Add the kvm_adjvtime vcpu property for ARM Cortex-A72 cpu model,
so that virtual time adjust will be enabled for it.
Signed-off-by: Ying Fang <fangying1@huawei.com>
This patch drops the vtimer virtual timer adjust, cross version migration
from openEuler qemu-4.0.1 to qemu-4.1.0 is not supported as a consequence.
By default openEuler qemu-4.1.0 use kvm_adjvtime as the virtual timer.
Signed-off-by: Ying Fang <fangying1@huawei.com>
Vtimer adjust is used in openEuler qemu-4.0.1, however kvm_adjvtime
is introduced in openEuler qemu-4.1.0. To maintain the compatibility
and enable cross version migration, let's enable vtimer adjust only
if kvm_adjvtime is not enabled, otherwise there may be conflicts
between vtimer adjust and kvm_adjvtime.
After this modification:
1: openEuler qemu-4.0.1 use vtimer as the default virtual timer
2: openEuler qemu-4.1.0 use kvm_adjvtime as the defaut virtual timer
Migration from openEuler qemu-4.0.1 to openEuler qemu-4.1.0 will
be ok, but migration path from upstream qemu-4.0.1 to openEuler
qemu-4..0.1 will be broken.
Since openEuler qemu-4.1.0, kvm_adjvtime is used as the default
virtual timer. So please upgrade to openEuler qemu-4.1.0 and
use the virt-4.1 machine.
Signed-off-by: Ying Fang <fangying1@huawei.com>
Machine compatibility for kvm-no-adjvtime is missed,
let's add it for virt machine 4.0, thus kvm-no-adjvtime
is supported in v4.1.0.
Signed-off-by: Ying Fang <fangying1@huawei.com>
To support cross version migration, we had to add the vtimer back
which was introduced in openEuler qemu-4.0.1.
Signed-off-by: Ying Fang <fangying1@huawei.com>
This adds CPU cold plug support to arm virt machine board.
CPU cold plug means adding CPU by using "-device xx-arm-cpu"
when we bring up Qemu.
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
vtimer feature was added to qemu v4.0.1 to record timer tick when vcpu
is stopped. However this feature is discared and the new virtual time
adjustment is introduced.
This patch add the missing vtimer parameter to ARMCPUState in order
to compat cross version migration fromm v4.0.1 openEuler 2003 lts release.
Singed-off-by: Ying Fang <fangying1@huawei.com>
This series is an attempt to provide CPU hotplug support on ARM
virt platform. This is based on ACPI GED device.
We should enable ACPI support, and use vGICv3 and 64bit CPU to
support CPU hotplug.
Under KVM accel, the KVM vCPUs is pre-created. Besides, vGIC IRIs
is pre-created too. However, QEMU vCPU objects are defer-created.
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
This series is an attempt to provide device memory hotplug support
on ARM virt platform. This is based on Eric's recent works here[1]
and carries some of the pc-dimm related patches dropped from his
series.
The kernel support for arm64 memory hot add was added recently by
Robin and hence the guest kernel should be => 5.0-rc1.
NVDIM support is not included currently as we still have an unresolved
issue while hot adding NVDIMM[2]. However NVDIMM cold plug patches
can be included, but not done for now, for keeping it simple.
This makes use of GED device to sent hotplug ACPI events to the
Guest. GED code is based on Nemu. Thanks to the efforts of Samuel and
Sebastien to add the hardware-reduced support to Nemu using GED
device[3]. (Please shout if I got the author/signed-off wrong for
those patches or missed any names).
This is sanity tested on a HiSilicon ARM64 platform and appreciate
any further testing.
Note:
Attempted adding dimm_pxm test case to bios-tables-test for arm/virt.
But noticed the issue decribed here[5]. This is under investigation
now.
upstream url: https://patchwork.kernel.org/cover/11150345/
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
v3:
- Added a target/arm/kvm_arm.h comment cleanup patch (1/6)
- Minor refactoring of assert_has_feature_enabled/disabled in 4/6,
kept Richard's r-b.
- Rewrote kvm-no-adjvtime documentation in 6/6.
- Reworked approach in 5/6 to properly deal with migration and to
track running vs. !running, rather than running vs. paused states.
v2:
- Reworked it enough that I brought back the RFC tag and retitled the
series. Also had to drop r-b's from a couple of patches, and even
drop patches.
- Changed approach from writing the QEMU virtual time to the guest
vtime counter to saving and restoring the guest vtime counter.
- Changed the kvm-adjvtime property, which was off by default, to a
kvm-no-adjvtime property, which is also off by default, meaning the
effective "adjust vtime" property is now on by default (but only
for 5.0 virt machine types and later)
v1:
- move from RFC status to v1
- put kvm_arm_vm_state_change() in kvm.c to share among kvm32.c and kvm64.c
- add r-b's from Richard
This series is inspired by a series[1] posted by Bijan Mottahedeh over
a year ago and by the patch[2] posted by Heyi Guo almost a year ago.
The problem described in the cover letter of [1] is easily reproducible
and some users would like to have the option to avoid it. However the
solution, which is to adjust the virtual counter each time the VM
transitions to the running state, introduces a different problem, which
is that the virtual and physical counters diverge. As described in the
cover letter of [1] this divergence is easily observed when comparing
the output of `date` and `hwclock` after suspending the guest, waiting
a while, and then resuming it. Because this different problem may actually
be worse for some users, unlike [1], the series posted here makes the
virtual counter adjustment optional. Besides the adjustment being
optional, this series approaches the needed changes differently to apply
them in more appropriate locations.
Additional notes
----------------
Note 1
------
As described above, when running a guest with kvm-no-adjtime disabled
it will be less likely the guest OS and guest applications get surprise
time jumps when they use the virtual counter. However the counter will
no longer reflect real time. It will lag behind. If this is a problem
then the guest can resynchronize its time from an external source or
even from its physical counter. If the suspend/resume is done with
libvirt's virsh, and the guest is running the guest agent, then it's
also possible to use a sequence like this
$ virsh suspend $GUEST
$ virsh resume $GUEST
$ virsh domtime --sync $GUEST
in order to resynchronize a guest right after the resume. Of course
there will still be time when the clock is not right, possibly creating
confusing timestamps in logs, for example, and the guest must still be
tolerant to the time synchronizations.
Note 2
------
Userspace that wants to set KVM_REG_ARM_TIMER_CNT should beware that
the KVM register ID is not correct. This cannot be fixed because it's
UAPI and if the UAPI headers are used then it can't be a problem.
However, if a userspace attempts to create the ID themselves from the
register's specification, then they will get KVM_REG_ARM_TIMER_CVAL
instead, as the _CNT and _CVAL definitions have their register
parameters swapped.
Note 3
------
I didn't test this with a 32-bit KVM host, but the changes to kvm32.c
are the same as kvm64.c. So what could go wrong? Test results would be
appreciated.
[1] https://lists.gnu.org/archive/html/qemu-devel/2018-11/msg05713.html
[2] https://lists.gnu.org/archive/html/qemu-devel/2019-03/msg03695.html
upstream url:
https://patchwork.kernel.org/cover/11341629/
