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Mon, 26 May 2025 10:36:02 +0000 (GMT) Message-ID: <609a3511-4dae-47b8-a6a6-45b8f3b989a8@linux.ibm.com> Date: Mon, 26 May 2025 12:36:02 +0200 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/3] KVM: s390: Always allocate esca_block To: Christoph Schlameuss , kvm@vger.kernel.org Cc: linux-s390@vger.kernel.org, Christian Borntraeger , Claudio Imbrenda , David Hildenbrand , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Thomas Huth References: <20250522-rm-bsca-v3-0-51d169738fcf@linux.ibm.com> <20250522-rm-bsca-v3-2-51d169738fcf@linux.ibm.com> Content-Language: en-US From: Janosch Frank Autocrypt: addr=frankja@linux.ibm.com; keydata= xsFNBFubpD4BEADX0uhkRhkj2AVn7kI4IuPY3A8xKat0ihuPDXbynUC77mNox7yvK3X5QBO6 qLqYr+qrG3buymJJRD9xkp4mqgasHdB5WR9MhXWKH08EvtvAMkEJLnqxgbqf8td3pCQ2cEpv 15mH49iKSmlTcJ+PvJpGZcq/jE42u9/0YFHhozm8GfQdb9SOI/wBSsOqcXcLTUeAvbdqSBZe zuMRBivJQQI1esD9HuADmxdE7c4AeMlap9MvxvUtWk4ZJ/1Z3swMVCGzZb2Xg/9jZpLsyQzb lDbbTlEeyBACeED7DYLZI3d0SFKeJZ1SUyMmSOcr9zeSh4S4h4w8xgDDGmeDVygBQZa1HaoL Esb8Y4avOYIgYDhgkCh0nol7XQ5i/yKLtnNThubAcxNyryw1xSstnKlxPRoxtqTsxMAiSekk 0m3WJwvwd1s878HrQNK0orWd8BzzlSswzjNfQYLF466JOjHPWFOok9pzRs+ucrs6MUwDJj0S cITWU9Rxb04XyigY4XmZ8dywaxwi2ZVTEg+MD+sPmRrTw+5F+sU83cUstuymF3w1GmyofgsU Z+/ldjToHnq21MNa1wx0lCEipCCyE/8K9B9bg9pUwy5lfx7yORP3JuAUfCYb8DVSHWBPHKNj HTOLb2g2UT65AjZEQE95U2AY9iYm5usMqaWD39pAHfhC09/7NQARAQABzSVKYW5vc2NoIEZy YW5rIDxmcmFua2phQGxpbnV4LmlibS5jb20+wsF3BBMBCAAhBQJbm6Q+AhsjBQsJCAcCBhUI CQoLAgQWAgMBAh4BAheAAAoJEONU5rjiOLn4p9gQALjkdj5euJVI2nNT3/IAxAhQSmRhPEt0 AmnCYnuTcHRWPujNr5kqgtyER9+EMQ0ZkX44JU2q7OWxTdSNSAN/5Z7qmOR9JySvDOf4d3mS bMB5zxL9d8SbnSs1uW96H9ZBTlTQnmLfsiM9TetAjSrR8nUmjGhe2YUhJLR1v1LguME+YseT eXnLzIzqqpu311/eYiiIGcmaOjPCE+vFjcXL5oLnGUE73qSYiujwhfPCCUK0850o1fUAYq5p CNBCoKT4OddZR+0itKc/cT6NwEDwdokeg0+rAhxb4Rv5oFO70lziBplEjOxu3dqgIKbHbjza EXTb+mr7VI9O4tTdqrwJo2q9zLqqOfDBi7NDvZFLzaCewhbdEpDYVu6/WxprAY94hY3F4trT rQMHJKQENtF6ZTQc9fcT5I3gAmP+OEvDE5hcTALpWm6Z6SzxO7gEYCnF+qGXqp8sJVrweMub UscyLqHoqdZC2UG4LQ1OJ97nzDpIRe0g6oJ9ZIYHKmfw5jjwH6rASTld5MFWajWdNsqK15k/ RZnHAGICKVIBOBsq26m4EsBlfCdt3b/6emuBjUXR1pyjHMz2awWzCq6/6OWs5eANZ0sdosNq dq2v0ULYTazJz2rlCXV89qRa7ukkNwdBSZNEwsD4eEMicj1LSrqWDZMAALw50L4jxaMD7lPL jJbazsFNBFubpD4BEADAcUTRqXF/aY53OSH7IwIK9lFKxIm0IoFkOEh7LMfp7FGzaP7ANrZd cIzhZi38xyOkcaFY+npGEWvko7rlIAn0JpBO4x3hfhmhBD/WSY8LQIFQNNjEm3vzrMo7b9Jb JAqQxfbURY3Dql3GUzeWTG9uaJ00u+EEPlY8zcVShDltIl5PLih20e8xgTnNzx5c110lQSu0 iZv2lAE6DM+2bJQTsMSYiwKlwTuv9LI9Chnoo6+tsN55NqyMxYqJgElk3VzlTXSr3+rtSCwf tq2cinETbzxc1XuhIX6pu/aCGnNfuEkM34b7G1D6CPzDMqokNFbyoO6DQ1+fW6c5gctXg/lZ 602iEl4C4rgcr3+EpfoPUWzKeM8JXv5Kpq4YDxhvbitr8Dm8gr38+UKFZKlWLlwhQ56r/zAU v6LIsm11GmFs2/cmgD1bqBTNHHcTWwWtRTLgmnqJbVisMJuYJt4KNPqphTWsPY8SEtbufIlY HXOJ2lqUzOReTrie2u0qcSvGAbSfec9apTFl2Xko/ddqPcZMpKhBiXmY8tJzSPk3+G4tqur4 6TYAm5ouitJsgAR61Cu7s+PNuq/pTLDhK+6/Njmc94NGBcRA4qTuysEGE79vYWP2oIAU4Fv6 gqaWHZ4MEI2XTqH8wiwzPdCQPYsSE0fXWiYu7ObeErT6iLSTZGx4rQARAQABwsFfBBgBCAAJ BQJbm6Q+AhsMAAoJEONU5rjiOLn4DDEP/RuyckW65SZcPG4cMfNgWxZF8rVjeVl/9PBfy01K 8R0hajU40bWtXSMiby7j0/dMjz99jN6L+AJHJvrLz4qYRzn2Ys843W+RfXj62Zde4YNBE5SL jJweRCbMWKaJLj6499fctxTyeb9+AMLQS4yRSwHuAZLmAb5AyCW1gBcTWZb8ON5BmWnRqeGm IgC1EvCnHy++aBnHTn0m+zV89BhTLTUal35tcjUFwluBY39R2ux/HNlBO1GY3Z+WYXhBvq7q katThLjaQSmnOrMhzqYmdShP1leFTVbzXUUIYv/GbynO/YrL2gaQpaP1bEUEi8lUAfXJbEWG dnHFkciryi092E8/9j89DJg4mmZqOau7TtUxjRMlBcIliXkzSLUk+QvD4LK1kWievJse4mte FBdkWHfP4BH/+8DxapRcG1UAheSnSRQ5LiO50annOB7oXF+vgKIaie2TBfZxQNGAs3RQ+bga DchCqFm5adiSP5+OT4NjkKUeGpBe/aRyQSle/RropTgCi85pje/juYEn2P9UAgkfBJrOHvQ9 Z+2Sva8FRd61NJLkCJ4LFumRn9wQlX2icFbi8UDV3do0hXJRRYTWCxrHscMhkrFWLhYiPF4i phX7UNdOWBQ90qpHyAxHmDazdo27gEjfvsgYMdveKknEOTEb5phwxWgg7BcIDoJf9UMC In-Reply-To: <20250522-rm-bsca-v3-2-51d169738fcf@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=AOOMbaiN c=1 sm=1 tr=0 ts=68344418 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=dt9VzEwgFbYA:10 a=VnNF1IyMAAAA:8 a=Nht_sg-W_4d_RaGhDA8A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: 7OfBPDgFMme-oQ1W_vOD5PVhYIbrckU4 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNTI2MDA4OSBTYWx0ZWRfXwOUVdFRdTFwm haewGcf/C2cnQQL4uDqa0y3F277AAlcbx5ieBbsjz7gxLDiQd7baoCip64O5h7A/IEhpSZy0Hsr Iz7SXQaShfB0Bg8s0YQvuEjkBYMzmBKI0BIwnUcB758fUH22f8ZTlXhFeZCB/jQRBw1rI50vo69 0rX5T+Aue6zb6wDPq1nr3UcQX+v040p6pmgM5uobQ2H2fFUmRoABtTz4nkivWkr1rT7DUyEfPC2 /dG+rwz1kCUlnoZWpQ20ibIHZZ3HykXoJ4xBrnUH4Q/vbtO1417BC/ZTPN1fOJw+0ddxsbDsbFe V30uTVLupanL4C03HjfOUZoFrJTPWx+oLILlGiX7WSIegj3djXDUulzSVQA2N4wrg6w5UdOgvm9 EQALPnzEV63MKWPOE+UKWNQaewkrHv2o/hINyp1jXrkU23tbN8FoXWPvg5XVSxbpRX5FXFDr X-Proofpoint-GUID: 7OfBPDgFMme-oQ1W_vOD5PVhYIbrckU4 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-05-26_05,2025-05-22_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 priorityscore=1501 adultscore=0 bulkscore=0 mlxscore=0 spamscore=0 impostorscore=0 mlxlogscore=999 malwarescore=0 lowpriorityscore=0 phishscore=0 clxscore=1011 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505160000 definitions=main-2505260089 On 5/22/25 11:31 AM, Christoph Schlameuss wrote: > Instead of allocating a BSCA and upgrading it for PV or when adding the > 65th cpu we can always use the ESCA. > > The only downside of the change is that we will always allocate 4 pages > for a 248 cpu ESCA instead of a single page for the BSCA per VM. > In return we can delete a bunch of checks and special handling depending > on the SCA type as well as the whole BSCA to ESCA conversion. > > As a fallback we can still run without SCA entries when the SIGP > interpretation facility or ESCA are not available. > > Signed-off-by: Christoph Schlameuss > --- > arch/s390/include/asm/kvm_host.h | 1 - > arch/s390/kvm/interrupt.c | 71 +++++------------ > arch/s390/kvm/kvm-s390.c | 161 ++++++--------------------------------- > arch/s390/kvm/kvm-s390.h | 4 +- > 4 files changed, 45 insertions(+), 192 deletions(-) > > diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h > index f51bac835260f562eaf4bbfd373a24bfdbc43834..d03e354a63d9c931522c1a1607eba8685c24527f 100644 > --- a/arch/s390/include/asm/kvm_host.h > +++ b/arch/s390/include/asm/kvm_host.h > @@ -631,7 +631,6 @@ struct kvm_s390_pv { > [...] > int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) > { > - gfp_t alloc_flags = GFP_KERNEL_ACCOUNT; > - int i, rc; > + gfp_t alloc_flags = GFP_KERNEL_ACCOUNT | __GFP_ZERO; > char debug_name[16]; > - static unsigned long sca_offset; > + int i, rc; > > rc = -EINVAL; > #ifdef CONFIG_KVM_S390_UCONTROL > @@ -3358,17 +3341,12 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) > if (!sclp.has_64bscao) > alloc_flags |= GFP_DMA; > rwlock_init(&kvm->arch.sca_lock); > - /* start with basic SCA */ > - kvm->arch.sca = (struct bsca_block *) get_zeroed_page(alloc_flags); > - if (!kvm->arch.sca) > - goto out_err; > mutex_lock(&kvm_lock); > - sca_offset += 16; > - if (sca_offset + sizeof(struct bsca_block) > PAGE_SIZE) > - sca_offset = 0; > - kvm->arch.sca = (struct bsca_block *) > - ((char *) kvm->arch.sca + sca_offset); > + > + kvm->arch.sca = alloc_pages_exact(sizeof(*kvm->arch.sca), alloc_flags); kvm->arch.sca is (void *) at the point of this patch, which makes this a very bad idea. Granted, you fix that up in the next patch but this is still wrong. Any reason why you have patch #3 at all? We could just squash it and avoid this problem? > mutex_unlock(&kvm_lock); > + if (!kvm->arch.sca) > + goto out_err; > > sprintf(debug_name, "kvm-%u", current->pid); > [...] > /* needs disabled preemption to protect from TOD sync and vcpu_load/put */ > @@ -3919,7 +3808,7 @@ static int kvm_s390_vcpu_setup(struct kvm_vcpu *vcpu) > vcpu->arch.sie_block->eca |= ECA_IB; > if (sclp.has_siif) > vcpu->arch.sie_block->eca |= ECA_SII; > - if (sclp.has_sigpif) > + if (kvm_s390_use_sca_entries()) > vcpu->arch.sie_block->eca |= ECA_SIGPI; > if (test_kvm_facility(vcpu->kvm, 129)) { > vcpu->arch.sie_block->eca |= ECA_VX; > diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h > index 8d3bbb2dd8d27802bbde2a7bd1378033ad614b8e..2c8e177e4af8f2dab07fd42a904cefdea80f6855 100644 > --- a/arch/s390/kvm/kvm-s390.h > +++ b/arch/s390/kvm/kvm-s390.h > @@ -531,7 +531,7 @@ int kvm_s390_handle_per_event(struct kvm_vcpu *vcpu); > /* support for Basic/Extended SCA handling */ > static inline union ipte_control *kvm_s390_get_ipte_control(struct kvm *kvm) > { > - struct bsca_block *sca = kvm->arch.sca; /* SCA version doesn't matter */ > + struct esca_block *sca = kvm->arch.sca; /* SCA version doesn't matter */ Remove the comment as well please > > return &sca->ipte_control; > } > @@ -542,7 +542,7 @@ static inline int kvm_s390_use_sca_entries(void) > * might use the entries. By not setting the entries and keeping them > * invalid, hardware will not access them but intercept. > */ > - return sclp.has_sigpif; > + return sclp.has_sigpif && sclp.has_esca; > } > void kvm_s390_reinject_machine_check(struct kvm_vcpu *vcpu, > struct mcck_volatile_info *mcck_info); >