On 08/25/2011 05:06 PM, Avi Kivity wrote:
On 08/25/2011 04:21 PM, Marcelo Tosatti wrote:
On Thu, Aug 25, 2011 at 07:42:10AM +0300, Avi Kivity wrote:
> On 08/25/2011 05:04 AM, Marcelo Tosatti wrote:
> >>
> >> It could increase the flood count independently of the
accessed bit of
> >> the spte being updated, zapping after 3 attempts as it is now.
> >>
> >> But additionally reset the flood count if the gpte appears to
be valid
> >> (points to an existant gfn if the present bit is set, or if
its zeroed).
> >
> >Well not zero, as thats a common pattern for non ptes.
> >
>
> On 32-bit with 4GB RAM, practically anything is a valid gpte.
The following could be required to consider a valid gpte, for write
flood detection purposes:
- Must be present.
- PageCacheDisable must be unset.
- PageWriteThrough must be unset.
Unless the guest is using PAT.
And not swapping.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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