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Tue, 19 May 2026 11:40:43 +0000 (GMT) Received: from p-imbrenda (unknown [9.111.4.60]) by smtpav05.fra02v.mail.ibm.com (Postfix) with SMTP; Tue, 19 May 2026 11:40:43 +0000 (GMT) Date: Tue, 19 May 2026 13:38:36 +0200 From: Claudio Imbrenda To: Christian Borntraeger Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, david@kernel.org, seiden@linux.ibm.com, nrb@linux.ibm.com, schlameuss@linux.ibm.com, gra@linux.ibm.com Subject: Re: [PATCH v2 5/5] KVM: s390: Properly reset zero bit in PGSTE Message-ID: <20260519133836.0d344247@p-imbrenda> In-Reply-To: <0f114ba1-72f6-4ffb-b179-01b8baaaec4c@de.ibm.com> References: <20260512175251.300882-1-imbrenda@linux.ibm.com> <20260512175251.300882-6-imbrenda@linux.ibm.com> <0f114ba1-72f6-4ffb-b179-01b8baaaec4c@de.ibm.com> Organization: IBM X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 56OoCYomJ7swpYka2fULvTz0x-V2nYgO X-Authority-Analysis: v=2.4 cv=GYMnWwXL c=1 sm=1 tr=0 ts=6a0c4c43 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=kj9zAlcOel0A:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=lyqXx9i4DOjL6YLBd3gA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-ORIG-GUID: 56OoCYomJ7swpYka2fULvTz0x-V2nYgO X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTE5MDExNSBTYWx0ZWRfX8OQvWwJUFlXu 2PbRZF1BRJmj497Rhq9AlIWZ+WHTduUsqKxokziMDy9JHtVVIKg3axxOeF40X1ia8NaAw8jyR8m 7rZ0sLQLhqT8el61R84kMnkeCXkb5iOX+9mry/caSW07y2lceyUrxDVcFGE9unzyNdnTxIE2FG/ Derh7tMZ7IsJBrjJ+iQ5MSl6nqa2ib/ShPu8ybbeB4wGdUm+zUyheL58h94MHws5X+7PUh4766W zKUQLk/s2AxTqcAjQkcR8bd5Mzr/6dhv8Y69Bfm8Qjhh/CwEGPeFO1SIc1aZKdidgTPusAHEVG/ BM+kFCN2za6NZ1QT3bSeWlI8CRUQnEolCTp8Th/dIQKuMMq4jyT/dDnxa2WPCFNJXC99m+vtqWJ ca4ApGT6Q6Wzq8lwM91sHfOd8axZUsdaVz6PpfHV9RZLPTxMYVFZ4CqFxcrhft/ZxqCpVyJwW4+ CaaHghfM695ZeyfDDWw== 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_03,2026-05-18_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-2605190115 On Mon, 18 May 2026 13:44:45 +0200 Christian Borntraeger wrote: > Am 12.05.26 um 19:52 schrieb Claudio Imbrenda: > > When calling _gmap_ptep_xchg(), always clear the pgste.zero bit. This > > prevents the page from being accidentally discarded when getting > > unmapped. > > Ideally have some example in the patch description, that makes review easier.> will do > > Signed-off-by: Claudio Imbrenda > > Was this broken before the rework as well? Do we need a stable backport into 6.19 > and older? no, this breakage is a product of the gmap rewrite > > > --- > > arch/s390/kvm/gmap.h | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/s390/kvm/gmap.h b/arch/s390/kvm/gmap.hcd R > > index e490f2995a26..4de9ed8d58ba 100644 > > --- a/arch/s390/kvm/gmap.h > > +++ b/arch/s390/kvm/gmap.h > > @@ -199,6 +199,7 @@ 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 = 0; > > return __dat_ptep_xchg(ptep, pgste, newpte, gfn, gmap->asce, uses_skeys(gmap)); > > } > > >