linux.git/drivers/virtio/virtio.c, branch v5.17

virtio: document virtio_reset_device

2022-03-04T13:33:22+00:00

Looks like most callers get driver/device removal wrong.
Document what's expected of callers.

Signed-off-by: Michael S. Tsirkin

virtio: acknowledge all features before access

2022-03-04T13:33:21+00:00

The feature negotiation was designed in a way that
makes it possible for devices to know which config
fields will be accessed by drivers.

This is broken since commit 404123c2db79 ("virtio: allow drivers to
validate features") with fallout in at least block and net.  We have a
partial work-around in commit 2f9a174f918e ("virtio: write back
F_VERSION_1 before validate") which at least lets devices find out which
format should config space have, but this is a partial fix: guests
should not access config space without acknowledging features since
otherwise we'll never be able to change the config space format.

To fix, split finalize_features from virtio_finalize_features and
call finalize_features with all feature bits before validation,
and then - if validation changed any bits - once again after.

Since virtio_finalize_features no longer writes out features
rename it to virtio_features_ok - since that is what it does:
checks that features are ok with the device.

As a side effect, this also reduces the amount of hypervisor accesses -
we now only acknowledge features once unless we are clearing any
features when validating (which is uncommon).

IRC I think that this was more or less always the intent in the spec but
unfortunately the way the spec is worded does not say this explicitly, I
plan to address this at the spec level, too.

Acked-by: Jason Wang 
Cc: stable@vger.kernel.org
Fixes: 404123c2db79 ("virtio: allow drivers to validate features")
Fixes: 2f9a174f918e ("virtio: write back F_VERSION_1 before validate")
Cc: "Halil Pasic" 
Signed-off-by: Michael S. Tsirkin

virtio: unexport virtio_finalize_features

2022-03-04T13:33:21+00:00

virtio_finalize_features is only used internally within virtio.
No reason to export it.

Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Cornelia Huck 
Acked-by: Jason Wang

virtio: wrap config->reset calls

2022-01-14T23:50:52+00:00

This will enable cleanups down the road.
The idea is to disable cbs, then add "flush_queued_cbs" callback
as a parameter, this way drivers can flush any work
queued after callbacks have been disabled.

Signed-off-by: Michael S. Tsirkin 
Link: https://lore.kernel.org/r/20211013105226.20225-1-mst@redhat.com
Signed-off-by: Michael S. Tsirkin

virtio: write back F_VERSION_1 before validate

2021-10-13T12:35:36+00:00

The virtio specification virtio-v1.1-cs01 states: "Transitional devices
MUST detect Legacy drivers by detecting that VIRTIO_F_VERSION_1 has not
been acknowledged by the driver."  This is exactly what QEMU as of 6.1
has done relying solely on VIRTIO_F_VERSION_1 for detecting that.

However, the specification also says: "... the driver MAY read (but MUST
NOT write) the device-specific configuration fields to check that it can
support the device ..." before setting FEATURES_OK.

In that case, any transitional device relying solely on
VIRTIO_F_VERSION_1 for detecting legacy drivers will return data in
legacy format.  In particular, this implies that it is in big endian
format for big endian guests. This naturally confuses the driver which
expects little endian in the modern mode.

It is probably a good idea to amend the spec to clarify that
VIRTIO_F_VERSION_1 can only be relied on after the feature negotiation
is complete. Before validate callback existed, config space was only
read after FEATURES_OK. However, we already have two regressions, so
let's address this here as well.

The regressions affect the VIRTIO_NET_F_MTU feature of virtio-net and
the VIRTIO_BLK_F_BLK_SIZE feature of virtio-blk for BE guests when
virtio 1.0 is used on both sides. The latter renders virtio-blk unusable
with DASD backing, because things simply don't work with the default.
See Fixes tags for relevant commits.

For QEMU, we can work around the issue by writing out the feature bits
with VIRTIO_F_VERSION_1 bit set.  We (ab)use the finalize_features
config op for this. This isn't enough to address all vhost devices since
these do not get the features until FEATURES_OK, however it looks like
the affected devices actually never handled the endianness for legacy
mode correctly, so at least that's not a regression.

No devices except virtio net and virtio blk seem to be affected.

Long term the right thing to do is to fix the hypervisors.

Cc:  #v4.11
Signed-off-by: Halil Pasic 
Fixes: 82e89ea077b9 ("virtio-blk: Add validation for block size in config space")
Fixes: fe36cbe0671e ("virtio_net: clear MTU when out of range")
Reported-by: markver@us.ibm.com
Reviewed-by: Cornelia Huck 
Link: https://lore.kernel.org/r/20211011053921.1198936-1-pasic@linux.ibm.com
Signed-off-by: Michael S. Tsirkin

virtio: don't fail on !of_device_is_compatible

2021-09-14T22:09:57+00:00

A recent change checking of_device_is_compatible on probe broke some
powerpc/pseries setups. Apparently there virtio devices do not have a
"compatible" property - they are matched by PCI vendor/device ids.

Let's just skip of_node setup but proceed with initialization like we
did previously.

Fixes: 694a1116b405 ("virtio: Bind virtio device to device-tree node")
Reported-by: Alexey Kardashevskiy 
Cc: Arnd Bergmann 
Cc: Viresh Kumar 
Tested-by: Guenter Roeck 
Acked-by: Jason Wang 
Reviewed-by: Viresh Kumar 
Signed-off-by: Michael S. Tsirkin

Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

2021-09-11T21:48:42+00:00

Pull virtio updates from Michael Tsirkin:

 - vduse driver ("vDPA Device in Userspace") supporting emulated virtio
   block devices

 - virtio-vsock support for end of record with SEQPACKET

 - vdpa: mac and mq support for ifcvf and mlx5

 - vdpa: management netlink for ifcvf

 - virtio-i2c, gpio dt bindings

 - misc fixes and cleanups

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (39 commits)
  Documentation: Add documentation for VDUSE
  vduse: Introduce VDUSE - vDPA Device in Userspace
  vduse: Implement an MMU-based software IOTLB
  vdpa: Support transferring virtual addressing during DMA mapping
  vdpa: factor out vhost_vdpa_pa_map() and vhost_vdpa_pa_unmap()
  vdpa: Add an opaque pointer for vdpa_config_ops.dma_map()
  vhost-iotlb: Add an opaque pointer for vhost IOTLB
  vhost-vdpa: Handle the failure of vdpa_reset()
  vdpa: Add reset callback in vdpa_config_ops
  vdpa: Fix some coding style issues
  file: Export receive_fd() to modules
  eventfd: Export eventfd_wake_count to modules
  iova: Export alloc_iova_fast() and free_iova_fast()
  virtio-blk: remove unneeded "likely" statements
  virtio-balloon: Use virtio_find_vqs() helper
  vdpa: Make use of PFN_PHYS/PFN_UP/PFN_DOWN helper macro
  vsock_test: update message bounds test for MSG_EOR
  af_vsock: rename variables in receive loop
  virtio/vsock: support MSG_EOR bit processing
  vhost/vsock: support MSG_EOR bit processing
  ...

virtio: Bind virtio device to device-tree node

2021-09-05T20:23:08+00:00

Bind the virtio devices with their of_node. This will help users of the
virtio devices to mention their dependencies on the device in the DT
itself. Like GPIO pin users can use the phandle of the device node, or
the node may contain more subnodes to add i2c or spi eeproms and other
users.

Reviewed-by: Arnd Bergmann 
Signed-off-by: Viresh Kumar 
Link: https://lore.kernel.org/r/94c12705602929968477aaf27e02439eb7a7f253.1627362340.git.viresh.kumar@linaro.org
Signed-off-by: Michael S. Tsirkin

Merge tag 'driver-core-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2021-09-01T15:44:42+00:00

Pull driver core updates from Greg KH:
 "Here is the big set of driver core patches for 5.15-rc1.

  These do change a number of different things across different
  subsystems, and because of that, there were 2 stable tags created that
  might have already come into your tree from different pulls that did
  the following

   - changed the bus remove callback to return void

   - sysfs iomem_get_mapping rework

  Other than those two things, there's only a few small things in here:

   - kernfs performance improvements for huge numbers of sysfs users at
     once

   - tiny api cleanups

   - other minor changes

  All of these have been in linux-next for a while with no reported
  problems, other than the before-mentioned merge issue"

* tag 'driver-core-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (33 commits)
  MAINTAINERS: Add dri-devel for component.[hc]
  driver core: platform: Remove platform_device_add_properties()
  ARM: tegra: paz00: Handle device properties with software node API
  bitmap: extend comment to bitmap_print_bitmask/list_to_buf
  drivers/base/node.c: use bin_attribute to break the size limitation of cpumap ABI
  topology: use bin_attribute to break the size limitation of cpumap ABI
  lib: test_bitmap: add bitmap_print_bitmask/list_to_buf test cases
  cpumask: introduce cpumap_print_list/bitmask_to_buf to support large bitmask and list
  sysfs: Rename struct bin_attribute member to f_mapping
  sysfs: Invoke iomem_get_mapping() from the sysfs open callback
  debugfs: Return error during {full/open}_proxy_open() on rmmod
  zorro: Drop useless (and hardly used) .driver member in struct zorro_dev
  zorro: Simplify remove callback
  sh: superhyway: Simplify check in remove callback
  nubus: Simplify check in remove callback
  nubus: Make struct nubus_driver::remove return void
  kernfs: dont call d_splice_alias() under kernfs node lock
  kernfs: use i_lock to protect concurrent inode updates
  kernfs: switch kernfs to use an rwsem
  kernfs: use VFS negative dentry caching
  ...

virtio: Protect vqs list access

2021-08-10T15:50:55+00:00

VQs may be accessed to mark the device broken while they are
created/destroyed. Hence protect the access to the vqs list.

Fixes: e2dcdfe95c0b ("virtio: virtio_break_device() to mark all virtqueues broken.")
Signed-off-by: Parav Pandit 
Link: https://lore.kernel.org/r/20210721142648.1525924-4-parav@nvidia.com
Signed-off-by: Michael S. Tsirkin