Avi Kivity wrote:

On 07/01/2010 11:18 AM, Alexander Graf wrote:

quoted

How does dirty bitmap flushing work on x86 atm? I loop through all
mapped pages and flush the ones that match the range of the region I
need to flush. But wouldn't it be a lot more efficient to have an
hlist in the memslot and loop through that when I need to flush that
memslot?
   

x86 loops through the reverse-map link list rooted at the memory
slot.  The linked list links all sptes for a single hva.

So, it's like you describe, except it's an array of lists instead of a
single list.  We need per-page rmap lists to be able to remove a
page's sptes in response to an mmu notifier callback, and to be able
to write protect a guest page if it's used as a page table.

But doesn't that mean that you still need to loop through all the hvas
that you want to invalidate? Wouldn't it speed up dirty bitmap flushing
a lot if we'd just have a simple linked list of all sPTEs belonging to
that memslot?

Alex