On 11/17/2015 02:37 PM, Boris Ostrovsky wrote:
On 11/17/2015 02:16 PM, Andy Lutomirski wrote:
Looks good to me. Does Xen have any sysexit/sysret32 equivalent to
return to 32-bit user mode? If so, it could be worth trying to wire
it up by patching the jz instead of the test instruction.
We ca
On 11/17/2015 02:16 PM, Andy Lutomirski wrote:
Looks good to me. Does Xen have any sysexit/sysret32 equivalent to
return to 32-bit user mode? If so, it could be worth trying to wire
it up by patching the jz instead of the test instruction.
We can actually make patching a little bit more effic
On Tue, Nov 17, 2015 at 11:29 AM, Andrew Cooper
wrote:
> On 17/11/15 19:16, Andy Lutomirski wrote:
>> On Tue, Nov 17, 2015 at 11:12 AM, Andrew Cooper
>> wrote:
>>> On 17/11/15 18:49, Andy Lutomirski wrote:
On Nov 17, 2015 6:40 AM, "Boris Ostrovsky"
wrote:
> On 11/16/2015 04:55 PM,
On 17/11/15 19:16, Andy Lutomirski wrote:
> On Tue, Nov 17, 2015 at 11:12 AM, Andrew Cooper
> wrote:
>> On 17/11/15 18:49, Andy Lutomirski wrote:
>>> On Nov 17, 2015 6:40 AM, "Boris Ostrovsky"
>>> wrote:
On 11/16/2015 04:55 PM, H. Peter Anvin wrote:
> On 11/16/15 12:22, Borislav Petkov
On Tue, Nov 17, 2015 at 11:16:11AM -0800, Andy Lutomirski wrote:
> Works for me, too, although seeing "xen_pv_host" in the Linux cpu
> features would be very strange indeed :)
That feature would be, of course, *not* in /proc/cpuinfo.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails wh
On Tue, Nov 17, 2015 at 11:12 AM, Andrew Cooper
wrote:
> On 17/11/15 18:49, Andy Lutomirski wrote:
>> On Nov 17, 2015 6:40 AM, "Boris Ostrovsky"
>> wrote:
>>> On 11/16/2015 04:55 PM, H. Peter Anvin wrote:
On 11/16/15 12:22, Borislav Petkov wrote:
> Huh, so what's wrong with a jump:
On 17/11/15 18:49, Andy Lutomirski wrote:
> On Nov 17, 2015 6:40 AM, "Boris Ostrovsky" wrote:
>> On 11/16/2015 04:55 PM, H. Peter Anvin wrote:
>>> On 11/16/15 12:22, Borislav Petkov wrote:
Huh, so what's wrong with a jump:
jmp 1f
swapgs
1:
>>>
On Nov 17, 2015 6:40 AM, "Boris Ostrovsky" wrote:
>
> On 11/16/2015 04:55 PM, H. Peter Anvin wrote:
>>
>> On 11/16/15 12:22, Borislav Petkov wrote:
>>>
>>> Huh, so what's wrong with a jump:
>>>
>>> jmp 1f
>>> swapgs
>>> 1:
>>>
>> What is the point of that jump?
>>
If i
On 11/16/2015 04:55 PM, H. Peter Anvin wrote:
On 11/16/15 12:22, Borislav Petkov wrote:
Huh, so what's wrong with a jump:
jmp 1f
swapgs
1:
What is the point of that jump?
If it would make you feel better, it could be X86_BUG_XENPV :-p
That doesn't matter - I just do
On 11/16/2015 09:04 PM, Andy Lutomirski wrote:
> On Mon, Nov 16, 2015 at 1:03 PM, Konrad Rzeszutek Wilk
> wrote:
>> On Mon, Nov 16, 2015 at 12:50:19PM -0800, Andy Lutomirski wrote:
>>> On Mon, Nov 16, 2015 at 12:48 PM, Boris Ostrovsky
>>> wrote:
On 11/16/2015 03:22 PM, Borislav Petkov wrot
On 11/16/15 12:22, Borislav Petkov wrote:
>
> Huh, so what's wrong with a jump:
>
> jmp 1f
> swapgs
> 1:
>
What is the point of that jump?
>> If it would make you feel better, it could be X86_BUG_XENPV :-p
>
> That doesn't matter - I just don't want to open the flood gates o
On Mon, Nov 16, 2015 at 1:03 PM, Konrad Rzeszutek Wilk
wrote:
> On Mon, Nov 16, 2015 at 12:50:19PM -0800, Andy Lutomirski wrote:
>> On Mon, Nov 16, 2015 at 12:48 PM, Boris Ostrovsky
>> wrote:
>> > On 11/16/2015 03:22 PM, Borislav Petkov wrote:
>> >>
>> >> On Mon, Nov 16, 2015 at 12:11:11PM -0800,
On Mon, Nov 16, 2015 at 12:50:19PM -0800, Andy Lutomirski wrote:
> On Mon, Nov 16, 2015 at 12:48 PM, Boris Ostrovsky
> wrote:
> > On 11/16/2015 03:22 PM, Borislav Petkov wrote:
> >>
> >> On Mon, Nov 16, 2015 at 12:11:11PM -0800, Andy Lutomirski wrote:
> >>
> >>> Are there really multiple feature b
On Mon, Nov 16, 2015 at 12:50:19PM -0800, Andy Lutomirski wrote:
> (In fact, I'm slowly working on removing KVM_GUEST's dependency on
> PARAVIRT.)
Good! The hope that we'll be able to remove paravirt one day is != 0
again.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you repl
On Mon, Nov 16, 2015 at 12:48 PM, Boris Ostrovsky
wrote:
> On 11/16/2015 03:22 PM, Borislav Petkov wrote:
>>
>> On Mon, Nov 16, 2015 at 12:11:11PM -0800, Andy Lutomirski wrote:
>>
>>> Are there really multiple feature bits for this stuff? I'd like to
>>> imagine that the entry code is all either
On 11/16/2015 03:22 PM, Borislav Petkov wrote:
On Mon, Nov 16, 2015 at 12:11:11PM -0800, Andy Lutomirski wrote:
Are there really multiple feature bits for this stuff? I'd like to
imagine that the entry code is all either Xen PV or native/PVH/PVHVM
-- i.e. I assumed that PVH works like native f
On 11/16/2015 02:03 PM, Andy Lutomirski wrote:
It's still a waste of effort, though. Also, I'd eventually like the
number of places in Xen code in which rsp/esp is invalid to be exactly
zero, and this approach makes this harder or even impossible.
That's what PVH is going to do.
Does PVH h
On Mon, Nov 16, 2015 at 12:11:11PM -0800, Andy Lutomirski wrote:
> On Mon, Nov 16, 2015 at 11:59 AM, Borislav Petkov wrote:
> > On Mon, Nov 16, 2015 at 11:03:22AM -0800, Andy Lutomirski wrote:
> >
> >> ...
> >> The reader surely doesn't remember that this isn't guaranteed to be a
> >> swapgs instr
On Mon, Nov 16, 2015 at 11:59 AM, Borislav Petkov wrote:
> On Mon, Nov 16, 2015 at 11:03:22AM -0800, Andy Lutomirski wrote:
>
>> ...
>> The reader surely doesn't remember that this isn't guaranteed to be a
>> swapgs instruction on native. Using:
>>
>> ALTERNATIVE "swapgs" "" X86_FEATURE_XENPV
>>
On Mon, Nov 16, 2015 at 11:03:22AM -0800, Andy Lutomirski wrote:
> ...
> The reader surely doesn't remember that this isn't guaranteed to be a
> swapgs instruction on native. Using:
>
> ALTERNATIVE "swapgs" "" X86_FEATURE_XENPV
>
> would be safer (it would get rid of the SWAPGS_UNSAFE_STACK mes
On Mon, Nov 16, 2015 at 8:25 AM, Boris Ostrovsky
wrote:
> On 11/15/2015 01:02 PM, Andy Lutomirski wrote:
>>
>> On Nov 13, 2015 5:23 PM, "Boris Ostrovsky"
>> wrote:
>>>
>>>
>>>
>>> On 11/13/2015 06:26 PM, Andy Lutomirski wrote:
On Fri, Nov 13, 2015 at 3:18 PM, Boris Ostrovsky
wrote
On 11/15/2015 01:02 PM, Andy Lutomirski wrote:
On Nov 13, 2015 5:23 PM, "Boris Ostrovsky" wrote:
On 11/13/2015 06:26 PM, Andy Lutomirski wrote:
On Fri, Nov 13, 2015 at 3:18 PM, Boris Ostrovsky
wrote:
After 32-bit syscall rewrite, and specifically after commit 5f310f739b4c
("x86/entry/32: R
On Nov 13, 2015 5:23 PM, "Boris Ostrovsky" wrote:
>
>
>
> On 11/13/2015 06:26 PM, Andy Lutomirski wrote:
>>
>> On Fri, Nov 13, 2015 at 3:18 PM, Boris Ostrovsky
>> wrote:
>>>
>>> After 32-bit syscall rewrite, and specifically after commit 5f310f739b4c
>>> ("x86/entry/32: Re-implement SYSENTER usin
On 11/13/2015 06:26 PM, Andy Lutomirski wrote:
On Fri, Nov 13, 2015 at 3:18 PM, Boris Ostrovsky
wrote:
After 32-bit syscall rewrite, and specifically after commit 5f310f739b4c
("x86/entry/32: Re-implement SYSENTER using the new C path"), the stack
frame that is passed to xen_sysexit is no lon
On Fri, Nov 13, 2015 at 3:18 PM, Boris Ostrovsky
wrote:
> After 32-bit syscall rewrite, and specifically after commit 5f310f739b4c
> ("x86/entry/32: Re-implement SYSENTER using the new C path"), the stack
> frame that is passed to xen_sysexit is no longer a "standard" one (i.e.
> it's not pt_regs)
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