Avi Kivity <[email protected]> wrote:
> > It should not be necessary, atomicity of updates to
> > memslot->dirty_bitmap, because of RCU updates to the memslot pointer
> > (note memslot = gfn_to_memslot(kvm, gfn); in mark_page_dirty).
> >
> > The order is:
> >
> > - update page data.
> > - grab memslot pointer.
> > - set page bit in memslot.
> >
>
> What if both grab the same memslot pointer, but set different bits?
(Sorry for my bad wording, that is what I wanted to explain.)
There seems to be possible concurrent __set_bit()'s to the same word
which will result in bit loss.
I was thinking to change the kvm-unit-tests' dirty log test to write
to two consecutive pages concurrently. Is this good for debugging this?
Takuya
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