linux/drivers/virtio, branch v4.0

virtio_mmio: fix access width for mmio

2015-03-17T01:42:21Z

Going over the virtio mmio code, I noticed that it doesn't correctly access modern device config values using "natural" accessors: it uses readb to get/set them byte by byte, while the virtio 1.0 spec explicitly states: 4.2.2.2 Driver Requirements: MMIO Device Register Layout ... The driver MUST only use 32 bit wide and aligned reads and writes to access the control registers described in table 4.1. For the device-specific configuration space, the driver MUST use 8 bit wide accesses for 8 bit wide fields, 16 bit wide and aligned accesses for 16 bit wide fields and 32 bit wide and aligned accesses for 32 and 64 bit wide fields. Borrow code from virtio_pci_modern to do this correctly. Signed-off-by: Michael S. Tsirkin Signed-off-by: Rusty Russell

virtio_mmio: generation support

2015-03-13T05:25:43Z

virtio_mmio currently lacks generation support which makes multi-byte field access racy. Fix by getting the value at offset 0xfc for version 2 devices. Nothing we can do for version 1, so return generation id 0. Signed-off-by: Michael S. Tsirkin Signed-off-by: Rusty Russell

virtio-balloon: do not call blocking ops when !TASK_RUNNING

2015-03-10T01:26:15Z

virtio balloon has this code: wait_event_interruptible(vb->config_change, (diff = towards_target(vb)) != 0 || vb->need_stats_update || kthread_should_stop() || freezing(current)); Which is a problem because towards_target() call might block after wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing the task_struct::state collision typical of nesting of sleeping primitives See also http://lwn.net/Articles/628628/ or Thomas's bug report http://article.gmane.org/gmane.linux.kernel.virtualization/24846 for a fuller explanation. To fix, rewrite using wait_woken. Cc: stable@vger.kernel.org Reported-by: Thomas Huth Signed-off-by: Michael S. Tsirkin Tested-by: Thomas Huth Reviewed-by: Cornelia Huck Signed-off-by: Rusty Russell

virtio_balloon: set DRIVER_OK before using device

2015-03-10T01:18:28Z

virtio spec requires that all drivers set DRIVER_OK before using devices. While balloon isn't yet included in the virtio 1 spec, previous spec versions also required this. virtio balloon might violate this rule: probe calls kthread_run before setting DRIVER_OK, which might run immediately and cause balloon to inflate/deflate. To fix, call virtio_device_ready before running the kthread. Signed-off-by: Michael S. Tsirkin Signed-off-by: Rusty Russell Cc: stable@kernel.org

virtio: don't set VIRTIO_CONFIG_S_DRIVER_OK twice.

2015-02-17T05:49:29Z

I noticed this with the console device. It's not *wrong*, just a bit weird. Signed-off-by: Rusty Russell

virtio_pci: use 16-bit accessor for queue_enable.

2015-02-11T04:33:16Z

Since PCI is little endian, 8-bit access might work, but the spec section is very clear on this: 4.1.3.1 Driver Requirements: PCI Device Layout The driver MUST access each field using the “natural” access method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for 16-bit fields and 8-bit accesses for 8-bit fields. Signed-off-by: Rusty Russell Acked-by: Michael S. Tsirkin

virtio: Avoid possible kernel panic if DEBUG is enabled.

2015-02-11T04:33:14Z

The virtqueue_add() calls START_USE() upon entry. The virtqueue_kick() is called if vq->num_added == (1 << 16) - 1 before calling END_USE(). The virtqueue_kick_prepare() called via virtqueue_kick() calls START_USE() upon entry, and will call panic() if DEBUG is enabled. Move this virtqueue_kick() call to after END_USE() call. Signed-off-by: Tetsuo Handa Signed-off-by: Rusty Russell

virtio-mmio: Update the device to OASIS spec version

2015-01-23T04:27:10Z

This patch add a support for second version of the virtio-mmio device, which follows OASIS "Virtual I/O Device (VIRTIO) Version 1.0" specification. Main changes: 1. The control register symbolic names use the new device/driver nomenclature rather than the old guest/host one. 2. The driver detect the device version (version 1 is the pre-OASIS spec, version 2 is compatible with fist revision of the OASIS spec) and drives the device accordingly. 3. New version uses direct addressing (64 bit address split into two low/high register) instead of the guest page size based one, and addresses each part of the queue (descriptors, available, used) separately. 4. The device activity is now explicitly triggered by writing to the "queue ready" register. 5. Whole 64 bit features are properly handled now (both ways). Signed-off-by: Pawel Moll Acked-by: Michael S. Tsirkin Signed-off-by: Rusty Russell

virtio_pci_modern: drop an unused function

2015-01-21T05:59:01Z

release function in modern driver is unused: it's a left-over from when each driver had to have its own release. Signed-off-by: Michael S. Tsirkin

virtio_pci: add module param to force legacy mode

2015-01-21T05:59:01Z

If set, try legacy interface first, modern one if that fails. Useful to work around device/driver bugs, and for compatibility testing. Signed-off-by: Michael S. Tsirkin Signed-off-by: Rusty Russell