This patch has been cherry-picked from the Firecracker tree. The
reference commit is 78ca0a942f32140465c67ea4b45d68c52c72d751.
Signed-off-by: Gabriel Ionescu <gbi@amazon.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
This patch has been cherry-picked from the Firecracker tree. The
reference commit is 6dbe8e021a64ba3742081741a7538cdfd93a102e.
Signed-off-by: Gabriel Ionescu <gbi@amazon.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
This patch has been cherry-picked from the Firecracker tree. The
reference commit is 78819f35f63f5777a58e3e1e774b3270b32881ed.
The vsock TX buffer flush operation would report inconsistent results,
under specific circumstances.
The flush operation is performed in two steps, since it's dealing with a
ring buffer, an the data to be flushed may wrap around. If the first
step was successful, but the second one failed, the whole flush
operation would report an error, thus causing flow control accounting to
lose track of the bytes that were successfully written by the first
pass.
This commit changes the flush behavior to always report success when
some data has been written to the backing stream.
Signed-off-by: Dan Horobeanu <dhr@amazon.com>
Signed-off-by: Gabriel Ionescu <gbi@amazon.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
This patch has been cherry-picked from the Firecracker tree. The
reference commit is 2da612a9cdce85c91fb54ab22d950ec6ccc93b27.
Fixed a bug introduced by a271d08f0b1ba0ee82761cd49244b6a8017bcede,
whereby the flow control accouting would be off by a few bytes, for
host-initiated connections.
The connection ack message ("OK <port_num><CR>") was accounted for as
data sent by the guest, so its length was substracted from the total
amount of data the guest was allowed to send.
This commit changes the way this ack message is sent, so that it
bypasses flow control accouting.
Signed-off-by: Dan Horobeanu <dhr@amazon.com>
Signed-off-by: Gabriel Ionescu <gbi@amazon.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
This patch has been cherry-picked from the Firecracker tree. The
reference commit is 109e631566350867dafa4b16c3919dfd1533eeea.
This commit changes the vsock connection state machine behavior to absorb
any EWOULDBLOCK errors recevied while handling an EPOLLOUT event. Previously,
this condition would lead to immediate connection termination.
Signed-off-by: Dan Horobeanu <dhr@amazon.com>
Signed-off-by: Gabriel Ionescu <gbi@amazon.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
This patch has been cherry-picked from the Firecracker tree. The
reference commit is 660d18cf7fee5b38c3b1b17a5da6544b9025909d.
Apparently, epoll_wait sometimes yields false EPOLLIN events (i.e. events
follwing which read() would fail with EWOULDBLOCK). This would cause the
vsock connection state machine to terminate connections, since an error
was detected on the underlying Unix socket.
This commit changes the vsock connection state machine code to handle such
erroneous EPOLLIN events by absorbing EWOULDBLOCK read() errors.
Signed-off-by: Dan Horobeanu <dhr@amazon.com>
Signed-off-by: Gabriel Ionescu <gbi@amazon.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
This patch has been cherry-picked from the Firecracker tree. The
reference commit is 1cc8b8a678eb28b20f5843556bdb7fbb2dfa6284.
Fixed a logical error in the vsock flow control, that would cause credit
update packets to not be sent at the right time.
Signed-off-by: Dan Horobeanu <dhr@amazon.com>
Signed-off-by: Gabriel Ionescu <gbi@amazon.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
This patch has been cherry-picked from the Firecracker tree. The
reference commit is d2475773557c82d2abad2fc8bdf69e7d01444109.
Fixed a vsock muxer issue that would cause a connection to be removed
from the RX queue, even though it still had pending RX data.
Signed-off-by: Dan Horobeanu <dhr@amazon.com>
Signed-off-by: Gabriel Ionescu <gbi@amazon.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
This patch adds `is_empty` method to VsockPacket to fix the
following clippy error:
error: item `vsock::packet::VsockPacket` has a public `len` method but no corresponding `is_empty` method
--> vm-virtio/src/vsock/packet.rs💯1
|
100 | / impl VsockPacket {
101 | | /// Create the packet wrapper from a TX virtq chain head.
102 | | ///
103 | | /// The chain head is expected to hold valid packet header data. A following packet buffer
... |
334 | | }
335 | | }
| |_^
|
= note: `-D clippy::len-without-is-empty` implied by `-D warnings`
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#len_without_is_empty
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
This removes the need to use CAP_NET_ADMIN privileges and instead the
host MAC addres is either provided by the user or alternatively it is
retrieved from the kernel.
TEST=Run cloud-hypervisor without CAP_NET_ADMIN permission and a
preconfigured tap device:
sudo ip tuntap add name tap0 mode tap
sudo ifconfig tap0 192.168.249.1 netmask 255.255.255.0 up
cargo clean
cargo build
target/debug/cloud-hypervisor --serial tty --console off --kernel ~/src/rust-hypervisor-firmware/target/target/release/hypervisor-fw --disk path=~/workloads/clear-33190-kvm.img --net tap=tap0
VM was also rebooted to check that works correctly.
Fixes: #1274
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The API has change to use generic GuestMemory trait:
pub fn get_host_address_range<M: GuestMemory>(
mem: &M,
addr: GuestAddress,
size: usize,
) -> Option<*mut u8> {
Signed-off-by: Arron Wang <arron.wang@intel.com>
If VIRTIO_RING_F_EVENT_IDX is negotiated only generate suppress
interrupts if the guest has asked us to do so.
Fixes: #788
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
In some situations it is seen that the first interrupt sent to the guest
is lost upon a restore (due to the tap worker being awake ahead of the
vPUs).
This causes problems with VIRTIO_RING_F_EVENT_IDX interrupt suppression
as the guest will not be interrupted again in order to mitigate this we
always interrupt the guest until the device itself has been signalled by
the guest.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This requires exposing the struct members and also using Option<..>
types for the main epoll fd and the memory as they are initialised later
in vhost-user-net.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Split handling of behaviour that is independent of the device itself so
that it can be reused in the vhost-user-net device.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Split out functions that work just on the TAP device and queues. Whilst
doing so also improve the error handling to return Results rather than
drop errors.
This change also addresses a bug where the TAP event suppression could
ineffectual because it was being enabled immediately after it may have
been disabled:
resume_rx -> rx_single_frame -> unregister_listener -> resume_rx ->
register_listener.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This config option provided very little value and instead we now enable
this feature (which then lets the guest control the cache mode)
unconditionally.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Correctly implement the virtio specification by setting the writeback
field on the request based on the algorithm in the spec.
TEST=Boot with hypervisor-firmware with CH in verbose mode. See info
level messages saying cache mode is writethrough in firmware (no support
for flush or WCE). Once in the Linux kernel see messages that mode is
writeback.
Fixes: #1216Fixes: #680
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
When this is set to false the write needs to be followed by a flush on
the underlying disk (leading to a fsync()).
The default behaviour is not changed with this change.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Move the method that is used to decide whether the guest should be
signalled into the Queue implementation from vm-virtio. This removes
duplicated code between vhost_user_backend and the vm-virtio block
implementation.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The implementation of this virtio block (and vhost-user block) command
called a function that was a no-op on Linux. Use the same function as
virtio-pmem to ensure that data is not lost when the guest asks for it
to be flused to disk.
Fixes: #399
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
For both virtio-mmio and virtio-pci transport layers, we were setting
every field from the saved snapshot during a restore. This is a problem
when we don't want to override specific fields such as iommu_mapping_cb
because the saved snapshot doesn't contain the appropriate information.
That's why this commit sets only the appropriate field from the saved
snapshot during a restore.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Provide implementation for both snapshot() and restore() methods from
the Snapshottable trait, so that we can snapshot and restore a VM with
devices attached to a virtual IOMMU.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
According to the virtio spec the guest should always be interrupted when
"used" descriptors are returned from the device to the driver. However
this was not the case for the TX queue in either the virtio-net
implementation or the vhost-user-net implementation.
This would have meant that the guest could end up with a reduced TX
throughput as it would not know that the packets had been dispatched via
the VMM.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Add a new "host_mac" parameter to "--net" and "--net-backend" and use
this to set the MAC address on the tap interface. If no address is given
one is randomly assigned and is stored in the config.
Support for vhost-user-net self spawning was also included.
Fixes: #1177
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
From a VirtioPciDevice perspective, there are two types of BARs, either
the virtio configuration BAR or the SHaredMemory BAR.
The SHaredMemory BAR address comes from the virtio device directly as
the memory region had been previously allocated when the virtio device
has been created. So for this BAR, there's nothing to do when restoring
a VM, since the associated virtio device is already restored with the
appropriate resources, hence the BAR will already be at the right
address.
The remaining configuration BAR is different, as we usually get its
address from the SystemAllocator. This means in case we restore a VM,
we must provide this value, bypassing the allocator. This is what this
commit takes care of, by letting the caller set the base address for the
configuration BAR prior to allocating the BARs.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This gives Cloud-Hypervisor the possibility to snapshot and restore a
VM running with virtio-pci devices attached to it.
The VirtioPciDevice snapshot contains a vector of sub-snapshots to store
and restore information related to MsixConfig, VirtioPciCommonConfig and
PciConfiguration structures, along with snapshot data related to
VirtioPciDevice itself.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This structure contains all the virtio generic information, and as part
of restoring a VM with virtio-pci devices, it is important to restore
these values to ensure the device's proper functioning.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Upon a virtio reset, the driver expects that available and used indexes
will be reset to 0. That's why we need to reset these values from the
VMM for any virtio device that might get reset.
This issue was not detected before because the Vec<Queue> maintained
through VirtioPciDevice or MmioDevice was never updated from the virtio
device thread after the device had been actived. For this reason, upon
reset, both available and used indexes were already at the value 0.
The issue arose when trying to reset a device after the VM was restored.
That's because during the restore, each queue is assigned with the right
available and used indexes before it is passed to the device through the
activate function. And that's why upon reset, each queue was still
assigned with these indexes while it should have been reset to 0.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
All our virtio devices support to be reset, but the virtio-mmio
transport layer was not implemented for it. This patch fixes this
lack of support.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
It's not possible to call UnixListener::Bind() on an existing file so
unlink the created socket when shutting down the Vsock device.
This will allow the VM to be rebooted with a vsock device.
Fixes: #1083
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
It is based off the name from the virtio device attached to this
transport layer.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
It is based off the name from the virtio device attached to this
transport layer.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Now that all virtio devices are assigned with identifiers, they could
all be removed from the VM. This is not something that we want to allow
because it does not make sense for some devices. That's why based on the
device type, we remove the device or we return an error to the user.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
FS_IO is part of the actions a vhost-user-fs daemon can ask the VMM to
perform on its behalf. It is meant to read/write the content from a file
descriptor directly into a guest memory region. This region can either
be a RAM region or the dedicated cache region for virtio-fs.
The way FS_IO was implemented, it was only expecting the guest physical
address provided through the "cache_offset" field to refer to the cache
region. Unfortunately, this was only implementing FS_IO partially.
This patch extends the existing FS_IO implementation by checking the GPA
against the cache region as a first step, but if it is not part of the
cache region address range, then we fallback onto searching for a RAM
region that could match. If there is a matching RAM region, we retrieve
the corresponding host address to let the VMM read/write from/to it.
Fixes: #1054
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Jose Carlos Venegas Munoz <jose.carlos.venegas.munoz@intel.com>
This patch implements the Snapshottable trait for virtio-console, which
enables migration support for it. A VM with a virtio-console device
attached can be snapshot and then restored without issues.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
This brings the migration support to virtio-pmem device.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
The frame buffer must be updated depending on the amount read from it,
which depends on the number and depth of descriptors available at the
time of the processing.
This patch handles this buffer update, and allow for large buffers to be
correctly processed in multiple rounds.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
On the restore path, using the available and used indexes read from
memory to fill the Queue structure was a mistake. Indeed, the available
index is written from the guest and it reflects the last available index
in the descriptor table. But the driver might have queued a lot of
buffers which have not yet been used by the device. This leads to a
situation where the next_avail from Queue is completely different from
the one we can read from memory.
Instead, the right way to determine the next_avail index that should be
used by the device is by relying on the used index from the memory. This
index represents the correct information we're looking for as it has
been updated before the snapshot to let the guest know the next index to
process.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
First, this modifies the existing helpers on how to get indexes for
available and used rings from memory. Instead of updating the queue
through each helper, they are now used as simple getters.
Based on these new getters, we could create a new helper to determine if
the queue has some available descriptors already queued from the driver
side. This helper is going to be particularly helpful when trying to
determine from a virtio thread if a queue is already loaded with some
available buffers that can be used to send information to the guest.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Since the virtio-fs device is backed by a vhost-user process, it is
important to implement the proper shutdown() function from the
VirtioDevice trait, as vhost-user-blk and vhost-user-net do.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
When hot-unplugging the virtio-pmem from the VM, we don't remove the
associated userspace mapping. This patch will let us fix this in a
following patch. For now, it simply adapts the code so that the Pmem
device knows about the mapping associated with it. By knowing about it,
it can expose it to the caller through the new userspace_mappings()
function.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This will help when we will implement the hot-unplug of the virtio-fs
device, as we will have to remove correctly the userspace mappings
associated with the device.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Introduce new getter function to the VirtioDevice trait, as it will
allow the caller to retrieve the list of userspace mappings associated
with the device.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In the context of the shared memory region used by virtio-fs in order to
support DAX feature, the shared region is exposed as a dedicated PCI
BAR, and it is backed by a KVM userspace mapping.
Upon BAR remapping, the BAR is moved to a different location in the
guest address space, and the KVM mapping must be updated accordingly.
Additionally, we need the VirtioDevice to report the updated guest
address through the shared memory region returned by get_shm_regions().
That's why a new setter is added to the VirtioDevice trait, so that
after the mapping has been updated for KVM, we can tell the VirtioDevice
the new guest address the shared region is located at.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
By adding the shared memory regions to the list of BARs, we make sure
the DeviceManager will register it as a BAR on the PCI bus. Without
this, when PCI BAR reprogramming happens, the PCI bus errors since it
does not know about any BAR at the specified address.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Any virtio device relying on the mmio transport layer can be snapshotted
and restored thanks to this new patch. From the MmioDevice perspective,
it is mainly a matter of saving the information about the virtqueues as
the restore path will need them to activate the device (if needed
because it has been activated before being snapshotted).
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In anticipation for adding snapshot/restore support to virtio devices,
this commit introduces two new helpers updating the available and used
indexes of a queue, relying on the guest memory.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit relies on serde to serialize and deserialize the content of
a Queue structure. This will be useful information to store when
implementing snapshot/restore feature for virtio devices.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
Add support for specifying the PCI revision in the PCI configuration and
populate this with the value of 1 for virtio-pci devices.
The virtio-pci specification is slightly ambiguous only saying that
transitional (i.e. devices that support legacy and virtio 1.0) should
set this to 0. In practice it seems that software expects the revision
to be set to 1 for modern only devices.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Add an accessor to return the underlying VirtioDevice. This is useful
for managing the removal of the device from internal datastructures when
handling virtio-pci device unplug.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
In order to support freeing the memory that is allocated we need to make
sure that we update the internal representation so that free_bars() can
correctly free the memory if the device has its BARs moved.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Implement the free_bars() method from the PciDevice trait which is used
as part of the device removal process. Although there is only one BAR
allocated by VirtioPciDevice simplify the code by using a vector.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Move the release of the managed memory region from the DeviceManager to
the vhost-user-fs device. This ensures that the memory will be freed when
the device is unplugged which will lead to it being Drop()ed.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Move the release of the managed memory region from the DeviceManager to
the virtio-pmem device. This ensures that the memory will be freed when
the device is unplugged which will lead to it being Drop()ed.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
A Snapshottable component can snapshot itself and
provide a MigrationSnapshot payload as a result.
A MigrationSnapshot payload is a map of component IDs to a list of
migration sections (MigrationSection). As component can be made of
several Migratable sub-components (e.g. the DeviceManager and its
device objects), a migration snapshot can be made of multiple snapshot
itself.
A snapshot is a list of migration sections, each section being a
component state snapshot. Having multiple sections allows for easier and
backward compatible migration payload extensions.
Once created, a migratable component snapshot may be transported and this
is what the Transportable trait defines, through 2 methods: send and recv.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
Return libc::EINVAL instead of custom "Wrong offset" error, as mmap(2)
returns EINVAL when offset/len is invalid.
Signed-off-by: Eryu Guan <eguan@linux.alibaba.com>
In fs_slave_map/unmap/sync, we only made sure offset < cache_size, but
didn't validate (offset + len). We should ensure [offset, offset+len]
is within cache range as well.
Signed-off-by: Eryu Guan <eguan@linux.alibaba.com>
The basic idea of virtio-mem is to provide a flexible, cross-architecture
memory hot plug and hot unplug solution that avoids many limitations
imposed by existing technologies, architectures, and interfaces. More
details can be found in https://lkml.org/lkml/2019/12/12/681.
This commit add virtio-mem device.
Signed-off-by: Hui Zhu <teawater@antfin.com>
We made sure gpa is in cache range, but not the end addr of request,
which is (gpa + len). If the end addr of request is beyond dax cache
window, vmm would corrupt guest memory or crash.
Fix it by making sure end addr of request is within cache range as well.
And while we're at it, return EFAULT if the request is out of range, as
write(2)/read(2) returns EFAULT when buffer is outside accessible
address space.
Signed-off-by: Eryu Guan <eguan@linux.alibaba.com>
In order to keep vhost-user backend to work across guest memory resizing
happening when memory is hot-plugged or hot-unplugged, both blk, net and
fs devices are implementing the notifier to let the backend know.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
By factorizing the setup of the memory table for vhost-user, we
anticipate the fact that vhost-user devices are going to reuse this
function when the guest memory will be updated.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The virtio devices backed by a vhost-user backend must send an update to
the associated backend with the new file descriptors corresponding to
the memory regions.
This patch allows such devices to be notified when such update needs to
happen.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Virtio-fs daemon expects fs_slave_io() returns the number of bytes
read/written on success, but we always return 0 and make userspace think
nothing has been read/written.
Fix it by returning the actual bytes read/written. Note that This
depends on the corresponding fix in vhost crate.
Fixes: #949
Signed-off-by: Eryu Guan <eguan@linux.alibaba.com>
On x86_64, a hint to the compiler is not enough, we need to issue a
MFENCE instruction. Replace the Acquire fence with a SeqCst one.
Without this, it's still possible to miss an used_event update,
leading to the omission of a notification, possibly stalling the
vring.
Signed-off-by: Sergio Lopez <slp@redhat.com>
