[PATCH v4 1/2] KVM: remove NULL return path for vcpu ids >= KVM_MAX_VCPUS

Greg Kurz
2016-04-21T14:15:05Z

Commit c896939f7cff ("KVM: use heuristic for fast VCPU lookup by id") added
a return path that prevents vcpu ids to exceed KVM_MAX_VCPUS. This is a
problem for powerpc where vcpu ids can grow up to 8*KVM_MAX_VCPUS.

This patch simply reverses the logic so that we only try fast path if the
vcpu id can be tried as an index in kvm->vcpus[]. The slow path is not
affected by the change.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
---
include/linux/kvm_host.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 5276fe0916fc..23bfe1bd159c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -447,12 +447,13 @@ static inline struct kvm_vcpu *kvm_get_vcpu(struct kvm *kvm, int i)

static inline struct kvm_vcpu *kvm_get_vcpu_by_id(struct kvm *kvm, int id)
{
- struct kvm_vcpu *vcpu;
+ struct kvm_vcpu *vcpu = NULL;
int i;

- if (id < 0 || id >= KVM_MAX_VCPUS)
+ if (id < 0)
return NULL;
- vcpu = kvm_get_vcpu(kvm, id);
+ if (id < KVM_MAX_VCPUS)
+ vcpu = kvm_get_vcpu(kvm, id);
if (vcpu && vcpu->vcpu_id == id)
return vcpu;
kvm_for_each_vcpu(i, vcpu, kvm)