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 32c8a675e5a4a33c89a12cdfd69d3d558b92f95f..3833736dd064c5a97ba0eb961a7e0d05e19df1be 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 863a0d158fb838ddae042d0aad9a926f91a2160f..55ebb9ea74f6428ea7bd3a1c3720c6fff3bb3fe9 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 2c343c346b79ad9f7d6d59ce9af596e862a3a41c..e28b5a946e26caeca0e278b9f82b726c261704d0 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 9787cdec33e6441a3ace1a01553e8dee808c2b55..99ed08aff31eb35bdae54f1153b8dda432fff085 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 c2984cb6dfa7332a6822f83ec5aa5e302aadbf29..888afe8d35cc87dd8f1f1773058acc65c34f4b75 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 d6bcd34f3ec329c5cb5603254c470d900d650839..176f74cc22573229b5dbf95289c76104a2546edf 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 389ff1b7cd43f63f260c5e2d932a00765bef186f..a560a368f92c2acacf67b043cb0a01f98d4b3c74 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 a3ce391c9e7a2a78573fabf4d05130c61c061615..fd78bd44b2d6f760ef847729a8c5342be0d1015b 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 7fb7c1a8f1a54fad87afeb8575c72ef2aff5f717..471fccf7f85018f42746a14d938b31eb833ddbfe 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 11844fad60fd6069071ef08763149e0e0352494c..da6da386b59189d2e224b8f3c7b60a399cad58ec 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);