diff options
| author | Andre Przywara <[email protected]> | 2023-11-07 16:09:00 +0000 |
|---|---|---|
| committer | Tom Rini <[email protected]> | 2023-11-17 11:58:26 -0500 |
| commit | 45c4b276f0a4d67e06c94de3d0a5dadf4bee530a (patch) | |
| tree | 5378af6bbb11115d1eb807df683ba0efac866043 /drivers/timer/sandbox_timer.c | |
| parent | 741d1e9d3f368908e3cd1861ddd707e81e1fd576 (diff) | |
virtio: rng: gracefully handle 0 byte returns
According to the virtio v1.x "entropy device" specification, a virtio-rng
device is supposed to always return at least one byte of entropy.
However the virtio v0.9 spec does not mention such a requirement.
The Arm Fixed Virtual Platform (FVP) implementation of virtio-rng always
returns 8 bytes less of entropy than requested. If 8 bytes or less are
requested, it will return 0 bytes.
This behaviour makes U-Boot's virtio_rng_read() implementation go into an
endless loop, hanging the system.
Work around this problem by always requesting 8 bytes more than needed,
but only if a previous call to virtqueue_get_buf() returned 0 bytes.
This should never trigger on a v1.x spec compliant implementation, but
fixes the hang on the Arm FVP.
Signed-off-by: Andre Przywara <[email protected]>
Reported-by: Peter Hoyes <[email protected]>
Diffstat (limited to 'drivers/timer/sandbox_timer.c')
0 files changed, 0 insertions, 0 deletions