On Fri, 30 Aug 2019 18:19:29 +0200
Christian Borntraeger <borntrae...@de.ibm.com> wrote:
> On 30.08.19 11:41, Igor Mammedov wrote:
> > On Thu, 29 Aug 2019 14:41:13 +0200
> > Christian Borntraeger <borntrae...@de.ibm.com> wrote:
> >
> >> On 29.08.19 14:31, Igor Mammedov wrote:
> >>> On Thu, 29 Aug 2019 14:07:44 +0200
> >>> Christian Borntraeger <borntrae...@de.ibm.com> wrote:
> >>>
> >>>> On 29.08.19 14:04, Igor Mammedov wrote:
> >>>>> 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.
> >>>>
> >>>> Right. The split in KVM code is transparent to migration and other parts
> >>>> of QEMU, correct?
> >>>
> >>> it should not affect other QEMU parts and migration (to my limited
> >>> understanding of it),
> >>> we are passing to KVM memory slots upto KVM_SLOT_MAX_BYTES as we were
> >>> doing before by
> >>> creating several memory regions instead of one as described in [2/2]
> >>> commit message.
> >>>
> >>> Also could you also test migration of +9Tb guest, to check that nothing
> >>> where broken by
> >>> accident in QEMU migration code?
> >>
> >> I only have one server that is large enough :-/
> > Could you test offline migration on it (to a file and restore from it)?
>
> I tested migration with a hacked QEMU (basically split in KVM code at 1GB
> instead of 8TB) and
> the restore from file failed with data corruption in the guest. The current
> code
> does work when I use small memslots. No idea yet what is wrong.
I've tested 2Gb (max, I can test) guest (also hacked up version)
and it worked for me.
How do you test it and detect corruption so I could try to reproduce it locally?
(given it worked before, there is no much hope but I could try)
