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| author | David Matlack <dmatlack@google.com> | 2016-03-09 00:19:44 (GMT) |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-03-09 10:54:14 (GMT) |
| commit | 313f636d5c490c9741d3f750dc8da33029edbc6b (patch) | |
| tree | 56e9b7133f98991b710c8776712a2e574c41b78c | |
| parent | 9522b37f5a8c7bfabe46eecadf2e130f1103f337 (diff) | |
| download | linux-313f636d5c490c9741d3f750dc8da33029edbc6b.tar.xz | |
kvm: cap halt polling at exactly halt_poll_ns
When growing halt-polling, there is no check that the poll time exceeds
the limit. It's possible for vcpu->halt_poll_ns grow once past
halt_poll_ns, and stay there until a halt which takes longer than
vcpu->halt_poll_ns. For example, booting a Linux guest with
halt_poll_ns=11000:
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 0 (shrink 10000)
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 10000 (grow 0)
... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 20000 (grow 10000)
Signed-off-by: David Matlack <dmatlack@google.com>
Fixes: aca6ff29c4063a8d467cdee241e6b3bf7dc4a171
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | virt/kvm/kvm_main.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index a11cfd2..9102ae1 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1952,6 +1952,9 @@ static void grow_halt_poll_ns(struct kvm_vcpu *vcpu) else val *= halt_poll_ns_grow; + if (val > halt_poll_ns) + val = halt_poll_ns; + vcpu->halt_poll_ns = val; trace_kvm_halt_poll_ns_grow(vcpu->vcpu_id, val, old); } |