Re: [PATCH] virtio_balloon: Fix endless deflation and inflation on arm64
From: Zhenyu Zhang
Date: Wed Aug 30 2023 - 15:04:40 EST
[PATCH] virtio_balloon: Fix endless deflation and inflation on arm64
The patches work well on my arm Ampere host.
The test results are as expected.
Testing
=======
(1) boot 64KB base page size guest, deflation balloon.
/home/zhenyzha/sandbox/qemu.main/build/qemu-system-aarch64 \
-device '{"id": "pcie-root-port-0", "driver": "pcie-root-port",
"multifunction": true, "bus": "pcie.0", "addr": "0x1", "chassis": 1}'
\
-device '{"id": "pcie-pci-bridge-0", "driver": "pcie-pci-bridge",
"addr": "0x0", "bus": "pcie-root-port-0"}' \
-nodefaults \
-device '{"id": "pcie-root-port-1", "port": 1, "driver":
"pcie-root-port", "addr": "0x1.0x1", "bus": "pcie.0", "chassis": 2}' \
-device '{"driver": "virtio-gpu-pci", "bus": "pcie-root-port-1",
"addr": "0x0"}' \
-m 8192 \
-object '{"size": 4294967296, "id": "mem-machine_mem0", "qom-type":
"memory-backend-ram"}' \
-object '{"size": 4294967296, "id": "mem-machine_mem1", "qom-type":
"memory-backend-ram"}' \
-numa node,nodeid=0,memdev=mem-machine_mem0,cpus=0-3 \
-numa node,nodeid=1,memdev=mem-machine_mem1,cpus=4-7 \
-smp 8,maxcpus=8,cores=2,threads=1,clusters=2,sockets=2 \
-cpu 'host' \
-enable-kvm \
: \
-device '{"id": "pcie-root-port-5", "port": 5, "driver":
"pcie-root-port", "addr": "0x1.0x5", "bus": "pcie.0", "chassis": 6}' \
-device '{"driver": "virtio-balloon-pci", "id": "balloon0",
"free-page-reporting": true, "bus": "pcie-root-port-5", "addr":
"0x0"}' \
{ "execute" : "balloon", "arguments": { "value" : 7515705344 }}
{"return": {}}
{"timestamp": {"seconds": 1693284182, "microseconds": 597003},
"event": "BALLOON_CHANGE", "data": {"actual": 8588886016}}
{"timestamp": {"seconds": 1693284183, "microseconds": 598037},
"event": "BALLOON_CHANGE", "data": {"actual": 7515668480}}
{"timestamp": {"seconds": 1693284184, "microseconds": 599116},
"event": "BALLOON_CHANGE", "data": {"actual": 7515734016}}
{"timestamp": {"seconds": 1693284185, "microseconds": 600167},
"event": "BALLOON_CHANGE", "data": {"actual": 7515668480}}
{"timestamp": {"seconds": 1693284186, "microseconds": 601226},
"event": "BALLOON_CHANGE", "data": {"actual": 7515734016}}
{"timestamp": {"seconds": 1693284187, "microseconds": 602287},
"event": "BALLOON_CHANGE", "data": {"actual": 7515668480}}
{"timestamp": {"seconds": 1693284188, "microseconds": 603386},
"event": "BALLOON_CHANGE", "data": {"actual": 7515668480}}
{"timestamp": {"seconds": 1693284189, "microseconds": 604401},
"event": "BALLOON_CHANGE", "data": {"actual": 7515668480}}
{"timestamp": {"seconds": 1693284190, "microseconds": 605467},
"event": "BALLOON_CHANGE", "data": {"actual": 7515734016}}
:
<The similar QMP events repeat>
git am this patch
{ "execute" : "balloon", "arguments": { "value" : 7515705344 }}
{"return": {}}
{"timestamp": {"seconds": 1693301553, "microseconds": 809765},
"event": "BALLOON_CHANGE", "data": {"actual": 8588886016}}
{"timestamp": {"seconds": 1693301553, "microseconds": 986697},
"event": "BALLOON_CHANGE", "data": {"actual": 7515668480}}
{ "execute" : "query-balloon" }
{"return": {"actual": 7515668480}}
(2) Run kvm-unit-tests:
6 cases skip, 32 cases pass.
(3) Run selftests TARGETS=kvm:
23 cases all pass
Tested-by: Zhenyu Zhang <zhenzha@xxxxxxxxxx>
On Wed, Aug 30, 2023 at 12:24 PM Gavin Shan <gshan@xxxxxxxxxx> wrote:
>
> On 8/29/23 11:54, Gavin Shan wrote:
> > The deflation request to the target, which isn't unaligned to the
> > guest page size causes endless deflation and inflation actions. For
> > example, we receive the flooding QMP events for the changes on memory
> > balloon's size after a deflation request to the unaligned target is
> > sent for the ARM64 guest, where we have 64KB base page size.
> >
> > /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64 \
> > -accel kvm -machine virt,gic-version=host -cpu host \
> > -smp maxcpus=8,cpus=8,sockets=2,clusters=2,cores=2,threads=1 \
> > -m 1024M,slots=16,maxmem=64G \
> > -object memory-backend-ram,id=mem0,size=512M \
> > -object memory-backend-ram,id=mem1,size=512M \
> > -numa node,nodeid=0,memdev=mem0,cpus=0-3 \
> > -numa node,nodeid=1,memdev=mem1,cpus=4-7 \
> > : \
> > -device virtio-balloon-pci,id=balloon0,bus=pcie.10
> >
> > { "execute" : "balloon", "arguments": { "value" : 1073672192 } }
> > {"return": {}}
> > {"timestamp": {"seconds": 1693272173, "microseconds": 88667}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}}
> > {"timestamp": {"seconds": 1693272174, "microseconds": 89704}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}}
> > {"timestamp": {"seconds": 1693272175, "microseconds": 90819}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}}
> > {"timestamp": {"seconds": 1693272176, "microseconds": 91961}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}}
> > {"timestamp": {"seconds": 1693272177, "microseconds": 93040}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}}
> > {"timestamp": {"seconds": 1693272178, "microseconds": 94117}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}}
> > {"timestamp": {"seconds": 1693272179, "microseconds": 95337}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}}
> > {"timestamp": {"seconds": 1693272180, "microseconds": 96615}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}}
> > {"timestamp": {"seconds": 1693272181, "microseconds": 97626}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}}
> > {"timestamp": {"seconds": 1693272182, "microseconds": 98693}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}}
> > {"timestamp": {"seconds": 1693272183, "microseconds": 99698}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}}
> > {"timestamp": {"seconds": 1693272184, "microseconds": 100727}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}}
> > {"timestamp": {"seconds": 1693272185, "microseconds": 90430}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}}
> > {"timestamp": {"seconds": 1693272186, "microseconds": 102999}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073676288}}
> > :
> > <The similar QMP events repeat>
> >
> > Fix it by having the target aligned to the guest page size, 64KB
> > in this specific case. With this applied, no flooding QMP event
> > is observed and the memory balloon's size can be stablizied to
> > 0x3ffe0000 soon after the deflation request is sent.
> >
> > { "execute" : "balloon", "arguments": { "value" : 1073672192 } }
> > {"return": {}}
> > {"timestamp": {"seconds": 1693273328, "microseconds": 793075}, \
> > "event": "BALLOON_CHANGE", "data": {"actual": 1073610752}}
> > { "execute" : "query-balloon" }
> > {"return": {"actual": 1073610752}}
> >
> > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> > drivers/virtio/virtio_balloon.c | 13 ++++++++++++-
> > 1 file changed, 12 insertions(+), 1 deletion(-)
> >
>
> It was supposed to copy David, Jason and Zhenyu. I don't know how they have been
> missed. My script may run into problems temporarily. Amending for it.
>
> Thanks,
> Gavin
>
> > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> > index 5b15936a5214..625caac35264 100644
> > --- a/drivers/virtio/virtio_balloon.c
> > +++ b/drivers/virtio/virtio_balloon.c
> > @@ -386,6 +386,17 @@ static void stats_handle_request(struct virtio_balloon *vb)
> > virtqueue_kick(vq);
> > }
> >
> > +static inline s64 align_pages_up(s64 diff)
> > +{
> > + if (diff == 0)
> > + return diff;
> > +
> > + if (diff > 0)
> > + return ALIGN(diff, VIRTIO_BALLOON_PAGES_PER_PAGE);
> > +
> > + return -ALIGN(-diff, VIRTIO_BALLOON_PAGES_PER_PAGE);
> > +}
> > +
> > static inline s64 towards_target(struct virtio_balloon *vb)
> > {
> > s64 target;
> > @@ -396,7 +407,7 @@ static inline s64 towards_target(struct virtio_balloon *vb)
> > &num_pages);
> >
> > target = num_pages;
> > - return target - vb->num_pages;
> > + return align_pages_up(target - vb->num_pages);
> > }
> >
> > /* Gives back @num_to_return blocks of free pages to mm. */
>