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Message-ID: <c70d614c66982bde591aa075946322b9225bb17e.camel@intel.com>
Date: Wed, 23 Nov 2022 21:58:37 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
"Hansen, Dave" <dave.hansen@...el.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: "Luck, Tony" <tony.luck@...el.com>,
"bagasdotme@...il.com" <bagasdotme@...il.com>,
"ak@...ux.intel.com" <ak@...ux.intel.com>,
"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
"kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
"Christopherson,, Sean" <seanjc@...gle.com>,
"Chatre, Reinette" <reinette.chatre@...el.com>,
"pbonzini@...hat.com" <pbonzini@...hat.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"Yamahata, Isaku" <isaku.yamahata@...el.com>,
"Shahar, Sagi" <sagis@...gle.com>,
"imammedo@...hat.com" <imammedo@...hat.com>,
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"Brown, Len" <len.brown@...el.com>,
"peterz@...radead.org" <peterz@...radead.org>,
"sathyanarayanan.kuppuswamy@...ux.intel.com"
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
"Huang, Ying" <ying.huang@...el.com>,
"Williams, Dan J" <dan.j.williams@...el.com>
Subject: Re: [PATCH v7 04/20] x86/virt/tdx: Add skeleton to initialize TDX on
demand
On Wed, 2022-11-23 at 08:58 -0800, Dave Hansen wrote:
> On 11/23/22 02:18, Huang, Kai wrote:
> > > Again, there are a lot of words in that comment, but I'm not sure why
> > > it's here. Despite all the whinging about ACPI, doesn't it boil down to:
> > >
> > > The TDX module itself establishes its own concept of how many
> > > logical CPUs there are in the system when it is loaded.
> > >
> > This isn't accurate. TDX MCHECK records the total number of logical CPUs when
> > the BIOS enables TDX. This happens before the TDX module is loaded. In fact
> > the TDX module only gets this information from a secret location.
>
> Kai, this is the point where I lose patience with the conversation
> around this series. I'll you paste you the line of code where the TDX
> module literally "establishes its own concept of how many logical CPUs
> there are in the system":
>
> > //NUM_LPS
> > tdx_global_data_ptr->num_of_lps = sysinfo_table_ptr->mcheck_fields.tot_num_lps;
>
> Yes, this is derived directly from MCHECK. But, this concept is
> separate from MCHECK. We have seen zero actual facts from you or other
> folks at Intel that this is anything other than an arbitrary choice made
> for the convenience of the TDX module. It _might_ not be this way. I'm
> open to hearing those facts and changing my position on this.
>
> But, please bring facts, not random references to "secret locations"
> that aren't that secret.
Agreed. Thanks for providing the comment and will use it.
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