From: Jakub Kicinski <kuba@kernel.org> Sent: Thursday, February 9, 2023 12:22 PM

On Thu, 9 Feb 2023 19:10:16 +0000 Haiyang Zhang wrote:

quoted

But I'm just worried about if a VM sending at high speed, and host side is,
for some reason, not able to send them correctly, the log file will become
really big and difficult to download and read. With rate limit, we still see
dozens of messages every 5 seconds or so, and it tells you how many
messages are skipped. And, if the rate is lower, it won't skip anything.
Isn't this info sufficient to debug?

Agreed.

quoted

By the way, guests cannot trust the host -- probably we shouldn't allow the
host to have a way to jam guest's log file?

Actually, preventing jamming the guest's log file is not a requirement
in Confidential VMs where the host is not trusted.  Confidential VMs
do not prevent denial-of-service attacks, or similar.  But that's another
topic. :-)

+1 FWIW, the general guidance is to always rate limit prints
which may be triggered from the datapath (which I'm guessing
this is based on the names of things)

Fair enough.  I'll do a v2 with the rate limiting.

Michael