From: Joerg Roedel <joro@8bytes.org>
To: Auger Eric <eric.auger@redhat.com>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>,
kevin.tian@intel.com, mst@redhat.com, linux-pci@vger.kernel.org,
jasowang@redhat.com, virtualization@lists.linux-foundation.org,
iommu@lists.linux-foundation.org, sebastien.boeuf@intel.com,
jacob.jun.pan@intel.com, bhelgaas@google.com,
robin.murphy@arm.com
Subject: Re: [PATCH v2 1/3] iommu/virtio: Add topology description to virtio-iommu config space
Date: Tue, 3 Mar 2020 14:01:56 +0100 [thread overview]
Message-ID: <20200303130155.GA13185@8bytes.org> (raw)
In-Reply-To: <9004f814-2f7c-9024-3465-6f9661b97b7a@redhat.com>
Hi Eric,
On Tue, Mar 03, 2020 at 11:19:20AM +0100, Auger Eric wrote:
> Michael has pushed this solution (putting the "configuration in the PCI
> config space"), I think for those main reasons:
> - ACPI may not be supported on some archs/hyps
But on those there is device-tree, right?
> - the virtio-iommu is a PCIe device so binding should not need ACPI
> description
The other x86 IOMMUs are PCI devices too and they definitly need a ACPI
table to be configured.
> Another issue with ACPI integration is we have different flavours of
> tables that exist: IORT, DMAR, IVRS
An integration with IORT might be the best, but if it is not possible
ther can be a new table-type for Virtio-iommu. That would still follow
platform best practices.
> x86 ACPI integration was suggested with IORT. But it seems ARM is
> reluctant to extend IORT to support para-virtualized IOMMU. So the VIOT
> was proposed as a different atternative in "[RFC 00/13] virtio-iommu on
> non-devicetree platforms"
> (https://patchwork.kernel.org/cover/11257727/). Proposing a table that
> may be used by different vendors seems to be a challenging issue here.
Yeah, if I am reading that right this proposes a one-fits-all solution.
That is not needed as the other x86 IOMMUs already have their tables
defined and implemented. There is no need to change anything there.
> So even if the above solution does not look perfect, it looked a
> sensible compromise given the above arguments. Please could you explain
> what are the most compelling arguments against it?
It is a hack and should be avoided if at all possible. And defining an
own ACPI table type seems very much possible.
Regards,
Joerg
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next prev parent reply other threads:[~2020-03-03 13:02 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-28 17:25 [PATCH v2 0/3] virtio-iommu on x86 and non-devicetree platforms Jean-Philippe Brucker
2020-02-28 17:25 ` [PATCH v2 1/3] iommu/virtio: Add topology description to virtio-iommu config space Jean-Philippe Brucker
2020-03-01 11:17 ` Michael S. Tsirkin
2020-03-02 16:16 ` Joerg Roedel
2020-03-03 10:19 ` Auger Eric
2020-03-03 13:01 ` Joerg Roedel [this message]
2020-03-03 14:00 ` Michael S. Tsirkin
2020-03-03 15:53 ` Joerg Roedel
2020-03-03 16:09 ` Michael S. Tsirkin
2020-03-03 16:21 ` Auger Eric
2020-03-04 13:37 ` Joerg Roedel
2020-03-04 15:38 ` Jean-Philippe Brucker
2020-03-04 17:40 ` Joerg Roedel
2020-03-04 21:37 ` Jacob Pan (Jun)
2020-03-04 21:54 ` Joerg Roedel
2020-03-05 15:42 ` Michael S. Tsirkin
2020-03-04 15:48 ` Jacob Pan
2020-03-04 17:34 ` Joerg Roedel
2020-03-04 19:34 ` Michael S. Tsirkin
2020-03-04 21:50 ` Joerg Roedel
2020-03-05 15:39 ` Michael S. Tsirkin
2020-03-03 14:02 ` Michael S. Tsirkin
2020-03-05 8:07 ` Tian, Kevin
2020-03-11 17:48 ` Jean-Philippe Brucker
2020-03-11 21:48 ` Michael S. Tsirkin
2020-04-13 13:22 ` Michael S. Tsirkin
2020-04-21 7:31 ` Tian, Kevin
2020-08-21 8:39 ` Jean-Philippe Brucker
2020-02-28 17:25 ` [PATCH v2 2/3] PCI: Add DMA configuration for virtual platforms Jean-Philippe Brucker
2020-03-18 21:10 ` Bjorn Helgaas
2020-02-28 17:25 ` [PATCH v2 3/3] iommu/virtio: Enable x86 support Jean-Philippe Brucker
2020-02-29 14:23 ` kbuild test robot
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