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xen-devel
Re: [Xen-devel] Switching from writeable pagetable to shadowlog-dirtyat
On 14 Oct 2005, at 03:46, Li, Chengyuan wrote:
I don't see ptwr_flush() when shadow mode enable in both ia32 and
x86_64 code. Why plain ia32 log dirty shadow can work?
Perhaps it can't, properly. :-)
The best fix will be to make domain_pause() call
sync_pagetable_state(d). The main problem I can see is that the
cleanup_writeable_pagetable() function is not currently safe to be
called by other than the subject domain. For example, failure paths
crash the calling domain rather than the subject domain! This needs
fixing.
audit_adjust_pgtables() is for plain ia32 only and it doesn't work for
both ia32 pae and x86_64, but this function only check the ref counts
and doesn't update guest PTE entry, e.g. R/W bit.
Another question is that how does guest update its guest page-table
after shadow mode is enabled? As writable-pagetable can't be used
after shadow mode is enabled.
Shadow pagetable code has its own quite separate writeable pagetable
logic, I believe. Which is why the non-shadow wrpt state must be
flushed before switching to shadow pagetables.
-- Keir
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