On Thu, 29 Aug 2019 08:47:49 +0200 Christian Borntraeger <borntrae...@de.ibm.com> wrote:
> On 27.08.19 14:56, Igor Mammedov wrote: > > On Tue, 20 Aug 2019 18:07:27 +0200 > > Cornelia Huck <coh...@redhat.com> wrote: > > > >> On Wed, 7 Aug 2019 11:32:41 -0400 > >> Igor Mammedov <imamm...@redhat.com> wrote: > >> > >>> Max memslot size supported by kvm on s390 is 8Tb, > >>> move logic of splitting RAM in chunks upto 8T to KVM code. > >>> > >>> This way it will hide KVM specific restrictions in KVM code > >>> and won't affect baord level design decisions. Which would allow > >>> us to avoid misusing memory_region_allocate_system_memory() API > >>> and eventually use a single hostmem backend for guest RAM. > >>> > >>> Signed-off-by: Igor Mammedov <imamm...@redhat.com> > >>> --- > >>> v5: > >>> * move computation 'size -= slot_size' inside of loop body > >>> (David Hildenbrand <da...@redhat.com>) > >>> v4: > >>> * fix compilation issue > >>> (Christian Borntraeger <borntrae...@de.ibm.com>) > >>> * advance HVA along with GPA in kvm_set_phys_mem() > >>> (Christian Borntraeger <borntrae...@de.ibm.com>) > >>> > >>> patch prepares only KVM side for switching to single RAM memory region > >>> another patch will take care of dropping manual RAM partitioning in > >>> s390 code. > >> > >> I may have lost track a bit -- what is the status of this patch (and > >> the series)? > > > > Christian, > > > > could you test it on a host that have sufficient amount of RAM? > > > This version looks good. I was able to start a 9TB guest. > [pid 215723] ioctl(10, KVM_SET_USER_MEMORY_REGION, {slot=0, flags=0, > guest_phys_addr=0, memory_size=8796091973632, userspace_addr=0x3ffee700000}) > = 0 > [pid 215723] ioctl(10, KVM_SET_USER_MEMORY_REGION, {slot=1, flags=0, > guest_phys_addr=0x7fffff00000, memory_size=1099512676352, > userspace_addr=0xbffee600000}) = 0 > > The only question is if we want to fix the weird alignment (0x7fffff00000) > when > we already add a migration barrier for uber-large guests. > Maybe we could split at 4TB to avoid future problem with larger page sizes? That probably should be a separate patch on top.