Re: [PATCH] KVM: VMX: CPU frequency scaling for intel x86_64 KVM guests

From: Paolo Bonzini
Date: Tue May 31 2022 - 14:11:47 EST


On 5/31/22 13:43, Metin Kaya wrote:
Thanks, Jack.

Reviewed-by: Metin Kaya <metikaya@xxxxxxxxxxxx>


Please try a bit harder. "Reviewed-by" is neither "this matches what's been forever in the Amazon kernel" nor "I guarantee that Jack is a nice guy and doesn't screw up". I'm sure he is but everybody screws up, and in this case the patch:

- does not even *apply* to the upstream kernel, because it uses (presumably Amazon-specific) CAP numbers above 10000

- does not work if the vCPU is moved from one physical CPU to another

- does not work if the intel_pstate driver writes to MSR_HWP_REQUEST

- does not include documentation for the new capability

- does not include a selftest

- is unacceptable anyway because, as mentioned in the cover letter, it isn't undone when the process exits

Jack, please understand that I am not really blaming you in any way, and ask some of your colleagues with upstream kernel experience (Alex Graf, David Woodhouse, Filippo Sironi, Jan Schoenherr, Amit Shah are the ones I know) which patches could be good targets for including upstream.

Paolo