On 11/14/23 2:53 PM, Shrikanth Hegde wrote:
>
>
> On 11/14/23 12:42 PM, Aneesh Kumar K.V wrote:
>> No functional change in this patch. A helper is added to find if
>> vcpu is dispatched by hypervisor. Use that instead of opencoding.
>> Also clarify some of the comments.
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
>> ---
>> arch/powerpc/include/asm/paravirt.h | 33 ++++++++++++++++++++++-------
>> 1 file changed, 25 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/paravirt.h
>> b/arch/powerpc/include/asm/paravirt.h
>> index ac4279208d63..b78b82d66057 100644
>> --- a/arch/powerpc/include/asm/paravirt.h
>> +++ b/arch/powerpc/include/asm/paravirt.h
>> @@ -76,6 +76,17 @@ static inline bool is_vcpu_idle(int vcpu)
>> {
>> return lppaca_of(vcpu).idle;
>> }
>> +
>> +static inline bool vcpu_is_dispatched(int vcpu)
>> +{
>> + /*
>> + * This is the yield_count. An "odd" value (low bit on) means that
>> + * the processor is yielded (either because of an OS yield or a
>> + * hypervisor preempt). An even value implies that the processor is
>> + * currently executing.
>> + */
>> + return (!(yield_count_of(vcpu) & 1));
>> +}
>> #else
>> static inline bool is_shared_processor(void)
>> {
>> @@ -109,6 +120,10 @@ static inline bool is_vcpu_idle(int vcpu)
>> {
>> return false;
>> }
>> +static inline bool vcpu_is_dispatched(int vcpu)
>> +{
>> + return true;
>> +}
>> #endif
>>
>
> Similar code can be changed in lib/qspinlock.c and lib/locks.c as well.
I avoided doing that because they used the fetched yield_count value
yield_to_preempted(owner, yield_count);
and the checking comes with a comment
if ((yield_count & 1) == 0)
goto relax; /* owner vcpu is running */
-aneesh
