Re: [PATCH v1 02/20] iommu: Introduce a test_dev domain op and an internal helper

From: Nicolin Chen <nicolinc@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>
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Subject: Re: [PATCH v1 02/20] iommu: Introduce a test_dev domain op and an internal helper
Date: Mon, 27 Oct 2025 21:37:59 -0700	[thread overview]
Message-ID: <aQBIp/0UW0/UiC4Z@Asurada-Nvidia> (raw)
In-Reply-To: <20251027232310.GD1018328@nvidia.com>

On Mon, Oct 27, 2025 at 08:23:10PM -0300, Jason Gunthorpe wrote:
> On Mon, Oct 20, 2025 at 11:51:49AM -0700, Nicolin Chen wrote:
> > On Mon, Oct 20, 2025 at 01:27:36PM -0300, Jason Gunthorpe wrote:
> > > On Sun, Oct 12, 2025 at 05:04:59PM -0700, Nicolin Chen wrote:
> > > > @@ -751,6 +760,8 @@ struct iommu_ops {
> > > >   * @free: Release the domain after use.
> > > >   */
> > > >  struct iommu_domain_ops {
> > > > +	int (*test_dev)(struct iommu_domain *domain, struct device *dev,
> > > > +			ioasid_t pasid, struct iommu_domain *old);
> > > 
> > > Because of the starting remark I'm skeptical that old should be
> > > included here.
> > 
> > Hmm, the followings functions sanitizes "old":
> >  - qcom_iommu_identity_attach() drivers/iommu/arm/arm-smmu/qcom_iommu.c
> 
> That shouldn't be copied over to test??
> 
>         if (domain == identity_domain || !domain)
>                 return 0;
> 
> That is just optimizing away the attach if it has nothing to do
> 
>         qcom_domain = to_qcom_iommu_domain(domain);
>         if (WARN_ON(!qcom_domain->iommu))
>                 return -EINVAL;
> 
> That can't never happen
> 
> >  - iommu_sva_set_dev_pasid() in drivers/iommu/amd/pasid.c
> 
> Its broken, you are not required by API to detach a domain before
> setting a new one. Keep it in attach, hope someone fixes this driver
> someday.

OK. I am leaving them alone. And no more old passed to test_dev.

Thanks
Nicolin

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