On Wed, Oct 21, 2020 at 06:42:19PM +0100, Dr. David Alan Gilbert wrote:
> * Peter Xu (pet...@redhat.com) wrote:
> > On Wed, Oct 21, 2020 at 03:23:45PM +0100, Dr. David Alan Gilbert wrote:
> > > > @@ -354,8 +368,33 @@ int
> > > > migrate_send_rp_message_req_pages(MigrationIncomingState *mis,
> > > > }
> > > >
> > > > int migrate_send_rp_req_pages(MigrationIncomingState *mis,
> > > > - RAMBlock *rb, ram_addr_t start)
> > > > + RAMBlock *rb, ram_addr_t start, uint64_t
> > > > haddr)
> > > > {
> > > > + void *aligned = (void *)(uintptr_t)(haddr &
> > > > qemu_real_host_page_mask);
> > >
> > > Can you remind me, what happens here for hugepages?
> >
> > Sure. Previously it was:
> >
> > (haddr & (-qemu_target_page_size())
> >
> > Now it is:
> >
> > (haddr & qemu_real_host_page_mask)
> >
> > Basically we changed the psize alignment from guest to host.
> >
> > The bug triggered previously on ppc64 where host_psize=64k, then when guest
> > psize is smaller, e.g., 4k, we can have some addr that aligned to 4k rather
> > than 64k, so we failed later on checking the host psize alignment (because
> > this
> > pointer should point to a host page, so it should align with host psize).
>
> But my question is what happens when we have say a 2MB hugepage?
Oops, I definitely misread.
Good point, I think it can break hugepages. So the mask should really be
"(qemu_ram_pagesize(rb) - 1)".
I'll fix and smoke it with some huge pages before another repost.
Thanks!
--
Peter Xu
