From: David Gibson <david@gibson.dropbear.id.au>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] vfio powerpc: implement IOMMU driver for VFIO
Date: Thu, 21 Mar 2013 12:55:41 +1100 [thread overview]
Message-ID: <20130321015541.GA13838@truffula.fritz.box> (raw)
In-Reply-To: <1363812324.24132.544.camel@bling.home>
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On Wed, Mar 20, 2013 at 02:45:24PM -0600, Alex Williamson wrote:
> On Tue, 2013-03-19 at 18:08 +1100, Alexey Kardashevskiy wrote:
> > VFIO implements platform independent stuff such as
> > a PCI driver, BAR access (via read/write on a file descriptor
> > or direct mapping when possible) and IRQ signaling.
> >
> > The platform dependent part includes IOMMU initialization
> > and handling. This patch implements an IOMMU driver for VFIO
> > which does mapping/unmapping pages for the guest IO and
> > provides information about DMA window (required by a POWERPC
> > guest).
> >
> > The counterpart in QEMU is required to support this functionality.
> >
> > Changelog:
> > * documentation updated
> > * containter enable/disable ioctls added
> > * request_module(spapr_iommu) added
> > * various locks fixed
> >
> > Cc: David Gibson <david@gibson.dropbear.id.au>
> > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> > ---
>
>
> Looking pretty good. There's one problem with the detach_group,
> otherwise just some trivial comments below. What's the status of the
> tce code that this depends on? Thanks,
[snip]
> > +static void tce_iommu_detach_group(void *iommu_data,
> > + struct iommu_group *iommu_group)
> > +{
> > + struct tce_container *container = iommu_data;
> > + struct iommu_table *tbl = iommu_group_get_iommudata(iommu_group);
> > +
> > + BUG_ON(!tbl);
> > + mutex_lock(&container->lock);
> > + if (tbl != container->tbl) {
> > + pr_warn("tce_vfio: detaching group #%u, expected group is #%u\n",
> > + iommu_group_id(iommu_group),
> > + iommu_group_id(tbl->it_group));
> > + } else if (container->enabled) {
> > + pr_err("tce_vfio: detaching group #%u from enabled container\n",
> > + iommu_group_id(tbl->it_group));
>
> Hmm, something more than a pr_err needs to happen here. Wouldn't this
> imply a disable and going back to an unprivileged container?
Uh, no. I think the idea here is that we use the enable/disable
semantic to address some other potential problems. Specifically,
sidestepping the problems of what happens if you change the
container's capabilities by adding/removing groups while in the middle
of using it. So the point is that the detach fails when the group is
enabled, rather than implicitly doing anything.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2013-03-21 3:02 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-11 11:54 [PATCH 0/2] vfio on power Alexey Kardashevskiy
2013-02-11 11:54 ` [PATCH 1/2] vfio powerpc: enabled on powernv platform Alexey Kardashevskiy
2013-02-11 22:16 ` Alex Williamson
2013-02-11 23:19 ` Alexey Kardashevskiy
2013-02-12 0:01 ` Alex Williamson
2013-02-25 2:21 ` Paul Mackerras
2013-02-11 11:54 ` [PATCH 2/2] vfio powerpc: implemented IOMMU driver for VFIO Alexey Kardashevskiy
2013-02-11 22:17 ` Alex Williamson
2013-02-11 23:45 ` Alexey Kardashevskiy
2013-02-12 0:25 ` Alex Williamson
2013-02-12 4:06 ` [PATCH] iommu: making IOMMU sysfs nodes API public Alexey Kardashevskiy
2013-02-12 5:07 ` Alex Williamson
2013-02-12 14:42 ` Alexey Kardashevskiy
2013-02-12 17:15 ` Alex Williamson
2013-02-18 6:15 ` Alexey Kardashevskiy
2013-02-19 5:24 ` Alex Williamson
2013-02-19 5:48 ` Alexey Kardashevskiy
2013-02-19 19:53 ` Alex Williamson
2013-02-19 7:38 ` David Gibson
2013-02-19 20:11 ` Alex Williamson
2013-02-20 2:31 ` Alexey Kardashevskiy
2013-02-20 3:47 ` Alex Williamson
2013-02-20 4:20 ` Alexey Kardashevskiy
2013-02-20 4:33 ` Alex Williamson
2013-03-18 3:53 ` Alexey Kardashevskiy
2013-03-19 2:40 ` Alex Williamson
2013-03-19 7:08 ` [PATCH] vfio powerpc: implement IOMMU driver for VFIO Alexey Kardashevskiy
2013-03-20 20:45 ` Alex Williamson
2013-03-21 0:57 ` Alexey Kardashevskiy
2013-03-21 1:29 ` Alex Williamson
2013-03-21 1:55 ` David Gibson [this message]
2013-03-21 3:16 ` Alex Williamson
2013-03-25 2:12 ` David Gibson
2013-02-22 0:04 ` [PATCH] iommu: making IOMMU sysfs nodes API public David Gibson
2013-02-22 4:11 ` Alex Williamson
2013-02-25 0:03 ` David Gibson
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