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Re: [Xen-devel] [PATCH v2 1/2] x86/vmx: Introduce a bitfield structure for EPT_VIOLATION EXIT_QUALIFICATIONs

On 08/02/17 12:30, Jan Beulich wrote:
>>>> On 08.02.17 at 12:56, <andrew.cooper3@xxxxxxxxxx> wrote:
>> On 08/02/17 11:53, Jan Beulich wrote:
>>>>>> On 08.02.17 at 11:44, <andrew.cooper3@xxxxxxxxxx> wrote:
>>>> On 08/02/17 10:42, Andrew Cooper wrote:
>>>>> This results in rather more readable code.  No functional change.
>>>>> All fields currently specified are included, but commented out as no 
>>>>> support
>>>>> for their use is present.
>>>> Apologies - sent a slightly stale version of the patch.  I have dropped
>>>> this paragraph from the commit message, but the code is correct for v2.
>>> With that and despite ...
>>>>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>>>> ---
>>>>> CC: Jan Beulich <JBeulich@xxxxxxxx>
>>>>> CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
>>>>> CC: Kevin Tian <kevin.tian@xxxxxxxxx>
>>>>> v2:
>>>>>  * Use a transparent union rather than modifying the caller of
>>>>>    ept_handle_violation()
>>>>>  * Drop the extranious commented out bitfield names, but keep 
>>>>> eff_user_exec so
>>>>>    gla_{valid,fault} are appropriately located.
>>> ... this not really being what Kevin and I had asked for,
>>> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
>> In which case I am confused?  What were you asking for if it isn't this?
> The request was to keep commented out just the one field use of
> which needs enabling work elsewhere, but present as normal
> (named) fields the three higher ones we currently lack.

All of the originally commented out bits need further work in Xen to enable.

The higher bits are undefined if advanced EPT Violation VM-exit
information is unavailable in hardware, meaning that they are not safe
to use currently.


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