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Peter Anvin" , Matthew Rosato , Farhan Ali , Eric Farman , Tony Krowiak , Halil Pasic , Jason Herne , Harald Freudenberger , Holger Dengler , Alex Williamson Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Steffen Eiden X-Mailer: b4 0.14.3 X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=FYWiV5+6 c=1 sm=1 tr=0 ts=6aba6688 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=1XWaLZrsAAAA:8 a=VnNF1IyMAAAA:8 a=q3OYOvv_GcRzabu4IdsA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI4MDA1MiBTYWx0ZWRfXy3LeECcVSdxw pzj7331NAkz+lJkQTCOU3CIxCCrLMJ1HqXd7qDRaKGNWMLSoYZlX3IKfXRbbH+amvprR6A0YZ4Y FFwLlnFzuG4JpMXbiKWsMm3SZX+YOkY= X-Proofpoint-ORIG-GUID: rzk93jYv8F0L9X5JccCoOU6j0O9cXNzJ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTI4MDA1MiBTYWx0ZWRfX0TSy/28ufPmY JrA8s3cJZDRmiAhfQ+XAE/3er9IfwCry1K6dIK3A/gwZi4OwrSuU66U+z33MtTNrv0JtxorAdzX LGUYOwYmOctKpFZFjlhZ9mln/OCvZBEdGvC0MBObt00AtrPtS7WGwRrYWHART/NWTW0uHev/3GD oR5LC/mKsXFxVEzi3sa95g9Geh75ZLNfDezs2bY+w8HHDbkwFjSHcKADOnoOtrYVxWmJ7At+bAx pNNWC99In6pSu7v9NUMKdZ2Wr2TxX3T2uN19n0AQZeovvr6GlE7DIOv/J2D47DpoCXz+MAenMvg 8KKXiixLrgqMPRbZoTnGJ7xpI0W3EX6YP3Ccd7/jTpCMpA2IvuJYMJZwXwdUr5AxRKjSuSm552Z JOEkBJCTyfqUj6r29RfvpZ3EExeJi55OZ8MS+QMTEIhkOZD/9RkUFU8Bx7dQy9M/JD5cld+wVJe f2a6tKhSBPMgt7iNTog== X-Proofpoint-GUID: bF9R-Xfu-IVk8sNKhiOdUuomudFDc8K- 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=2026-09-28_03,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 clxscore=1015 impostorscore=0 spamscore=0 phishscore=0 priorityscore=1501 malwarescore=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609280052 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 bc3abfde8393..3c5a389361c6 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 07fc874a38e1..8e49ea809528 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; } @@ -5555,6 +5557,8 @@ 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