kernel/linux.git/drivers/char/virtio_console.c, branch v4.4.171

virtio_console: free buffers after reset

2018-05-02T14:53:40+00:00

commit a7a69ec0d8e4a58be7db88d33cbfa2912807bb2b upstream. Console driver is out of spec. The spec says: A driver MUST NOT decrement the available idx on a live virtqueue (ie. there is no way to “unexpose” buffers). and it does exactly that by trying to detach unused buffers without doing a device reset first. Defer detaching the buffers until device unplug. Of course this means we might get an interrupt for a vq without an attached port now. Handle that by discarding the consumed buffer. Reported-by: Tiwei Bie Fixes: b3258ff1d6 ("virtio: Decrement avail idx on buffer detach") Cc: stable@vger.kernel.org Signed-off-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman

virtio_console: fix a crash in config_work_handler

2017-07-05T12:37:18+00:00

[ Upstream commit 8379cadf71c3ee8173a1c6fc1ea7762a9638c047 ] Using control_work instead of config_work as the 3rd argument to container_of results in an invalid portdev pointer. Indeed, the work structure is initialized as below: INIT_WORK(&portdev->config_work, &config_work_handler); It leads to a crash when portdev->vdev is dereferenced later. This bug is triggered when the guest uses a virtio-console without multiport feature and receives a config_changed virtio interrupt. Signed-off-by: G. Campana Reviewed-by: Amit Shah Signed-off-by: Michael S. Tsirkin Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

virtio-console: avoid DMA from stack

2017-04-21T07:30:07+00:00

commit c4baad50297d84bde1a7ad45e50c73adae4a2192 upstream. put_chars() stuffs the buffer it gets into an sg, but that buffer may be on the stack. This breaks with CONFIG_VMAP_STACK=y (for me, it manifested as printks getting turned into NUL bytes). Signed-off-by: Omar Sandoval Signed-off-by: Michael S. Tsirkin Reviewed-by: Amit Shah Cc: Ben Hutchings Cc: Brad Spengler Signed-off-by: Greg Kroah-Hartman

virtio: console: Unlock vqs while freeing buffers

2016-11-10T15:36:34+00:00

commit 34563769e438d2881f62cf4d9badc4e589ac0ec0 upstream. Commit c6017e793b93 ("virtio: console: add locks around buffer removal in port unplug path") added locking around the freeing of buffers in the vq. However, when free_buf() is called with can_sleep = true and rproc is enabled, it calls dma_free_coherent() directly, requiring interrupts to be enabled. Currently a WARNING is triggered due to the spin locking around free_buf, with a call stack like this: WARNING: CPU: 3 PID: 121 at ./include/linux/dma-mapping.h:433 free_buf+0x1a8/0x288 Call Trace: [<8040c538>] show_stack+0x74/0xc0 [<80757240>] dump_stack+0xd0/0x110 [<80430d98>] __warn+0xfc/0x130 [<80430ee0>] warn_slowpath_null+0x2c/0x3c [<807e7c6c>] free_buf+0x1a8/0x288 [<807ea590>] remove_port_data+0x50/0xac [<807ea6a0>] unplug_port+0xb4/0x1bc [<807ea858>] virtcons_remove+0xb0/0xfc [<807b6734>] virtio_dev_remove+0x58/0xc0 [<807f918c>] __device_release_driver+0xac/0x134 [<807f924c>] device_release_driver+0x38/0x50 [<807f7edc>] bus_remove_device+0xfc/0x130 [<807f4b74>] device_del+0x17c/0x21c [<807f4c38>] device_unregister+0x24/0x38 [<807b6b50>] unregister_virtio_device+0x28/0x44 Fix this by restructuring the loops to allow the locks to only be taken where it is necessary to protect the vqs, and release it while the buffer is being freed. Fixes: c6017e793b93 ("virtio: console: add locks around buffer removal in port unplug path") Signed-off-by: Matt Redfearn Signed-off-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman

virtio_console: silence a static checker warning

2015-05-24T19:24:35+00:00

My static checker complains that this sprintf() can overflow but really it can't. Just silence the warning by using snprintf(). Signed-off-by: Dan Carpenter Reviewed-by: Amit Shah Signed-off-by: Greg Kroah-Hartman

virtio_console: Use bool function return values of true/false not 1/0

2015-04-03T14:15:30+00:00

Use the normal return values for bool functions Signed-off-by: Joe Perches Reviewed-by: Amit Shah Signed-off-by: Greg Kroah-Hartman

virtio_console: avoid config access from irq

2015-03-05T03:06:18+00:00

when multiport is off, virtio console invokes config access from irq context, config access is blocking on s390. Fix this up by scheduling work from config irq - similar to what we do for multiport configs. Signed-off-by: Michael S. Tsirkin Reviewed-by: Amit Shah Signed-off-by: Rusty Russell Cc: stable@kernel.org

virtio_console: init work unconditionally

2015-03-05T03:06:17+00:00

when multiport is off, we don't initialize config work, but we then cancel uninitialized control_work on freeze. Signed-off-by: Michael S. Tsirkin Reviewed-by: Amit Shah Signed-off-by: Rusty Russell Cc: stable@kernel.org

virtio: don't require a config space on the console device.

2015-02-11T04:33:17+00:00

Strictly, it's only needed when we have features (size or multiport). Signed-off-by: Rusty Russell

virtio/console: verify device has config space

2015-01-21T05:58:46+00:00

Some devices might not implement config space access (e.g. remoteproc used not to - before 3.9). virtio/console needs config space access so make it fail gracefully if not there. Signed-off-by: Michael S. Tsirkin Signed-off-by: Rusty Russell