From: Jing Zhang <jingzhangos@xxxxxxxxxx>
Add a "blocking" stat that userspace can use to detect the case where a
vCPU is not being run because of an vCPU/guest action, e.g. HLT or WFS on
x86, WFI on arm64, etc... Current guest/host/halt stats don't show this
well, e.g. if a guest halts for a long period of time then the vCPU could
could appear pathologically blocked due to a host condition, when in
reality the vCPU has been put into a not-runnable state by the guest.
Originally-by: Cannon Matthews <cannonmatthews@xxxxxxxxxx>
Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: David Matlack <dmatlack@xxxxxxxxxx>
Signed-off-by: Jing Zhang <jingzhangos@xxxxxxxxxx>
[sean: renamed stat to "blocking", massaged changelog]
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
include/linux/kvm_host.h | 3 ++-
include/linux/kvm_types.h | 1 +
virt/kvm/kvm_main.c | 4 ++++
3 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 2d837e06eeec..bdaa0e70b060 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1462,7 +1462,8 @@ struct _kvm_stats_desc {
STATS_DESC_LOGHIST_TIME_NSEC(VCPU_GENERIC, halt_poll_fail_hist, \
HALT_POLL_HIST_COUNT), \
STATS_DESC_LOGHIST_TIME_NSEC(VCPU_GENERIC, halt_wait_hist, \
- HALT_POLL_HIST_COUNT)
+ HALT_POLL_HIST_COUNT), \
+ STATS_DESC_ICOUNTER(VCPU_GENERIC, blocking)
extern struct dentry *kvm_debugfs_dir;
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index 2237abb93ccd..c4f9257bf32d 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -94,6 +94,7 @@ struct kvm_vcpu_stat_generic {
u64 halt_poll_success_hist[HALT_POLL_HIST_COUNT];
u64 halt_poll_fail_hist[HALT_POLL_HIST_COUNT];
u64 halt_wait_hist[HALT_POLL_HIST_COUNT];
+ u64 blocking;
};
#define KVM_STATS_NAME_SIZE 48
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 42894ff7c474..a36ccdc93a72 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3211,6 +3211,8 @@ bool kvm_vcpu_block(struct kvm_vcpu *vcpu)
struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
bool waited = false;
+ vcpu->stat.generic.blocking = 1;
+
kvm_arch_vcpu_blocking(vcpu);
prepare_to_rcuwait(wait);
@@ -3227,6 +3229,8 @@ bool kvm_vcpu_block(struct kvm_vcpu *vcpu)
kvm_arch_vcpu_unblocking(vcpu);
+ vcpu->stat.generic.blocking = 0;
+
return waited;
}
--
2.33.0.882.g93a45727a2-goog
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