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From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     Maxim Levitsky <mlevitsk@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Vineeth Pillai <viremana@linux.microsoft.com>,
        Lan Tianyu <Tianyu.Lan@microsoft.com>,
        Michael Kelley <mikelley@microsoft.com>,
        Sean Christopherson <seanjc@google.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, Wei Liu <wei.liu@kernel.org>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>
Cc:     "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "K. Y. Srinivasan" <kys@microsoft.com>, x86@kernel.org,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-hyperv@vger.kernel.org
Subject: Re: [PATCH v5 0/7] Hyper-V nested virt enlightenments for SVM
In-Reply-To: <683fa50765b29f203cb4b0953542dc43226a7a2f.camel@redhat.com>
References: <cover.1622730232.git.viremana@linux.microsoft.com>
 <5af1ccce-a07d-5a13-107b-fc4c4553dd4d@redhat.com>
 <683fa50765b29f203cb4b0953542dc43226a7a2f.camel@redhat.com>
Date:   Fri, 11 Jun 2021 11:44:35 +0200
Message-ID: <878s3gybuk.fsf@vitty.brq.redhat.com>
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Maxim Levitsky <mlevitsk@redhat.com> writes:

> On Thu, 2021-06-10 at 17:17 +0200, Paolo Bonzini wrote:
>> On 03/06/21 17:14, Vineeth Pillai wrote:
>> > This patch series enables the nested virtualization enlightenments for
>> > SVM. This is very similar to the enlightenments for VMX except for the
>> > fact that there is no enlightened VMCS. For SVM, VMCB is already an
>> > architectural in-memory data structure.
>> >=20
>> > Note: v5 is just a rebase on hyperv-next(5.13-rc1) and needed a rework
>> > based on the patch series: (KVM: VMX: Clean up Hyper-V PV TLB flush)
>> > https://lore.kernel.org/lkml/20210305183123.3978098-1-seanjc@google.co=
m/
>> >=20
>> > The supported enlightenments are:
>> >=20
>> > Enlightened TLB Flush: If this is enabled, ASID invalidations invalida=
te
>> > only gva -> hpa entries. To flush entries derived from NPT, hyper-v
>> > provided hypercalls (HvFlushGuestPhysicalAddressSpace or
>> > HvFlushGuestPhysicalAddressList) should be used.
>> >=20
>> > Enlightened MSR bitmap(TLFS 16.5.3): "When enabled, L0 hypervisor does
>> > not monitor the MSR bitmaps for changes. Instead, the L1 hypervisor mu=
st
>> > invalidate the corresponding clean field after making changes to one of
>> > the MSR bitmaps."
>> >=20
>> > Direct Virtual Flush(TLFS 16.8): The hypervisor exposes hypercalls
>> > (HvFlushVirtualAddressSpace, HvFlushVirtualAddressSpaceEx,
>> > HvFlushVirtualAddressList, and HvFlushVirtualAddressListEx) that allow
>> > operating systems to more efficiently manage the virtual TLB. The L1
>> > hypervisor can choose to allow its guest to use those hypercalls and
>> > delegate the responsibility to handle them to the L0 hypervisor. This
>> > requires the use of a partition assist page."
>> >=20
>> > L2 Windows boot time was measured with and without the patch. Time was
>> > measured from power on to the login screen and was averaged over a
>> > consecutive 5 trials:
>> >    Without the patch: 42 seconds
>> >    With the patch: 29 seconds
>> > --
>> >=20
>> > Changes from v4
>> > - Rebased on top of 5.13-rc1 and reworked based on the changes in the
>> >    patch series: (KVM: VMX: Clean up Hyper-V PV TLB flush)
>> >=20=20=20=20
>> > Changes from v3
>> > - Included definitions for software/hypervisor reserved fields in SVM
>> >    architectural data structures.
>> > - Consolidated Hyper-V specific code into svm_onhyperv.[ch] to reduce
>> >    the "ifdefs". This change applies only to SVM, VMX is not touched a=
nd
>> >    is not in the scope of this patch series.
>> >=20
>> > Changes from v2:
>> > - Refactored the Remote TLB Flush logic into separate hyperv specific
>> >    source files (kvm_onhyperv.[ch]).
>> > - Reverted the VMCB Clean bits macro changes as it is no longer needed.
>> >=20
>> > Changes from v1:
>> > - Move the remote TLB flush related fields from kvm_vcpu_hv and kvm_hv
>> >    to kvm_vcpu_arch and kvm_arch.
>> > - Modify the VMCB clean mask runtime based on whether L1 hypervisor
>> >    is running on Hyper-V or not.
>> > - Detect Hyper-V nested enlightenments based on
>> >    HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS.
>> > - Address other minor review comments.
>> > ---
>> >=20
>> > Vineeth Pillai (7):
>> >    hyperv: Detect Nested virtualization support for SVM
>> >    hyperv: SVM enlightened TLB flush support flag
>> >    KVM: x86: hyper-v: Move the remote TLB flush logic out of vmx
>> >    KVM: SVM: Software reserved fields
>> >    KVM: SVM: hyper-v: Remote TLB flush for SVM
>> >    KVM: SVM: hyper-v: Enlightened MSR-Bitmap support
>> >    KVM: SVM: hyper-v: Direct Virtual Flush support
>> >=20
>> >   arch/x86/include/asm/hyperv-tlfs.h |   9 ++
>> >   arch/x86/include/asm/kvm_host.h    |   9 ++
>> >   arch/x86/include/asm/svm.h         |   9 +-
>> >   arch/x86/include/uapi/asm/svm.h    |   3 +
>> >   arch/x86/kernel/cpu/mshyperv.c     |  10 ++-
>> >   arch/x86/kvm/Makefile              |   9 ++
>> >   arch/x86/kvm/kvm_onhyperv.c        |  93 +++++++++++++++++++++
>> >   arch/x86/kvm/kvm_onhyperv.h        |  32 +++++++
>> >   arch/x86/kvm/svm/svm.c             |  14 ++++
>> >   arch/x86/kvm/svm/svm.h             |  22 ++++-
>> >   arch/x86/kvm/svm/svm_onhyperv.c    |  41 +++++++++
>> >   arch/x86/kvm/svm/svm_onhyperv.h    | 129 +++++++++++++++++++++++++++=
++
>> >   arch/x86/kvm/vmx/vmx.c             | 105 +----------------------
>> >   arch/x86/kvm/vmx/vmx.h             |   9 --
>> >   arch/x86/kvm/x86.c                 |   9 ++
>> >   15 files changed, 384 insertions(+), 119 deletions(-)
>> >   create mode 100644 arch/x86/kvm/kvm_onhyperv.c
>> >   create mode 100644 arch/x86/kvm/kvm_onhyperv.h
>> >   create mode 100644 arch/x86/kvm/svm/svm_onhyperv.c
>> >   create mode 100644 arch/x86/kvm/svm/svm_onhyperv.h
>> >=20
>>=20
>> Queued, thanks.
>>=20
>> Paolo
>>=20
>
> Hi!
>
> This patch series causes a build failure here:
>
> arch/x86/kvm/vmx/vmx.c: In function =E2=80=98hardware_setup=E2=80=99:
> arch/x86/kvm/vmx/vmx.c:7752:34: error: =E2=80=98hv_remote_flush_tlb=E2=80=
=99 undeclared (first use in this function)
>  7752 |   vmx_x86_ops.tlb_remote_flush =3D hv_remote_flush_tlb;
>       |                                  ^~~~~~~~~~~~~~~~~~~
> arch/x86/kvm/vmx/vmx.c:7752:34: note: each undeclared identifier is repor=
ted only once for each function it appears in
> arch/x86/kvm/vmx/vmx.c:7754:5: error: =E2=80=98hv_remote_flush_tlb_with_r=
ange=E2=80=99 undeclared (first use in this function)
>  7754 |     hv_remote_flush_tlb_with_range;
>       |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
> Also this:
>
> arch/x86/kvm/vmx/vmx.c: In function =E2=80=98hardware_setup=E2=80=99:
> arch/x86/kvm/vmx/vmx.c:7752:34: error: =E2=80=98hv_remote_flush_tlb=E2=80=
=99 undeclared (first use in this function)
>  7752 |   vmx_x86_ops.tlb_remote_flush =3D hv_remote_flush_tlb;
>       |                                  ^~~~~~~~~~~~~~~~~~~
> arch/x86/kvm/vmx/vmx.c:7752:34: note: each undeclared identifier is repor=
ted only once for each function it appears in
> arch/x86/kvm/vmx/vmx.c:7754:5: error: =E2=80=98hv_remote_flush_tlb_with_r=
ange=E2=80=99 undeclared (first use in this function)
>  7754 |     hv_remote_flush_tlb_with_range;
>       |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>=20=20

Yea, reported already:

https://lore.kernel.org/kvm/683fa50765b29f203cb4b0953542dc43226a7a2f.camel@=
redhat.com/T/#mf732ba9567923d800329f896761e4ee104475894

>
> Best regards,
> 	Maxim Levitsky
>

--=20
Vitaly