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Mon, 3 Aug 2026 12:40:44 +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 v8 08/13] KVM: s390: cmma: Fix dirty tracking when removing memslot Date: Mon, 3 Aug 2026 14:40:35 +0200 Message-ID: <20260803124040.126471-9-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260803124040.126471-1-imbrenda@linux.ibm.com> References: <20260803124040.126471-1-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwODAzMDExMCBTYWx0ZWRfXw7nuvcnhzlBT Ru7kvJys6Ppg+3m2tmFwkX0L4bws0cD8qiipPI5RoyYgptvXoyOrnHzio61gh4zOnkXBIr0+AOV VBFKbbzN81GNC8F5ZoUylymtS5mu8bw= X-Authority-Analysis: v=2.4 cv=I7VVgtgg c=1 sm=1 tr=0 ts=6a708c54 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=xy2Bf3EjJieBI87QFfgA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODAzMDExMCBTYWx0ZWRfX4yxJWxwX/Fr8 mF3aHlxXEy4M3vaOYhif0jv9gLCMnAZ4e/taRuEYh+DoDbvnzkG6N/YosJjup+w0diSgDOSlQFX W6HsK+CVFwZ8TvPWhNOw284RBiflDLCTJX4Jm0Q/6z3Wz96BlNPKMKNsV89jMG8Xn7uVe+KGlTB HVVMxt8aw5WfhuvovGxplv4WAQ5k7pcnb+2pKqArfNg1BfKFw78Gp2cZBVboxaaeNmuv5J6Wi76 8Z5clP2e4SP/kdtD65chQSCCo7/ud1fvgYJi7AewHDuMKx+Hlv6NJEaaWKmrZfOcA7ao5jQJBhj be7x8K7GTMXcL+lMWF3gZL+ZRMUjC65idyFagEa/nQnQP8fC60avu+2DRTEZA5FjjitzozU4X/m Ix2pMOw4tjvNONRvvZRh7qNP3QGpM41Iu0iaIey8hSYyBcqaxm6wGdfSE3JU9KaIoQdbgvumlFv U99szTeF+PD1NSV9s6A== X-Proofpoint-ORIG-GUID: SF5tn60_wXxhyXOY8usyIfi-1YxNw77t X-Proofpoint-GUID: SF5tn60_wXxhyXOY8usyIfi-1YxNw77t X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-03_03,2026-07-30_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 impostorscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 malwarescore=0 adultscore=0 lowpriorityscore=0 phishscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608030110 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 e5c5e9f61cb2..ba811f0673d1 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -5812,14 +5812,30 @@ 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; @@ -5830,6 +5846,12 @@ 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); @@ -5851,7 +5873,6 @@ 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