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Wed, 26 Feb 2025 16:58:35 +0000 (GMT) Date: Wed, 26 Feb 2025 17:58:33 +0100 From: Claudio Imbrenda To: David Hildenbrand Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, borntraeger@de.ibm.com, nrb@linux.ibm.com, seiden@linux.ibm.com, nsg@linux.ibm.com, schlameuss@linux.ibm.com, hca@linux.ibm.com Subject: Re: [PATCH v2 1/1] KVM: s390: pv: fix race when making a page secure Message-ID: <20250226175833.16a7a970@p-imbrenda> In-Reply-To: <0dfeabca-5c41-4555-a43b-341a54096036@redhat.com> References: <20250226123725.247578-1-imbrenda@linux.ibm.com> <20250226123725.247578-2-imbrenda@linux.ibm.com> <0dfeabca-5c41-4555-a43b-341a54096036@redhat.com> Organization: IBM X-Mailer: Claws Mail 4.3.0 (GTK 3.24.43; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-s390@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-ORIG-GUID: WrNXnQvLPCPgrc_P8En33TtwvtL5axnM X-Proofpoint-GUID: WrNXnQvLPCPgrc_P8En33TtwvtL5axnM X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-02-26_04,2025-02-26_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 priorityscore=1501 suspectscore=0 mlxlogscore=827 spamscore=0 phishscore=0 mlxscore=0 adultscore=0 malwarescore=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502100000 definitions=main-2502260131 On Wed, 26 Feb 2025 16:05:11 +0100 David Hildenbrand wrote: > > +int make_hva_secure(struct mm_struct *mm, unsigned long hva, struct uv_cb_header *uvcb) > > +{ > > + struct folio *folio; > > + spinlock_t *ptelock; > > + pte_t *ptep; > > + int rc; > > + > > + ptep = get_locked_valid_pte(mm, hva, &ptelock); > > + if (!ptep) > > + return -ENXIO; > > You very likely need a pte_write() check we had there before, as you > might effectively modify page content by clearing the page. it's not really needed, but it doesn't hurt either, I'll add a check