From: Jason Gunthorpe <jgg@nvidia.com>
To: Yi Liu <yi.l.liu@intel.com>
Cc: alex.williamson@redhat.com, kevin.tian@intel.com,
cohuck@redhat.com, eric.auger@redhat.com, nicolinc@nvidia.com,
kvm@vger.kernel.org, mjrosato@linux.ibm.com,
chao.p.peng@linux.intel.com, yi.y.sun@linux.intel.com,
peterx@redhat.com, jasowang@redhat.com
Subject: Re: [RFC 05/12] kvm/vfio: Accept vfio device file from userspace
Date: Fri, 6 Jan 2023 12:08:20 -0400 [thread overview]
Message-ID: <Y7hHdOo3UHAcVFLp@nvidia.com> (raw)
In-Reply-To: <17e6b31c-1149-018b-e76f-f3c82e702144@intel.com>
On Fri, Jan 06, 2023 at 11:04:42PM +0800, Yi Liu wrote:
> > This will allow the VFIO device file to close and drop the users_count
>
> yeah. It's interesting I haven't hit real problem so far. But this does
> look to be a circular. When I ctrl+c to kill qemu, I can boot qemu again
> with the same device assigned. anyhow, let me add some prtink to check
> it. thanks for the catch.
You have to test with one of the situations that hold the kvm ref
during open, eg gvt on intel
To make it happen hack the vfio code to hold the reference at
open_device and let it go during close_device, then you should see the
problem.
Jason
next prev parent reply other threads:[~2023-01-06 16:09 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-19 8:47 [RFC 00/12] Add vfio_device cdev for iommufd support Yi Liu
2022-12-19 8:47 ` [RFC 01/12] vfio: Allocate per device file structure Yi Liu
2022-12-21 3:57 ` Tian, Kevin
2022-12-21 6:46 ` Yi Liu
2022-12-19 8:47 ` [RFC 02/12] vfio: Refine vfio file kAPIs Yi Liu
2022-12-19 8:47 ` [RFC 03/12] vfio: Accept vfio device file in the driver facing kAPI Yi Liu
2022-12-21 4:07 ` Tian, Kevin
2022-12-21 7:02 ` Yi Liu
2023-01-04 18:25 ` Jason Gunthorpe
2023-01-09 4:13 ` Tian, Kevin
2022-12-19 8:47 ` [RFC 04/12] kvm/vfio: Rename kvm_vfio_group to prepare for accepting vfio device fd Yi Liu
2022-12-19 8:47 ` [RFC 05/12] kvm/vfio: Accept vfio device file from userspace Yi Liu
2023-01-06 14:32 ` Jason Gunthorpe
2023-01-06 14:46 ` Yi Liu
2023-01-06 14:55 ` Jason Gunthorpe
2023-01-06 15:04 ` Yi Liu
2023-01-06 16:08 ` Jason Gunthorpe [this message]
2023-01-09 4:17 ` Tian, Kevin
2023-01-09 4:26 ` Yi Liu
2022-12-19 8:47 ` [RFC 06/12] vfio: Pass struct vfio_device_file * to vfio_device_open/close() Yi Liu
2022-12-21 4:10 ` Tian, Kevin
2022-12-21 7:04 ` Yi Liu
2022-12-19 8:47 ` [RFC 07/12] vfio: Block device access via device fd until device is opened Yi Liu
2022-12-21 4:18 ` Tian, Kevin
2023-01-04 20:47 ` Jason Gunthorpe
2022-12-19 8:47 ` [RFC 08/12] vfio: Add infrastructure for bind_iommufd and attach Yi Liu
2023-01-09 5:46 ` Tian, Kevin
2023-01-09 13:21 ` Jason Gunthorpe
2023-01-10 2:53 ` Tian, Kevin
2022-12-19 8:47 ` [RFC 09/12] vfio: Make vfio_device_open() exclusive between group path and device cdev path Yi Liu
2023-01-09 6:03 ` Tian, Kevin
2022-12-19 8:47 ` [RFC 10/12] vfio: Add cdev for vfio_device Yi Liu
2023-01-09 6:54 ` Tian, Kevin
2022-12-19 8:47 ` [RFC 11/12] vfio: Add ioctls for device cdev iommufd Yi Liu
2023-01-09 7:47 ` Tian, Kevin
2023-01-09 14:14 ` Jason Gunthorpe
2023-01-09 15:07 ` Yi Liu
2023-01-09 15:12 ` Jason Gunthorpe
2023-01-09 15:20 ` Yi Liu
2023-01-09 14:55 ` Yi Liu
2023-01-10 2:57 ` Tian, Kevin
2022-12-19 8:47 ` [RFC 12/12] vfio: Compile group optionally Yi Liu
2022-12-19 8:51 ` [RFC 00/12] Add vfio_device cdev for iommufd support Yi Liu
2023-01-04 15:23 ` Yi Liu
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