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@xxxxxxxxxx>
Reviewed-by: Liran Alon <liran.alon@xxxxxxxxxx>
Signed-off-by: Nir Weiner <nir.weiner@xxxxxxxxxx>
Suggested-by: Liran Alon <liran.alon@xxxxxxxxxx>
---
arch/powerpc/kvm/book3s_hv.c | 5 ++++-
virt/kvm/kvm_main.c | 6 +++++-
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 5a066fc299e1..e316a2ddb70b 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -3631,8 +3631,11 @@ static void kvmppc_wait_for_exec(struct kvmppc_vcore *vc,
static void grow_halt_poll_ns(struct kvmppc_vcore *vc)
{
+ if (!halt_poll_ns_grow)
+ return;
+
/* 10us base */
- if (vc->halt_poll_ns == 0 && halt_poll_ns_grow)
+ if (vc->halt_poll_ns == 0)
vc->halt_poll_ns = 10000;
else
vc->halt_poll_ns *= halt_poll_ns_grow;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5ecea812cb6a..23518e063344 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2189,8 +2189,11 @@ 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;
@@ -2199,6 +2202,7 @@ 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);
}
--
2.20.1
