On 5/13/20 4:16 AM, Cornelia Huck wrote: > On Wed, 13 May 2020 09:43:37 +0200 > Janosch Frank <fran...@linux.ibm.com> wrote: > >> On 5/12/20 6:01 PM, Cornelia Huck wrote: >>> On Mon, 11 May 2020 17:02:06 +0200 >>> David Hildenbrand <da...@redhat.com> wrote: >>> >>>> 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? >>> >>> Probably >>> >>> Fixes: 832be0d8a3bb ("s390x: sclp: Report insufficient SCCB length") >>> >>> ? >>> >>>>>>> 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 :) >>> >>> Same here. Sounds plausible, but I have to trust the folks with the >>> documentation :) >>> >> >> The AR states that: >> * Command validity check (has prio over length, as length is dependent >> on command) >> * boundary (if extended-length is not available) >> * Sufficient length check >> >> are done before "any other command action is taken". >> If a test fails the command is suppressed. > > Thanks, makes sense. >
Thanks, Janosch! (I suppose I could've said the same as well. Sorry about that). -- -- Regards, Collin Stay safe and stay healthy