linux-kernel - Re: [PATCH v19 039/130] KVM: TDX: initialize VM with TDX specific parameters

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Date: Fri, 22 Mar 2024 18:22:24 -0700
From: Isaku Yamahata <isaku.yamahata@...el.com>
To: "Huang, Kai" <kai.huang@...el.com>
Cc: "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Yamahata, Isaku" <isaku.yamahata@...el.com>,
	"Zhang, Tina" <tina.zhang@...el.com>,
	"seanjc@...gle.com" <seanjc@...gle.com>,
	"Yuan, Hang" <hang.yuan@...el.com>, "Chen, Bo2" <chen.bo@...el.com>,
	"sagis@...gle.com" <sagis@...gle.com>,
	"isaku.yamahata@...il.com" <isaku.yamahata@...il.com>,
	"Aktas, Erdem" <erdemaktas@...gle.com>,
	"Li, Xiaoyao" <xiaoyao.li@...el.com>,
	"pbonzini@...hat.com" <pbonzini@...hat.com>,
	isaku.yamahata@...ux.intel.com
Subject: Re: [PATCH v19 039/130] KVM: TDX: initialize VM with TDX specific
 parameters

On Fri, Mar 22, 2024 at 11:20:01AM +0000,
"Huang, Kai" <kai.huang@...el.com> wrote:

> On Mon, 2024-02-26 at 00:25 -0800, isaku.yamahata@...el.com wrote:
> > +struct kvm_tdx_init_vm {
> > +	__u64 attributes;
> > +	__u64 mrconfigid[6];	/* sha384 digest */
> > +	__u64 mrowner[6];	/* sha384 digest */
> > +	__u64 mrownerconfig[6];	/* sha384 digest */
> > +	/*
> > +	 * For future extensibility to make sizeof(struct kvm_tdx_init_vm) = 8KB.
> > +	 * This should be enough given sizeof(TD_PARAMS) = 1024.
> > +	 * 8KB was chosen given because
> > +	 * sizeof(struct kvm_cpuid_entry2) * KVM_MAX_CPUID_ENTRIES(=256) = 8KB.
> > +	 */
> > +	__u64 reserved[1004];
> 
> This is insane.
> 
> You said you want to reserve 8K for CPUID entries, but how can these 1004 * 8
> bytes be used for CPUID entries since ...

I tried to overestimate it. It's too much, how about to make it
1024, reserved[109]?
-- 
Isaku Yamahata <isaku.yamahata@...el.com>