On 9/9/2024 3:11 PM, Colton Lewis wrote:
> Mingwei Zhang <mizhang@xxxxxxxxxx> writes:
>
>> From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
>
>> Implement switch_interrupt interface for x86 PMU, switch PMI to dedicated
>> KVM_GUEST_PMI_VECTOR at perf guest enter, and switch PMI back to
>> NMI at perf guest exit.
>
>> Signed-off-by: Xiong Zhang <xiong.y.zhang@xxxxxxxxxxxxxxx>
>> Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
>> Tested-by: Yongwei Ma <yongwei.ma@xxxxxxxxx>
>> Signed-off-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
>> ---
>> arch/x86/events/core.c | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>
>> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
>> index 5bf78cd619bf..b17ef8b6c1a6 100644
>> --- a/arch/x86/events/core.c
>> +++ b/arch/x86/events/core.c
>> @@ -2673,6 +2673,15 @@ static bool x86_pmu_filter(struct pmu *pmu, int
>> cpu)
>> return ret;
>> }
>
>> +static void x86_pmu_switch_interrupt(bool enter, u32 guest_lvtpc)
>> +{
>> + if (enter)
>> + apic_write(APIC_LVTPC, APIC_DM_FIXED | KVM_GUEST_PMI_VECTOR |
>> + (guest_lvtpc & APIC_LVT_MASKED));
>> + else
>> + apic_write(APIC_LVTPC, APIC_DM_NMI);
>> +}
>> +
>
> Similar issue I point out in an earlier patch. #define
> KVM_GUEST_PMI_VECTOR is guarded by CONFIG_KVM but this code is not,
> which can result in compile errors.
Since KVM_GUEST_PMI_VECTOR and the interrupt handler are owned by KVM,
how about to simplify it to:
static void x86_pmu_switch_guest_ctx(bool enter, void *data)
{
if (enter)
apic_write(APIC_LVTPC, *(u32 *)data);
...
}
In KVM side:
perf_guest_enter(whatever_lvtpc_value_it_decides);
>> static struct pmu pmu = {
>> .pmu_enable = x86_pmu_enable,
>> .pmu_disable = x86_pmu_disable,
>> @@ -2702,6 +2711,8 @@ static struct pmu pmu = {
>> .aux_output_match = x86_pmu_aux_output_match,
>
>> .filter = x86_pmu_filter,
>> +
>> + .switch_interrupt = x86_pmu_switch_interrupt,
>> };
>
>> void arch_perf_update_userpage(struct perf_event *event,
>
