| 07622bd4 | 30-Aug-2023 |
Gavin Shan <gshan@redhat.com> |
virtio_balloon: Fix endless deflation and inflation on arm64
The deflation request to the target, which isn't unaligned to the
guest page size causes endless deflation and inflation actions. For
exa
virtio_balloon: Fix endless deflation and inflation on arm64
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 aligning the target up to the guest page size, 64KB in this
specific case. With this applied, no flooding QMP events are 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}}
Cc: stable@vger.kernel.org
Signed-off-by: Gavin Shan <gshan@redhat.com>
Tested-by: Zhenyu Zhang <zhenyzha@redhat.com>
Message-Id: <20230831011007.1032822-1-gshan@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
show more ...
|
| 1acfe2c1 | 08-Aug-2023 |
Yuan Yao <yuanyaogoog@chromium.org> |
virtio_ring: fix avail_wrap_counter in virtqueue_add_packed
In current packed virtqueue implementation, the avail_wrap_counter won't
flip, in the case when the driver supplies a descriptor chain wit
virtio_ring: fix avail_wrap_counter in virtqueue_add_packed
In current packed virtqueue implementation, the avail_wrap_counter won't
flip, in the case when the driver supplies a descriptor chain with a
length equals to the queue size; total_sg == vq->packed.vring.num.
Let’s assume the following situation:
vq->packed.vring.num=4
vq->packed.next_avail_idx: 1
vq->packed.avail_wrap_counter: 0
Then the driver adds a descriptor chain containing 4 descriptors.
We expect the following result with avail_wrap_counter flipped:
vq->packed.next_avail_idx: 1
vq->packed.avail_wrap_counter: 1
But, the current implementation gives the following result:
vq->packed.next_avail_idx: 1
vq->packed.avail_wrap_counter: 0
To reproduce the bug, you can set a packed queue size as small as
possible, so that the driver is more likely to provide a descriptor
chain with a length equal to the packed queue size. For example, in
qemu run following commands:
sudo qemu-system-x86_64 \
-enable-kvm \
-nographic \
-kernel "path/to/kernel_image" \
-m 1G \
-drive file="path/to/rootfs",if=none,id=disk \
-device virtio-blk,drive=disk \
-drive file="path/to/disk_image",if=none,id=rwdisk \
-device virtio-blk,drive=rwdisk,packed=on,queue-size=4,\
indirect_desc=off \
-append "console=ttyS0 root=/dev/vda rw init=/bin/bash"
Inside the VM, create a directory and mount the rwdisk device on it. The
rwdisk will hang and mount operation will not complete.
This commit fixes the wrap counter error by flipping the
packed.avail_wrap_counter, when start of descriptor chain equals to the
end of descriptor chain (head == i).
Fixes: 1ce9e6055fa0 ("virtio_ring: introduce packed ring support")
Signed-off-by: Yuan Yao <yuanyaogoog@chromium.org>
Message-Id: <20230808051110.3492693-1-yuanyaogoog@chromium.org>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
show more ...
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