On 06/28/2010 01:02 PM, Xiao Guangrong wrote:
Avi Kivity wrote:
Instead of adding a new bit, can you encode the protection in the direct
sp's access bits? So we'll have one sp for read-only or
writeable-but-not-dirty small pages, and another sp for
writeable-and-dirty small pages.
It looks like it can't solve all problems, it fix the access corrupted,
but will cause D bit losed:
mapping A and mapping B both are writable-and-dirty, when mapping A write
#PF occurs, the mapping is writable, then we can't set B's D bit anymore.
If B is writeable-and-dirty, then it's D bit is already set, and we
don't need to do anything.
If B is writeable-and-clean, then we'll have an spte pointing to a
read-only sp, so we'll get a write fault on access and an opportunity to
set the D bit.
Anyway, i think we should re-intall the mapping when the state is changed. :-(
When the gpte is changed from read-only to writeable or from clean to
dirty, we need to update the spte, yes. But that's true for other sptes
as well, not just large gptes.
--
error compiling committee.c: too many arguments to function
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