linux-kernel - Re: [PATCH v11 08/20] x86/virt/tdx: Get information about TDX module and TDX-capable memory

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Date:   Mon, 12 Jun 2023 02:00:29 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "Hansen, Dave" <dave.hansen@...el.com>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "Luck, Tony" <tony.luck@...el.com>,
        "david@...hat.com" <david@...hat.com>,
        "bagasdotme@...il.com" <bagasdotme@...il.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "imammedo@...hat.com" <imammedo@...hat.com>,
        "Shahar, Sagi" <sagis@...gle.com>,
        "Gao, Chao" <chao.gao@...el.com>,
        "Brown, Len" <len.brown@...el.com>,
        "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 v11 08/20] x86/virt/tdx: Get information about TDX module
 and TDX-capable memory

On Thu, 2023-06-08 at 06:13 -0700, Dave Hansen wrote:
> On 6/8/23 04:41, kirill.shutemov@...ux.intel.com wrote:
> > These structures take 1.5K of memory and the memory will be allocated for
> > all machines that boots the kernel with TDX enabled, regardless if the
> > machine has TDX or not. It seems very wasteful to me.
> 
> Actually, those variables are in .bss.  They're allocated forever for
> anyone that runs a kernel that has TDX support.
> 

Hi Dave/Kirill,

Thanks for feedback.

My understanding is you both prefer dynamic allocation.  I'll change to use
that.  Also I will free them after module initialization as for now they are
only used by module initialization.

Please let me know if you have any comments.