Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <cover.1625186503.git.isaku.yamahata@intel.com>
 <d29b2ac2090f20e8de96888742feb413f597f1dc.1625186503.git.isaku.yamahata@intel.com>
 <CAAYXXYy=fn9dUMjY6b6wgCHSTLewnTZLKb00NMupDXSWbNC9OQ@mail.gmail.com> <1057bbfe-c73e-a182-7696-afc59a4786d8@intel.com>
In-Reply-To: <1057bbfe-c73e-a182-7696-afc59a4786d8@intel.com>
From:   Erdem Aktas <erdemaktas@google.com>
Date:   Wed, 4 Aug 2021 13:43:04 -0700
Message-ID: <CAAYXXYwDuRMQ16X3mshkGcBQXhvgoxPTCu8UGggYgfCzHOWwtQ@mail.gmail.com>
Subject: Re: [RFC PATCH v2 05/69] KVM: TDX: Add architectural definitions for
 structures and values
To:     Xiaoyao Li <xiaoyao.li@intel.com>
Cc:     "Yamahata, Isaku" <isaku.yamahata@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H . Peter Anvin" <hpa@zytor.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Connor Kuehl <ckuehl@redhat.com>,
        Sean Christopherson <seanjc@google.com>, x86 <x86@kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:KERNEL VIRTUAL MACHINE (KVM)" <kvm@vger.kernel.org>,
        isaku.yamahata@gmail.com,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Kai Huang <kai.huang@linux.intel.com>,
        Chao Gao <chao.gao@intel.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Aug 2, 2021 at 6:25 AM Xiaoyao Li <xiaoyao.li@intel.com> wrote:
>
> No. bit 63 is not for readonly fields, but for non_arch fields.
>
> Please see 18.7.1 General definition
Thank you so much! make sense.

> > Is this information correct and is this included in the spec? I tried
> > to find it but somehow I do not see it clearly defined.
> >
> >> +#define TDX1_NR_TDCX_PAGES             4
> >> +#define TDX1_NR_TDVPX_PAGES            5
> >> +
> >> +#define TDX1_MAX_NR_CPUID_CONFIGS      6
> > Why is this just 6? I am looking at the CPUID table in the spec and
> > there are already more than 6 CPUID leaves there.
>
> This is the number of CPUID config reported by TDH.SYS.INFO. Current KVM
> only reports 6 leaves.

I, personally, still think that it should be enumerated, rather than
hardcoded. It is not clear to me why it is 6 and nothing in the spec
says it will not change.

> >> +#define TDX1_MAX_NR_CMRS               32
> >> +#define TDX1_MAX_NR_TDMRS              64
> >> +#define TDX1_MAX_NR_RSVD_AREAS         16
> >> +#define TDX1_PAMT_ENTRY_SIZE           16
> >> +#define TDX1_EXTENDMR_CHUNKSIZE                256
> >
> > I believe all of the defined variables above need to be enumerated
> > with TDH.SYS.INFO.
>
> No. Only TDX1_MAX_NR_TDMRS, TDX1_MAX_NR_RSVD_AREAS and
> TDX1_PAMT_ENTRY_SIZE can be enumerated from TDH.SYS.INFO.
>
> - TDX1_MAX_NR_CMRS is described in 18.6.3 CMR_INFO, which tells
>
>    TDH.SYS.INFO leaf function returns a MAX_CMRS(32) entry array
>    of CMR_INFO entries.
>
> - TDX1_EXTENDMR_CHUNKSIZE is describe in 20.2.23 TDH.MR.EXTEND

Thanks for the pointers for MAX_CMRS and TDX1_EXTENDMR_CHUNKSIZE.
Will the rest of it be enumerated or hardcoded?

> >> +#define TDX_TDMR_ADDR_ALIGNMENT        512
> > Is TDX_TDMR_ADDR_ALIGNMENT used anywhere or is it just for completeness?
>
> It's the leftover during rebase. We will clean it up.
Thanks!

> SEAMCALL TDH.SYS.INFO requires each cmr info in CMR_INFO_ARRAY to be
> 512B aligned

Make sense, Thanks for the explanation.