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Tue, 26 Nov 2024 10:25:20 +0000 Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay04.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 4AQAPG8X17039676 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 26 Nov 2024 10:25:16 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C0AF22007A; Tue, 26 Nov 2024 10:25:16 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9CEA120072; Tue, 26 Nov 2024 10:25:16 +0000 (GMT) Received: from tuxmaker.lnxne.boe (unknown [9.152.85.9]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 26 Nov 2024 10:25:16 +0000 (GMT) From: Heiko Carstens To: Christian Borntraeger , Janosch Frank , Claudio Imbrenda , David Hildenbrand Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 3/3] KVM: s390: Increase size of union sca_utility to four bytes Date: Tue, 26 Nov 2024 11:25:15 +0100 Message-ID: <20241126102515.3178914-4-hca@linux.ibm.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20241126102515.3178914-1-hca@linux.ibm.com> References: <20241126102515.3178914-1-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: ORVJqAXtxQzjV-c0v6KcYgqQt0kr4q7F X-Proofpoint-ORIG-GUID: ORVJqAXtxQzjV-c0v6KcYgqQt0kr4q7F X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1051,Hydra:6.0.680,FMLib:17.12.62.30 definitions=2024-10-15_01,2024-10-11_01,2024-09-30_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 priorityscore=1501 lowpriorityscore=0 mlxlogscore=999 bulkscore=0 spamscore=0 impostorscore=0 mlxscore=0 suspectscore=0 malwarescore=0 adultscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2409260000 definitions=main-2411260079 kvm_s390_update_topology_change_report() modifies a single bit within sca_utility using cmpxchg(). Given that the size of the sca_utility union is two bytes this generates very inefficient code. Change the size to four bytes, so better code can be generated. Even though the size of sca_utility doesn't reflect architecture anymore this seems to be the easiest and most pragmatic approach to avoid inefficient code. Acked-by: Claudio Imbrenda Signed-off-by: Heiko Carstens --- arch/s390/include/asm/kvm_host.h | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index 1cd8eaebd3c0..1cb1de232b9e 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -95,10 +95,10 @@ union ipte_control { }; union sca_utility { - __u16 val; + __u32 val; struct { - __u16 mtcr : 1; - __u16 reserved : 15; + __u32 mtcr : 1; + __u32 : 31; }; }; @@ -107,7 +107,7 @@ struct bsca_block { __u64 reserved[5]; __u64 mcn; union sca_utility utility; - __u8 reserved2[6]; + __u8 reserved2[4]; struct bsca_entry cpu[KVM_S390_BSCA_CPU_SLOTS]; }; @@ -115,7 +115,7 @@ struct esca_block { union ipte_control ipte_control; __u64 reserved1[6]; union sca_utility utility; - __u8 reserved2[6]; + __u8 reserved2[4]; __u64 mcn[4]; __u64 reserved3[20]; struct esca_entry cpu[KVM_S390_ESCA_CPU_SLOTS];