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From: "Tian, Kevin" <kevin.tian@intel.com>
To: Christoph Hellwig <hch@lst.de>, Jason Gunthorpe <jgg@nvidia.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	Eric Auger <eric.auger@redhat.com>,
	"Liu, Yi L" <yi.l.liu@intel.com>
Subject: RE: [PATCH v2 5/8] vfio: Change vfio_external_check_extension() to vfio_file_enforced_coherent()
Date: Fri, 22 Apr 2022 00:32:58 +0000	[thread overview]
Message-ID: <BN9PR11MB527616A86D88299C7E5F4B598CF79@BN9PR11MB5276.namprd11.prod.outlook.com> (raw)
In-Reply-To: <BN9PR11MB5276CFD31471D4EE85DD705A8CF79@BN9PR11MB5276.namprd11.prod.outlook.com>

> From: Tian, Kevin
> Sent: Friday, April 22, 2022 8:13 AM
> 
> > From: Christoph Hellwig <hch@lst.de>
> > Sent: Thursday, April 21, 2022 1:41 PM
> >
> > I can see why a specific error might be nice for some cases and am
> > open to that, but as a simple transformation this already looks good:
> >
> 
> There is a slight semantics change together with patch7.
> 
> Before patch7 the container must be attached before calling
> KVM_DEV_VFIO_GROUP_ADD, otherwise vfio_group_get_external_user()
> will fail. In this case the result of cache coherency for a group is
> deterministic, either true or false.
> 
> After patch7 vfio_group_get_external_user() is not called. It's possible
> that KVM_DEV_VFIO_GROUP_ADD is called before a container is attached
> by the group. In this case cache coherency of the group cannot be
> determined at that point. I prefer to returning an error in this callback
> so KVM can still fail adding the group, instead of letting the inaccurate
> coherency info to bit the user in a much latter point...
> 

More accurately: s/cache coherency/enforced coherency/ in above.

  parent reply	other threads:[~2022-04-22  0:33 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-20 19:23 [PATCH v2 0/8] Remove vfio_group from the struct file facing VFIO API Jason Gunthorpe
2022-04-20 19:23 ` [PATCH v2 1/8] kvm/vfio: Move KVM_DEV_VFIO_GROUP_* ioctls into functions Jason Gunthorpe
2022-04-21 13:22   ` Cornelia Huck
2022-04-21 14:46   ` Yi Liu
2022-04-21 14:51   ` Jason Gunthorpe
2022-04-20 19:23 ` [PATCH v2 2/8] kvm/vfio: Store the struct file in the kvm_vfio_group Jason Gunthorpe
2022-04-21 14:46   ` Yi Liu
2022-04-20 19:23 ` [PATCH v2 3/8] vfio: Change vfio_external_user_iommu_id() to vfio_file_iommu_group() Jason Gunthorpe
2022-04-20 23:38   ` Tian, Kevin
2022-04-21  5:39   ` Christoph Hellwig
2022-04-21 14:57   ` Yi Liu
2022-04-22 17:05     ` Jason Gunthorpe
2022-04-23 12:53       ` Yi Liu
2022-04-20 19:23 ` [PATCH v2 4/8] vfio: Remove vfio_external_group_match_file() Jason Gunthorpe
2022-04-21  5:39   ` Christoph Hellwig
2022-04-21 14:50   ` Yi Liu
2022-04-20 19:23 ` [PATCH v2 5/8] vfio: Change vfio_external_check_extension() to vfio_file_enforced_coherent() Jason Gunthorpe
2022-04-20 23:49   ` Tian, Kevin
2022-04-21  5:41   ` Christoph Hellwig
2022-04-22  0:12     ` Tian, Kevin
     [not found]     ` <BN9PR11MB5276CFD31471D4EE85DD705A8CF79@BN9PR11MB5276.namprd11.prod.outlook.com>
2022-04-22  0:32       ` Tian, Kevin [this message]
2022-04-22 16:58         ` Jason Gunthorpe
2022-04-24  5:51           ` Tian, Kevin
2022-04-20 19:23 ` [PATCH v2 6/8] vfio: Change vfio_group_set_kvm() to vfio_file_set_kvm() Jason Gunthorpe
2022-04-20 23:51   ` Tian, Kevin
2022-04-21  5:41   ` Christoph Hellwig
2022-04-20 19:23 ` [PATCH v2 7/8] kvm/vfio: Remove vfio_group from kvm Jason Gunthorpe
2022-04-20 23:55   ` Tian, Kevin
2022-04-21  5:42   ` Christoph Hellwig
2022-04-20 19:23 ` [PATCH v2 8/8] vfio/pci: Use the struct file as the handle not the vfio_group Jason Gunthorpe
2022-04-21  0:05   ` Tian, Kevin
2022-04-21  5:43   ` Christoph Hellwig
2022-04-21 14:51 ` [PATCH v2 0/8] Remove vfio_group from the struct file facing VFIO API Yi Liu

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