Re: [Xen-devel] [PATCH] vm_event: Record FS_BASE/GS_BASE during events

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 02/11/2016 09:55 PM, Andrew Cooper wrote:
> On 11/02/16 19:54, Razvan Cojocaru wrote:
>> On 02/11/2016 09:51 PM, Tamas K Lengyel wrote:
>>> While the public vm_event header specifies fs_base/gs_base as registers that
>>> should be recorded for each event, that hasn't actually been the case. In
>>> this patch we remedy the issue.
>>>
>>> Signed-off-by: Tamas K Lengyel <tlengyel@xxxxxxxxxxx>
>>> Cc: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
>>> Cc: Keir Fraser <keir@xxxxxxx>
>>> Cc: Jan Beulich <jbeulich@xxxxxxxx>
>>> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>> ---
>>>  xen/arch/x86/hvm/event.c | 9 ++++++++-
>>>  1 file changed, 8 insertions(+), 1 deletion(-)
>> Fair enough.
>>
>> Acked-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
> 
> Oops.
> 
> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

This has actually been intentional, in that we've only needed those
fields for EPT events, and thought that not filling what's not needed
until it's needed would save a tiny bit of hypervisor processing time.
They are being filled in only for page fault events at the moment.

I believe it's been discussed at the time. We still don't need those
coming with the events that use hvm_event_fill_regs(), but if Tamas
needs them then by all means.


Thanks,
Razvan

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