From: joro <joro@8bytes.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: "xxm@rock-chips.com" <xxm@rock-chips.com>, hch <hch@lst.de>,
will <will@kernel.org>, iommu <iommu@lists.linux-foundation.org>,
linux-rockchip <linux-rockchip@lists.infradead.org>
Subject: Re: Different type iommus integrated in a SoC
Date: Fri, 4 Jun 2021 17:44:45 +0200 [thread overview]
Message-ID: <YLpKbRVU1YPD/73L@8bytes.org> (raw)
In-Reply-To: <5d7127d5-b73c-2002-1734-98aab2295c8e@arm.com>
On Thu, Jun 03, 2021 at 01:05:43PM +0100, Robin Murphy wrote:
> Hooray! I've been forecasting this for years, but the cases we regularly hit
> with internal FPGA prototyping (nor the secret unused MMU-400 I found on
> RK3288) have never really been a strong enough argument to stand behind.
>
> Based on what I remember from looking into this a few years ago, converting
> *most* of the API to per-device ops (now via dev->iommu) is trivial; the
> main challenge will be getting the per-device data bootstrapped in
> iommu_probe_device(), which would probably need to rely on the fwspec and/or
> list of registered IOMMU instances.
>
> The other notable thing which will need to change is the domain allocation
> interface, but in practice I think everyone who calls iommu_domain_alloc()
> today is in fact doing so for a specific device, so I don't think it's as
> big a problem as it might first appear.
Yeah, I think for that we have to give up on the promise that a domain
can be assigned to _any_ device. But this promise doesn't even hold true
now when there are several IOMMU of the same type but with different
feature sets in a system.
So I happily review patches enabling the Multi-IOMMU SOCs :)
Regards,
Joerg
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prev parent reply other threads:[~2021-06-04 15:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <2021052710373173260118@rock-chips.com>
2021-06-03 12:05 ` Different type iommus integrated in a SoC Robin Murphy
2021-06-03 12:24 ` Peter Geis
2021-06-03 12:49 ` Robin Murphy
2021-06-04 15:44 ` joro [this message]
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