Re: [kvm-unit-tests PATCH 1/2] s390x: smp: Use full PSW to bringup new cpu

David Hildenbrand
2019-12-11T12:54:43Z

On 11.12.19 13:34, Janosch Frank wrote:
> On 12/11/19 1:31 PM, David Hildenbrand wrote:
>> On 11.12.19 12:59, Janosch Frank wrote:
>>> Up to now we ignored the psw mask and only used the psw address when
>>> bringing up a new cpu. For DAT we need to also load the mask, so let's
>>> do that.
>>>
>>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>>> ---
>>> lib/s390x/smp.c | 2 ++
>>> s390x/cstart64.S | 2 +-
>>> 2 files changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/lib/s390x/smp.c b/lib/s390x/smp.c
>>> index f57f420..e17751a 100644
>>> --- a/lib/s390x/smp.c
>>> +++ b/lib/s390x/smp.c
>>> @@ -185,6 +185,8 @@ int smp_cpu_setup(uint16_t addr, struct psw psw)
>>> cpu->stack = (uint64_t *)alloc_pages(2);
>>>
>>> /* Start without DAT and any other mask bits. */
>>> + cpu->lowcore->sw_int_psw.mask = psw.mask;
>>> + cpu->lowcore->sw_int_psw.addr = psw.addr;
>>> cpu->lowcore->sw_int_grs[14] = psw.addr;
>>
>> Not looking at the code (sorry :D ), do we still need this then? (you
>> drop the br bewlo)
>
> r14 is the return address, saving/initialising it doesn't sound like a
> bad idea to me. If we ever have stack traces, it might show up, or won't it?
>
>>
>>> cpu->lowcore->sw_int_grs[15] = (uint64_t)cpu->stack + (PAGE_SIZE * 4);
>>> lc->restart_new_psw.mask = 0x0000000180000000UL;
>>> diff --git a/s390x/cstart64.S b/s390x/cstart64.S
>>> index 86dd4c4..e6a6bdb 100644
>>> --- a/s390x/cstart64.S
>>> +++ b/s390x/cstart64.S
>>> @@ -159,7 +159,7 @@ smp_cpu_setup_state:
>>> xgr %r1, %r1
>>> lmg %r0, %r15, GEN_LC_SW_INT_GRS
>>> lctlg %c0, %c0, GEN_LC_SW_INT_CRS
>>> - br %r14
>>> + lpswe GEN_LC_SW_INT_PSW
>>>

Makes sense

Reviewed-by: David Hildenbrand <david@redhat.com>