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From: Christoph Hellwig <hch@lst.de>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
	Eric Auger <eric.auger@redhat.com>,
	Christoph Hellwig <hch@lst.de>, Yi Liu <yi.l.liu@intel.com>
Subject: Re: [PATCH 05/10] vfio: Move vfio_external_user_iommu_id() to vfio_file_ops
Date: Fri, 15 Apr 2022 09:31:25 +0200	[thread overview]
Message-ID: <20220415073125.GC24824@lst.de> (raw)
In-Reply-To: <5-v1-33906a626da1+16b0-vfio_kvm_no_group_jgg@nvidia.com>

On Thu, Apr 14, 2022 at 03:46:04PM -0300, Jason Gunthorpe wrote:
> The only user wants to get a pointer to the struct iommu_group associated
> with the VFIO file being used. Instead of returning the group ID then
> searching sysfs for that string just directly return the iommu_group
> pointer already held by the vfio_group struct.
> 
> It already has a safe lifetime due to the struct file kref.

Except for the strange function pointer indirection this does looks
sensible to me, but I wonder if we want to do this change even more
high level: The only thing that needs the IOMMU group is the PPC
kvm_spapr_tce_attach_iommu_group / kvm_spapr_tce_release_vfio_group
helpers.  And these use it only to find the iommu_table_group
structure.  Why can't we just have the vfio_group point to that
table group diretly in vfio or the vfio SPAPR backend and remove
all the convoluted lookups?

  parent reply	other threads:[~2022-04-15  7:31 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-14 18:45 [PATCH 00/10] Remove vfio_group from the struct file facing VFIO API Jason Gunthorpe
2022-04-14 18:46 ` [PATCH 01/10] kvm/vfio: Move KVM_DEV_VFIO_GROUP_* ioctls into functions Jason Gunthorpe
2022-04-15  3:36   ` Tian, Kevin
2022-04-15  7:18   ` Christoph Hellwig
2022-04-14 18:46 ` [PATCH 02/10] kvm/vfio: Reduce the scope of PPC #ifdefs Jason Gunthorpe
2022-04-15  4:47   ` Christoph Hellwig
2022-04-15 12:13     ` Jason Gunthorpe
2022-04-15 12:35       ` Jason Gunthorpe
2022-04-15 14:36         ` Christoph Hellwig
2022-04-14 18:46 ` [PATCH 03/10] kvm/vfio: Store the struct file in the kvm_vfio_group Jason Gunthorpe
2022-04-15  3:44   ` Tian, Kevin
2022-04-15 22:24     ` Jason Gunthorpe
2022-04-15  7:20   ` Christoph Hellwig
2022-04-19 19:24     ` Jason Gunthorpe
2022-04-14 18:46 ` [PATCH 04/10] vfio: Use a struct of function pointers instead of a many symbol_get()'s Jason Gunthorpe
2022-04-15  3:57   ` Tian, Kevin
2022-04-15 21:54     ` Jason Gunthorpe
2022-04-16  0:00       ` Tian, Kevin
2022-04-16  1:33         ` Jason Gunthorpe
2022-04-18  3:56           ` Tian, Kevin
2022-04-19 12:16             ` Jason Gunthorpe
2022-04-15  4:45   ` Christoph Hellwig
2022-04-15 12:13     ` Jason Gunthorpe
2022-04-15 14:36       ` Christoph Hellwig
2022-04-15 15:31         ` Jason Gunthorpe
2022-04-14 18:46 ` [PATCH 05/10] vfio: Move vfio_external_user_iommu_id() to vfio_file_ops Jason Gunthorpe
2022-04-15  3:59   ` Tian, Kevin
2022-04-15  7:31   ` Christoph Hellwig [this message]
2022-04-15 12:25     ` Jason Gunthorpe
2022-04-15 14:37       ` Christoph Hellwig
2022-04-14 18:46 ` [PATCH 06/10] vfio: Remove vfio_external_group_match_file() Jason Gunthorpe
2022-04-15  4:02   ` Tian, Kevin
2022-04-15  7:32   ` Christoph Hellwig
2022-04-14 18:46 ` [PATCH 07/10] vfio: Move vfio_external_check_extension() to vfio_file_ops Jason Gunthorpe
2022-04-15  4:07   ` Tian, Kevin
2022-04-19 19:23     ` Jason Gunthorpe
2022-04-20  3:05       ` Tian, Kevin
2022-04-15  4:48   ` Christoph Hellwig
2022-04-14 18:46 ` [PATCH 08/10] vfio: Move vfio_group_set_kvm() into vfio_file_ops Jason Gunthorpe
2022-04-15  4:09   ` Tian, Kevin
2022-04-14 18:46 ` [PATCH 09/10] kvm/vfio: Remove vfio_group from kvm Jason Gunthorpe
2022-04-15  4:21   ` Tian, Kevin
2022-04-15 21:56     ` Jason Gunthorpe
2022-04-16  0:42       ` Tian, Kevin
2022-04-16  1:34         ` Jason Gunthorpe
2022-04-18  6:09           ` Tian, Kevin
2022-04-14 18:46 ` [PATCH 10/10] vfio/pci: Use the struct file as the handle not the vfio_group Jason Gunthorpe

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