On 5/15/2025 7:19 AM, Sean Christopherson wrote:
On Fri, Apr 25, 2025, Peter Zijlstra wrote:
On Mon, Mar 24, 2025 at 05:30:45PM +0000, Mingwei Zhang wrote:
@@ -6040,6 +6041,71 @@ void perf_put_mediated_pmu(void) } EXPORT_SYMBOL_GPL(perf_put_mediated_pmu); +static inline void perf_host_exit(struct perf_cpu_context *cpuctx) +{
- perf_ctx_disable(&cpuctx->ctx, EVENT_GUEST);
- ctx_sched_out(&cpuctx->ctx, NULL, EVENT_GUEST);
- perf_ctx_enable(&cpuctx->ctx, EVENT_GUEST);
- if (cpuctx->task_ctx) {
perf_ctx_disable(cpuctx->task_ctx, EVENT_GUEST);task_ctx_sched_out(cpuctx->task_ctx, NULL, EVENT_GUEST);perf_ctx_enable(cpuctx->task_ctx, EVENT_GUEST);- }
+}
+/* When entering a guest, schedule out all exclude_guest events. */ +void perf_guest_enter(void) +{
- struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
- lockdep_assert_irqs_disabled();
- perf_ctx_lock(cpuctx, cpuctx->task_ctx);
- if (WARN_ON_ONCE(__this_cpu_read(perf_in_guest)))
goto unlock;- perf_host_exit(cpuctx);
- __this_cpu_write(perf_in_guest, true);
+unlock:
- perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
+} +EXPORT_SYMBOL_GPL(perf_guest_enter);
+static inline void perf_host_enter(struct perf_cpu_context *cpuctx) +{
- perf_ctx_disable(&cpuctx->ctx, EVENT_GUEST);
- if (cpuctx->task_ctx)
perf_ctx_disable(cpuctx->task_ctx, EVENT_GUEST);- perf_event_sched_in(cpuctx, cpuctx->task_ctx, NULL, EVENT_GUEST);
- if (cpuctx->task_ctx)
perf_ctx_enable(cpuctx->task_ctx, EVENT_GUEST);- perf_ctx_enable(&cpuctx->ctx, EVENT_GUEST);
+}
+void perf_guest_exit(void) +{
- struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
- lockdep_assert_irqs_disabled();
- perf_ctx_lock(cpuctx, cpuctx->task_ctx);
- if (WARN_ON_ONCE(!__this_cpu_read(perf_in_guest)))
goto unlock;- perf_host_enter(cpuctx);
- __this_cpu_write(perf_in_guest, false);
+unlock:
- perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
+} +EXPORT_SYMBOL_GPL(perf_guest_exit);
This naming is confusing on purpose? Pick either guest/host and stick with it.
+1. I also think the inner perf_host_{enter,exit}() helpers are superflous. These flows
After a bit of hacking, and with a few spoilers, this is what I ended up with (not anywhere near fully tested). I like following KVM's kvm_xxx_{load,put}() nomenclature to tie everything together, so I went with "guest" instead of "host" even though the majority of work being down is to shedule out/in host context.
/* When loading a guest's mediated PMU, schedule out all exclude_guest events. */ void perf_load_guest_context(unsigned long data) { struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
lockdep_assert_irqs_disabled();
perf_ctx_lock(cpuctx, cpuctx->task_ctx);
if (WARN_ON_ONCE(__this_cpu_read(guest_ctx_loaded))) goto unlock;
perf_ctx_disable(&cpuctx->ctx, EVENT_GUEST); ctx_sched_out(&cpuctx->ctx, NULL, EVENT_GUEST); perf_ctx_enable(&cpuctx->ctx, EVENT_GUEST); if (cpuctx->task_ctx) { perf_ctx_disable(cpuctx->task_ctx, EVENT_GUEST); task_ctx_sched_out(cpuctx->task_ctx, NULL, EVENT_GUEST); perf_ctx_enable(cpuctx->task_ctx, EVENT_GUEST); }
arch_perf_load_guest_context(data);
__this_cpu_write(guest_ctx_loaded, true);
unlock: perf_ctx_unlock(cpuctx, cpuctx->task_ctx); } EXPORT_SYMBOL_GPL(perf_load_guest_context);
void perf_put_guest_context(void) { struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
lockdep_assert_irqs_disabled();
perf_ctx_lock(cpuctx, cpuctx->task_ctx);
if (WARN_ON_ONCE(!__this_cpu_read(guest_ctx_loaded))) goto unlock;
arch_perf_put_guest_context();
perf_ctx_disable(&cpuctx->ctx, EVENT_GUEST); if (cpuctx->task_ctx) perf_ctx_disable(cpuctx->task_ctx, EVENT_GUEST);
perf_event_sched_in(cpuctx, cpuctx->task_ctx, NULL, EVENT_GUEST);
if (cpuctx->task_ctx) perf_ctx_enable(cpuctx->task_ctx, EVENT_GUEST); perf_ctx_enable(&cpuctx->ctx, EVENT_GUEST);
__this_cpu_write(guest_ctx_loaded, false); unlock: perf_ctx_unlock(cpuctx, cpuctx->task_ctx); } EXPORT_SYMBOL_GPL(perf_put_guest_context);
I'm fine with the name. Thanks.