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Fri, 18 Sep 2026 13:31:08 +0000 (GMT) Received: from tuxmaker.lnxne.boe (unknown [9.87.85.9]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 18 Sep 2026 13:31:08 +0000 (GMT) From: Steffen Eiden To: kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Cc: Alexander Gordeev , Andreas Grapentin , Arnd Bergmann , Catalin Marinas , Christian Borntraeger , Claudio Imbrenda , David Hildenbrand , Friedrich Welter , Fuad Tabba , Gautam Gala , Hariharan Mari , Heiko Carstens , Hendrik Brueckner , Ilya Leoshkevich , Janosch Frank , Joey Gouly , Marc Zyngier , Nico Boehr , Nina Schoetterl-Glausch , Oliver Upton , Paolo Bonzini , Suzuki K Poulose , Sven Schnelle , Ulrich Weigand , Vasily Gorbik , Will Deacon , Zenghui Yu Subject: [PATCH v8 02/29] KVM: Add file back-pointer to struct kvm Date: Fri, 18 Sep 2026 15:30:39 +0200 Message-ID: <20260918133107.1042730-3-seiden@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260918133107.1042730-1-seiden@linux.ibm.com> References: <20260918133107.1042730-1-seiden@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE4MDE4NCBTYWx0ZWRfX9xIhu1g9ugrX rH4DjmJFGl8+lyQPTbtptshAtETCkgumxcoebAzSqdVptl4BKNfxgmwR5CWWeHNj7t4X+XFS8H8 OoJ6tytuZd6znqTlmLnzkuow6Wvvvt7QOF3rDLpsGX9J9g+3p4Xomo8WC3nb8PUWtTi/mTaIYWJ h/LiiGRKzWIL/Z/rthHqr+/ZaXTt4zwM5qjoFvMS86ULz/cj7OZ7+tWCC+WY0V99GxVa9a+9KeH AWeh38cbWwX/lJj3E1pBPLHTuDZvVuwmZ80jHiEmW3zcOfp8VpIwkmOWAaCUjhtcVZV7IFU5I0l Of8O38piHZDqih2GmuoXZt1zG78Xl+UlH46BuLtjTDr6xLsRUc/RjbGTfmolG4xa0Y2Z55hqCvr 00WibjrLsXQ/zdx3KxpQlpxxJyYxEw6L3GLKzhQisz7pKVLlLNikNfYme9U2e1hIIMppWnVYD6V FwyDd/RYi2DSNNZgTPg== X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE4MDE4NCBTYWx0ZWRfX6I+kRjZoQGyD vpYKSCuMscvu/Vxtyd30LkMGo8FBLEAp5tGdrIUeTJhqCCdShCZc9ERtbIZc2O96UMP7Bak0sR6 /JYJ/q3d4yvfGTiBlulpDZ8UMOewdvI= X-Authority-Analysis: v=2.4 cv=Zsx4uN7G c=1 sm=1 tr=0 ts=6aad3d29 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=1XWaLZrsAAAA:8 a=VnNF1IyMAAAA:8 a=q3OYOvv_GcRzabu4IdsA:9 X-Proofpoint-ORIG-GUID: hhakXsoQk_t-0CLSijhO_PAbfQM46rA6 X-Proofpoint-GUID: tNskIW43qKDl8CnCnNcc1c165n-p9K5N 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=2026-09-18_03,2026-09-16_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 impostorscore=0 clxscore=1015 priorityscore=1501 lowpriorityscore=0 bulkscore=0 adultscore=0 phishscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609180184 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260918_143135_976559_48C0336E X-CRM114-Status: GOOD ( 17.18 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Add kvm->file as a no-reference back-pointer to the VM file in struct kvm. The pointer is set at VM creation time and cleared under WRITE_ONCE() in kvm_vm_release() before the file is freed. Callers storing the file must take their own reference. Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson Signed-off-by: Steffen Eiden --- include/linux/kvm_host.h | 6 ++++++ virt/kvm/kvm_main.c | 4 ++++ 2 files changed, 10 insertions(+) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index a1bf6d4a8f46..2b56fb4e8555 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -784,6 +784,12 @@ struct kvm { * kvm_swap_active_memslots(). */ struct mutex slots_arch_lock; + /* + * Back-reference to the VM file for subsystems (e.g., VFIO). Holds no + * reference to avoid pinning the VM. Callers storing the file must + * take their own reference. + */ + struct file *file; struct mm_struct *mm; /* userspace tied to this vm */ unsigned long nr_memslot_pages; /* The two memslot sets - active and inactive (per address space) */ diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 0172ca94f82e..bab71d398236 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1352,6 +1352,8 @@ static int kvm_vm_release(struct inode *inode, struct file *filp) kvm_irqfd_release(kvm); + WRITE_ONCE(kvm->file, NULL); + kvm_put_kvm(kvm); return 0; } @@ -5532,6 +5534,8 @@ static int kvm_dev_ioctl_create_vm(unsigned long type) goto put_kvm; } + kvm->file = file; + /* * Don't call kvm_put_kvm anymore at this point; file->f_op is * already set, with ->release() being kvm_vm_release(). In error -- 2.53.0