| Message ID | 20250324173121.1275209-11-mizhang@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v4,01/38] perf: Support get/put mediated PMU interfaces | expand |
On Mon, Mar 24, 2025 at 05:30:50PM +0000, Mingwei Zhang wrote: > From: Kan Liang <kan.liang@linux.intel.com> > > Implement switch_guest_ctx 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@linux.intel.com> > Signed-off-by: Kan Liang <kan.liang@linux.intel.com> > Tested-by: Yongwei Ma <yongwei.ma@intel.com> > Signed-off-by: Mingwei Zhang <mizhang@google.com> > --- > arch/x86/events/core.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c > index 8f218ac0d445..28161d6ff26d 100644 > --- a/arch/x86/events/core.c > +++ b/arch/x86/events/core.c > @@ -2677,6 +2677,16 @@ static bool x86_pmu_filter(struct pmu *pmu, int cpu) > return ret; > } > > +static void x86_pmu_switch_guest_ctx(bool enter, void *data) > +{ > + u32 guest_lvtpc = *(u32 *)data; > + > + if (enter) > + apic_write(APIC_LVTPC, guest_lvtpc); > + else > + apic_write(APIC_LVTPC, APIC_DM_NMI); > +} This, why can't it use x86_pmu.guest_lvtpc here and call it a day? Why is that argument passed around through the generic code only to get back here?
On 2025-04-25 7:15 a.m., Peter Zijlstra wrote: > On Mon, Mar 24, 2025 at 05:30:50PM +0000, Mingwei Zhang wrote: >> From: Kan Liang <kan.liang@linux.intel.com> >> >> Implement switch_guest_ctx 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@linux.intel.com> >> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> >> Tested-by: Yongwei Ma <yongwei.ma@intel.com> >> Signed-off-by: Mingwei Zhang <mizhang@google.com> >> --- >> arch/x86/events/core.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c >> index 8f218ac0d445..28161d6ff26d 100644 >> --- a/arch/x86/events/core.c >> +++ b/arch/x86/events/core.c >> @@ -2677,6 +2677,16 @@ static bool x86_pmu_filter(struct pmu *pmu, int cpu) >> return ret; >> } >> >> +static void x86_pmu_switch_guest_ctx(bool enter, void *data) >> +{ >> + u32 guest_lvtpc = *(u32 *)data; >> + >> + if (enter) >> + apic_write(APIC_LVTPC, guest_lvtpc); >> + else >> + apic_write(APIC_LVTPC, APIC_DM_NMI); >> +} > > This, why can't it use x86_pmu.guest_lvtpc here and call it a day? Why > is that argument passed around through the generic code only to get back > here? The vector has to be from the KVM. However, the current interfaces only support KVM read perf variables, e.g., perf_get_x86_pmu_capability and perf_get_hw_event_config. We need to add an new interface to allow the KVM write a perf variable, e.g., perf_set_guest_lvtpc. Thanks, Kan
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 8f218ac0d445..28161d6ff26d 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2677,6 +2677,16 @@ static bool x86_pmu_filter(struct pmu *pmu, int cpu) return ret; } +static void x86_pmu_switch_guest_ctx(bool enter, void *data) +{ + u32 guest_lvtpc = *(u32 *)data; + + if (enter) + apic_write(APIC_LVTPC, guest_lvtpc); + else + apic_write(APIC_LVTPC, APIC_DM_NMI); +} + static struct pmu pmu = { .pmu_enable = x86_pmu_enable, .pmu_disable = x86_pmu_disable, @@ -2706,6 +2716,8 @@ static struct pmu pmu = { .aux_output_match = x86_pmu_aux_output_match, .filter = x86_pmu_filter, + + .switch_guest_ctx = x86_pmu_switch_guest_ctx, }; void arch_perf_update_userpage(struct perf_event *event,