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Thu, 11 Sep 2025 12:57:41 +0000 (GMT) Message-ID: <91f044a5-803f-4672-960b-cd83f725af44@linux.ibm.com> Date: Thu, 11 Sep 2025 14:57:40 +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 v2 09/20] KVM: s390: KVM page table management functions: clear and replace To: Claudio Imbrenda , kvm@vger.kernel.org Cc: linux-s390@vger.kernel.org, borntraeger@de.ibm.com, nsg@linux.ibm.com, nrb@linux.ibm.com, seiden@linux.ibm.com, schlameuss@linux.ibm.com, hca@linux.ibm.com, svens@linux.ibm.com, agordeev@linux.ibm.com, david@redhat.com, gerald.schaefer@linux.ibm.com References: <20250910180746.125776-1-imbrenda@linux.ibm.com> <20250910180746.125776-10-imbrenda@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: <20250910180746.125776-10-imbrenda@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: wvykhuyix2L0-v8ERm8djJRGNnrwabD8 X-Authority-Analysis: v=2.4 cv=Mp1S63ae c=1 sm=1 tr=0 ts=68c2c74a cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=yJojWOMRYYMA:10 a=VnNF1IyMAAAA:8 a=oLOAamk-4IdpVz_s3UIA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: wvykhuyix2L0-v8ERm8djJRGNnrwabD8 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwOTA2MDAwMCBTYWx0ZWRfX964qGeKG6dC1 Wo+aEYE/lZT76zg+kUjJqSbv+jF0VoEVIPatkicB5poIUFB/DIeuGzxMMMLDtF5geHn5Iu8c16J PFcm9c8rwZ7seVTF14Xd8ZVwecIMVRrpyBLG7xHAhGL8OTlYaeqPE8/rkflkIJOQMPCrmhUFJbt XskHK0ieQB4YvrfcesbNj79dHeXRWUo3f7vLKkivS2pCoTXxW/94WSBfiw5/EPoQIDX++AxwljU 6/yg6nguz3oEfeeWZv8Fo5Kg833yBaP4d82YGz4rTlCeLsBFqtKuafcBqVyROzjZb3sFwOCbIWy wWePKA0p/h9v/UNURIkJ5206/fAWP8JiC89D/iKLV/XiO1gQzvlAcmYfCWd10HMJlGm/+vxOGXa Kpc32EHN X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1117,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-09-10_04,2025-09-11_02,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 malwarescore=0 clxscore=1015 phishscore=0 spamscore=0 adultscore=0 priorityscore=1501 bulkscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2509060000 On 9/10/25 8:07 PM, Claudio Imbrenda wrote: > Add page table management functions to be used for KVM guest (gmap) > page tables. > > This patch adds functions to clear, replace or exchange DAT table > entries. > > Signed-off-by: Claudio Imbrenda > --- > arch/s390/kvm/dat.c | 120 ++++++++++++++++++++++++++++++++++++++++++++ > arch/s390/kvm/dat.h | 40 +++++++++++++++ > 2 files changed, 160 insertions(+) > > diff --git a/arch/s390/kvm/dat.c b/arch/s390/kvm/dat.c > index 326be78adcda..f26e3579bd77 100644 > --- a/arch/s390/kvm/dat.c > +++ b/arch/s390/kvm/dat.c > @@ -89,3 +89,123 @@ void dat_free_level(struct crst_table *table, bool owns_ptes) > } > dat_free_crst(table); > } > + > +/** > + * dat_crstep_xchg - exchange a guest CRST with another > + * @crstep: pointer to the CRST entry > + * @new: replacement entry > + * @gfn: the affected guest address > + * @asce: the ASCE of the address space > + * > + * This function is assumed to be called with the guest_table_lock > + * held. > + */ > +void dat_crstep_xchg(union crste *crstep, union crste new, gfn_t gfn, union asce asce) > +{ > + if (crstep->h.i) { > + WRITE_ONCE(*crstep, new); > + return; > + } else if (cpu_has_edat2()) { > + crdte_crste(crstep, *crstep, new, gfn, asce); > + return; > + } > + > + if (machine_has_tlb_guest()) > + idte_crste(crstep, gfn, IDTE_GUEST_ASCE, asce, IDTE_GLOBAL); > + else if (cpu_has_idte()) > + idte_crste(crstep, gfn, 0, NULL_ASCE, IDTE_GLOBAL); > + else > + csp_invalidate_crste(crstep); I'm wondering if we can make stfle 3 (DTE) a requirement for KVM or Linux as a whole since it was introduced with z990 AFAIK. > + WRITE_ONCE(*crstep, new); > +} > + > +/** > + * dat_crstep_xchg_atomic - exchange a gmap pmd with another > + * @crstep: pointer to the crste entry > + * @old: expected old value > + * @new: replacement entry > + * @gfn: the affected guest address > + * @asce: the asce of the address space > + * > + * This function should only be called on invalid crstes, or on crstes with > + * FC = 1, as that guarantees the presence of CSPG. > + * > + * Return: true if the exchange was successful. > + */ > +bool dat_crstep_xchg_atomic(union crste *crstep, union crste old, union crste new, gfn_t gfn, > + union asce asce) > +{ > + if (old.h.i) > + return arch_try_cmpxchg((long *)crstep, &old.val, new.val); > + if (cpu_has_edat2()) > + return crdte_crste(crstep, old, new, gfn, asce); > + if (cpu_has_idte()) > + return cspg_crste(crstep, old, new); > + > + WARN_ONCE(1, "Machine does not have CSPG and DAT table was not invalid."); > + return false; > +}