Re: [Xen-devel] [PATCH] VMX: Corrections to XSA-60 fix

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.11.13 at 12:44, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
>>>> On 07.11.13 at 12:15, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>> On 07/11/13 11:09, Jan Beulich wrote:
>>>>>> On 07.11.13 at 11:56, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>>>> This patch is somewhat RFC, partly because I have only compile-tested it, 
>>>> and
>>>> because of a few further questions.
>>>>
>>>> 1) Are there any other places other than unmap_domain_page() we might want 
>> to
>>>>    put hooks? Any well behaved access should use {map,unmap}_domain_page() 
>> as
>>>>    far as I am aware.
>>> Any writes done through map_domain_page_global() mappings.
>> 
>> Ooh yes.  I will hook unmap_domain_page_global() as well
> 
> That won't suffice (and is really the wrong place) - global mappings
> are usually used in order to be able to write to the same area over
> an extended period of time. I.e. here you'd need to hunt down the
> individual writes (hopefully not too many, since quite a few of the
> mappings involved are r/o).

Which would get pretty ugly:
- guest_walk_tables() (accumulating set_ad_bits() results)
- all writes through vcpu_info()
- event_fifo.c would need this scattered around
- hvm_load_segment_selector()'s setting of the accessed bit
- hvm_task_switch()'s handling of the busy bit
- all the nested HVM code's writes through ->nv_vvmcx

Jan


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