From: Jason Gunthorpe <jgg@nvidia.com>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Kevin Tian <kevin.tian@intel.com>,
iommu@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/5] iommu/vt-d: Add support for static identity domain
Date: Wed, 29 Nov 2023 16:28:51 -0400 [thread overview]
Message-ID: <20231129202851.GG436702@nvidia.com> (raw)
In-Reply-To: <20231129202615.GN1312390@ziepe.ca>
On Wed, Nov 29, 2023 at 04:26:15PM -0400, Jason Gunthorpe wrote:
> On Mon, Nov 20, 2023 at 07:29:43PM +0800, Lu Baolu wrote:
>
> > @@ -2311,6 +2316,13 @@ static int device_def_domain_type(struct device *dev)
> > return IOMMU_DOMAIN_IDENTITY;
> > }
> >
> > + /*
> > + * Hardware does not support the passthrough translation mode.
> > + * Always use a dynamaic mapping domain.
> > + */
> > + if (!ecap_pass_through(iommu->ecap))
> > + return IOMMU_DOMAIN_DMA;
> > +
>
> Doesn't this return from def_domain_type completely prevent using an
> identity domain?
>
> I thought the point of this was to allow the identity domain but have
> it be translating?
I suppose the answer is the next patch deletes that stuff.
I would probably have structured this in the other order, first add
this hunk and say that old HW is being de-supported. Remove all the
now-dead code creating the 1:1 page table, then refactor the remainder
to create the global static.
Jason
next prev parent reply other threads:[~2023-11-29 20:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-20 11:29 [PATCH 0/5] iommu/vt-d: Convert to use static identity domain Lu Baolu
2023-11-20 11:29 ` [PATCH 1/5] iommu/vt-d: Setup scalable mode context entry in probe path Lu Baolu
2023-11-20 11:29 ` [PATCH 2/5] iommu/vt-d: Remove scalable mode context entry setup from attach_dev Lu Baolu
2023-11-20 11:29 ` [PATCH 3/5] iommu/vt-d: Refactor domain_context_mapping_one() to be reusable Lu Baolu
2023-11-20 11:29 ` [PATCH 4/5] iommu/vt-d: Add support for static identity domain Lu Baolu
2023-11-29 20:26 ` Jason Gunthorpe
2023-11-29 20:28 ` Jason Gunthorpe [this message]
2023-11-30 6:09 ` Baolu Lu
2023-11-20 11:29 ` [PATCH 5/5] iommu/vt-d: Remove si_domain Lu Baolu
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