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Date: Fri, 12 Jun 2015 15:23:29 +0100
From: Will Deacon <will.deacon@arm.com>
Message-ID: <20150612142328.GF12174@arm.com>
References: <1434118810-28219-1-git-send-email-b.reynal@virtualopensystems.com>
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In-Reply-To: <1434118810-28219-1-git-send-email-b.reynal@virtualopensystems.com>
Subject: Re: [Qemu-devel] [RFC 0/6] vSMMU initialization
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To: Baptiste Reynal <b.reynal@virtualopensystems.com>
Cc: "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>, "tech@virtualopensystems.com" <tech@virtualopensystems.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>

On Fri, Jun 12, 2015 at 03:20:04PM +0100, Baptiste Reynal wrote:
> The ARM SMMU has support for 2-stages address translations, allowing a virtual
> address to be translated at two levels:
> - Stage 1 translates a virtual address (VA) into an intermediate physical
> address (IPA)
> - Stage 2 translates an IPA into a physical address (PA)
> 
> Will Deacon introduced a virtual SMMU interface for KVM, which gives a virtual
> machine the possibility to use an IOMMU with native drivers. While the VM will
> program the first stage of translation (stage 1), the interface will program
> the second (stage 2) on the physical SMMU.

Please note that I have no plans to merge the kernel-side of this at the
moment. It was merely an exploratory tool to see what a non-PV vSMMU
implementation might look like and certainly not intended to be used in
anger.

Will