On 2024-10-14 8:03 a.m., Peter Zijlstra wrote:
> On Thu, Aug 01, 2024 at 04:58:23AM +0000, Mingwei Zhang wrote:
>> From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
>>
>> There will be a dedicated interrupt vector for guests on some platforms,
>> e.g., Intel. Add an interface to switch the interrupt vector while
>> entering/exiting a guest.
>>
>> When PMI switch into a new guest vector, guest_lvtpc value need to be
>> reflected onto HW, e,g., guest clear PMI mask bit, the HW PMI mask
>> bit should be cleared also, then PMI can be generated continuously
>> for guest. So guest_lvtpc parameter is added into perf_guest_enter()
>> and switch_interrupt().
>>
>> At switch_interrupt(), the target pmu with PASSTHROUGH cap should
>> be found. Since only one passthrough pmu is supported, we keep the
>> implementation simply by tracking the pmu as a global variable.
>>
>> Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
>>
>> [Simplify the commit with removal of srcu lock/unlock since only one pmu is
>> supported.]
>>
>> Signed-off-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
>> ---
>> include/linux/perf_event.h | 9 +++++++--
>> kernel/events/core.c | 36 ++++++++++++++++++++++++++++++++++--
>> 2 files changed, 41 insertions(+), 4 deletions(-)
>>
>> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
>> index 75773f9890cc..aeb08f78f539 100644
>> --- a/include/linux/perf_event.h
>> +++ b/include/linux/perf_event.h
>> @@ -541,6 +541,11 @@ struct pmu {
>> * Check period value for PERF_EVENT_IOC_PERIOD ioctl.
>> */
>> int (*check_period) (struct perf_event *event, u64 value); /* optional */
>> +
>> + /*
>> + * Switch the interrupt vectors, e.g., guest enter/exit.
>> + */
>> + void (*switch_interrupt) (bool enter, u32 guest_lvtpc); /* optional */
>> };
>
> I'm thinking the guets_lvtpc argument shouldn't be part of the
> interface. That should be PMU implementation data and accessed by the
> method implementation.
I think the name of the perf_switch_interrupt() is too specific.
Here should be to switch the guest context. The interrupt should be just
part of the context. Maybe a interface as below
void (*switch_guest_ctx) (bool enter, void *data); /* optional */
Thanks,
Kan
