Re: [PATCH v8 08/16] x86/virt/tdx: Add placeholder to construct TDMRs to cover all TDX memory regions

From: Dave Hansen <dave.hansen@intel.com>
To: "Huang, Kai" <kai.huang@intel.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: "Luck, Tony" <tony.luck@intel.com>,
	"bagasdotme@gmail.com" <bagasdotme@gmail.com>,
	"ak@linux.intel.com" <ak@linux.intel.com>,
	"Wysocki, Rafael J" <rafael.j.wysocki@intel.com>,
	"kirill.shutemov@linux.intel.com"
	<kirill.shutemov@linux.intel.com>, "Christopherson,,
	Sean" <seanjc@google.com>,
	"Chatre, Reinette" <reinette.chatre@intel.com>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"Yamahata, Isaku" <isaku.yamahata@intel.com>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"Shahar, Sagi" <sagis@google.com>,
	"imammedo@redhat.com" <imammedo@redhat.com>,
	"Gao, Chao" <chao.gao@intel.com>,
	"Brown, Len" <len.brown@intel.com>,
	"sathyanarayanan.kuppuswamy@linux.intel.com" 
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	"Huang, Ying" <ying.huang@intel.com>,
	"Williams, Dan J" <dan.j.williams@intel.com>
Subject: Re: [PATCH v8 08/16] x86/virt/tdx: Add placeholder to construct TDMRs to cover all TDX memory regions
Date: Mon, 9 Jan 2023 16:47:50 -0800	[thread overview]
Message-ID: <92aba287-c839-8841-a9f7-28a2c0b3097a@intel.com> (raw)
In-Reply-To: <81b814f096513e69e3099ab2b54034deadf8d7fd.camel@intel.com>

On 1/9/23 16:40, Huang, Kai wrote:
> On Fri, 2023-01-06 at 11:24 -0800, Dave Hansen wrote:
...
>> Also, tdmr_sz and max_tdmrs can both be derived from 'sysinfo'.  Do they
>> really need to be stored here?
> 
> It's not mandatory to keep them here.  I did it mainly because I want to avoid
> passing 'sysinfo' as argument for almost all functions related to constructing
> TDMRs.

I don't think it hurts readability that much.  On the contrary, it makes
it more clear what data is needed for initialization.

>> If so, I think I'd probably do something
>> like this with the structure:
>>
>> struct tdmr_info_list {
>>       struct tdmr_info *tdmrs;
>>       int nr_consumed_tdmrs; // How many @tdmrs are in use
>>
>>       /* Metadata for freeing this structure: */
>>       int tdmr_sz;   // Size of one 'tdmr_info' (has a flex array)
>>       int max_tdmrs; // How many @tdmrs are allocated
>> };
>>
>> Modulo whataver folks are doing for comments these days.
> 
> Looks nice to me.  Will use.  A slight thing is 'tdmr_sz' is also used to get
> the TDMR at a given index, but not just freeing the structure.
> 
> Btw, is C++ style comment "//" OK in kernel code?

It's OK with me, but I don't think there's much consensus on it.
Probably best to stick with normal arch/x86 style for now.