linux-kernel - Re: [PATCH v4 00/11] KVM: Implement nested TSC scaling

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Message-ID: <f3d9acf6be9d3fad0282b2771a146bc997611920.camel@amazon.com>
Date:   Tue, 15 Jun 2021 09:33:43 +0000
From:   "Stamatis, Ilias" <ilstam@...zon.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>
CC:     "jmattson@...gle.com" <jmattson@...gle.com>,
        "Woodhouse, David" <dwmw@...zon.co.uk>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "joro@...tes.org" <joro@...tes.org>,
        "mtosatti@...hat.com" <mtosatti@...hat.com>,
        "zamsden@...il.com" <zamsden@...il.com>,
        "seanjc@...gle.com" <seanjc@...gle.com>,
        "mlevitsk@...hat.com" <mlevitsk@...hat.com>,
        "wanpengli@...cent.com" <wanpengli@...cent.com>
Subject: Re: [PATCH v4 00/11] KVM: Implement nested TSC scaling

On Tue, 2021-06-15 at 09:43 +0100, Ilias Stamatis wrote:
> On Wed, 2021-05-26 at 19:44 +0100, Ilias Stamatis wrote:
> > KVM currently supports hardware-assisted TSC scaling but only for L1;
> > the feature is not exposed to nested guests. This patch series adds
> > support for nested TSC scaling and allows both L1 and L2 to be scaled
> > with different scaling factors. That is achieved by "merging" the 01 and
> > 02 values together.
> > 
> > Most of the logic in this series is implemented in common code (by doing
> > the necessary restructurings), however the patches add support for VMX
> > only. Adding support for SVM should be easy at this point and Maxim
> > Levitsky has volunteered to do this (thanks!).
> > 
> > Changelog:
> > 
> > Only patch 9 needs reviewing at this point, but I am re-sending the
> > whole series as I also applied nitpicks suggested to some of the other
> > pathces.
> > 
> > v4:
> >   - Added vendor callbacks for writing the TSC multiplier
> >   - Moved the VMCS multiplier writes from the VMCS load path to common
> >     code that only gets called on TSC ratio changes
> >   - Merged together patches 10 and 11 of v3
> >   - Applied all nitpick-feedback of the previous versions
> > 
> > v3:
> >   - Applied Sean's feedback
> >   - Refactored patches 7 to 10
> > 
> > v2:
> >   - Applied all of Maxim's feedback
> >   - Added a mul_s64_u64_shr function in math64.h
> >   - Added a separate kvm_scale_tsc_l1 function instead of passing an
> >     argument to kvm_scale_tsc
> >   - Implemented the 02 fields calculations in common code
> >   - Moved all of write_l1_tsc_offset's logic to common code
> >   - Added a check for whether the TSC is stable in patch 10
> >   - Used a random L1 factor and a negative offset in patch 10
> > 
> > Ilias Stamatis (11):
> >   math64.h: Add mul_s64_u64_shr()
> >   KVM: X86: Store L1's TSC scaling ratio in 'struct kvm_vcpu_arch'
> >   KVM: X86: Rename kvm_compute_tsc_offset() to
> >     kvm_compute_l1_tsc_offset()
> >   KVM: X86: Add a ratio parameter to kvm_scale_tsc()
> >   KVM: nVMX: Add a TSC multiplier field in VMCS12
> >   KVM: X86: Add functions for retrieving L2 TSC fields from common code
> >   KVM: X86: Add functions that calculate the nested TSC fields
> >   KVM: X86: Move write_l1_tsc_offset() logic to common code and rename
> >     it
> >   KVM: X86: Add vendor callbacks for writing the TSC multiplier
> >   KVM: nVMX: Enable nested TSC scaling
> >   KVM: selftests: x86: Add vmx_nested_tsc_scaling_test
> > 
> >  arch/x86/include/asm/kvm-x86-ops.h            |   5 +-
> >  arch/x86/include/asm/kvm_host.h               |  15 +-
> >  arch/x86/kvm/svm/svm.c                        |  35 ++-
> >  arch/x86/kvm/vmx/nested.c                     |  33 ++-
> >  arch/x86/kvm/vmx/vmcs12.c                     |   1 +
> >  arch/x86/kvm/vmx/vmcs12.h                     |   4 +-
> >  arch/x86/kvm/vmx/vmx.c                        |  55 ++--
> >  arch/x86/kvm/vmx/vmx.h                        |  11 +-
> >  arch/x86/kvm/x86.c                            | 114 +++++++--
> >  include/linux/math64.h                        |  19 ++
> >  tools/testing/selftests/kvm/.gitignore        |   1 +
> >  tools/testing/selftests/kvm/Makefile          |   1 +
> >  .../kvm/x86_64/vmx_nested_tsc_scaling_test.c  | 242 ++++++++++++++++++
> >  13 files changed, 451 insertions(+), 85 deletions(-)
> >  create mode 100644 tools/testing/selftests/kvm/x86_64/vmx_nested_tsc_scaling_test.c
> > 
> 
> Hello,
> 
> What is the status of these? I think all patches have been reviewed and
> approved at this point.
> 
> (There's a new revision v6 of patch 9 that has been reviewed too)
> 
> Thanks,
> Ilias

Never mind this, I was probably checking at the wrong place, I just realised
that they have been queued since last Friday.

Thanks!