kvm: add halt-polling cpu usage stats

Two new stats for exposing halt-polling cpu usage:
halt_poll_success_ns
halt_poll_fail_ns

Thus sum of these 2 stats is the total cpu time spent polling. "success"
means the VCPU polled until a virtual interrupt was delivered. "fail"
means the VCPU had to schedule out (either because the maximum poll time
was reached or it needed to yield the CPU).

To avoid touching every arch's kvm_vcpu_stat struct, only update and
export halt-polling cpu usage stats if we're on x86.

Exporting cpu usage as a u64 and in nanoseconds means we will overflow at
~500 years, which seems reasonably large.

Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Jon Cargille <jcargill@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Message-Id: <20200508182240.68440-1-jcargill@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 32c8a67..3833736 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -415,6 +415,8 @@ struct kvm_vm_stat {
 struct kvm_vcpu_stat {
        u64 halt_successful_poll;
        u64 halt_attempted_poll;
+       u64 halt_poll_success_ns;
+       u64 halt_poll_fail_ns;
        u64 halt_poll_invalid;
        u64 halt_wakeup;
        u64 hvc_exit_stat;

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 863a0d1..55ebb9e 100644 (file)
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -40,6 +40,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
        VCPU_STAT("mmio_exit_user", mmio_exit_user),
        VCPU_STAT("mmio_exit_kernel", mmio_exit_kernel),
        VCPU_STAT("exits", exits),
+       VCPU_STAT("halt_poll_success_ns", halt_poll_success_ns),
+       VCPU_STAT("halt_poll_fail_ns", halt_poll_fail_ns),
        { NULL }
 };
 

diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 2c343c3..e28b5a9 100644 (file)
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -174,6 +174,8 @@ struct kvm_vcpu_stat {
 #endif
        u64 halt_successful_poll;
        u64 halt_attempted_poll;
+       u64 halt_poll_success_ns;
+       u64 halt_poll_fail_ns;
        u64 halt_poll_invalid;
        u64 halt_wakeup;
 };

diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 9787cde..99ed08a 100644 (file)
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -72,6 +72,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
        VCPU_STAT("halt_attempted_poll", halt_attempted_poll),
        VCPU_STAT("halt_poll_invalid", halt_poll_invalid),
        VCPU_STAT("halt_wakeup", halt_wakeup),
+       VCPU_STAT("halt_poll_success_ns", halt_poll_success_ns),
+       VCPU_STAT("halt_poll_fail_ns", halt_poll_fail_ns),
        {NULL}
 };
 

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index c2984cb..888afe8 100644 (file)
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -54,6 +54,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
        VCPU_STAT("halt_wakeup", halt_wakeup),
        VCPU_STAT("doorbell", dbell_exits),
        VCPU_STAT("guest doorbell", gdbell_exits),
+       VCPU_STAT("halt_poll_success_ns", halt_poll_success_ns),
+       VCPU_STAT("halt_poll_fail_ns", halt_poll_fail_ns),
        VM_STAT("remote_tlb_flush", remote_tlb_flush),
        { NULL }
 };

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index d6bcd34..176f74c 100644 (file)
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -375,6 +375,8 @@ struct kvm_vcpu_stat {
        u64 halt_poll_invalid;
        u64 halt_no_poll_steal;
        u64 halt_wakeup;
+       u64 halt_poll_success_ns;
+       u64 halt_poll_fail_ns;
        u64 instruction_lctl;
        u64 instruction_lctlg;
        u64 instruction_stctl;

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 389ff1b..a560a36 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -75,6 +75,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
        VCPU_STAT("halt_poll_invalid", halt_poll_invalid),
        VCPU_STAT("halt_no_poll_steal", halt_no_poll_steal),
        VCPU_STAT("halt_wakeup", halt_wakeup),
+       VCPU_STAT("halt_poll_success_ns", halt_poll_success_ns),
+       VCPU_STAT("halt_poll_fail_ns", halt_poll_fail_ns),
        VCPU_STAT("instruction_lctlg", instruction_lctlg),
        VCPU_STAT("instruction_lctl", instruction_lctl),
        VCPU_STAT("instruction_stctl", instruction_stctl),

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a3ce391..fd78bd4 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1031,6 +1031,8 @@ struct kvm_vcpu_stat {
        u64 irq_injections;
        u64 nmi_injections;
        u64 req_event;
+       u64 halt_poll_success_ns;
+       u64 halt_poll_fail_ns;
 };
 
 struct x86_instruction_info;

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7fb7c1a..471fccf 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -217,6 +217,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
        VCPU_STAT("nmi_injections", nmi_injections),
        VCPU_STAT("req_event", req_event),
        VCPU_STAT("l1d_flush", l1d_flush),
+       VCPU_STAT("halt_poll_success_ns", halt_poll_success_ns),
+       VCPU_STAT("halt_poll_fail_ns", halt_poll_fail_ns),
        VM_STAT("mmu_shadow_zapped", mmu_shadow_zapped),
        VM_STAT("mmu_pte_write", mmu_pte_write),
        VM_STAT("mmu_pte_updated", mmu_pte_updated),

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 11844fa..da6da38 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2667,18 +2667,27 @@ out:
        return ret;
 }
 
+static inline void
+update_halt_poll_stats(struct kvm_vcpu *vcpu, u64 poll_ns, bool waited)
+{
+       if (waited)
+               vcpu->stat.halt_poll_fail_ns += poll_ns;
+       else
+               vcpu->stat.halt_poll_success_ns += poll_ns;
+}
+
 /*
  * The vCPU has executed a HLT instruction with in-kernel mode enabled.
  */
 void kvm_vcpu_block(struct kvm_vcpu *vcpu)
 {
-       ktime_t start, cur;
+       ktime_t start, cur, poll_end;
        bool waited = false;
        u64 block_ns;
 
        kvm_arch_vcpu_blocking(vcpu);
 
-       start = cur = ktime_get();
+       start = cur = poll_end = ktime_get();
        if (vcpu->halt_poll_ns && !kvm_arch_no_poll(vcpu)) {
                ktime_t stop = ktime_add_ns(ktime_get(), vcpu->halt_poll_ns);
 
@@ -2694,7 +2703,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
                                        ++vcpu->stat.halt_poll_invalid;
                                goto out;
                        }
-                       cur = ktime_get();
+                       poll_end = cur = ktime_get();
                } while (single_task_running() && ktime_before(cur, stop));
        }
 
@@ -2714,6 +2723,9 @@ out:
        kvm_arch_vcpu_unblocking(vcpu);
        block_ns = ktime_to_ns(cur) - ktime_to_ns(start);
 
+       update_halt_poll_stats(
+               vcpu, ktime_to_ns(ktime_sub(poll_end, start)), waited);
+
        if (!kvm_arch_no_poll(vcpu)) {
                if (!vcpu_valid_wakeup(vcpu)) {
                        shrink_halt_poll_ns(vcpu);