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

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Message-ID: <20161110161619.GK2078@8bytes.org>
Date:   Thu, 10 Nov 2016 17:16:19 +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 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.


	Joerg