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