Fix virtio kernel panic after processing 100 thousands outputs #301
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diegonehab
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This is a fix for issue #300 .
The bug occurred where the VirtIO device was generating unnecessary interrupt requests (IRQs) after consuming guest-supplied buffers. The kernel normally ignores these unhandled IRQs silently. However, the kernel maintains a counter of ignored IRQs, and when this counter exceeds 100000, it incorrectly assumes the driver is malfunctioning and triggers a kernel panic. This behavior is only visible when the kernel is compiled with debug information, which produces the message "virtqueue interrupt with no work for."
The root cause was the VirtIO device sending superfluous IRQs that the kernel driver didn't need. The solution was straightforward: modify the VirtIO device to stop generating IRQs when processing buffers sent by the kernel driver. So in short terms, we only need to trigger IRQs for inputs coming from the host, and never trigger IRQs to notify that an input coming from the guest was processed.