Re: [Xen-devel] [PATCH 00/11] Alternate p2m: support multiple copies of host p2m

[Ed White <edmund.h.white@xxxxxxxxx>]

On 01/15/2015 11:35 PM, Jan Beulich wrote:
>>>> On 15.01.15 at 18:28, <edmund.h.white@xxxxxxxxx> wrote:
>> On 01/15/2015 12:16 AM, Jan Beulich wrote:
>>>>>> On 14.01.15 at 18:35, <edmund.h.white@xxxxxxxxx> wrote:
>>>> Right. The key observation is that at any single point in time, a given
>>>> hardware thread can be fetching an instruction or reading data, but not
>>>> both.
>>>
>>> Fine, as long as an instruction reading itself isn't going to lead to
>>> a live lock.
>>
>> That's not how the hardware works. By the time you figure out that the
>> instruction you are executing reads memory, the instruction itself has
>> been fetched and decoded. That won't happen again during this execution.
>>
>> That's true for every CPU I've ever seen, not just Intel ones.
> 
> Certainly not if either the fetch or the data read faults/vmexits.

Sorry about that. As I explained, I rushed off a response before
actually engaging my brain.

Ed


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