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Date: Fri, 30 Mar 2012 22:27:28 +0300
From: Alon Levy <alevy@redhat.com>
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Subject: Re: [Qemu-devel] [RFC] qxl: don't panic on phys2virt
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To: Gerd Hoffmann <kraxel@redhat.com>
Cc: qemu-devel@nongnu.org

On Fri, Mar 30, 2012 at 10:09:42AM +0200, Gerd Hoffmann wrote:
> On 03/29/12 22:56, Alon Levy wrote:
> > Issues a qxl_guest_bug from qxl_phys2virt. Everywhere else will fail.
> 
> Nice start (there are more guest-triggerable asserts to be fixed this way).
> 
> > qxl_phys2virt requires an additional argument because all it's possible
> > return values are legit (well, I could use the fact it returns a pointer
> > so it should be word aligned but I don't want to go there, this is
> > totally internal).
> 
> Really?  What is bad with returning and checking for NULL?  Guest
> memslots are backed by guest ram and should never ever resolve to a NULL
> pointer in qemu's process address space.

phys2virt actually returns an offset, not a real pointer iirc. I'll
check it again.

> 
> cheers,
>   Gerd