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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-Proofpoint-ORIG-GUID: xI7UUMHWEUIGPCBirjqTeV813jRKW4xy X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTI0MDAzNiBTYWx0ZWRfX38C+FGOPUprG +ReWIkZpSEpn5RF818sfGUvBXb2NqZQ0vcfuf4tKfVUIGqCfxBwicOHfIw1bc4XLVZvJIEDGJD/ vE8e8IEEDWSO6GOIZzSIE5COjD62zgylEr+RP9rN3WoggNYKpnvKU/VeGCiX5ghqkMvcWrcdO6F 4NyXsmFIBiULdaZswmwN1LDJ6en9oBKR0jR3E+C1FCBQ3M5RZT8sB1m3EtWGjoh4MBeEJtgyb5s e3UM/QJQgcLedbGCpaZ8j78AlEv+4WrRdZoVrvsg1++2EUmbl7+XQHbaii7n8h/BqqVezNWsTRw 4ukbTCMr0/ITOtque7kW3ZTAExYS4qdLRX181oiJ7LLqj12TPM0Hd2nHZ0XuDAHfoiEW4LBB4pW KO+ZbD3SAzlE9d4JJ+OCfK0RZMpJdexQtaslQP0TCOHV2JacyrhceszNUfT8gRFM31oP6q4RXpH xyUJLZVQjA7O4BdSIXg== X-Authority-Analysis: v=2.4 cv=O/KsLx9W c=1 sm=1 tr=0 ts=6ab4e644 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=1XWaLZrsAAAA:8 a=VnNF1IyMAAAA:8 a=cw4uO_N-L75IYahiFhcA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI0MDAzNiBTYWx0ZWRfX1vvCZ7XCdFNA 1wfS7qPhSCnQGE8JpDb0UYPnOo0Wy16/wBadVafNYHw4iduPnR0cM354JIb7GipneYZiwK3tmP/ QStVK2mb8Q62ccCY1czNNKu4+MPZyUg= X-Proofpoint-GUID: 07eN4urjFPJge3Kc4XbpdxsHMAteikMn 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=2026-09-24_02,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 malwarescore=0 phishscore=0 impostorscore=0 suspectscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609240036 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 e840ceda9f16..943b108f01cd 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