All three memory backends (-file, -ram and -memfd) have .prealloc
attribute. Since we are setting it only for -file, the
corresponding code lives only under if() that handles that
specific backend. But in near future we will want to set the
attribute for other backends too. Therefore, move the
corresponding code outside of the if().
This causes some .argv files to be changed, but the only change
happening there is move of the attribute (best viewed with:
'git show --color-words=.').
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
In [1], changes were made to remove the existing auto-alignment
for pSeries NVDIMM devices. That design promotes strange situations
where the NVDIMM size reported in the domain XML is different
from what QEMU is actually using. We removed the auto-alignment
and relied on standard size validation.
However, this goes against Libvirt design philosophy of not
tampering with existing guest behavior, as pointed out by Daniel
in [2]. Since we can't know for sure whether there are guests that
are relying on the auto-alignment feature to work, the changes
made in [1] are a direct violation of this rule.
This patch reverts [1] entirely, re-enabling auto-alignment for
pSeries NVDIMM as it was before. Changes will be made to ease
the limitations of this design without hurting existing
guests.
This reverts the following commits:
- commit 2d93cbdea9
Revert "formatdomain.html.in: mention pSeries NVDIMM 'align down' mechanic"
- commit 0ee56369c8
qemu_domain.c: change qemuDomainMemoryDeviceAlignSize() return type
- commit 07de813924
qemu_domain.c: do not auto-align ppc64 NVDIMMs
- commit 0ccceaa57c
qemu_validate.c: add pSeries NVDIMM size alignment validation
- commit 4fa2202d88
qemu_domain.c: make qemuDomainGetMemorySizeAlignment() public
[1] https://www.redhat.com/archives/libvir-list/2020-July/msg02010.html
[2] https://www.redhat.com/archives/libvir-list/2020-September/msg00572.html
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>
The existing auto-align behavior for pSeries has the idea to
alleviate user configuration of the NVDIMM size, given that the
alignment calculation is not trivial to do (256MiB alignment
of mem->size - mem->label_size value, a.k.a guest area). We
align mem->size down to avoid end of file problems.
The end result is not ideal though. We do not touch the domain
XML, meaning that the XML can report a NVDIMM size 255MiB smaller
than the actual size the guest is seeing. It also adds one more
thing to consider in case the guest is reporting less memory
than declared, since the auto-align is transparent to the
user.
Following Andrea's suggestion in [1], let's instead do an
size alignment validation. If the NVDIMM is unaligned, error out
and suggest a rounded up value. This can be bothersome to users,
but will bring consistency of NVDIMM size between the domain XML
and the guest.
This approach will force existing non-running pSeries guests to
readjust the NVDIMM value in their XMLs, if necessary. No changes
were made for x86 NVDIMM support.
[1] https://www.redhat.com/archives/libvir-list/2020-July/msg01471.html
Suggested-by: Andrea Bolognani <abologna@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
The churn in the output files is caused primarily by the fact that
replies were generated on a POWER9 machine, which is good because
we didn't have coverage of that before.
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Using the 'uuid' element for ppc64 NVDIMM memory added in the
previous patch, use it in qemuBuildMemoryDeviceStr() to pass
it over to QEMU.
Another ppc64 restriction is the necessity of a mem->labelsize,
given than ppc64 only support label-area backed NVDIMMs.
Finally, we don't want ppc64 NVDIMMs to align up due to the
high risk of going beyond the end of file with a 256MiB
increment that the user didn't predict. Align it down
instead. If target size is less than the minimum of
256MiB + labelsize, error out since QEMU will error out
if we attempt to round it up to the minimum.
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
