Re: Linux Xen PV CPA W^X violation false-positives

[Anthony PERARD <anthony.perard@xxxxxxxxx>]

On Mon, Apr 08, 2024 at 11:22:59AM +0100, Anthony PERARD wrote:
> On Thu, Mar 28, 2024 at 02:00:14PM +0100, Jürgen Groß wrote:
> > Hi Jason,
> > 
> > On 28.03.24 02:24, Jason Andryuk wrote:
> > > On Wed, Mar 27, 2024 at 7:46 AM Jürgen Groß <jgross@xxxxxxxx> wrote:
> > > > 
> > > > On 24.01.24 17:54, Jason Andryuk wrote:
> > > > > +
> > > > > +                     return new;
> > > > > +             }
> > > > > +     }
> > > > > +
> > > > >        end = start + npg * PAGE_SIZE - 1;
> > > > >        WARN_ONCE(1, "CPA detected W^X violation: %016llx -> %016llx 
> > > > > range: 0x%016lx - 0x%016lx PFN %lx\n",
> > > > >                  (unsigned long long)pgprot_val(old),
> > > > 
> > > > Jason, do you want to send a V2 with your Signed-off, or would you like 
> > > > me to
> > > > try upstreaming the patch?
> > > 
> > > Hi Jürgen,
> > > 
> > > Yes, please upstream your approach.  I wasn't sure how to deal with
> > > it, so it was more of a bug report.
> > 
> > The final solution was a bit more complicated, as there are some
> > corner cases to be considered. OTOH it is now complete by looking
> > at all used translation entries.
> > 
> > Are you able to test the attached patch? I don't see the original
> > issue and can only verify the patch doesn't cause any regression.
> > 
> > 
> > Juergen
> 
> Hi Jürgen,
> 
> I gave a try to the patch in this email with osstest, and I can't find a
> single "CPA detected W^X violation" log entry, when there's seems to be
> many in osstest in general, from dom0 it seems as it's on the host
> serial console usually.
> 
> http://logs.test-lab.xenproject.org/osstest/logs/185252/
> 
> If you look in several "serial-$host.log*" files, there will be the
> "CPA detected" message, but they happen on previous test run.
> 
> I did an other smaller run before this one, and same thing:
> http://logs.test-lab.xenproject.org/osstest/logs/185186/
> 
> And this other run as well, which I failed to setup properly with lots
> of broken, but no failure due to the patch and I can't find any "CPA
> detected" messages.
> http://logs.test-lab.xenproject.org/osstest/logs/185248/
> 
> I hope that helps?

BTW, I did apply the patch to Linux 6.1:
https://xenbits.xen.org/gitweb/?p=people/aperard/linux.git;a=shortlog;h=refs/heads/9b5a105a-650c-4b33-9f4e-03612fb6701c@xxxxxxxx

-- 
Anthony PERARD