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: 1ce9e6055f ("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>
These API has been introduced:
* virtqueue_dma_need_sync
* virtqueue_dma_sync_single_range_for_cpu
* virtqueue_dma_sync_single_range_for_device
These APIs can be used together with the premapped mechanism to sync the
DMA address.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Message-Id: <20230810123057.43407-12-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Now we add a case where we skip dma unmap, the vq->premapped is true.
We can't just rely on use_dma_api to determine whether to skip the dma
operation. For convenience, I introduced the "do_unmap". By default, it
is the same as use_dma_api. If the driver is configured with premapped,
then do_unmap is false.
So as long as do_unmap is false, for addr of desc, we should skip dma
unmap operation.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Message-Id: <20230810123057.43407-7-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This helper allows the driver change the dma mode to premapped mode.
Under the premapped mode, the virtio core do not do dma mapping
internally.
This just work when the use_dma_api is true. If the use_dma_api is false,
the dma options is not through the DMA APIs, that is not the standard
way of the linux kernel.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Message-Id: <20230810123057.43407-4-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This patch put the dma addr error check in vring_map_one_sg().
The benefits of doing this:
1. reduce one judgment of vq->use_dma_api.
2. make vring_map_one_sg more simple, without calling
vring_mapping_error to check the return value. simplifies subsequent
code
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230810123057.43407-3-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
According to VirtIO spec v1.2, VIRTIO_F_NOTIFICATION_DATA feature
indicates that the driver passes extra data along with the queue
notifications.
In a split queue case, the extra data is 16-bit available index. In a
packed queue case, the extra data is 1-bit wrap counter and 15-bit
available index.
Add support for this feature for MMIO, channel I/O and modern PCI
transports.
Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Message-Id: <20230413081855.36643-2-alvaro.karsz@solid-run.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
In virtio_net, if we disable napi_tx, when we trigger a tx interrupt,
the vq->event_triggered will be set to true. It is then never reset
until we explicitly call virtqueue_enable_cb_delayed or
virtqueue_enable_cb_prepare.
If we disable the napi_tx, virtqueue_enable_cb* will only be called when
the tx ring is getting relatively empty.
Since event_triggered is true, VRING_AVAIL_F_NO_INTERRUPT or
VRING_PACKED_EVENT_FLAG_DISABLE will not be set. As a result we update
vring_used_event(&vq->split.vring) or vq->packed.vring.driver->off_wrap
every time we call virtqueue_get_buf_ctx. This causes more interrupts.
To summarize:
1) event_triggered was set to true in vring_interrupt()
2) after this nothing will happen in virtqueue_disable_cb() so
VRING_AVAIL_F_NO_INTERRUPT is not set in avail_flags_shadow
3) virtqueue_get_buf_ctx_split() will still think the cb is enabled
and then it will publish a new event index
To fix:
update VRING_AVAIL_F_NO_INTERRUPT or VRING_PACKED_EVENT_FLAG_DISABLE in
the vq when we call virtqueue_disable_cb even when event_triggered is
true.
Tested with iperf:
iperf3 tcp stream:
vm1 -----------------> vm2
vm2 just receives tcp data stream from vm1, and sends acks to vm1,
there are many tx interrupts in vm2.
with the patch applied there are just a few tx interrupts.
v2->v3:
-update the interrupt disable flag even with the event_triggered is set,
-instead of checking whether event_triggered is set in
-virtqueue_get_buf_ctx_{packed/split}, will cause the drivers which have
-not called virtqueue_{enable/disable}_cb to miss notifications.
v3->v4:
-remove change for
-"if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE)"
-in virtqueue_disable_cb_packed
Fixes: 8d622d21d2 ("virtio: fix up virtio_disable_cb")
Signed-off-by: Albert Huang <huangjie.albert@bytedance.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230329102300.61000-1-huangjie.albert@bytedance.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Add const to make the read-only pointer parameters clear, similar to
many existing functions.
To implement this change, the commit also introduces the use of
`container_of_const` to implement `to_vvq`, which ensures the const-ness
of read-only parameters and avoids accidental modification of their
members.
Signed-off-by: Feng Liu <feliu@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Gavin Li <gavinl@nvidia.com>
Reviewed-by: Bodong Wang <bodong@nvidia.com>
Message-Id: <20230310053428.3376-4-feliu@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This patch introduces a per virtqueue dma device. This will be used
for virtio devices whose virtqueue are backed by different underlayer
devices.
One example is the vDPA that where the control virtqueue could be
implemented through software mediation.
Some of the work are actually done before since the helper like
vring_dma_device(). This work left are:
- Let vring_dma_device() return the per virtqueue dma device instead
of the vdev's parent.
- Allow passing a dma_device when creating the virtqueue through a new
helper, old vring creation helper will keep using vdev's parent.
Reviewed-by: Eli Cohen <elic@nvidia.com>
Tested-by: Eli Cohen <elic@nvidia.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230119061525.75068-2-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Pull MM updates from Andrew Morton:
- Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any
negative reports (or any positive ones, come to that).
- Also the Maple Tree from Liam Howlett. An overlapping range-based
tree for vmas. It it apparently slightly more efficient in its own
right, but is mainly targeted at enabling work to reduce mmap_lock
contention.
Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.
Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
at [1]. This has yet to be addressed due to Liam's unfortunately
timed vacation. He is now back and we'll get this fixed up.
- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down
to the single bit level.
KMSAN keeps finding bugs. New ones, as well as the legacy ones.
- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.
- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
support file/shmem-backed pages.
- userfaultfd updates from Axel Rasmussen
- zsmalloc cleanups from Alexey Romanov
- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
memory-failure
- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.
- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.
- memcg cleanups from Kairui Song.
- memcg fixes and cleanups from Johannes Weiner.
- Vishal Moola provides more folio conversions
- Zhang Yi removed ll_rw_block() :(
- migration enhancements from Peter Xu
- migration error-path bugfixes from Huang Ying
- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.
- vma merging improvements from Jakub Matěn.
- NUMA hinting cleanups from David Hildenbrand.
- xu xin added aditional userspace visibility into KSM merging
activity.
- THP & KSM code consolidation from Qi Zheng.
- more folio work from Matthew Wilcox.
- KASAN updates from Andrey Konovalov.
- DAMON cleanups from Kaixu Xia.
- DAMON work from SeongJae Park: fixes, cleanups.
- hugetlb sysfs cleanups from Muchun Song.
- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.
Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1]
* tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits)
hugetlb: allocate vma lock for all sharable vmas
hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
hugetlb: fix vma lock handling during split vma and range unmapping
mglru: mm/vmscan.c: fix imprecise comments
mm/mglru: don't sync disk for each aging cycle
mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
mm: memcontrol: use do_memsw_account() in a few more places
mm: memcontrol: deprecate swapaccounting=0 mode
mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
mm/secretmem: remove reduntant return value
mm/hugetlb: add available_huge_pages() func
mm: remove unused inline functions from include/linux/mm_inline.h
selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory
selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd
selftests/vm: add thp collapse shmem testing
selftests/vm: add thp collapse file and tmpfs testing
selftests/vm: modularize thp collapse memory operations
selftests/vm: dedup THP helpers
mm/khugepaged: add tracepoint to hpage_collapse_scan_file()
mm/madvise: add file and shmem support to MADV_COLLAPSE
...
Introduce virtqueue_resize() to implement the resize of vring.
Based on these, the driver can dynamically adjust the size of the vring.
For example: ethtool -G.
virtqueue_resize() implements resize based on the vq reset function. In
case of failure to allocate a new vring, it will give up resize and use
the original vring.
During this process, if the re-enable reset vq fails, the vq can no
longer be used. Although the probability of this situation is not high.
The parameter recycle is used to recycle the buffer that is no longer
used.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220801063902.129329-25-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
virtio ring packed supports resize.
Only after the new vring is successfully allocated based on the new num,
we will release the old vring. In any case, an error is returned,
indicating that the vring still points to the old vring.
In the case of an error, re-initialize(by virtqueue_reinit_packed()) the
virtqueue to ensure that the vring can be used.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220801063902.129329-24-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Separate the logic of initializing vring, and subsequent patches will
call it separately.
This function completes the variable initialization of packed vring. It
together with the logic of atatch constitutes the initialization of
vring.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220801063902.129329-21-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
virtio ring split supports resize.
Only after the new vring is successfully allocated based on the new num,
we will release the old vring. In any case, an error is returned,
indicating that the vring still points to the old vring.
In the case of an error, re-initialize(virtqueue_reinit_split()) the
virtqueue to ensure that the vring can be used.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220801063902.129329-17-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Separate the logic of attach vring, subsequent patches will call it
separately.
virtqueue_vring_init_split() completes the initialization of other
variables of vring split. We can directly use
vq->split = *vring_split to complete attach.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220801063902.129329-14-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Separate the logic of initializing vring, and subsequent patches will
call it separately.
This function completes the variable initialization of split vring. It
together with the logic of atatch constitutes the initialization of
vring.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220801063902.129329-13-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
There is currently only one place to reference __vring_new_virtqueue()
directly from the outside of virtio core. And here vring_new_virtqueue()
can be used instead.
Subsequent patches will modify __vring_new_virtqueue, so stop it as an
export symbol for now.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220801063902.129329-8-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
