On 02/20/2018 04:41 PM, David Hildenbrand wrote:
> On 20.02.2018 16:36, Christian Borntraeger wrote:
>>
>>
>> On 02/07/2018 12:46 PM, David Hildenbrand wrote:
>>> For now, we don't take care of over/underflows. Especially underflows
>>> are critical:
>>>
>>> Assume the epoch is currently 0 and we get a sync request for delta=1,
>>> meaning the TOD is moved forward by 1 and we have to fix it up by
>>> subtracting 1 from the epoch. Right now, this will leave the epoch
>>> index untouched, resulting in epoch=-1, epoch_idx=0, which is wrong.
>>>
>>> We have to take care of over and underflows, also for the VSIE case. So
>>> let's factor out calculation into a separate function.
>>>
>>> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
>>> ---
>>> arch/s390/kvm/kvm-s390.c | 32 +++++++++++++++++++++++++++++---
>>> 1 file changed, 29 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>>> index d007b737cd4d..c2b62379049e 100644
>>> --- a/arch/s390/kvm/kvm-s390.c
>>> +++ b/arch/s390/kvm/kvm-s390.c
>>> @@ -179,6 +179,28 @@ int kvm_arch_hardware_enable(void)
>>> static void kvm_gmap_notifier(struct gmap *gmap, unsigned long start,
>>> unsigned long end);
>>>
>>> +static void kvm_clock_sync_scb(struct kvm_s390_sie_block *scb, u64 delta)
>>> +{
>>> + u64 delta_idx = 0;
>>
>> we only add it to epdx, so should it be u8?
>
> Indeed, this should be u8.
>
>>> +
>>> + /*
>>> + * The TOD jumps by delta, we have to compensate this by adding
>>> + * -delta to the epoch.
>>> + */
>>> + delta = -delta;
>>> +
>>> + /* sign-extension - we're adding to signed values below */
>>> + if ((s64)delta < 0)
>>> + delta_idx = 0xff;
>>
>> and -1 then here?
>
> Yes, thanks!
with that
Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
applied and changed to u8.
In plan to submit patch 1,3 and 4 for 4.16
