linux-kernel - RE: [PATCH v6 05/21] x86/fpu: Make XFD initialization in __fpstate

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Message-ID: <BN9PR11MB527688406C0BDCF093C718858C509@BN9PR11MB5276.namprd11.prod.outlook.com>
Date:   Mon, 10 Jan 2022 05:15:44 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Borislav Petkov <bp@...en8.de>, Paolo Bonzini <pbonzini@...hat.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "Zeng, Guang" <guang.zeng@...el.com>,
        "Liu, Jing2" <jing2.liu@...el.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "Wang, Wei W" <wei.w.wang@...el.com>,
        "Zhong, Yang" <yang.zhong@...el.com>
Subject: RE: [PATCH v6 05/21] x86/fpu: Make XFD initialization in
 __fpstate_reset() a function argument

> From: Borislav Petkov <bp@...en8.de>
> Sent: Saturday, January 8, 2022 3:44 AM
> 
> On Fri, Jan 07, 2022 at 01:54:56PM -0500, Paolo Bonzini wrote:
> > From: Jing Liu <jing2.liu@...el.com>
> >
> > vCPU threads are different from native tasks regarding to the initial XFD
> > value. While all native tasks follow a fixed value (init_fpstate::xfd)
> > established by the FPU core at boot, vCPU threads need to obey the reset
> > value (i.e. ZERO) defined by the specification, to meet the expectation of
> > the guest.
> >
> > Let the caller supply an argument and adjust the host and guest related
> > invocations accordingly.
> >
> > Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> 
> If Jing is author, then tglx's SOB should come after Jing's to mean,
> tglx handled it further.
> 
> As it is now, it looks wrong.

Thanks for pointing it out! Actually this is one area which we didn't get
a clear answer from 'submitting-patches.rst' and now possibly a good
chance to get it clarified.

This patch was handled in an interesting way due to Jing's two absences:

Internal version: Jing was the original author

	Signed-off-by: Jing Liu <jing2.liu@...el.com>

--- Jing's first absence ---

v1: Yang was the submitter:

	Signed-off-by: Jing Liu <jing2.liu@...el.com>
	Signed-off-by: Yang Zhong <yang.zhong@...el.com>

Thomas updated it in his personal branch when reviewing v1:

	From: Jing Liu <jing2.liu@...el.com>

	Signed-off-by: Jing Liu <jing2.liu@...el.com>
	Signed-off-by: Yang Zhong <yang.zhong@...el.com>
	Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

--- Jing was back ---

v2-v3: Jing was the submitter:

The open here is whether Jing should change the SoB order:

	Signed-off-by: Yang Zhong <yang.zhong@...el.com>
	Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
	Signed-off-by: Jing Liu <jing2.liu@...el.com>

or just append her name again:

	Signed-off-by: Jing Liu <jing2.liu@...el.com>
	Signed-off-by: Yang Zhong <yang.zhong@...el.com>
	Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
	Signed-off-by: Jing Liu <jing2.liu@...el.com>

The former was selected for this patch.

--- Jing's 2nd absence ---

v4-v5: Yang was the submitter.

SoB order was partially changed (for Yang's SoB) but forgot to make Jing's
SoB as the first. It should be:

	From: Jing Liu <jing2.liu@...el.com>

	Signed-off-by: Jing Liu <jing2.liu@...el.com>
	Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
	Signed-off-by: Yang Zhong <yang.zhong@...el.com>

If the rule is that SoB order should not be changed, then it will be:

	From: Jing Liu <jing2.liu@...el.com>

	Signed-off-by: Jing Liu <jing2.liu@...el.com>
	Signed-off-by: Yang Zhong <yang.zhong@...el.com>
	Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
	Signed-off-by: Jing Liu <jing2.liu@...el.com>
	Signed-off-by: Yang Zhong <yang.zhong@...el.com>

> 
> Ditto for patches 10, 11, 12, 13.
> 
> Also, I wonder if all those Signed-off-by's do mean "handled" or
> Co-developed-by but I haven't tracked that particular pile so...
> 
> > Signed-off-by: Jing Liu <jing2.liu@...el.com>
> > Signed-off-by: Yang Zhong <yang.zhong@...el.com>
> > Message-Id: <20220105123532.12586-6-yang.zhong@...el.com>
> > Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> 
> --
> Regards/Gruss,
>     Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette