On Wed, Sep 09, 2020 at 06:45:33PM -0700, Richard Henderson wrote:

On 9/9/20 8:25 AM, Andrew Jones wrote:

quoted

quoted

 * Provide a KVM-specific method to extract the tags from guest memory.
   This might also have benefits in terms of providing an easy way to
   read bulk tag data from guest memory (since the LDGM instruction
   isn't available at EL0).

Maybe we need a new version of KVM_GET_DIRTY_LOG that also provides
the tags for all addresses of each dirty page.

KVM_GET_DIRTY_LOG just provides one bit per dirty page, no?  Then VMM copies
the data out from its local address to guest memory.

There'd be no difference with or without tags, afaik.  It's just about how VMM
copies the data, with or without tags.

Right, as long as it's fast enough to do

  for_each_dirty_page(page, dirty_log)
    for (i = 0; i < host-page-size/16; i += 16)
      append_tag(LDG(page + i))

to get all the tags for each dirty page. I understood it would be faster
to use LDGM, but we'd need a new ioctl for that. So I was proposing we
just piggyback on a new dirty-log ioctl instead.

Thanks,
drew 


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel