linux-kernel - Re: [PATCH 2/5] iommu: Add blocking_domain_ops field in iommu

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Message-ID: <20220516130530.GU1343366@nvidia.com>
Date:   Mon, 16 May 2022 10:05:30 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Eric Auger <eric.auger@...hat.com>,
        Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] iommu: Add blocking_domain_ops field in iommu_ops

On Mon, May 16, 2022 at 12:27:41AM -0700, Christoph Hellwig wrote:
> On Mon, May 16, 2022 at 09:57:56AM +0800, Lu Baolu wrote:
> > Each IOMMU driver must provide a blocking domain ops. If the hardware
> > supports detaching domain from device, setting blocking domain equals
> > detaching the existing domain from the deivce. Otherwise, an UNMANAGED
> > domain without any mapping will be used instead.
> 
> blocking in this case means not allowing any access?  The naming
> sounds a bit odd to me as blocking in the kernel has a specific
> meaning.  Maybe something like noaccess ops might be a better name?

It is because of this:

include/linux/iommu.h: *        IOMMU_DOMAIN_BLOCKED    - All DMA is blocked, can be used to isolate
include/linux/iommu.h:#define IOMMU_DOMAIN_BLOCKED      (0U)

noaccess might be clearer

Jason