linux-kernel - Re: [PATCH v8 0/5] Add a unified parameter "nopvspin"

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Message-ID: <e31f932b-9838-09a7-49d4-f90dc673960c@redhat.com>
Date:   Sat, 14 Mar 2020 12:14:13 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Zhenzhong Duan <zhenzhong.duan@...cle.com>,
        linux-kernel@...r.kernel.org, tglx@...utronix.de, x86@...nel.org,
        peterz@...radead.org
Cc:     mingo@...hat.com, bp@...en8.de, rkrcmar@...hat.com,
        sean.j.christopherson@...el.com, vkuznets@...hat.com,
        wanpengli@...cent.com, jmattson@...gle.com, joro@...tes.org,
        boris.ostrovsky@...cle.com, jgross@...e.com, will@...nel.org,
        linux-hyperv@...r.kernel.org, kvm@...r.kernel.org,
        mikelley@...rosoft.com, kys@...rosoft.com, haiyangz@...rosoft.com,
        sthemmin@...rosoft.com, sashal@...nel.org
Subject: Re: [PATCH v8 0/5] Add a unified parameter "nopvspin"

Peter/Thomas, can you apply this to tip or give your Acked-by?

Thanks,

Paolo

On 23/10/19 13:16, Zhenzhong Duan wrote:
> There are cases folks want to disable spinlock optimization for
> debug/test purpose. Xen and hyperv already have parameters "xen_nopvspin"
> and "hv_nopvspin" to support that, but kvm doesn't.
> 
> The first patch adds that feature to KVM guest with "nopvspin".
> 
> For compatibility reason original parameters "xen_nopvspin" and
> "hv_nopvspin" are retained and marked obsolete.
> 
> v8:
> PATCH2: use 'kvm-guest' instead of 'kvm_guest'        [Sean Christopherson]
> PATCH3: add a comment to explain missed 'return'      [Sean Christopherson]
> 
> v7:
> PATCH3: update comment and use goto, add RB              [Vitaly Kuznetsov]
> 
> v6:
> PATCH1: add Reviewed-by                                  [Vitaly Kuznetsov]
> PATCH2: change 'pv' to 'PV', add Reviewed-by             [Vitaly Kuznetsov]
> PATCH3: refactor 'if' branch in kvm_spinlock_init()      [Vitaly Kuznetsov]
> 
> v5:
> PATCH1: new patch to revert a currently unnecessory commit,
>         code is simpler a bit after that change.         [Boris Ostrovsky]
> PATCH3: fold 'if' statement,add comments on virt_spin_lock_key,
>         reorder with PATCH2 to better reflect dependency                               
> PATCH4: fold 'if' statement, add Reviewed-by             [Boris Ostrovsky]
> PATCH5: add Reviewed-by                                  [Michael Kelley]
> 
> v4:
> PATCH1: use variable name nopvspin instead of pvspin and
>         defined it as __initdata, changed print message,
>         updated patch description                     [Sean Christopherson]
> PATCH2: remove Suggested-by, use "kvm-guest:" prefix  [Sean Christopherson]
> PATCH3: make variable nopvsin and xen_pvspin coexist
>         remove Reviewed-by due to code change         [Sean Christopherson]
> PATCH4: make variable nopvsin and hv_pvspin coexist   [Sean Christopherson]
> 
> v3:
> PATCH2: Fix indentation
> 
> v2:
> PATCH1: pick the print code change into separate PATCH2,
>         updated patch description             [Vitaly Kuznetsov]
> PATCH2: new patch with print code change      [Vitaly Kuznetsov]
> PATCH3: add Reviewed-by                       [Juergen Gross]
> 
> Zhenzhong Duan (5):
>   Revert "KVM: X86: Fix setup the virt_spin_lock_key before static key
>     get initialized"
>   x86/kvm: Change print code to use pr_*() format
>   x86/kvm: Add "nopvspin" parameter to disable PV spinlocks
>   xen: Mark "xen_nopvspin" parameter obsolete
>   x86/hyperv: Mark "hv_nopvspin" parameter obsolete
> 
>  Documentation/admin-guide/kernel-parameters.txt | 14 ++++-
>  arch/x86/hyperv/hv_spinlock.c                   |  4 ++
>  arch/x86/include/asm/qspinlock.h                |  1 +
>  arch/x86/kernel/kvm.c                           | 79 ++++++++++++++++---------
>  arch/x86/xen/spinlock.c                         |  4 +-
>  kernel/locking/qspinlock.c                      |  7 +++
>  6 files changed, 76 insertions(+), 33 deletions(-)
>