RE: [Xen-devel] [PATCh][VT] do_block upon hlt instruction

["Nakajima, Jun" <jun.nakajima@xxxxxxxxx>]

Keir Fraser wrote:
> On 21 Sep 2005, at 17:39, Nakajima, Jun wrote:
> 
>> At the same time, it disables the monitor/mwait
>> feature as it's not feasible to implement for vcpu.
> 
> Why is that?
> 
>   -- Keir

The major usage model of MONITOR/MWAIT is, the MONITOR instruction
specifies the address to watch, and MWAIT waits for any modification to
that address:
- The current VMX does not support VMExit upon the MONITOR instrucion,
so 
  we don't know which address the guest wants to minitor.
- even if it did, it's not efficient to check if modification is made 
  to that address range in shadow (so that we can unblock the guest from
  MWAIT).

Jun
---
Intel Open Source Technology Center

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