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Date: Wed, 30 Mar 2011 18:09:53 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 3/3] vhost: roll our own cpu map variant
Message-ID: <20110330160953.GB26439@redhat.com>
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: kwolf@redhat.com, gleb@redhat.com, Jes Sorensen <Jes.Sorensen@redhat.com>, Jason Wang <jasowang@redhat.com>, qemu-devel@nongnu.org, armbru@redhat.com, Christoph Hellwig <hch@infradead.org>, Alex Williamson <alex.williamson@redhat.com>, Amit Shah <amit.shah@redhat.com>

On Tue, Mar 29, 2011 at 11:53:54AM +0100, Stefan Hajnoczi wrote:
> On Mon, Mar 28, 2011 at 10:14 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> > vhost used cpu_physical_memory_map to get the
> > virtual address for the ring, however,
> > this will exit on an illegal RAM address.
> > Since the addresses are guest-controlled, we
> > shouldn't do that.
> >
> > Switch to our own variant that uses the vhost
> > tables and returns an error instead of exiting.
> 
> We should make all of QEMU more robust instead of just vhost.  Perhaps
> introduce cpu_physical_memory_map_nofail(...) that aborts like the
> current cpu_physical_memory_map() implementation and then make non-hw/
> users call that one.  hw/ users should check for failure.
> 
> Stefan

Yea, well ... at least vhost-net wants to also check
it is given a ram address, not some other physical address.
We could generally replace the memory management in vhost-net
by some other logic, when that's done this one can
go away as well.

-- 
MST