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Peter Anvin" , Matthew Rosato , Farhan Ali , Eric Farman , Tony Krowiak , Halil Pasic , Harald Freudenberger , Holger Dengler , Alex Williamson Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Jason Gunthorpe References: <20260924-vfio-v3-0-4a294307797b@linux.ibm.com> <20260924-vfio-v3-4-4a294307797b@linux.ibm.com> Content-Language: en-US From: "Jason J. Herne" In-Reply-To: <20260924-vfio-v3-4-4a294307797b@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: VuPTRVlfVh_aR3aEiGtkbeufOzj_RQPh X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTI0MDA1MiBTYWx0ZWRfXyyvwNlWlDoUG d+Q8HdEF4tZSQ1nTnu3N5mDsRmAR7oiYrb7dS6JcHqrB/IYg2W0vJZ7LDvr7bzQneTcg1mwxQva p0JFdXT5hyFMJ8BFBZ8/w+A315WlE1xk1dYf9Ht7cBxVhj7cLLbKTeUqKUCb924kNdHtcS/ZaIa dvwvYfAUYUPK17Qw5HXeW5v7fF9R+V5GkQD6M/dhErxOP/IHsDqQ6YINgw6zy9tPkA1rpkK5C8K pVsQneejI56XQmyIpKxVqT6U8hohS47GWklEs6aeuPWSyoCLxQdpEMtYtJ5twU5L8b88JojWtMY b9TYyz3i2ti5WGNFjL141CZCczVFnm7TcyYrL3RI2sxuQqpkR0Y0Y+nSW+ItgKzALXlPe+XaEv9 SJLUMA3eeKBY7aFvRCakh1Sguy6XABDMtPgCYU82wLFvLTwdIj06P4St7yuFrI1/Us0l4R88EEu 7VcT1PbLRSklYN8uNBw== X-Authority-Analysis: v=2.4 cv=O/KsLx9W c=1 sm=1 tr=0 ts=6ab51c65 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=Ikd4Dj_1AAAA:8 a=1XWaLZrsAAAA:8 a=VnNF1IyMAAAA:8 a=lFuzCTX72hcPMOq5MnUA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI0MDA1MiBTYWx0ZWRfXwHIPapv4zwhG ng3bF1CAkzA/I1Lu/OngQ3Te9USvuZiZS8nYC6esfs1WwEHVuGmm0FcMyfIlZloeZ2hMNjN72KX UAhBl6sY8OgX7rOiQJVC0FTuPcm1gm8= X-Proofpoint-GUID: 46gO1ejmXxZHVzLRdZbUxADVJ2T8xNmk 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_03,2026-09-21_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-2609240052 On 9/24/26 4:58 AM, Steffen Eiden wrote: > Replace manual module reference counting with file-based reference > counting for KVM integration. Previously, VFIO used symbol_get() to > obtain function pointers for kvm_get_kvm_safe() and kvm_put_kvm(), > then manually tracked module references through these symbols. This > approach required storing the put_kvm function pointer in each device > and carefully managing symbol references. > > Pass struct file pointers instead of struct kvm pointers throughout the > VFIO-KVM interface, leveraging the kernel's existing file reference > counting via get_file()/get_file_active() and fput(). Convert the x86 > page-track API and update s390 vfio to use file_to_kvm_(). This > simplifies the code and removes all remaining externally exported > symbols for KVM which would appear twice for when a second concurrent > KVM module is introduced. > > Suggested-by: Jason Gunthorpe > Co-developed-by: Sean Christopherson > Signed-off-by: Sean Christopherson > Signed-off-by: Steffen Eiden > --- > arch/s390/include/asm/kvm_host_s390.h | 2 +- > arch/s390/kvm/s390/pci.c | 9 ++++-- > arch/x86/include/asm/kvm_page_track.h | 8 ++--- > arch/x86/kvm/mmu/page_track.c | 22 +++++++++----- > drivers/s390/crypto/vfio_ap_ops.c | 20 ++++++++---- > drivers/vfio/group.c | 11 ++++++- > drivers/vfio/vfio.h | 12 ++++---- > drivers/vfio/vfio_main.c | 57 +++++++++++------------------------ > include/linux/vfio.h | 5 ++- > virt/kvm/vfio.c | 13 +++++--- > 10 files changed, 85 insertions(+), 74 deletions(-) > ... > diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c > index 940c0ff668be..556e643244f2 100644 > --- a/drivers/s390/crypto/vfio_ap_ops.c > +++ b/drivers/s390/crypto/vfio_ap_ops.c > @@ -1822,17 +1822,27 @@ static const struct attribute_group *vfio_ap_mdev_attr_groups[] = { > > /** > * vfio_ap_mdev_set_kvm - sets all data for @matrix_mdev that are needed > - * to manage AP resources for the guest whose state is represented by @kvm > + * to manage AP resources for the guest whose state is represented by > + * @kvm_file > * > * @matrix_mdev: a mediated matrix device > - * @kvm: reference to KVM instance > + * @kvm_file: the KVM VM file this vfio device is associated with > * > - * Return: 0 if no other mediated matrix device has a reference to @kvm; > + * Return: 0 if no other mediated matrix device has a reference to the VM; > * otherwise, returns an -EPERM. > */ > static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev, > - struct kvm *kvm) > + struct file *kvm_file) > { > + struct kvm *kvm; > + > + if (!kvm_file) > + return -ENOENT; > + > + kvm = file_to_kvm_s390(kvm_file); > + if (!kvm) > + return -ENOENT; > + > if (kvm->arch.crypto.crycbd) { > get_update_locks_for_kvm(kvm); > if (kvm->arch.crypto.pqap_hook) { > @@ -1841,7 +1851,6 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev, > } > kvm->arch.crypto.pqap_hook = &matrix_mdev->pqap_hook; > > - kvm_get_kvm(kvm); > matrix_mdev->kvm = kvm; > vfio_ap_mdev_update_guest_apcb(matrix_mdev); > release_update_locks_for_kvm(kvm); > @@ -1894,7 +1903,6 @@ static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev) > matrix_mdev->kvm = NULL; > > release_update_locks_for_kvm(kvm); > - kvm_put_kvm(kvm); > } > } > Reviewed-by: Jason J. Herne