Hi Linus,
On Tue, Jan 16, 2018 at 10:59:01AM -0800, Linus Torvalds wrote:
> Yes, I'm very happy to see that this is actually not nearly as bad as
> I feared it might be,
Yeah, I was looking at the original PTI patches and my impression was
that a lot of the complicated stuff (like setting up the cpu_entry_area)
was already in there for 32 bit too. So it was mostly about the entry
code and some changes to the 32bit page-table code.
> Some of those #ifdef's in the PTI code you added might want more
> commentary about what the exact differences are. And maybe they could
> be done more cleanly with some abstraction. But nothing looked
> _horrible_.
I'll add more comments and better abstraction, Dave has already
suggested some improvements here. Reading some of my comments again,
they need a rework anyway.
> .. and please run all the segment and syscall selfchecks that Andy has written.
Didn't know about them yet, thanks. I will run them too in my testing
> Xen PV and PTI don't work together even on x86-64 afaik, the Xen
> people apparently felt it wasn't worth it. See the
>
> if (hypervisor_is_type(X86_HYPER_XEN_PV)) {
> pti_print_if_insecure("disabled on XEN PV.");
> return;
> }
>
> in pti_check_boottime_disable().
But I might have broken something for them anyway, honestly I didn't pay
much attention to the XEN_PV case as I was trying to get it running
here. My hope is that someone who knows Xen better than I do will help
out :)
Regards,
Joerg
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