kvm: debugfs: aarch64 export cpu time related items to debugfs

virt inclusion
category: feature
bugzilla: 46853
CVE: NA

This patch export cpu time related items to vcpu_stat.
Contain:
	steal, st_max, utime, stime, gtime

The definitions of these items are:
steal: cpu time VCPU waits for PCPU while it is servicing another VCPU
st_max: max scheduling delay
utime: cpu time in userspace
stime: cpu time in sys
gtime: cpu time in guest

Through these items, user can get many cpu usage info of vcpu, such as:
CPU Usage of Guest =  gtime_delta / delta_cputime
CPU Usage of Hyp = (utime_delta - gtime_delta + stime_delta) / delta_cputime
CPU Usage of Steal = steal_delta / delta_cputime
Max Scheduling Delay = st_max
Signed-off-by: Nliangpeng <liangpeng10@huawei.com>
Signed-off-by: Nchenjiajun <chenjiajun8@huawei.com>
Reviewed-by: NXiangyou Xie <xiexiangyou@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>

arch/arm64/include/asm/kvm_host.h

@@ -483,6 +483,11 @@ struct kvm_vcpu_stat {
 	u64 smc_exit_stat;
 	u64 sve_exit_stat;
 	u64 debug_exit_stat;
+	u64 steal;
+	u64 st_max;
+	u64 utime;
+	u64 stime;
+	u64 gtime;
 };
 
 int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init);

arch/arm64/kvm/arm.c

@@ -343,6 +343,20 @@ void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
 	preempt_enable();
 }
 
+void kvm_arch_vcpu_stat_reset(struct kvm_vcpu_stat *vcpu_stat)
+{
+	vcpu_stat->st_max = 0;
+}
+
+static void update_steal_time(struct kvm_vcpu *vcpu)
+{
+	u64 delta;
+
+	delta = current->sched_info.run_delay - vcpu->stat.steal;
+	vcpu->stat.steal = current->sched_info.run_delay;
+	vcpu->stat.st_max = max(vcpu->stat.st_max, delta);
+}
+
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
 	struct kvm_s2_mmu *mmu;
@@ -376,6 +390,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	else
 		vcpu_set_wfx_traps(vcpu);
 
+	update_steal_time(vcpu);
 	if (vcpu_has_ptrauth(vcpu))
 		vcpu_ptrauth_disable(vcpu);
 }
@@ -649,6 +664,13 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu)
 	}
 }
 
+static void update_vcpu_stat_time(struct kvm_vcpu_stat *vcpu_stat)
+{
+	vcpu_stat->utime = current->utime;
+	vcpu_stat->stime = current->stime;
+	vcpu_stat->gtime = current->gtime;
+}
+
 /**
  * kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute guest code
  * @vcpu:	The VCPU pointer
@@ -844,6 +866,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		}
 
 		ret = handle_exit(vcpu, ret);
+		update_vcpu_stat_time(&vcpu->stat);
 	}
 
 	/* Tell userspace about in-kernel device output levels */

arch/arm64/kvm/guest.c

@@ -70,6 +70,11 @@ struct dfx_kvm_stats_debugfs_item dfx_debugfs_entries[] = {
 	DFX_STAT("smc_exit_stat", smc_exit_stat),
 	DFX_STAT("sve_exit_stat", sve_exit_stat),
 	DFX_STAT("debug_exit_stat", debug_exit_stat),
+	DFX_STAT("steal", steal),
+	DFX_STAT("st_max", st_max),
+	DFX_STAT("utime", utime),
+	DFX_STAT("stime", stime),
+	DFX_STAT("gtime", gtime),
 	{ NULL }
 };
 

include/linux/kvm_host.h

@@ -1481,6 +1481,8 @@ static inline int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
 }
 #endif /* CONFIG_HAVE_KVM_VCPU_RUN_PID_CHANGE */
 
+void kvm_arch_vcpu_stat_reset(struct kvm_vcpu_stat *vcpu_stat);
+
 typedef int (*kvm_vm_thread_fn_t)(struct kvm *kvm, uintptr_t data);
 
 int kvm_vm_create_worker_thread(struct kvm *kvm, kvm_vm_thread_fn_t thread_fn,

virt/kvm/kvm_main.c

@@ -4616,6 +4616,10 @@ static int vcpu_stat_clear(void *_offset, u64 val)
 DEFINE_SIMPLE_ATTRIBUTE(vcpu_stat_fops, vcpu_stat_get, vcpu_stat_clear,
 			"%llu\n");
 
+void __attribute__((weak)) kvm_arch_vcpu_stat_reset(struct kvm_vcpu_stat *vcpu_stat)
+{
+}
+
 #define DFX_MAX_VCPU		1024
 #define DFX_MAX_VCPU_STAT_SIZE	1024
 
@@ -4646,6 +4650,7 @@ static int __dfx_vcpu_stats_get(struct seq_file *p, void *v)
 				break;
 			memcpy(vcpu_stats + index, &vcpu->stat,
 			       sizeof(struct kvm_vcpu_stat));
+			kvm_arch_vcpu_stat_reset(&vcpu->stat);
 			++index;
 		}
 	mutex_unlock(&kvm_lock);