Commit 9170200e authored Aug 22, 2018 by Vitaly Kuznetsov Committed by Paolo Bonzini Oct 17, 2018

KVM: x86: hyperv: enforce vp_index < KVM_MAX_VCPUS



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>

parent 0624fca9

arch/x86/kvm/hyperv.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -132,7 +132,9 @@ 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)
		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;
		@@ -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;