Re: [PATCH] hw/ppc: fix decrementer with BookE timers

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Adding Cédric

On 27/8/24 13:49, Clément Chigot wrote:
> Hey,
> 
> Gentle ping
> 
> Thanks Clément
> 
> On Mon, Jul 29, 2024 at 10:33 AM Clément Chigot <chigot@adacore.com> wrote:
>>
>> Hi,
>>
>> Gentle ping + CC missing maintainers.
>>
>> Thanks Clément
>>
>> On Mon, Jul 15, 2024 at 10:46 AM Clément Chigot <chigot@adacore.com> wrote:
>>>
>>> The BookE decrementer stops at 0, meaning that it won't decremented
>>> towards "negative" values.
>>> However, the current logic is inverted: decr is updated solely when
>>> the resulting value would be negative.
>>>
>>> Signed-off-by: Clément Chigot <chigot@adacore.com>
>>> Fixed: 8e0a5ac87800 ("hw/ppc: Avoid decrementer rounding errors")
>>> ---
>>>   hw/ppc/ppc.c | 4 +++-
>>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
>>> index e6fa5580c0..9fc85c7de0 100644
>>> --- a/hw/ppc/ppc.c
>>> +++ b/hw/ppc/ppc.c
>>> @@ -729,7 +729,9 @@ static inline int64_t __cpu_ppc_load_decr(CPUPPCState *env, int64_t now,
>>>       int64_t decr;
>>>
>>>       n = ns_to_tb(tb_env->decr_freq, now);
>>> -    if (next > n && tb_env->flags & PPC_TIMER_BOOKE) {
>>> +
>>> +    /* BookE timers stop when reaching 0.  */
>>> +    if (next < n && tb_env->flags & PPC_TIMER_BOOKE) {
>>>           decr = 0;
>>>       } else {
>>>           decr = next - n;
>>> --
>>> 2.25.1
>>>
>