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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 3 Apr 2019 12:28:03 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x33BS1hb51052718 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 3 Apr 2019 11:28:01 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 847764C058; Wed, 3 Apr 2019 11:28:01 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1B6C74C046; Wed, 3 Apr 2019 11:28:01 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.152.224.116]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 3 Apr 2019 11:28:01 +0000 (GMT) Subject: Re: [PATCH v3 1/2] s390/setup: diag318: remove bit check and refactor struct To: Collin Walling , pbonzini@redhat.com, david@redhat.com, cohuck@redhat.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Cc: schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, frankja@linux.ibm.com References: <20190402174636.15175-1-walling@linux.ibm.com> <20190402174636.15175-2-walling@linux.ibm.com> From: Christian Borntraeger Openpgp: preference=signencrypt Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20190402174636.15175-2-walling@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19040311-0020-0000-0000-0000032BC6BB X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19040311-0021-0000-0000-0000217DD091 Message-Id: <92d69cf5-0510-cf22-9f72-ab3efe4ede9b@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-03_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904030079 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02.04.19 19:46, Collin Walling wrote: > Execution of DIAGNOSE 0x318 is fenced by checking an SCLP bit > for the availability of hardware support for the instruction. > > In order to support this instruction for a KVM/QEMU guest, we > would need to provide modifications to the SCLP Read SCP Info > data, which will in turn reduce the maximum number of CPUs that > may be provided to the guest. This issue introduces compatability > and legacy concerns. > > Let's circumvent this issue by removing the bit check and blindly > executing the instruction. An exception table rule is in place to > catch the case where hardware does not support this instruction. No, please keep the check. We have to extend the read scp field anyway for future extensions. > > While we're at it, let's condense the version code fields in the > diag318_info struct until we can determine how it will be used. > > This modifies commit 4ad78b8651aacf26b3ab6d1e784952eb70469c43 > > Signed-off-by: Collin Walling > --- > arch/s390/include/asm/diag.h | 6 ++---- > arch/s390/kernel/setup.c | 12 ++++++------ > 2 files changed, 8 insertions(+), 10 deletions(-) > > diff --git a/arch/s390/include/asm/diag.h b/arch/s390/include/asm/diag.h > index 19562be22b7e..215516284175 100644 > --- a/arch/s390/include/asm/diag.h > +++ b/arch/s390/include/asm/diag.h > @@ -298,10 +298,8 @@ struct diag26c_mac_resp { > union diag318_info { > unsigned long val; > struct { > - unsigned int cpnc : 8; > - unsigned int cpvc_linux : 24; > - unsigned char cpvc_distro[3]; > - unsigned char zero; > + unsigned long cpnc : 8; > + unsigned long cpvc : 56; > }; > }; > > diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c > index 2c642af526ce..fe70201f8b5d 100644 > --- a/arch/s390/kernel/setup.c > +++ b/arch/s390/kernel/setup.c > @@ -1011,15 +1011,15 @@ static void __init setup_control_program_code(void) > { > union diag318_info diag318_info = { > .cpnc = CPNC_LINUX, > - .cpvc_linux = 0, > - .cpvc_distro = {0}, > + .cpvc = 0, > }; > > - if (!sclp.has_diag318) > - return; > - > diag_stat_inc(DIAG_STAT_X318); > - asm volatile("diag %0,0,0x318\n" : : "d" (diag318_info.val)); > + asm volatile( > + " diag %0,0,0x318\n" > + "0: nopr %%r7\n" > + EX_TABLE(0b,0b) > + : : "d" (diag318_info.val)); > } > > /* >