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Peter Anvin" , Matthew Rosato , Farhan Ali , Tony Krowiak , Halil Pasic , Jason Herne , Harald Freudenberger , Holger Dengler , Alex Williamson , linux-kernel@vger.kernel.org, Steffen Eiden , Jason Gunthorpe Subject: [GIT PULL 2/6] KVM: Add file back-pointer to struct kvm Date: Fri, 9 Oct 2026 16:27:45 +0200 Message-ID: <20261009142749.186650-3-borntraeger@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261009142749.186650-1-borntraeger@linux.ibm.com> References: <20261009142749.186650-1-borntraeger@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: BypTR1YmscKcVHq_3kUghd3kgUEfqrJ6 X-Proofpoint-ORIG-GUID: 8cZeWaYyfxgOFIsm2dc306Top6aud3rY X-Authority-Analysis: v=2.4 cv=FoOQbGrq c=1 sm=1 tr=0 ts=6ac8f9f6 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=1XWaLZrsAAAA:8 a=iMsfdjsCwqIbG2x4yYUA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDA5MDA1NiBTYWx0ZWRfX88zLyEdnHnpK /M6rzUgsUyqlQS5eWqvwQopY1vsorwUNUbg/bOZ8SPDSq+gHHWSAr6ApeaYEIy1LyPOtrQg+0vH NTyXa6QsvPEVPNT6o/+Qm+vFBgg1Fv4= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDA5MDA1NiBTYWx0ZWRfX6u4B9iv+18sO lmGWQOtyS58iUjTP3HJDk+TYW7pSkDxcVk+HNlv6m+vpTlmKq9Bfc39QL0N6zMo/+fOkPhwX3jm Wbj5+46/B/+RgPeO+MY+VAJw56UTtOV4aPphx7wF10zBy3hurWa2bHGGksqBS01vMyliw+FuUvS 6LZAJzWw8AsjqfjhMykcS7HsnVdTI9pdZvPrejiAezIkNnGgKERY14PmyUT+lHhMD0MF9GVwwkB ID5yIVEWauiD7LO7mWW3sHMYCkORFrbWBWBHBqbMzVqAhlLs/nbkMBTRRaMIooic4pVs0dWhk6C 0gV/6+YL0eFw8i/6LOPe3zePK0lI7xYRA2+MIYlx0NeZ4h95S+kOJd/WPC9V7zdddVi8sIwK8IA Awl5NthFpqCA6fhOXF756k/EV1WBt0ZO/O1wv+3KXdVN1XT1etloEPy4TtzINXXp0XzLsIXeY2q kL10KnrimsZ4Zpacu/w== 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=2026-10-09_04,2026-10-08_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 clxscore=1015 lowpriorityscore=0 bulkscore=0 adultscore=0 priorityscore=1501 spamscore=0 phishscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610020000 definitions=main-2610090056 From: Steffen Eiden 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 Reviewed-by: Claudio Imbrenda Acked-by: Janosch Frank Acked-by: Sean Christopherson Signed-off-by: Christian Borntraeger --- 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