Re: [PATCH v2 3/10] KVM: MMU: fix direct sp's access corruptted
From: Avi Kivity
Date: Mon Jun 28 2010 - 07:13:32 EST
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 directIt looks like it can't solve all problems, it fix the access corrupted,
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.
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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