Re: [PATCH v4 1/5] KVM: x86: hyperv: enforce vp_index < KVM_MAX_VCPUS

[Roman Kagan]

On Tue, Jul 03, 2018 at 03:42:02PM +0200, Vitaly Kuznetsov wrote:
> 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@xxxxxxxxxx>
> ---
>  arch/x86/kvm/hyperv.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)

Reviewed-by: Roman Kagan <rkagan@xxxxxxxxxxxxx>