From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <lenb@kernel.org>, Joerg Roedel <joro@8bytes.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Lu Baolu <baolu.lu@linux.intel.com>,
David Woodhouse <dwmw2@infradead.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
"open list:AMD IOMMU (AMD-VI)" <iommu@lists.linux-foundation.org>,
virtualization@lists.linux-foundation.org,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Eric Auger <eric.auger@redhat.com>,
sebastien.boeuf@intel.com, Robin Murphy <robin.murphy@arm.com>,
kevin.tian@intel.com,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Hanjun Guo <guohanjun@huawei.com>,
Sudeep Holla <sudeep.holla@arm.com>
Subject: Re: [PATCH v2 3/6] ACPI: Add driver for the VIOT table
Date: Wed, 26 May 2021 12:04:03 +0200 [thread overview]
Message-ID: <YK4dE+46ukG1Gcza@myrica> (raw)
In-Reply-To: <CAJZ5v0hoM-y2ajCVx8y4pXdPgAiNUBU6NUZ9m==NiVH8QcvWtw@mail.gmail.com>
On Fri, May 21, 2021 at 06:39:24PM +0200, Rafael J. Wysocki wrote:
> > diff --git a/drivers/acpi/viot.c b/drivers/acpi/viot.c
> > new file mode 100644
> > index 000000000000..710e5a5eac70
> > --- /dev/null
> > +++ b/drivers/acpi/viot.c
> > @@ -0,0 +1,350 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Virtual I/O topology
>
> In the first place, more information on what this is all about, please.
>
> What it does and how it is used.
Sure, I can add:
*
* The Virtual I/O Translation Table (VIOT) describes the topology of
* para-virtual IOMMUs and the endpoints they manage. The OS uses it to
* initialize devices in the right order, preventing endpoints from
* issuing DMA before their IOMMU is ready.
*
* When binding a driver to a device, before calling the device driver's
* probe() method, the driver infrastructure calls dma_configure(). At
* that point the VIOT driver looks for an IOMMU associated to the device
* in the VIOT table. If an IOMMU exists and has been initialized, the
* VIOT driver initializes the device's IOMMU fwspec, allowing the DMA
* infrastructure to invoke the IOMMU ops when the device driver
* configures DMA mappings. If an IOMMU exists and hasn't yet been
* initialized, VIOT returns -EPROBE_DEFER to postpone probing the device
* until the IOMMU is available.
*/
Thanks,
Jean
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next prev parent reply other threads:[~2021-05-26 12:15 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-23 11:38 [PATCH v2 0/6] Add support for ACPI VIOT Jean-Philippe Brucker
2021-04-23 11:38 ` [PATCH v2 1/6] ACPI: arm64: Move DMA setup operations out of IORT Jean-Philippe Brucker
2021-04-23 11:38 ` [PATCH v2 2/6] ACPI: Move IOMMU setup code " Jean-Philippe Brucker
2021-05-21 16:42 ` Rafael J. Wysocki
2021-05-26 10:05 ` Jean-Philippe Brucker
2021-04-23 11:38 ` [PATCH v2 3/6] ACPI: Add driver for the VIOT table Jean-Philippe Brucker
2021-05-21 16:39 ` Rafael J. Wysocki
2021-05-26 10:04 ` Jean-Philippe Brucker [this message]
2021-04-23 11:38 ` [PATCH v2 4/6] iommu/dma: Pass address limit rather than size to iommu_setup_dma_ops() Jean-Philippe Brucker
2021-04-23 11:38 ` [PATCH v2 5/6] iommu/dma: Simplify calls " Jean-Philippe Brucker
2021-04-23 11:38 ` [PATCH v2 6/6] iommu/virtio: Enable x86 support Jean-Philippe Brucker
2021-05-14 12:34 ` Michael S. Tsirkin
2021-05-14 12:35 ` [PATCH v2 0/6] Add support for ACPI VIOT Michael S. Tsirkin
2021-05-17 11:51 ` Joerg Roedel
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