Re: [Xen-devel] xc_evtchn_status fails with EFAULT on HVM, the same on PV works

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Fri, Jan 13, 2017 at 06:37:06PM +0000, Andrew Cooper wrote:
> On 13/01/17 18:32, Marek Marczykowski-Górecki wrote:
> > On Fri, Jan 13, 2017 at 06:15:35PM +0000, Andrew Cooper wrote:
> >> Can you get the result of this piece of debugging in the failure case?
> > I've got this:
> > ** d4v0 CFG(24, 00007f794bd07004, 1) = 24
> 
> Silly question (and I really hope the answer isn't yes, but I have a
> sinking feeling it is).
> 
> Is the guest in question using SMAP? If so, does disabling SMAP fix the
> problem?

How can I check that? If looking at 0x200000 CR4 bit in `xl debug-keys
v` output enough, then yes - it's enabled. And booting hypervisor with
smap=0 "fixed" the problem.
So, what would be the correct solution? I'd prefer not to disable SMAP
"just" for this reason...

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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