linux-kernel - Re: ** POTENTIAL FRAUD ALERT - RED HAT ** RE: [PATCH v2 8/8] KVM: x86: Add checks for reserved-to-zero Hyper-V hypercall fields

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Date:   Fri, 03 Dec 2021 15:09:27 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     "Michael Kelley (LINUX)" <mikelley@...rosoft.com>,
        Sean Christopherson <seanjc@...gle.com>
Cc:     Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Ajay Garg <ajaygargnsit@...il.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: ** POTENTIAL FRAUD ALERT - RED HAT ** RE: [PATCH v2 8/8] KVM:
 x86: Add checks for reserved-to-zero Hyper-V hypercall fields

"Michael Kelley (LINUX)" <mikelley@...rosoft.com> writes:

> From: Sean Christopherson <seanjc@...gle.com> Sent: Wednesday, December 1, 2021 6:13 PM
>> 
>> On Mon, Nov 01, 2021, Vitaly Kuznetsov wrote:
>> > Sean Christopherson <seanjc@...gle.com> writes:
>> >
>> > > Add checks for the three fields in Hyper-V's hypercall params that must
>> > > be zero.  Per the TLFS, HV_STATUS_INVALID_HYPERCALL_INPUT is returned if
>> > > "A reserved bit in the specified hypercall input value is non-zero."
>> > >
>> > > Note, the TLFS has an off-by-one bug for the last reserved field, which
>> > > it defines as being bits 64:60.  The same section states "The input field
>> > > 64-bit value called a hypercall input value.", i.e. bit 64 doesn't
>> > > exist.
>> >
>> > This version are you looking at? I can't see this issue in 6.0b
>> 
>> It's the web-based documentation, the 6.0b PDF indeed does not have the same bug.
>> 
>> https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/hypercall-interface#hypercall-inputs
>
> Did you (or Vitaly) file a bug report on this doc issue?  If not, I can do so.
>

Done, https://github.com/MicrosoftDocs/Virtualization-Documentation/pull/1682

-- 
Vitaly