linux-kernel - Re: [RFC v2 8/8] iommu/arm-smmu: implement add_reserved

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 11 Nov 2016 16:03:16 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Eric Auger <eric.auger@...hat.com>, eric.auger.pro@...il.com,
        christoffer.dall@...aro.org, marc.zyngier@....com,
        alex.williamson@...hat.com, will.deacon@....com,
        tglx@...utronix.de, jason@...edaemon.net,
        linux-arm-kernel@...ts.infradead.org, kvm@...r.kernel.org,
        drjones@...hat.com, linux-kernel@...r.kernel.org,
        pranav.sawargaonkar@...il.com, iommu@...ts.linux-foundation.org,
        punit.agrawal@....com, diana.craciun@....com
Subject: Re: [RFC v2 8/8] iommu/arm-smmu: implement add_reserved_regions
 callback

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