[PATCH 0/4] Fix splats releated to using the iommu_group after destroying devices

From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	iommu@lists.linux.dev, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, Will Deacon <will@kernel.org>
Cc: Qian Cai <cai@lca.pw>, Joerg Roedel <jroedel@suse.de>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Matthew Rosato <mjrosato@linux.ibm.com>,
	Robin Murphy <robin.murphy@arm.com>
Subject: [PATCH 0/4] Fix splats releated to using the iommu_group after destroying devices
Date: Thu,  8 Sep 2022 15:44:57 -0300	[thread overview]
Message-ID: <0-v1-ef00ffecea52+2cb-iommu_group_lifetime_jgg@nvidia.com> (raw)

The basic issue is that the iommu_group is being used by VFIO after all
the device drivers have been removed.

In part this is caused by bad logic inside the iommu core that doesn't
sequence removing the device from the group properly, and in another part
this is bad logic in VFIO continuing to use device->iommu_group after all
VFIO device drivers have been removed.

Fix both situations. Either fix alone should fix the bug reported, but
both together bring a nice robust design to this area.

This is a followup from this thread:

https://lore.kernel.org/kvm/20220831201236.77595-1-mjrosato@linux.ibm.com/

Matthew confirmed an earlier version of the series solved the issue, it
would be best if he would test this as well to confirm the various changes
are still OK.

The iommu patch is independent of the other patches, it can go through the
iommu rc tree.

Jason Gunthorpe (4):
  vfio: Simplify vfio_create_group()
  vfio: Move the sanity check of the group to vfio_create_group()
  vfio: Follow a strict lifetime for struct iommu_group *
  iommu: Fix ordering of iommu_release_device()

 drivers/iommu/iommu.c    |  36 ++++++--
 drivers/vfio/vfio_main.c | 172 +++++++++++++++++++++------------------
 2 files changed, 120 insertions(+), 88 deletions(-)

base-commit: 245898eb9275ce31942cff95d0bdc7412ad3d589
-- 
2.37.3