Re: [Qemu-devel] [PATCH] walk_pml4e(): fix abort on bad PML4E/PDPTE/PDE/PTE addresses

[Luiz Capitulino <lcapitulino@redhat.com>]

On Thu, 30 May 2013 16:10:28 +0200
Andreas Färber <afaerber@suse.de> wrote:

> Am 30.05.2013 15:16, schrieb Luiz Capitulino:
> > On Thu, 30 May 2013 15:16:18 +0200
> > Laszlo Ersek <lersek@redhat.com> wrote:
> > 
> >> On 05/30/13 14:59, Luiz Capitulino wrote:
> >>> On Tue, 28 May 2013 14:19:22 -0400
> >>> Luiz Capitulino <lcapitulino@redhat.com> wrote:
> >>>
> >>>> The code used to walk IA-32e page-tables, and possibly PAE page-tables,
> >>>> uses the bit mask ~0xfff to get the next PML4E/PDPTE/PDE/PTE address.
> >>>>
> >>>> However, as we use a uint64_t to store the resulting address, that mask
> >>>> gets expanded to 0xfffffffffffff000 which not only ends up selecting
> >>>> reserved bits but also selects the XD bit (execute-disable) which
> >>>> happens to be enabled by Windows 8, causing qemu_get_ram_ptr() to abort.
> >>>>
> >>>> This commit fixes that problem by replacing ~0xfff by a correct mask
> >>>> that only selects the address bit range (ie. bits 51:12).
> >>>>
> >>>> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> >>>
> >>> Ping? Wen?
> >>>
> >>> Would be nice get a Reviewed-by before merging...
> >>
> >> I didn't miss your submission and did find it OK, I just felt unsure
> >> about stating so, because "simple" patches like this are prime territory
> >> to burn someone's R-b's worth (ie. to expose a reviewer's lack of
> >> information / experience). But hey, what can I lose? The patch does look
> >> good to me, so
> > 
> > Thank you Laszlo! It's also new territory for me, that's why I'm asking
> > for reviews (otherwise I'd just sneak it in some pull request :-)
> 
> Luiz, you aware aware that I have another fix by Nuohan queued that
> seemed orthogonal?

Yes, they should be orthogonal.

> If someone reviews my refactoring series (which
> resent that patch) I would like to send out a PULL for that rather soon,
> since it blocks further CPU work. I would then include your fix as well
> to avoid merge conflicts.

Thanks, although I was going to include it in my tomorrow's QMP pull
request. Will this disturb your work?