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KVM: x86: hyperv: enforce vp_index < KVM_MAX_VCPUS

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Hyper-V TLFS (5.0b) states:

> Virtual processors are identified by using an index (VP index). The
> maximum number of virtual processors per partition supported by the
> current implementation of the hypervisor can be obtained through CPUID
> leaf 0x40000005. A virtual processor index must be less than the
> maximum number of virtual processors per partition.

Forbid userspace to set VP_INDEX above KVM_MAX_VCPUS. get_vcpu_by_vpidx()
can now be optimized to bail early when supplied vpidx is >= KVM_MAX_VCPUS.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2018-08-22 12:18:28 +02:00 committed by Paolo Bonzini
parent 0624fca951
commit 9170200ec0
1 changed files with 5 additions and 3 deletions
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8
arch/x86/kvm/hyperv.c
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@ -132,8 +132,10 @@ static struct kvm_vcpu *get_vcpu_by_vpidx(struct kvm *kvm, u32 vpidx)
struct kvm_vcpu *vcpu = NULL;
int i;
if (vpidx < KVM_MAX_VCPUS)
vcpu = kvm_get_vcpu(kvm, vpidx);
if (vpidx >= KVM_MAX_VCPUS)
return NULL;
vcpu = kvm_get_vcpu(kvm, vpidx);
if (vcpu && vcpu_to_hv_vcpu(vcpu)->vp_index == vpidx)
return vcpu;
kvm_for_each_vcpu(i, vcpu, kvm)
@ -1044,7 +1046,7 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
switch (msr) {
case HV_X64_MSR_VP_INDEX:
if (!host)
if (!host || (u32)data >= KVM_MAX_VCPUS)
return 1;
hv->vp_index = (u32)data;
break;