linux-kernel - Re: [PATCH v12 09/22] x86/virt/tdx: Use all system memory when initializing TDX module as TDX memory

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Date:   Thu, 29 Jun 2023 00:57:13 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "peterz@...radead.org" <peterz@...radead.org>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        "david@...hat.com" <david@...hat.com>,
        "bagasdotme@...il.com" <bagasdotme@...il.com>,
        "Luck, Tony" <tony.luck@...el.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>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
        "nik.borisov@...e.com" <nik.borisov@...e.com>,
        "hpa@...or.com" <hpa@...or.com>, "Shahar, Sagi" <sagis@...gle.com>,
        "imammedo@...hat.com" <imammedo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>, "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>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH v12 09/22] x86/virt/tdx: Use all system memory when
 initializing TDX module as TDX memory

On Wed, 2023-06-28 at 16:17 +0200, Peter Zijlstra wrote:
> On Tue, Jun 27, 2023 at 02:12:39AM +1200, Kai Huang wrote:
> 
> > +static int tdx_memory_notifier(struct notifier_block *nb, unsigned long action,
> > +			       void *v)
> > +{
> > +	struct memory_notify *mn = v;
> > +
> > +	if (action != MEM_GOING_ONLINE)
> > +		return NOTIFY_OK;
> 
> So offlining TDX memory is ok?

Yes.  We want to support normal software memory hotplug logic even TDX is
enabled.  User can offline part of memory and then online again.

> 
> > +
> > +	/*
> > +	 * Empty list means TDX isn't enabled.  Allow any memory
> > +	 * to go online.
> > +	 */
> > +	if (list_empty(&tdx_memlist))
> > +		return NOTIFY_OK;
> > +
> > +	/*
> > +	 * The TDX memory configuration is static and can not be
> > +	 * changed.  Reject onlining any memory which is outside of
> > +	 * the static configuration whether it supports TDX or not.
> > +	 */
> > +	return is_tdx_memory(mn->start_pfn, mn->start_pfn + mn->nr_pages) ?
> > +		NOTIFY_OK : NOTIFY_BAD;
> 
> 	if (is_tdx_memory(...))
> 		return NOTIFY_OK;
> 
> 	return NOTIFY_BAD;
> 

Sure will do.  Thanks!
>