From: joro@8bytes•org (Joerg Roedel)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC v2 8/8] iommu/arm-smmu: implement add_reserved_regions callback
Date: Fri, 11 Nov 2016 16:03:16 +0100 [thread overview]
Message-ID: <20161111150316.GR2078@8bytes.org> (raw)
In-Reply-To: <479aeac0-71f9-a6b8-af6d-e2c25184a818@arm.com>
On Fri, Nov 11, 2016 at 02:34:39PM +0000, Robin Murphy wrote:
> On 10/11/16 16:16, Joerg Roedel wrote:
> > On Thu, Nov 10, 2016 at 04:07:08PM +0000, Robin Murphy wrote:
> >> On 10/11/16 15:46, Joerg Roedel wrote:
> >>> On Fri, Nov 04, 2016 at 11:24:06AM +0000, Eric Auger wrote:
> >>>> + resource_list_for_each_entry(window, &bridge->windows) {
> >>>> + if (resource_type(window->res) != IORESOURCE_MEM &&
> >>>> + resource_type(window->res) != IORESOURCE_IO)
> >>>> + continue;
> >>>
> >>> Why do you care about IO resources?
> >>
> >> [since this is essentially code I wrote]
> >>
> >> Because they occupy some area of the PCI address space, therefore I
> >> assumed that, like memory windows, they would be treated as P2P. Is that
> >> not the case?
> >
> > No, not at all. The IO-space is completly seperate from the MEM-space.
> > They are two different address-spaces, addressing different things. And
> > the IO-space is also not translated by any IOMMU I am aware of.
>
> OK. On the particular root complex I have to hand, though, any DMA to
> IOVAs between 0x5f800000 and 0x5fffffff sends an error back to the
> endpoint, and that just so happens to be where the I/O window is placed
> (both on the PCI side and the AXI (i.e. CPU MMIO) side. Whether it's
> that the external MMIO view of the RC's I/O window is explicitly
> duplicated in its PCI memory space as some side-effect of the PCI/AXI
> bridge, or that the thing just doesn't actually respect the access type
> on the PCI side I don't know, but that's how it is (and I spent this
> morning recreating it to make sure I wasn't mistaken).
What you see is that on your platform the io-ports are accessed by an
mmio-window. On x86 you have dedicated instructions to access io-ports.
And the io-port ranges are what is what the io-resources describe. These
resources do no tell you where the mmio-region for that devices io-ports
are.
Joerg
next prev parent reply other threads:[~2016-11-11 15:03 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-04 11:23 [RFC v2 0/8] KVM PCIe/MSI passthrough on ARM/ARM64 - Alt II Eric Auger
[not found] ` <1478258646-3117-5-git-send-email-eric.auger@redhat.com>
2016-11-04 14:00 ` [RFC v2 4/8] iommu: Add a list of iommu_reserved_region in iommu_domain Robin Murphy
2016-11-10 11:22 ` Auger Eric
2016-11-10 11:54 ` Robin Murphy
2016-11-10 12:14 ` Auger Eric
2016-11-10 12:48 ` Robin Murphy
2016-11-10 15:37 ` Joerg Roedel
2016-11-10 15:42 ` Auger Eric
[not found] ` <1478258646-3117-3-git-send-email-eric.auger@redhat.com>
2016-11-10 15:22 ` [RFC v2 2/8] iommu/iova: fix __alloc_and_insert_iova_range Joerg Roedel
2016-11-10 15:41 ` Auger Eric
[not found] ` <1478258646-3117-9-git-send-email-eric.auger@redhat.com>
2016-11-04 14:16 ` [RFC v2 8/8] iommu/arm-smmu: implement add_reserved_regions callback Robin Murphy
2016-11-10 15:46 ` Joerg Roedel
2016-11-10 15:57 ` Auger Eric
2016-11-10 16:13 ` Joerg Roedel
2016-11-10 18:00 ` Auger Eric
2016-11-11 11:42 ` Joerg Roedel
2016-11-11 15:47 ` Auger Eric
2016-11-11 16:22 ` Joerg Roedel
2016-11-11 16:45 ` Auger Eric
2016-11-14 15:31 ` Joerg Roedel
2016-11-14 16:08 ` Auger Eric
2016-11-14 16:20 ` Joerg Roedel
2016-11-14 16:57 ` Auger Eric
2016-11-10 16:07 ` Robin Murphy
2016-11-10 16:16 ` Joerg Roedel
2016-11-11 14:34 ` Robin Murphy
2016-11-11 15:03 ` Joerg Roedel [this message]
[not found] ` <1478258646-3117-4-git-send-email-eric.auger@redhat.com>
2016-11-14 12:36 ` [RFC v2 3/8] iommu/dma: Allow MSI-only cookies Robin Murphy
2016-11-14 23:23 ` Auger Eric
2016-11-15 14:52 ` Robin Murphy
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