From: Paolo Bonzini <pbonzini@redhat.com>
To: Xiao Guangrong <guangrong.xiao@linux.intel.com>,
Jike Song <jike.song@intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
kwankhede@nvidia.com, cjia@nvidia.com, kevin.tian@intel.com,
kvm@vger.kernel.org
Subject: Re: [v3 4/5] vfio: implement APIs to set/put kvm to/from vfio group
Date: Wed, 9 Nov 2016 14:31:01 +0100 [thread overview]
Message-ID: <02c27131-80fd-b882-1838-fe56f3f871d3@redhat.com> (raw)
In-Reply-To: <3e5299bc-e08e-f072-1001-7e0432cb1ca8@linux.intel.com>
On 09/11/2016 14:06, Xiao Guangrong wrote:
>
>
> On 11/09/2016 08:49 PM, Jike Song wrote:
>
>> +void vfio_group_attach_kvm(struct vfio_group *group, struct kvm *kvm,
>> + void (*fn)(struct kvm *))
>> +{
>> + mutex_lock(&group->udata.lock);
>
> This lock is needed, please see below.
*not* needed I guess.
>> +
>> + fn(kvm);
>> + blocking_notifier_call_chain(&group->udata.notifier,
>> + VFIO_GROUP_NOTIFY_ATTACH_KVM, kvm);
>
> As this is a callback before KVM releases its last refcount, i do not
> think vendor driver need to get additional KVM refcount.
The *group* driver doesn't need it indeed. The mdev vendor driver
however does, so it will use kvm_get_kvm under its own mutex. That is:
- attach kvm
mutex_lock(mdev_driver->lock);
mdev_driver->kvm = opaque;
kvm_get_kvm(mdev_driver->kvm);
mutex_unlock(mdev_driver->lock);
- detach kvm
mutex_lock(mdev_driver->lock);
kvm_put_kvm(mdev_driver->kvm);
WARN_ON(mdev_driver->kvm != opaque);
mdev_driver->kvm = NULL;
mutex_unlock(mdev_driver->lock);
- use kvm
mutex_lock(mdev_driver->lock);
kvm = mdev_driver->kvm;
...
mutex_unlock(mdev_driver->lock);
or if safe:
mutex_lock(mdev_driver->lock);
kvm = mdev_driver->kvm;
kvm_get_kvm(kvm);
mutex_unlock(mdev_driver->lock);
...
kvm_put_kvm(kvm);
Thanks,
Paolo
next prev parent reply other threads:[~2016-11-09 13:31 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-31 6:35 [v3 0/5] plumb kvm/vfio to allow getting kvm from vfio_group Jike Song
2016-10-31 6:35 ` [v3 1/5] vfio: Rearrange functions to get vfio_group from dev Jike Song
2016-10-31 6:35 ` [v3 2/5] vfio: export functions to get vfio_group from device and put it Jike Song
2016-10-31 6:35 ` [v3 3/5] KVM: move kvm_get_kvm to kvm_host.h Jike Song
2016-10-31 8:33 ` Paolo Bonzini
2016-10-31 6:35 ` [v3 4/5] vfio: implement APIs to set/put kvm to/from vfio group Jike Song
2016-11-07 18:04 ` Alex Williamson
2016-11-07 18:10 ` Paolo Bonzini
2016-11-07 18:28 ` Alex Williamson
2016-11-07 20:45 ` Paolo Bonzini
2016-11-09 12:49 ` Jike Song
2016-11-09 13:06 ` Xiao Guangrong
2016-11-09 13:31 ` Paolo Bonzini [this message]
2016-11-09 14:00 ` Xiao Guangrong
2016-11-09 14:28 ` Paolo Bonzini
2016-11-10 4:13 ` Jike Song
2016-11-09 17:53 ` Alex Williamson
2016-11-10 4:10 ` Jike Song
2016-11-10 6:04 ` Jike Song
2016-11-10 15:37 ` Alex Williamson
2016-11-11 7:29 ` Jike Song
2016-11-14 10:19 ` Jike Song
2016-11-14 15:52 ` Alex Williamson
2016-11-09 2:28 ` Jike Song
2016-11-09 2:52 ` Xiao Guangrong
2016-11-09 3:07 ` Jike Song
2016-10-31 6:35 ` [v3 5/5] KVM: set/clear kvm to/from vfio group during add/delete Jike Song
2016-10-31 8:33 ` Paolo Bonzini
2016-10-31 7:06 ` [v3 0/5] plumb kvm/vfio to allow getting kvm from vfio_group Xiao Guangrong
2016-10-31 7:24 ` Jike Song
2016-10-31 7:24 ` Xiao Guangrong
2016-10-31 7:30 ` Jike Song
2016-10-31 7:35 ` Xiao Guangrong
2016-11-02 1:06 ` Jike Song
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=02c27131-80fd-b882-1838-fe56f3f871d3@redhat.com \
--to=pbonzini@redhat.com \
--cc=alex.williamson@redhat.com \
--cc=cjia@nvidia.com \
--cc=guangrong.xiao@linux.intel.com \
--cc=jike.song@intel.com \
--cc=kevin.tian@intel.com \
--cc=kvm@vger.kernel.org \
--cc=kwankhede@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.