On Wed, Jan 08, 2020 at 01:53:51PM +0000, Dr. David Alan Gilbert (git) wrote: > Hyperv's synic (that we emulate) is a feature that allows the guest > to place some magic (4k) pages of RAM anywhere it likes in GPA. > This confuses vhost's RAM section merging when these pages > land over the top of hugepages. > > Since they're not normal RAM, and they shouldn't have vhost DMAing > into them, exclude them from the vhost set.
But they *are* normal RAM. If the guest driver sets up the device to DMA to a SynIC page so be it, and the guest deserves what it gets. > I do that by marking them as device-ram and then excluding device-ram > from vhost. > > bz: https://bugzilla.redhat.com/show_bug.cgi?id=1779041 I was pointed a while back by Vitaly at https://bugs.launchpad.net/qemu/+bug/1811533 which appeared to be the same issue, but failed to reproduce the problem. Can you please provide some more detail as to how it's triggered? Thanks, Roman.