linux-kernel - Re: [PATCH 0/4] KVM: x86: hyper-v: Check if guest is allowed to use XMM registers for hypercall input

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Message-ID: <44b5e202-7c38-db93-25c7-c91a0ba7eb65@redhat.com>
Date:   Tue, 3 Aug 2021 12:10:31 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Siddharth Chandrasekaran <sidcha@...zon.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] KVM: x86: hyper-v: Check if guest is allowed to use
 XMM registers for hypercall input

On 30/07/21 14:26, Vitaly Kuznetsov wrote:
> "KVM: x86: hyper-v: Fine-grained access check to Hyper-V hypercalls and
> MSRs" and "Add support for XMM fast hypercalls" series were developed
> at the same time so the later landed without a proper feature bit check
> for 'strict' (KVM_CAP_HYPERV_ENFORCE_CPUID) mode. Add it now.
> 
> TLFS states that "Availability of the XMM fast hypercall interface is
> indicated via the “Hypervisor Feature Identification” CPUID Leaf
> (0x40000003, see section 2.4.4) ... Any attempt to use this interface
> when the hypervisor does not indicate availability will result in a #UD
> fault."
> 
> Vitaly Kuznetsov (4):
>    KVM: x86: hyper-v: Check access to hypercall before reading XMM
>      registers
>    KVM: x86: Introduce trace_kvm_hv_hypercall_done()
>    KVM: x86: hyper-v: Check if guest is allowed to use XMM registers for
>      hypercall input
>    KVM: selftests: Test access to XMM fast hypercalls
> 
>   arch/x86/kvm/hyperv.c                         | 18 ++++++--
>   arch/x86/kvm/trace.h                          | 15 +++++++
>   .../selftests/kvm/include/x86_64/hyperv.h     |  5 ++-
>   .../selftests/kvm/x86_64/hyperv_features.c    | 41 +++++++++++++++++--
>   4 files changed, 71 insertions(+), 8 deletions(-)
> 

Queued, thanks.

Paolo