On 11.05.20 16:50, Janosch Frank wrote: > On 5/11/20 4:44 PM, David Hildenbrand wrote: >> On 11.05.20 16:36, Janosch Frank wrote: >>> On 5/9/20 1:08 AM, Collin Walling wrote: >>>> The SCCB must be checked for a sufficient length before it is filled >>>> with any data. If the length is insufficient, then the SCLP command >>>> is suppressed and the proper response code is set in the SCCB header. >>>> >>>> Signed-off-by: Collin Walling <wall...@linux.ibm.com> >>> >>> Fixes tag? >>> Reviewed-by: Janosch Frank <fran...@linux.ibm.com> >> >> This is not a fix AFAIKs. >> sclp_service_call()/sclp_service_call_protected() always supplies a full >> SCCB of exactly 4k size. >> > > We don't check for QEMU's 4k buffer here, but for the length that was > specified by the guest. > > It's valid for the guest to request cpu info and state that its buffer > is only 1k. We can't write everything in 1k if we have ~200 cpus, so > we'll report the insufficient length rc. > > What he fixes here is the time of the length check, it should be done > before any changes are being done to the work_sccb.
I don't have access to the spec, especially, if the guest can expect nothing else in the sccb to change in case we report an error code. So whatever you tell me, I have to trust you :) -- Thanks, David / dhildenb