linux-kernel - Re: [PATCH v4 1/5] KVM: x86: hyperv: enforce vp_index < KVM_MAX

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Message-ID: <20180709175620.GA3017@rkaganb.sw.ru>
Date:   Mon, 9 Jul 2018 20:56:21 +0300
From:   Roman Kagan <rkagan@...tuozzo.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>,
        Mohammed Gamal <mmorsy@...hat.com>,
        Cathy Avery <cavery@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/5] KVM: x86: hyperv: enforce vp_index < KVM_MAX_VCPUS

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@...hat.com>
> ---
>  arch/x86/kvm/hyperv.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)

Reviewed-by: Roman Kagan <rkagan@...tuozzo.com>