcb); check_pgm_int_code(PGM_INT_CODE_PRIVILEGED_OPERATION); report_prefix_pop(); @@ -47,7 +47,7 @@ static void test_priv(void) uvcb.len = sizeof(struct uv_cb_share); expect_pgm_int(); enter_pstate(); - uv_call(0, (u64)&uvcb); + uv_call_once(0, (u64)&uvcb); check_pgm_int_code(PGM_INT_CODE_PRIVILEGED_OPERATION); report_prefix_pop(); -- 2.25.1