Re: [PATCH] powerpc/pseries/vas: Don't print an error when VAS is unavailable

On 11/26/21 2:31 AM, Nicholas Piggin wrote:

Excerpts from Cédric Le Goater's message of November 26, 2021 5:13 pm:

quoted

On 11/26/21 06:21, Nicholas Piggin wrote:

quoted

KVM does not support VAS so guests always print a useless error on boot

     vas: HCALL(398) error -2, query_type 0, result buffer 0x57f2000

Change this to only print the message if the error is not H_FUNCTION.

Just being curious, why is it even called since "ibm,compression" should
not be exposed in the DT ?

It looks like vas does not test for it. I guess in theory there can be 
other functions than compression implemented as an accelerator. Maybe
that's why?

Thanks,
Nick

Looks like pseries_vas_init() simply calls h_query_vas_capabilities() to test
for VAS coprocessor support. I would assume KVM doesn't expose hcall-vas or
hcall-nx in /rtas/ibm,hypertas-functions? Doesn't look like hcall-vas or
hcall-nx have been added to the hypertas_fw_feature matching, but maybe they
should and we can gate VAS initialization on those, or at the minimum
FW_FEATURE_VAS?

-Tyrel