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From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     Sean Christopherson <seanjc@google.com>,
        "Michael Kelley (LINUX)" <mikelley@microsoft.com>
Cc:     KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/4] x86/hyperv: Move VMCB enlightenment definitions to
 hyperv-tlfs.h
In-Reply-To: <YyzgD0xp/Ki9a3jK@google.com>
References: <20220921201607.3156750-1-seanjc@google.com>
 <20220921201607.3156750-2-seanjc@google.com>
 <BYAPR21MB1688D04068DBA520366DA205D74E9@BYAPR21MB1688.namprd21.prod.outlook.com>
 <YyzgD0xp/Ki9a3jK@google.com>
Date:   Tue, 27 Sep 2022 12:11:56 +0200
Message-ID: <87tu4tktxv.fsf@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Sean Christopherson <seanjc@google.com> writes:

> On Thu, Sep 22, 2022, Michael Kelley (LINUX) wrote:
>> From: Sean Christopherson <seanjc@google.com> Sent: Wednesday, September 21, 2022 1:16 PM
>> > 
>> > Move Hyper-V's VMCB enlightenment definitions to the TLFS header; the
>> > definitions come directly from the TLFS[*], not from KVM.
>> > 
>> > No functional change intended.
>> > 
>> > [*] https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/datatypes/hv_svm_enlightened_vmcb_fields> 
>> > Signed-off-by: Sean Christopherson <seanjc@google.com>
>> > ---
>> >  arch/x86/include/asm/hyperv-tlfs.h | 22 +++++++++++++++++++
>> >  arch/x86/kvm/svm/hyperv.h          | 35 ------------------------------
>> >  arch/x86/kvm/svm/svm_onhyperv.h    |  3 ++-
>> >  3 files changed, 24 insertions(+), 36 deletions(-)
>> >  delete mode 100644 arch/x86/kvm/svm/hyperv.h
>> > 
>> > diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
>> > index 0a9407dc0859..4c4f81daf5a2 100644
>> > --- a/arch/x86/include/asm/hyperv-tlfs.h
>> > +++ b/arch/x86/include/asm/hyperv-tlfs.h
>> > @@ -584,6 +584,28 @@ struct hv_enlightened_vmcs {
>> > 
>> >  #define HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL			0xFFFF
>> > 
>> > +/*
>> > + * Hyper-V uses the software reserved 32 bytes in VMCB control area to expose
>> > + * SVM enlightenments to guests.
>> > + */
>> > +struct hv_enlightenments {
>> > +	struct __packed hv_enlightenments_control {
>> > +		u32 nested_flush_hypercall:1;
>> > +		u32 msr_bitmap:1;
>> > +		u32 enlightened_npt_tlb: 1;
>> > +		u32 reserved:29;
>> > +	} __packed hv_enlightenments_control;
>> > +	u32 hv_vp_id;
>> > +	u64 hv_vm_id;
>> > +	u64 partition_assist_page;
>> > +	u64 reserved;
>> > +} __packed;
>> > +
>> > +/*
>> > + * Hyper-V uses the software reserved clean bit in VMCB.
>> > + */
>> > +#define VMCB_HV_NESTED_ENLIGHTENMENTS		31
>> 
>> Is it feasible to change this identifier so it starts with HV_ like
>> everything else in this source code file, such as
>> HV_VMCB_NESTED_ENLIGHTENMENTS?  It doesn't look like it is
>> used in very many places.  
>
> Most definitely, IIRC it's used in only one spot.
>

I'll take these 4 patches to the next iteration of my "KVM: x86:
hyper-v: Fine-grained TLB flush + L2 TLB flush features" series and I'll
change VMCB_HV_NESTED_ENLIGHTENMENTS to HV_VMCB_NESTED_ENLIGHTENMENTS.

-- 
Vitaly