linux-kernel - Re: [PATCHv9 08/17] x86/tdx: Account shared memory

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Date: Tue, 26 Mar 2024 10:30:27 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>, "mingo@...hat.com"
	<mingo@...hat.com>, "x86@...nel.org" <x86@...nel.org>, "bp@...en8.de"
	<bp@...en8.de>, "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>
CC: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>, "Reshetova, Elena"
	<elena.reshetova@...el.com>, "Nakajima, Jun" <jun.nakajima@...el.com>,
	"rafael@...nel.org" <rafael@...nel.org>, "peterz@...radead.org"
	<peterz@...radead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "sathyanarayanan.kuppuswamy@...ux.intel.com"
	<sathyanarayanan.kuppuswamy@...ux.intel.com>, "Hunter, Adrian"
	<adrian.hunter@...el.com>, "thomas.lendacky@....com"
	<thomas.lendacky@....com>, "ashish.kalra@....com" <ashish.kalra@....com>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>, "seanjc@...gle.com"
	<seanjc@...gle.com>, "bhe@...hat.com" <bhe@...hat.com>,
	"linux-coco@...ts.linux.dev" <linux-coco@...ts.linux.dev>
Subject: Re: [PATCHv9 08/17] x86/tdx: Account shared memory

On Mon, 2024-03-25 at 12:39 +0200, Kirill A. Shutemov wrote:
> The kernel will convert all shared memory back to private during kexec.
> The direct mapping page tables will provide information on which memory
> is shared.
> 
> It is extremely important to convert all shared memory. If a page is
> missed, it will cause the second kernel to crash when it accesses it.
> 
> Keep track of the number of shared pages. This will allow for
> cross-checking against the shared information in the direct mapping and
> reporting if the shared bit is lost.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
> 

Reviewed-by: Kai Huang <kai.huang@...el.com>