virtio-devices: console: Fix descriptor chain processing - #7802
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rbradford
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I have removed the unused DescriptorChainTooShort. This should fix ci failures. |
likebreath
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Thanks for the contribution! This is a good fix. I have left a couple of minor suggestions below.
Gentle reminder: As a first-time contributor, please take a moment to review our contribution guidelines.
Also, this inspired me to audit our other virtio devices for similar issues. I've opened a tracking issue here: #7803.
The update_console_size method was using fetch_and on the acked_features atomic, which modified the atomic and cleared other feature bits. Changed it to use a non-destructive load and bitwise AND. Signed-off-by: Andrei Vagin <[email protected]>
For a transmit queue (guest to host), the host only reads from the guest-provided buffers and does not write to them. According to the virtio specification (e.g., Section 2.6.8 in Virtio 1.1), the 'len' field in the used ring has to be set to the number of bytes written to the buffers. Therefore, it should be 0 for the console transmit queue. Signed-off-by: Andrei Vagin <[email protected]>
Both process_input_queue and process_output_queue were only processing the first descriptor of a chain, leading to data loss if the driver used chained descriptors. This change iterates through all descriptors in a chain. It also moves the flush call out of the descriptor loops to improve performance. Signed-off-by: Andrei Vagin <[email protected]>
rbradford
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Both process_input_queue and process_output_queue were only processing the first descriptor of a chain, leading to data loss if the driver used chained descriptors.
This change iterates through all descriptors in a chain. It also fixes the
lenfield in the used ring for the transmit queue to be 0, as required by the virtio specification ((e.g., Section 2.6.8 in virtio 1.1).