From: Joerg Roedel <joro@8bytes.org>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Nicolin Chen <nicolinc@nvidia.com>,
will@kernel.org, robin.murphy@arm.com,
alex.williamson@redhat.com, suravee.suthikulpanit@amd.com,
marcan@marcan.st, sven@svenpeter.dev, alyssa@rosenzweig.io,
robdclark@gmail.com, dwmw2@infradead.org,
baolu.lu@linux.intel.com, mjrosato@linux.ibm.com,
gerald.schaefer@linux.ibm.com, orsonzhai@gmail.com,
baolin.wang@linux.alibaba.com, zhang.lyra@gmail.com,
thierry.reding@gmail.com, vdumpa@nvidia.com,
jonathanh@nvidia.com, jean-philippe@linaro.org,
cohuck@redhat.com, tglx@linutronix.de,
shameerali.kolothum.thodi@huawei.com, thunder.leizhen@huawei.com,
christophe.jaillet@wanadoo.fr, yangyingliang@huawei.com,
jon@solid-run.com, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org, asahi@lists.linux.dev,
linux-arm-kernel@lists.infradead.org,
linux-arm-msm@vger.kernel.org, linux-s390@vger.kernel.org,
linux-tegra@vger.kernel.org,
virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
kevin.tian@intel.com
Subject: Re: [PATCH v6 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group
Date: Thu, 8 Sep 2022 15:28:22 +0200 [thread overview]
Message-ID: <Yxnt9uQTmbqul5lf@8bytes.org> (raw)
In-Reply-To: <YxjQiVnpU0dr7SHC@nvidia.com>
On Wed, Sep 07, 2022 at 02:10:33PM -0300, Jason Gunthorpe wrote:
> Sure, rust has all sorts of nice things. But the kernel doesn't follow
> rust idioms, and I don't think this is a great place to start
> experimenting with them.
It is actually a great place to start experimenting. The IOMMU
interfaces are rather domain specific and if we get something wrong the
damage is limited to a few callers. There are APIs much more exposed in
the kernel which would be worse for that.
But anyway, I am not insisting on it.
> It has been 3 months since EMEDIUMTYPE was first proposed and 6
> iterations of the series, don't you think it is a bit late in the game
> to try to experiment with rust error handling idioms?
If I am not mistaken, I am the person who gets blamed when crappy IOMMU
code is sent upstream. So it is also up to me to decide in which state
and how close to merging a given patch series is an whether it is
already 'late in the game'.
> So, again, would you be happy with a simple
>
> #define IOMMU_EINCOMPATIBLE_DEVICE xx
>
> to make it less "re-using random error codes"?
I am wondering if this can be solved by better defining what the return
codes mean and adjust the call-back functions to match the definition.
Something like:
-ENODEV : Device not mapped my an IOMMU
-EBUSY : Device attached and domain can not be changed
-EINVAL : Device and domain are incompatible
...
That would be much more intuitive than using something obscure like
EMEDIUMTYPE.
Regards,
Joerg
next prev parent reply other threads:[~2022-09-08 13:29 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-15 18:14 [PATCH v6 0/5] Simplify vfio_iommu_type1 attach/detach routine Nicolin Chen
2022-08-15 18:14 ` [PATCH v6 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group Nicolin Chen
2022-09-07 12:41 ` Joerg Roedel
2022-09-07 13:47 ` Jason Gunthorpe
2022-09-07 14:06 ` Joerg Roedel
2022-09-07 17:10 ` Jason Gunthorpe
2022-09-08 13:28 ` Joerg Roedel [this message]
2022-09-08 16:14 ` Jason Gunthorpe
2022-09-09 3:17 ` Nicolin Chen
2022-09-09 5:00 ` Tian, Kevin
2022-09-09 12:07 ` Jason Gunthorpe
2022-09-13 2:22 ` Tian, Kevin
2022-09-13 5:07 ` Nicolin Chen
2022-09-07 14:23 ` Robin Murphy
2022-09-07 17:00 ` Jason Gunthorpe
2022-09-07 19:41 ` Robin Murphy
2022-09-08 0:43 ` Jason Gunthorpe
2022-09-08 9:30 ` Tian, Kevin
2022-09-08 12:08 ` Jason Gunthorpe
2022-09-10 23:35 ` Nicolin Chen
2022-09-13 2:24 ` Tian, Kevin
2022-09-13 8:36 ` Nicolin Chen
2022-09-08 9:54 ` Tian, Kevin
2022-09-08 10:25 ` Robin Murphy
2022-08-15 18:14 ` [PATCH v6 2/5] vfio/iommu_type1: Prefer to reuse domains vs match enforced cache coherency Nicolin Chen
2022-08-15 18:14 ` [PATCH v6 3/5] vfio/iommu_type1: Remove the domain->ops comparison Nicolin Chen
2022-08-15 18:14 ` [PATCH v6 4/5] vfio/iommu_type1: Clean up update_dirty_scope in detach_group() Nicolin Chen
2022-08-15 18:14 ` [PATCH v6 5/5] vfio/iommu_type1: Simplify group attachment Nicolin Chen
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