linux-kernel - Re: State Component 18 and Palette 1 (Re: [PATCH 16/19] kvm: x86: Introduce KVM_{G|S}ET

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Date:   Wed, 22 Dec 2021 23:51:22 +0000
From:   "Nakajima, Jun" <jun.nakajima@...el.com>
To:     "Hansen, Dave" <dave.hansen@...el.com>
CC:     Paolo Bonzini <pbonzini@...hat.com>,
        "Zhong, Yang" <yang.zhong@...el.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        "jing2.liu@...ux.intel.com" <jing2.liu@...ux.intel.com>,
        "Liu, Jing2" <jing2.liu@...el.com>
Subject: Re: State Component 18 and Palette 1 (Re: [PATCH 16/19] kvm: x86:
 Introduce KVM_{G|S}ET_XSAVE2 ioctl)


> On Dec 22, 2021, at 6:52 AM, Hansen, Dave <dave.hansen@...el.com> wrote:
> 
> On 12/20/21 9:54 AM, Nakajima, Jun wrote:
>>> So, I hope that save state 18 will be frozen to 8k.  In that case,
>>> and if palette 1 is frozen to the same values as today,
>>> implementing migration will not be a problem; it will be
>>> essentially the same as SSE->AVX (horizontal extension of existing
>>> registers) and/or AVX->AVX512 (both horizontal and vertical
>>> extension).
>> 
>> I would like to confirm that the state component 18 will remain 8KB
>> and palette 1 will remain the same.
> 
> Is that an architectural statement that will soon be making its way into
> the SDM?

Yes, with the other clarifications (e.g. setting IA32_XFD[18]).

Thanks,
--- 
Jun