After applying Paolo's patch, vpmu's data was migrated correctly. https://patchwork.kernel.org/patch/2850813/
But when I wrote a test module to make IA32_PMC1 to count the event of unhalted cpu-cycles, after migration the value of IA32_PMC1 never grows up again. I found that after migration perf_event was created exactly, but when it was created, "current" is qemu's main thread which won't enter no-root mode, so the count of perf_event will never increase. I have tried pid in the struct of kvm_vcpu to get the vcpu thread's task_struct, but after migration when create perf_event, pid is pointed to qemu's main thread but not vcpu thread because of the pid switching in vcpu_load. I don't understand this very well, I think vcpu is created in qemu_kvm_cpu_thread_fn, which is the vcpu thread, use the pid of current is enough, why switch is needed? Maybe I was totally wrong, so I kept these code unchanged, add a extra "tid" to keep the vcpu thread's pid, and use this "tid" to get the task_struct of vcpu thread when create perf_event. Thanks Wang Hui Signed-off-by: Wang Hui <[email protected]> --- arch/x86/kvm/pmu.c | 8 +++++++- arch/x86/kvm/x86.c | 6 ++++++ include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 1 + 4 files changed, 15 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 5c4f631..676227e 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -173,6 +173,8 @@ static void reprogram_counter(struct kvm_pmc *pmc, u32 type, .exclude_kernel = exclude_kernel, .config = config, }; + struct task_struct *task = NULL; + if (in_tx) attr.config |= HSW_IN_TX; if (in_tx_cp) @@ -180,7 +182,11 @@ static void reprogram_counter(struct kvm_pmc *pmc, u32 type, attr.sample_period = (-pmc->counter) & pmc_bitmask(pmc); - event = perf_event_create_kernel_counter(&attr, -1, current, + if (pmc->vcpu) + task = pid_task(pmc->vcpu->tid, PIDTYPE_PID); + if (!task) + task = current; + event = perf_event_create_kernel_counter(&attr, -1, task, intr ? kvm_perf_overflow_intr : kvm_perf_overflow, pmc); if (IS_ERR(event)) { diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 21ef1ba..f1f0e8e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6704,11 +6704,17 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu) { int r; + struct pid *cpu_thread_pid; vcpu->arch.mtrr_state.have_fixed = 1; r = vcpu_load(vcpu); if (r) return r; + + cpu_thread_pid = get_task_pid(current, PIDTYPE_PID); + rcu_assign_pointer(vcpu->tid, cpu_thread_pid); + synchronize_rcu(); + kvm_vcpu_reset(vcpu); kvm_mmu_setup(vcpu); vcpu_put(vcpu); diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 9523d2a..ad7af9d 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -235,6 +235,7 @@ struct kvm_vcpu { int guest_fpu_loaded, guest_xcr0_loaded; wait_queue_head_t wq; struct pid *pid; + struct pid *tid; int sigset_active; sigset_t sigset; struct kvm_vcpu_stat stat; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index a0aa84b..80bcce5 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -242,6 +242,7 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_init); void kvm_vcpu_uninit(struct kvm_vcpu *vcpu) { + put_pid(vcpu->tid); put_pid(vcpu->pid); kvm_arch_vcpu_uninit(vcpu); free_page((unsigned long)vcpu->run); -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
