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From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     Jason Gunthorpe <jgg@nvidia.com>,
        Nicolin Chen <nicolinc@nvidia.com>
CC:     "joro@8bytes.org" <joro@8bytes.org>,
        "will@kernel.org" <will@kernel.org>,
        "robin.murphy@arm.com" <robin.murphy@arm.com>,
        "baolu.lu@linux.intel.com" <baolu.lu@linux.intel.com>,
        "iommu@lists.linux.dev" <iommu@lists.linux.dev>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Liu, Yi L" <yi.l.liu@intel.com>
Subject: RE: [PATCH v3] iommufd: Only enforce cache coherency in
 iommufd_hw_pagetable_alloc
Thread-Topic: [PATCH v3] iommufd: Only enforce cache coherency in
 iommufd_hw_pagetable_alloc
Thread-Index: AQHaBeLDLztCnanYVUqlQIpqtTMrCLBX/veAgAAlKrA=
Date:   Tue, 24 Oct 2023 01:18:33 +0000
Message-ID: <BN9PR11MB5276D46F61B57553CB37AAAD8CDFA@BN9PR11MB5276.namprd11.prod.outlook.com>
References: <20231023185700.11407-1-nicolinc@nvidia.com>
 <20231023230509.GI3952@nvidia.com>
In-Reply-To: <20231023230509.GI3952@nvidia.com>
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> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Tuesday, October 24, 2023 7:05 AM
>=20
> On Mon, Oct 23, 2023 at 11:57:00AM -0700, Nicolin Chen wrote:
> > According to the conversion in the following link:
> > https://lore.kernel.org/linux-
> iommu/20231020135501.GG3952@nvidia.com/
> >
> > The enforce_cache_coherency should be set/enforced in the hwpt
> allocation
> > routine. The iommu driver in its attach_dev() op should decide whether =
to
> > reject or not a device that doesn't match with the configuration of cac=
he
> > coherency. Drop the enforce_cache_coherency piece in the attach/replace=
()
> > and move the remaining "num_devices" piece closer to the refcount that =
is
> > using it.
> >
> > Accordingly drop its function prototype in the header and mark it stati=
c.
> > Also add some extra comments to clarify the expected behaviors.
> >
> > Suggested-by: Kevin Tian <kevin.tian@intel.com>
> > Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
> > Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> > ---
> > Changelog
> > v3:
> >  * Reworked the first line of the added commets.
> > v2: https://lore.kernel.org/all/20231023035733.27378-1-
> nicolinc@nvidia.com/
> >  * Dropped "fixes" tags and merged two patches into one (Jason)
> >  * Added comments to the remaining enforce_cache_coherency call (Jason)
> >    [Please feel free to rephrase, or let me know what to change.]
> >  * Replace "num_devices++" with list_for_each_entry (Baolu)
> > v1: https://lore.kernel.org/all/cover.1697848510.git.nicolinc@nvidia.co=
m/
> >
> >  drivers/iommu/iommufd/device.c          | 20 ++------------------
> >  drivers/iommu/iommufd/hw_pagetable.c    |  9 ++++++++-
> >  drivers/iommu/iommufd/iommufd_private.h |  1 -
> >  3 files changed, 10 insertions(+), 20 deletions(-)
>=20
> This looks OK to me, Kevin is it what you think it should be now?
>=20

This looks good.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>