From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D43991C06 for ; Mon, 25 Mar 2024 15:43:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711381441; cv=none; b=aNFxFZuCVCz9trZnL5cu8TGD1jW9c/n1A8cJQuj+tKrXhl2dqpyqRsYQah2XzJ9cbM+cL7MIg22soldzewZQJtqyK0Y/juvWD2YgBatgtNyV+T7HzFgsHwoLGLv84A1KXHOXG0kTag36W0vO7JtgyPR117Zu8a/Jha9AJiubN9o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711381441; c=relaxed/simple; bh=kHE0zX1DU3TTa6UNYPRNZ7cQSTALakcksyGuk61DVw0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=o5jdvy96Sav3aRNy8p1ujynGvDBh4TlME9s64q27sMFT10icNAUQXD9qWscfH/Lx4TZY5MJRn9sfHSzsnV0o8U7jxSzIFQFuIG6sLYrTwDbD0bhghv4BvoxI+AjK5f03+BhT/njHTh55mh3OSLJP4DTSPp3moCMsNrA+Y+6VEWM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=gjbATJsz; arc=none smtp.client-ip=192.198.163.8 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="gjbATJsz" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1711381439; x=1742917439; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=kHE0zX1DU3TTa6UNYPRNZ7cQSTALakcksyGuk61DVw0=; b=gjbATJszyTrKpOy683b2dzwyrrHkeEqQLM/qa63zRcM0GgJMcufk1lwJ +5QVsAKJ2KY7ahUKIqaIIesJ6yDrpfFYZtDJSZYrAU9PMW39c04XVf4aM bdobzUQxdR90ZEDKNbn7k3HlQcIjk697wrzXPgNZ/dpAKiuIKokc8sgFL yacDtU3l4lQVnD+k6j9av3uW51W/1gn77ugZeR0c9tkUuxuR0IjOwK8IZ Vq7XRloEpMJHDPQjO+HRHreKp5UVya5uQrLi2MW1ekZC6gaga6IQKSZPl KX+TaRxPj56kQzVh7bqYzEvcGNrwXPr48B15dv1wu466fVuL7JpssVKMN w==; X-IronPort-AV: E=McAfee;i="6600,9927,11023"; a="23877007" X-IronPort-AV: E=Sophos;i="6.07,153,1708416000"; d="scan'208";a="23877007" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Mar 2024 08:43:58 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,153,1708416000"; d="scan'208";a="15526038" Received: from dvidmant-mobl.amr.corp.intel.com (HELO [10.209.80.233]) ([10.209.80.233]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Mar 2024 08:43:58 -0700 Message-ID: Date: Mon, 25 Mar 2024 08:43:57 -0700 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv9 08/17] x86/tdx: Account shared memory Content-Language: en-US To: "Kirill A. Shutemov" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org Cc: "Rafael J. Wysocki" , Peter Zijlstra , Adrian Hunter , Elena Reshetova , Jun Nakajima , Rick Edgecombe , Tom Lendacky , "Kalra, Ashish" , Sean Christopherson , "Huang, Kai" , Baoquan He , kexec@lists.infradead.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org References: <20240325103911.2651793-1-kirill.shutemov@linux.intel.com> <20240325103911.2651793-9-kirill.shutemov@linux.intel.com> From: Kuppuswamy Sathyanarayanan In-Reply-To: <20240325103911.2651793-9-kirill.shutemov@linux.intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/25/24 3:39 AM, 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 > --- Looks good to me. Reviewed-by: Kuppuswamy Sathyanarayanan > arch/x86/coco/tdx/tdx.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c > index 26fa47db5782..979891e97d83 100644 > --- a/arch/x86/coco/tdx/tdx.c > +++ b/arch/x86/coco/tdx/tdx.c > @@ -38,6 +38,8 @@ > > #define TDREPORT_SUBTYPE_0 0 > > +static atomic_long_t nr_shared; > + > /* Called from __tdx_hypercall() for unrecoverable failure */ > noinstr void __noreturn __tdx_hypercall_failed(void) > { > @@ -821,6 +823,11 @@ static int tdx_enc_status_change_finish(unsigned long vaddr, int numpages, > if (!enc && !tdx_enc_status_changed(vaddr, numpages, enc)) > return -EIO; > > + if (enc) > + atomic_long_sub(numpages, &nr_shared); > + else > + atomic_long_add(numpages, &nr_shared); > + > return 0; > } > -- Sathyanarayanan Kuppuswamy Linux Kernel Developer