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Thu, 30 Jul 2026 16:27:16 +0000 (GMT) Received: from p-imbrenda.ehn-de.ibm.com (unknown [9.224.75.30]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 30 Jul 2026 16:27:15 +0000 (GMT) From: Claudio Imbrenda To: linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, david@kernel.org, seiden@linux.ibm.com, nrb@linux.ibm.com, schlameuss@linux.ibm.com, gra@linux.ibm.com Subject: [PATCH v6 07/14] KVM: s390: cmma: Fix dirty tracking when removing memslot Date: Thu, 30 Jul 2026 18:27:07 +0200 Message-ID: <20260730162714.133327-8-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730162714.133327-1-imbrenda@linux.ibm.com> References: <20260730162714.133327-1-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: iAUeSiv_1RnVWGnc3IA7UdOTTo6lULTx X-Proofpoint-ORIG-GUID: iAUeSiv_1RnVWGnc3IA7UdOTTo6lULTx X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMwMDEyMyBTYWx0ZWRfX7U/LG4wAzCG3 iBGJYGgK7a9SfUfpJJCTJXCbe6l8zk6wIRcv0z0pOczmU/5YjvA9mScW0UKyQ0VpXh9X08Ahew2 UoL7kxpyxGt0rlR1pVwXf5Xmt6y9NaYiuO8mAIkbejKgA5qXooor/uPCpbex26U/8rV+v6pOEW2 4KmlABnrF2vWjgiur8pwrvP49HANarPfg3a50X+wwC6TgtXvkZR+mvWFhc0lts2Qi+dEapb8M3a tTezoMY7FEkPjTU3wvEMVYC2Cx9JyIhDpxgV+Hz+lVHEM+Lh4oD82g3f2IPpRiGVJIXsLdxxjQx 1ME6NG2RPOpAo9fwr5T1rF5hFOp3VGzjLg9OuHqkOk37MoHAZ/kD4vmHV5KO5IFAJoYaOWBABuN M+KQmMXqw2dEKQWiafE3meox141pnWcpxrhIJRQHBkheOzXgFGcuSL5K90GgKgyJofSttvKC0KO pfvYm0TNHehw57ayEVA== X-Authority-Analysis: v=2.4 cv=SKFykuvH c=1 sm=1 tr=0 ts=6a6b7b6a cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=xy2Bf3EjJieBI87QFfgA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzMwMDEyMyBTYWx0ZWRfX29bk0947YNEj jL/VOHDt5I38pxFqCHt2/5EILqnpBTlsLHv396GEJ7nyAyYLbn/aeiUcq0uPyPFZIa6bdAcakra aEk4AlhZTmSHO6pBK+Wp55vO5antWy4= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-30_04,2026-07-30_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 clxscore=1015 adultscore=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 phishscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607300123 When a memslot is removed, all ptes that mapped the slot are cleared or even deallocated. If this happens while the system is in migration mode, and if cmma-dirty pages are removed, the cmma-dirty counter will not reflect reality. Fix by appropriately decrementing the cmma-dirty counter when removing a memslot. Opportunistically improve kvm_arch_commit_memory_region() to use __free() for the struct kvm_s390_mmu_cache. Fixes: e38c884df921 ("KVM: s390: Switch to new gmap") Signed-off-by: Claudio Imbrenda --- arch/s390/kvm/dat.c | 7 ++++++- arch/s390/kvm/kvm-s390.c | 25 +++++++++++++++++++++++-- 2 files changed, 29 insertions(+), 3 deletions(-) diff --git a/arch/s390/kvm/dat.c b/arch/s390/kvm/dat.c index 171b61959908..3f2d6e8902d7 100644 --- a/arch/s390/kvm/dat.c +++ b/arch/s390/kvm/dat.c @@ -850,6 +850,7 @@ static long _dat_slot_pte(union pte *ptep, gfn_t gfn, gfn_t next, struct dat_wal struct slot_priv *p = walk->priv; union crste dummy = { .val = p->token }; union pte new_pte, pte = READ_ONCE(*ptep); + union pgste pgste; new_pte = _PTE_TOK(dummy.tok.type, dummy.tok.par); @@ -857,7 +858,11 @@ static long _dat_slot_pte(union pte *ptep, gfn_t gfn, gfn_t next, struct dat_wal if (pte.val == new_pte.val) return 0; - dat_ptep_xchg(ptep, new_pte, gfn, walk->asce, false); + pgste = pgste_get_lock(ptep); + pgste = __dat_ptep_xchg(ptep, pgste, new_pte, gfn, walk->asce, false); + pgste.cmma_d = 0; + pgste_set_unlock(ptep, pgste); + return 0; } diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 24c3bfcd5db2..c1984fe2f9a4 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -5809,14 +5809,30 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, return 0; } +static long cmma_d_count_pte(union pte *ptep, gfn_t gfn, gfn_t next, struct dat_walk *walk) +{ + union pgste pgste; + + pgste = pgste_get_lock(ptep); + if (pgste.cmma_d) { + pgste.cmma_d = 0; + atomic64_dec(walk->priv); + } + pgste_set_unlock(ptep, pgste); + return 0; +} + void kvm_arch_commit_memory_region(struct kvm *kvm, struct kvm_memory_slot *old, const struct kvm_memory_slot *new, enum kvm_mr_change change) { - struct kvm_s390_mmu_cache *mc = NULL; + const struct dat_walk_ops ops = { .pte_entry = cmma_d_count_pte, }; + struct kvm_s390_mmu_cache *mc __free(kvm_s390_mmu_cache) = NULL; int rc = 0; + guard(mutex)(&kvm->slots_arch_lock); + if (change == KVM_MR_FLAGS_ONLY) return; @@ -5827,6 +5843,12 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, } scoped_guard(write_lock, &kvm->mmu_lock) { + if (kvm->arch.migration_mode && kvm->arch.use_cmma && old) { + _dat_walk_gfn_range(old->base_gfn, old->base_gfn + old->npages, + kvm->arch.gmap->asce, &ops, DAT_WALK_IGN_HOLES, + &kvm->arch.cmma_dirty_pages); + } + switch (change) { case KVM_MR_DELETE: rc = dat_delete_slot(mc, kvm->arch.gmap->asce, old->base_gfn, old->npages); @@ -5848,7 +5870,6 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, out: if (rc) pr_warn("failed to commit memory region\n"); - kvm_s390_free_mmu_cache(mc); return; } -- 2.55.0