From: Julien Grall <julien.grall@arm.com>
To: jinchen <jinchen1227@qq.com>,
xen-devel <xen-devel@lists.xenproject.org>,
Stefano Stabellini <sstabellini@kernel.org>
Subject: Re: Xen ARM smmu questions
Date: Tue, 12 Mar 2019 11:42:23 +0000 [thread overview]
Message-ID: <996e86f5-7059-9fb1-1aa1-734ab760f70a@arm.com> (raw)
In-Reply-To: <tencent_4E03A65ACF45B3490239A3A479F5E64FA506@qq.com>
On 3/12/19 8:58 AM, jinchen wrote:
> Hello xen-devel,
Hello,
> I'm reading the code of xen arm smmu in drivers/passthrough/arm, and I
> have some questions that confused me.
> I think if the board use SMMU, xen will take charge of it before dom0
> boot, and will not pass the node of SMMU to dom0 in device tree,
> so my question is how dom0 use SMMU? or can dom0 use SMMU? What dom0 use
> if it wants to use IOMMU?
> What about domU? The SMMU could be passed to domU?
Some SMMU are able to provide Stage 1 (Guest VA to Guest PA) and Stage 2
(Guest PA to Host PA) support. In the current configuration, Xen will
use the Stage 2 part to isolate device passthrough. Stage 1 is not
supported.
If you wanted a guest to use the SMMU, you would either need to provide
Stage 1 support (requires HW support) or a PV IOMMU.
Alternatively, you might be able to give the SMMU to Dom0. I haven't
explored it so far. Do you have a use case for using the IOMMU in guest?
Cheers,
--
Julien Grall
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next prev parent reply other threads:[~2019-03-12 11:42 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-12 8:58 Xen ARM smmu questions jinchen
2019-03-12 11:42 ` Julien Grall [this message]
2019-03-12 13:47 ` Jinch
2019-03-12 19:20 ` Stefano Stabellini
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