From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: dev@dpdk.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [dpdk-dev] [PATCH] vfio/noiommu: Don't use iommu_present() to track fake groups
Date: Mon, 25 Jan 2016 11:20:24 +1100 [thread overview]
Message-ID: <56A56A48.9090405@ozlabs.ru> (raw)
In-Reply-To: <20160122172159.5655.55830.stgit@gimli.home>
On 01/23/2016 04:23 AM, Alex Williamson wrote:
> Using iommu_present() to determine whether an IOMMU group is real or
> fake has some problems. First, apparently Power systems don't
> register an IOMMU on the device bus, so the groups and containers get
> marked as noiommu and then won't bind to their actual IOMMU driver.
> Second, I expect we'll run into the same issue as we try to support
> vGPUs through vfio, since they're likely to emulate this behavior of
> creating an IOMMU group on a virtual device and then providing a vfio
> IOMMU backend tailored to the sort of isolation they provide, which
> won't necessarily be fully compatible with the IOMMU API.
>
> The solution here is to use the existing iommudata interface to IOMMU
> groups, which allows us to easily identify the fake groups we've
> created for noiommu purposes. The iommudata we set is purely
> arbitrary since we're only comparing the address, so we use the
> address of the noiommu switch itself.
>
> Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> Fixes: 03a76b60f8ba ("vfio: Include No-IOMMU mode")
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Thanks!
--
Alexey
next prev parent reply other threads:[~2016-01-25 0:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-22 17:23 Alex Williamson
2016-01-25 0:20 ` Alexey Kardashevskiy [this message]
2016-01-27 13:21 ` Burakov, Anatoly
2016-01-27 13:41 ` Santosh Shukla
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