Re: [kvm-unit-tests PULL 1/2] powerpc: Allow for a custom decr value to be specified to load on decr excp

[Laurent Vivier <lvivier@redhat.com>]

On 20/05/2019 06:47, Suraj Jitindar Singh wrote:
> On Fri, 2019-05-17 at 15:10 +0200, Thomas Huth wrote:
>> On 17/05/2019 15.03, Laurent Vivier wrote:
>>> From: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
>>>
>>> Currently the handler for a decrementer exception will simply
>>> reload the
>>> maximum value (0x7FFFFFFF), which will take ~4 seconds to expire
>>> again.
>>> This means that if a vcpu cedes, it will be ~4 seconds between
>>> wakeups.
>>>
>>> The h_cede_tm test is testing a known breakage when a guest cedes
>>> while
>>> suspended. To be sure we cede 500 times to check for the bug.
>>> However
>>> since it takes ~4 seconds to be woken up once we've ceded, we only
>>> get
>>> through ~20 iterations before we reach the 90 seconds timeout and
>>> the
>>> test appears to fail.
>>>
>>> Add an option when registering the decrementer handler to specify
>>> the
>>> value which should be reloaded by the handler, allowing the timeout
>>> to be
>>> chosen.
>>>
>>> Modify the spr test to use the max timeout to preserve existing
>>> behaviour.
>>> Modify the h_cede_tm test to use a 10ms timeout to ensure we can
>>> perform
>>> 500 iterations before hitting the 90 second time limit for a test.
>>>
>>> This means the h_cede_tm test now succeeds rather than timing out.
>>>
>>> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
>>> Reviewed-by: Thomas Huth <thuth@redhat.com>
>>> Reviewed-by: Laurent Vivier <lvivier@redhat.com>
>>> [lv: reset initial value to 0x3FFFFFFF]
>>
>> Looks like something went wrong here? There is still the 0x7FFFFFFF
>> in
>> the hunk below...
> 
> No, I think this is correct.
> Max value is ox7FFFFFFF, but the initial value we load via mtdec is the
> original 0x3FFFFFFF.

Yes, that's it.

Thanks,
Laurent