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authorNir Weiner <nir.weiner@oracle.com>2019-01-27 12:17:14 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2019-02-20 22:48:50 +0100
commit7fa08e71b4a0591a518814fa78b32e124f90d587 (patch)
treef8b66306b476c5b6e833bceef8a0434bc9116652 /virt
parent8ab3c471eef20925bf64c6d4fa46e88cdb4e86d5 (diff)
KVM: grow_halt_poll_ns() should never shrink vCPU halt_poll_ns
grow_halt_poll_ns() have a strange behavior in case (halt_poll_ns_grow == 0) && (vcpu->halt_poll_ns != 0). In this case, vcpu->halt_pol_ns will be set to zero. That results in shrinking instead of growing. Fix issue by changing grow_halt_poll_ns() to not modify vcpu->halt_poll_ns in case halt_poll_ns_grow is zero Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Reviewed-by: Liran Alon <liran.alon@oracle.com> Signed-off-by: Nir Weiner <nir.weiner@oracle.com> Suggested-by: Liran Alon <liran.alon@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c9d0bc01f8cb..9c8a8bf6e686 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2188,8 +2188,11 @@ static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
old = val = vcpu->halt_poll_ns;
grow = READ_ONCE(halt_poll_ns_grow);
+ if (!grow)
+ goto out;
+
/* 10us base */
- if (val == 0 && grow)
+ if (val == 0)
val = 10000;
else
val *= grow;
@@ -2198,6 +2201,7 @@ static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
val = halt_poll_ns;
vcpu->halt_poll_ns = val;
+out:
trace_kvm_halt_poll_ns_grow(vcpu->vcpu_id, val, old);
}