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Tue, 19 May 2026 15:01:15 +0000 (GMT) Received: from p-imbrenda.ibmuc.com (unknown [9.111.4.60]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 19 May 2026 15:01:15 +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 v3 1/5] KVM: s390: vsie: Fix memory leak when unshadowing Date: Tue, 19 May 2026 17:01:10 +0200 Message-ID: <20260519150114.264309-2-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260519150114.264309-1-imbrenda@linux.ibm.com> References: <20260519150114.264309-1-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: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Y9SVFoVvSgAUWkbTy2_YPXjM5jSY9Eqt X-Authority-Analysis: v=2.4 cv=GYMnWwXL c=1 sm=1 tr=0 ts=6a0c7b44 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=HcuRRwaqOfwKfrSmNnAA:9 X-Proofpoint-ORIG-GUID: Y9SVFoVvSgAUWkbTy2_YPXjM5jSY9Eqt X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTE5MDE0NSBTYWx0ZWRfX4U+UxjPwtVWa mVAk6XN/TouhukIEJ84ZkZKtpYD2rHSJXiy1P3e7jEKUctN5NnB6+Hi3E/CtnvLNioeR5vsoWCp 1D+I5M5OQ0sK0cHMT0EmGnac2Sw/yP2t93+0ToP+KwW37E9KqFzUfIAISUkq28KDOID5eAZ9nL5 rSq8C/ikqeHs5LzVj/0Ab1OtHFj/c7d3T9YYYuGqJoopjGqLSztqirqr+wzFnKOqHObY7fkXTW6 MaVOu317fbyFwUwlouKQn9OgppArzacRYzG9jL545I2Vk/oGbxYZGES5k7X9s9SSgpmYg9B+Vvr SSB+uk+R5ZPRrLjD9FQNWDdDdx2swGLmTPvppVXhOT27Q26guVFNuaF79s2QvVQmOY96HQ5wFzg zCd4cjAzwbcdIDWAK9V+BxRDmtqlgmQpn0KjxbksGBOCjldazzVI+yY6cg4vAdSPoedOUTgp7vv E+zxJc864WJGRty+vtg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-19_04,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 adultscore=0 suspectscore=0 spamscore=0 clxscore=1015 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605190145 Content-Type: text/plain; charset="utf-8" When performing a partial unshadowing, the rmap was being leaked. Add the missing kfree(). Fixes: a2c17f9270cc ("KVM: s390: New gmap code") Signed-off-by: Claudio Imbrenda Reviewed-by: Christoph Schlameuss Reviewed-by: Christian Borntraeger --- arch/s390/kvm/gmap.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/s390/kvm/gmap.c b/arch/s390/kvm/gmap.c index 3c26e35af0ef..fd1927761980 100644 --- a/arch/s390/kvm/gmap.c +++ b/arch/s390/kvm/gmap.c @@ -1143,8 +1143,10 @@ void _gmap_handle_vsie_unshadow_event(struct gmap *p= arent, gfn_t gfn) } scoped_guard(spinlock, &sg->host_to_rmap_lock) head =3D radix_tree_delete(&sg->host_to_rmap, gfn); - gmap_for_each_rmap_safe(rmap, rnext, head) + gmap_for_each_rmap_safe(rmap, rnext, head) { gmap_unshadow_level(sg, rmap->r_gfn, rmap->level); + kfree(rmap); + } } } =20 --=20 2.54.0 From nobody Mon May 25 01:58:15 2026 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DCA66285CAE; 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charset="utf-8" Fix a memory leak that can happen if gmap_ucas_map_one() or kvm_s390_mmu_cache_topup() return error values. Also fix a similar issue in gmap_set_limit(). Signed-off-by: Claudio Imbrenda Fixes: a2c17f9270cc ("KVM: s390: New gmap code") Reported-by: Jiaxin Fan Reviewed-by: Christian Borntraeger --- arch/s390/kvm/gmap.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/s390/kvm/gmap.c b/arch/s390/kvm/gmap.c index fd1927761980..10c98c8cc1d8 100644 --- a/arch/s390/kvm/gmap.c +++ b/arch/s390/kvm/gmap.c @@ -125,7 +125,7 @@ struct gmap *gmap_new_child(struct gmap *parent, gfn_t = limit) =20 int gmap_set_limit(struct gmap *gmap, gfn_t limit) { - struct kvm_s390_mmu_cache *mc; + struct kvm_s390_mmu_cache *mc __free(kvm_s390_mmu_cache) =3D NULL; int rc, type; =20 type =3D gmap_limit_to_type(limit); @@ -142,7 +142,6 @@ int gmap_set_limit(struct gmap *gmap, gfn_t limit) rc =3D dat_set_asce_limit(mc, &gmap->asce, type); } while (rc =3D=3D -ENOMEM); =20 - kvm_s390_free_mmu_cache(mc); return 0; } =20 @@ -822,8 +821,8 @@ int gmap_ucas_translate(struct kvm_s390_mmu_cache *mc, = struct gmap *gmap, gpa_t =20 int gmap_ucas_map(struct gmap *gmap, gfn_t p_gfn, gfn_t c_gfn, unsigned lo= ng count) { - struct kvm_s390_mmu_cache *mc; 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charset="utf-8" In some cases (i.e. under extreme memory pressure on the host), attempting to shadow memory will result in the same memory being unshadowed, causing a loop. Add a PGSTE bit to distinguish between shadowed memory and shadowed DAT tables, fix the unshadowing logic in _gmap_ptep_xchg() to prevent unnecessary unshadowing and perform better checks. Also fix the unshadowing logic in _gmap_crstep_xchg_atomic() which did not unshadow properly when the large page would become unprotected. Opportunistically add a check in gmap_protect_rmap() to make sure it won't be called with level =3D=3D TABLE_TYPE_PAGE_TABLE. Signed-off-by: Claudio Imbrenda Fixes: a2c17f9270cc ("KVM: s390: New gmap code") --- arch/s390/kvm/dat.c | 1 + arch/s390/kvm/dat.h | 3 ++- arch/s390/kvm/gaccess.c | 1 + arch/s390/kvm/gmap.c | 3 ++- arch/s390/kvm/gmap.h | 60 ++++++++++++++++++++++++++++++++++++++--- 5 files changed, 63 insertions(+), 5 deletions(-) diff --git a/arch/s390/kvm/dat.c b/arch/s390/kvm/dat.c index 7b8d70fe406d..4a41c0247ffa 100644 --- a/arch/s390/kvm/dat.c +++ b/arch/s390/kvm/dat.c @@ -267,6 +267,7 @@ static int dat_split_ste(struct kvm_s390_mmu_cache *mc,= union pmd *pmdp, gfn_t g /* No need to take locks as the page table is not installed yet. */ pgste_init.prefix_notif =3D old.s.fc1.prefix_notif; pgste_init.vsie_notif =3D old.s.fc1.vsie_notif; + pgste_init.vsie_gmem =3D old.s.fc1.vsie_notif; pgste_init.pcl =3D uses_skeys && init.h.i; dat_init_pgstes(pt, pgste_init.val); } else { diff --git a/arch/s390/kvm/dat.h b/arch/s390/kvm/dat.h index 8f8278c44879..873e13ac5a27 100644 --- a/arch/s390/kvm/dat.h +++ b/arch/s390/kvm/dat.h @@ -145,7 +145,8 @@ union pgste { unsigned long cmma_d : 1; /* Dirty flag for CMMA bits */ unsigned long prefix_notif : 1; /* Guest prefix invalidation notificatio= n */ unsigned long vsie_notif : 1; /* Referenced in a shadow table */ - unsigned long : 5; + unsigned long vsie_gmem : 1; /* Contains nested guest memory */ + unsigned long : 4; unsigned long : 8; }; struct { diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c index b07accd19618..4f8d5592c9a9 100644 --- a/arch/s390/kvm/gaccess.c +++ b/arch/s390/kvm/gaccess.c @@ -1445,6 +1445,7 @@ static int _do_shadow_pte(struct gmap *sg, gpa_t radd= r, union pte *ptep_h, union } else { pgste =3D _gmap_ptep_xchg(sg->parent, ptep_h, newpte, pgste, f->gfn, fal= se); pgste.vsie_notif =3D 1; + pgste.vsie_gmem =3D 1; } pgste_set_unlock(ptep_h, pgste); if (rc) diff --git a/arch/s390/kvm/gmap.c b/arch/s390/kvm/gmap.c index 10c98c8cc1d8..8cff0cf5ce24 100644 --- a/arch/s390/kvm/gmap.c +++ b/arch/s390/kvm/gmap.c @@ -1031,7 +1031,8 @@ int gmap_protect_rmap(struct kvm_s390_mmu_cache *mc, = struct gmap *sg, gfn_t p_gf union pte pte; int flags, rc; =20 - KVM_BUG_ON(!is_shadow(sg), sg->kvm); + if (KVM_BUG_ON(!is_shadow(sg) || level <=3D TABLE_TYPE_PAGE_TABLE, sg->kv= m)) + return -EINVAL; lockdep_assert_held(&sg->parent->children_lock); =20 flags =3D DAT_WALK_SPLIT_ALLOC | (uses_skeys(sg->parent) ? DAT_WALK_USES_= SKEYS : 0); diff --git a/arch/s390/kvm/gmap.h b/arch/s390/kvm/gmap.h index 96ee1395a592..6e51ec6066b4 100644 --- a/arch/s390/kvm/gmap.h +++ b/arch/s390/kvm/gmap.h @@ -167,6 +167,36 @@ static inline bool gmap_unmap_prefix(struct gmap *gmap= , gfn_t gfn, gfn_t end) return _gmap_unmap_prefix(gmap, gfn, end, false); } =20 +/** + * pte_needs_unshadow() -- Check if the pte operations triggers unshadowin= g. + * @oldpte: the previous value for the guest pte. + * @newpte: the new pte being set. + * @pgste: the pgste for the pte entry. + * + * If the pgste.vsie_notif bit is not set, return false: the page is not + * involved in vsie and thus should not trigger an unshadow operation. + * + * If the pgste.vsie_gmem bit is set, this pte represents shadowed guest + * memory. The access rights on g3's memory should be synchronized with g1= 's + * and g2's. Therefore unshadowing is triggered if the new and old pte + * differ in protection, or if the new pte is invalid. + * + * If the pgste.vsie_gmem bit is not set, this pte maps the g2 dat tables + * for g3. If the entry becomes writable or absent, it becomes impossible = to + * guarantee that the shadow mapping will match g2's mapping. In that case, + * trigger an unshadow event. + * + * Return: true if an unshadow event should be triggered, otherwise false. + */ +static inline bool pte_needs_unshadow(union pte oldpte, union pte newpte, = union pgste pgste) +{ + if (!pgste.vsie_notif) + return false; + if (pgste.vsie_gmem) + return (oldpte.h.p !=3D newpte.h.p) || newpte.h.i; + return !newpte.h.p || !newpte.s.pr; +} + static inline union pgste _gmap_ptep_xchg(struct gmap *gmap, union pte *pt= ep, union pte newpte, union pgste pgste, gfn_t gfn, bool needs_lock) { @@ -180,8 +210,9 @@ static inline union pgste _gmap_ptep_xchg(struct gmap *= gmap, union pte *ptep, un pgste.prefix_notif =3D 0; gmap_unmap_prefix(gmap, gfn, gfn + 1); } - if (pgste.vsie_notif && (ptep->h.p !=3D newpte.h.p || newpte.h.i)) { + if (pte_needs_unshadow(*ptep, newpte, pgste)) { pgste.vsie_notif =3D 0; + pgste.vsie_gmem =3D 0; if (needs_lock) gmap_handle_vsie_unshadow_event(gmap, gfn); else @@ -198,6 +229,30 @@ static inline union pgste gmap_ptep_xchg(struct gmap *= gmap, union pte *ptep, uni return _gmap_ptep_xchg(gmap, ptep, newpte, pgste, gfn, true); } =20 +/** + * crste_needs_unshadow() -- Check if the crste operations triggers unshad= owing. + * @oldcrste: the previous value for the crste. + * @newcrste: the new value for the crste. + * + * If the old crste did not have the vsie_notif bit set, return false: the + * page is not involved in vsie and thus should not trigger an unshadow + * operation. Conversely, if the bit is set, it can only be g3 memory, sin= ce + * dat tables are never mapped using large pages. + * + * Similar to the pgste.vsie_gmem case of pte_needs_unshadow(), if the + * protection bit is changing or the new page is invalid, trigger an + * unshadow event. Also trigger an unshadow event if the new crste does not + * have the vsie_notif bit set. + * + * Return: true if an unshadow event should be triggered, otherwise false. + */ +static inline bool crste_needs_unshadow(union crste oldcrste, union crste = newcrste) +{ + if (!oldcrste.s.fc1.vsie_notif) + return false; + return (newcrste.h.p !=3D oldcrste.h.p) || newcrste.h.i || !newcrste.s.fc= 1.vsie_notif; +} + static inline bool __must_check _gmap_crstep_xchg_atomic(struct gmap *gmap= , union crste *crstep, union crste oldcrste, union crste newcrste, gfn_t gfn, bool needs_lock) @@ -216,8 +271,7 @@ static inline bool __must_check _gmap_crstep_xchg_atomi= c(struct gmap *gmap, unio newcrste.s.fc1.prefix_notif =3D 0; gmap_unmap_prefix(gmap, gfn, gfn + align); } - if (crste_leaf(oldcrste) && oldcrste.s.fc1.vsie_notif && - (newcrste.h.p || newcrste.h.i || !newcrste.s.fc1.vsie_notif)) { + if (crste_leaf(oldcrste) && crste_needs_unshadow(oldcrste, newcrste)) { newcrste.s.fc1.vsie_notif =3D 0; if (needs_lock) gmap_handle_vsie_unshadow_event(gmap, gfn); 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Tue, 19 May 2026 15:01:18 +0000 (GMT) Received: from p-imbrenda.ibmuc.com (unknown [9.111.4.60]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 19 May 2026 15:01:18 +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 v3 4/5] KVM: s390: vsie: Fix redundant rmap entries Date: Tue, 19 May 2026 17:01:13 +0200 Message-ID: <20260519150114.264309-5-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260519150114.264309-1-imbrenda@linux.ibm.com> References: <20260519150114.264309-1-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: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: Zib5GkZ0d55qdV6sVNIRij0eIbhRFos3 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTE5MDE0NSBTYWx0ZWRfX4ZiFxDoO/WUE wlYn5MWDQVbMQ00YwJnflxBi63YWAU4gAoOWvjUdshAOTF0clfQJQbPxw3MES8YLt8c+iYcB2K3 ekifmxK7DIItUU9FjbNfvJJJ3pB4w7hWRIR6FonY9wEfInYRyQ7mt/lGN/g0fQRIwCstrL29bNK JBS5Xw7HkRTstZoCq95Z8SqkqsKHRQMw15pzig/7YP7dwA0Hsygtn4f3MaeMXYkCcD8sIg5PO3N j72j1+6FnaU9/e9WQPZc53Wb6FYiHHRe6GGKpb7Sf4i/x/1tx4w44n+eVh5xUL+iIk25UNbk9O+ rq6DSKcni8qk1X7RTHPCh3uZZ2Jyn9zHKpm6EXQZaz44ty4ac8EP3Qk4so+kmmi5nO9MMS9Kbr2 1hB1nof+rW4rADOO2mbsjxW+xW/oeg== X-Proofpoint-GUID: Zib5GkZ0d55qdV6sVNIRij0eIbhRFos3 X-Authority-Analysis: v=2.4 cv=apyCzyZV c=1 sm=1 tr=0 ts=6a0c7b46 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VnNF1IyMAAAA:8 a=7eV5o87doowNvqF6OWkA:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-19_04,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 malwarescore=0 adultscore=0 bulkscore=0 spamscore=0 phishscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605190145 Content-Type: text/plain; charset="utf-8" The address passed to the gmap rmap was not being masked. As a consequence several different (but functionally equivalent) rmap entries were being created for each shadowed table. Fix this by properly masking the address depending on the table level. Signed-off-by: Claudio Imbrenda Fixes: a2c17f9270cc ("KVM: s390: New gmap code") Reviewed-by: Christian Borntraeger --- arch/s390/kvm/gmap.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/s390/kvm/gmap.c b/arch/s390/kvm/gmap.c index 8cff0cf5ce24..957126ab991c 100644 --- a/arch/s390/kvm/gmap.c +++ b/arch/s390/kvm/gmap.c @@ -1025,6 +1025,7 @@ int gmap_insert_rmap(struct gmap *sg, gfn_t p_gfn, gf= n_t r_gfn, int level) int gmap_protect_rmap(struct kvm_s390_mmu_cache *mc, struct gmap *sg, gfn_= t p_gfn, gfn_t r_gfn, kvm_pfn_t pfn, int level, bool wr) { + unsigned long bitmask; union crste *crstep; union pgste pgste; union pte *ptep; @@ -1041,8 +1042,9 @@ int gmap_protect_rmap(struct kvm_s390_mmu_cache *mc, = struct gmap *sg, gfn_t p_gf if (rc) return rc; if (level <=3D TABLE_TYPE_REGION1) { + bitmask =3D -1UL << (8 + 11 * level); scoped_guard(spinlock, &sg->host_to_rmap_lock) - rc =3D gmap_insert_rmap(sg, p_gfn, r_gfn, level); + rc =3D gmap_insert_rmap(sg, p_gfn, r_gfn & bitmask, level); 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Tue, 19 May 2026 15:01:19 +0000 (GMT) Received: from p-imbrenda.ibmuc.com (unknown [9.111.4.60]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 19 May 2026 15:01:19 +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 v3 5/5] KVM: s390: Properly reset zero bit in PGSTE Date: Tue, 19 May 2026 17:01:14 +0200 Message-ID: <20260519150114.264309-6-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260519150114.264309-1-imbrenda@linux.ibm.com> References: <20260519150114.264309-1-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: quoted-printable X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=ffCdDUQF c=1 sm=1 tr=0 ts=6a0c7b47 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=P9Cbi09riAs7zLUs0OgA:9 X-Proofpoint-ORIG-GUID: i2IOlo9PbEkCjJiw3HyI6rtS6TboBsm1 X-Proofpoint-GUID: i2IOlo9PbEkCjJiw3HyI6rtS6TboBsm1 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTE5MDE0NSBTYWx0ZWRfX5naYB3cp8ZXA vnMRgpKmJ3O1Vp/u4iRuizLv0vPO9MduVDIuLESoRLkFgPjBJ1SLEfdJwzqVdZvUxg2NN/tgMYn o6hmCwnzC9bLX3mPb1hhxm5eOWLtqYH5ujNVI7zz5npNWk7nM4pQrU8hQnHWXgd2PLOyKeprrdB /GpFJd+oB868e833m919TygulR3lvXtyMBc12Q1Dmd9K58CNakLh62OtSQv5qZ+GkUSrf76Pvur WOW6XYlzx7n1sYLZEzBKuBvrDh1K10SN7JOni8vFtoA7L4OW64wT45vFQZxMjpEeAPw3Zgnsvos 4HUoMjaW2e7ym/aJrG3woK9OA6YIyRg3L90VyivRNMRLe9QPdxZ7qJcx0Og6EqUYMtei7+MCFc7 l8TodYEPrgE6cU693rd1h8TJWQxV1p5m0z9hpC6OQbXX3+lzHOstOHXuvMwTzMpNneG2ZkGxyzb Ntbb+YA32nL135la9YQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-19_04,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 spamscore=0 phishscore=0 suspectscore=0 adultscore=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605190145 Content-Type: text/plain; charset="utf-8" In case of memory pressure, it's possible that a guest page gets freed and then almost immediately reused by the guest. If CMMA is enabled, _essa_clear_cbrl() will discard all pages that are either unused or zero. If a discarded page is reused before _essa_clear_cbrl() is called, and the pgste.zero bit is not cleared, the page will be discarded despite not being unused. When calling _gmap_ptep_xchg(), always clear the pgste.zero bit. This prevents the page from being accidentally discarded when not unused. Signed-off-by: Claudio Imbrenda Fixes: a2c17f9270cc ("KVM: s390: New gmap code") Reviewed-by: Steffen Eiden --- arch/s390/kvm/gmap.h | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/kvm/gmap.h b/arch/s390/kvm/gmap.h index 6e51ec6066b4..742e42a31744 100644 --- a/arch/s390/kvm/gmap.h +++ b/arch/s390/kvm/gmap.h @@ -220,6 +220,7 @@ static inline union pgste _gmap_ptep_xchg(struct gmap *= gmap, union pte *ptep, un } if (!ptep->s.d && newpte.s.d && !newpte.s.s) SetPageDirty(pfn_to_page(newpte.h.pfra)); + pgste.zero =3D 0; return __dat_ptep_xchg(ptep, pgste, newpte, gfn, gmap->asce, uses_skeys(g= map)); } =20 --=20 2.54.0