From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Cc: Ian.Jackson@eu.citrix.com, jeremy@goop.org,
xen-devel@lists.xensource.com, keir@xen.org
Subject: Re: [PATCH 2/2] xen/gnt{dev, alloc}: reserve event channels for notify
Date: Tue, 25 Oct 2011 15:51:56 -0400 [thread overview]
Message-ID: <20111025195156.GC13644@phenom.dumpdata.com> (raw)
In-Reply-To: <4EA710EB.3030809@tycho.nsa.gov>
> That same SELinux category-based isolation mechanism is also a good solution for xen
> qemu-dm processes, although moving qemu to a stubdom provides better isolation since
> SELinux currently cannot talk to XSM to determine what domains a particular qemu-dm
> process should be able to manipulate.
<nods>
>
> Only allowing event channels allocated by userspace to be used in gnt* notify is
> a good idea, since there's no reason for userspace to need to manipulate an event
> channel set up by the kernel.
>
.. snip..
> >
> > How would that work when the IRQ subsystem (so everything is setup in the kernel)
> > gets an event? Would the refcount be for that -1.. oh. You would only set
> > the refcnt when the _get/_put calls are made and not when in-kernel calls to setup
> > IRQs are done?
> >
>
> Right. The reference count would be a dual-purpose field indicating if the event
> channel is kernel-internal (value -1) or userspace-visible (reference count > 0).
> New event channels would start out at -1, and evtchn.c would change them to 1.
The tricky bit is going to be with the xen_free_irq which might have to deal with kernel
events and grantdev events... oh wait, the event_put is going to decrement it and then
call xen_free_irq, so that will come out to be the right number.
Looking forward to the patches! Thanks for doing this work.
next prev parent reply other threads:[~2011-10-25 19:51 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-16 21:14 [PATCH 0/2] Add reference counting to grant notify ioctls Daniel De Graaf
2011-09-16 21:14 ` [PATCH 1/2] xen/event: Add reference counting to event channel Daniel De Graaf
2011-09-17 4:50 ` Jeremy Fitzhardinge
2011-09-17 6:11 ` Keir Fraser
2011-09-19 15:50 ` Daniel De Graaf
2011-09-19 16:22 ` Jeremy Fitzhardinge
2011-09-19 17:53 ` Daniel De Graaf
2011-09-16 21:14 ` [PATCH 2/2] xen/gnt{dev, alloc}: reserve event channels for notify Daniel De Graaf
2011-10-18 21:04 ` [PATCH v2 0/2] Add reference counting to grant notify ioctls Daniel De Graaf
2011-10-18 21:04 ` [PATCH 1/2] xen/event: Add reference counting to event channel Daniel De Graaf
2011-10-19 9:20 ` Ian Campbell
2011-10-24 20:22 ` Konrad Rzeszutek Wilk
2011-10-24 22:20 ` Daniel De Graaf
2011-10-25 19:05 ` Konrad Rzeszutek Wilk
2011-10-25 8:17 ` Ian Campbell
2011-10-25 19:09 ` Konrad Rzeszutek Wilk
2011-10-25 20:44 ` Ian Campbell
2011-10-18 21:04 ` [PATCH 2/2] xen/gnt{dev, alloc}: reserve event channels for notify Daniel De Graaf
2011-10-19 9:24 ` Ian Campbell
2011-10-19 14:23 ` Daniel De Graaf
2011-10-19 14:45 ` [PATCH 2/2] xen/gnt{dev,alloc}: " Ian Campbell
2011-10-24 20:57 ` [PATCH 2/2] xen/gnt{dev, alloc}: " Konrad Rzeszutek Wilk
2011-10-24 22:01 ` Daniel De Graaf
2011-10-25 19:02 ` Konrad Rzeszutek Wilk
2011-10-25 19:41 ` Daniel De Graaf
2011-10-25 19:51 ` Konrad Rzeszutek Wilk [this message]
2011-10-25 20:27 ` Ian Campbell
2011-10-25 20:42 ` Daniel De Graaf
2011-10-25 20:50 ` Ian Campbell
2011-10-25 21:07 ` Daniel De Graaf
2011-10-26 15:47 ` [PATCH v3 0/3] Add reference counting to grant notify ioctls Daniel De Graaf
2011-10-26 15:47 ` [PATCH 1/3] xen/event: Add reference counting to event channels Daniel De Graaf
2011-10-26 16:51 ` Ian Campbell
2011-10-26 16:57 ` Ian Campbell
2011-10-26 17:28 ` Daniel De Graaf
2011-10-27 9:03 ` Ian Campbell
2011-10-26 18:42 ` [PATCH 1/3 v3.2] " Daniel De Graaf
2011-10-26 15:47 ` [PATCH 2/3] xen/gntalloc: Change gref_lock to a mutex Daniel De Graaf
2011-10-26 15:47 ` [PATCH 3/3] xen/gnt{dev, alloc}: reserve event channels for notify Daniel De Graaf
2011-10-27 21:58 ` [PATCH v4 0/3] Add reference counting to grant notify ioctls Daniel De Graaf
2011-10-27 21:58 ` [PATCH 1/3] xen/event: Add reference counting to event channels Daniel De Graaf
2011-10-27 21:58 ` [PATCH 2/3] xen/gntalloc: Change gref_lock to a mutex Daniel De Graaf
2011-10-27 21:58 ` [PATCH 3/3] xen/gnt{dev, alloc}: reserve event channels for notify Daniel De Graaf
2011-11-11 20:33 ` [PATCH v4 0/3] Add reference counting to grant notify ioctls Konrad Rzeszutek Wilk
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