virtio-devices: Fix some spec compliance issues - #8066
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generally LGTM! Did you use an LLM to find all the spec inconsistencies?
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Yes, I updated the PR description. |
The virtio spec says the used-ring length is bytes the device wrote to device writable descriptors. The net TX descriptors are device readable only (the device wrote nothing back) so the length needs to be 0. On the ctrl queue the number of bytes reported was wrongly the size of the status descriptor not the number of bytes written (the descriptor is permitted to be larger). Signed-off-by: Rob Bradford <[email protected]>
The virtio spec allows the use of larger descriptors (for future expansion). Relax the bounds check to only reject descriptors that are too small. Signed-off-by: Rob Bradford <[email protected]>
The virtio spec allows the use of larger descriptors (for future expansion). Relax the bounds check to only reject descriptors that are too small. Signed-off-by: Rob Bradford <[email protected]>
The virtio spec requires that a status response is always written on error. This was missing from the path where we had a valid request but not for one we support. Signed-off-by: Rob Bradford <[email protected]>
The virtio spec allows a chain of writable descriptors however the rng device was assuming just a single writable descriptor. Instead fill in all writable descriptors. There is no status byte (unlike e.g. block) and instead 0 bytes used is used to indicate error. Signed-off-by: Rob Bradford <[email protected]>
The number of bytes written into descriptors should be reported for `add_used()`. Here it is either just the status byte or also the size of serial ID for the block device. Signed-off-by: Rob Bradford <[email protected]>
The driver needs to be notified with the number of bytes written by the device. Ensure that the correct number of bytes is reported. Signed-off-by: Rob Bradford <[email protected]>
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@phip1611 PTAL! |
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Fix some basic spec compliance issues. :
add_used()I used Claude to compare the virtio spec with our implementation. There was a lot of issues; these are fixes for all those related to reporting wrong bytes written with
.add_used()and incorrect descriptor chain expectations (multiple writable, too strict.)