From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 02DF310F6 for ; Thu, 1 Dec 2022 09:37:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75389C43470; Thu, 1 Dec 2022 09:37:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669887451; bh=BfOt5syWCVHNIGlCb5w84CIS4Di9VpSeQ2OX3cIcr0g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=m/T9mQyWRqPURKZX3ywro3KQASCx/8OPjCwEnX3ONXn1gZnBx+Sf4nS2Tr/dDZE2x JyUxtPoL1HCM9kIie8EN+AD1YLaixfOtfzCR1TDv2XoJlmHA1wAEvGMZhzo+0m8Jmb /Z2h7e2XFK1uzrzHO/WpDhAwHo/7pP05AeWgSl29p7Q2yjqRtzC8fb3wzrI6OJ1HkZ KB8ipJ01wFYCSsMZ0DfDAgXLPcPBCSfVY1M5fIW1FlzEpAGu+s5g2QcDyh2qR9Mg8x RYP0Su61tWvN/xP44ZIh2d1yEm7nm1xsw/TWgw2675xlSDvo4WotLTgBYleKetNWad mf5S8Ws3o/j6w== Date: Thu, 1 Dec 2022 11:37:10 +0200 From: Mike Rapoport To: "Kirill A. Shutemov" Cc: Borislav Petkov , "Kirill A. Shutemov" , Andy Lutomirski , Sean Christopherson , Andrew Morton , Joerg Roedel , Ard Biesheuvel , Andi Kleen , Kuppuswamy Sathyanarayanan , David Rientjes , Vlastimil Babka , Tom Lendacky , Thomas Gleixner , Peter Zijlstra , Paolo Bonzini , Ingo Molnar , Varad Gautam , Dario Faggioli , Dave Hansen , David Hildenbrand , marcelo.cerri@canonical.com, tim.gardner@canonical.com, khalid.elmously@canonical.com, philip.cox@canonical.com, x86@kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, Mike Rapoport Subject: Re: [PATCHv7 08/14] x86/mm: Reserve unaccepted memory bitmap Message-ID: References: <20220614120231.48165-1-kirill.shutemov@linux.intel.com> <20220614120231.48165-9-kirill.shutemov@linux.intel.com> <20221130012840.sf4rvddzc4ev7bj5@box.shutemov.name> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221130012840.sf4rvddzc4ev7bj5@box.shutemov.name> On Wed, Nov 30, 2022 at 04:28:40AM +0300, Kirill A. Shutemov wrote: > On Tue, Jul 26, 2022 at 11:07:14AM +0200, Borislav Petkov wrote: > > On Tue, Jun 14, 2022 at 03:02:25PM +0300, Kirill A. Shutemov wrote: > > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > > > index f267205f2d5a..22d1fe48dcba 100644 > > > --- a/arch/x86/kernel/e820.c > > > +++ b/arch/x86/kernel/e820.c > > > @@ -1316,6 +1316,16 @@ void __init e820__memblock_setup(void) > > > int i; > > > u64 end; > > > > > > + /* Mark unaccepted memory bitmap reserved */ > > > + if (boot_params.unaccepted_memory) { > > > + unsigned long size; > > > + > > > + /* One bit per 2MB */ > > > + size = DIV_ROUND_UP(e820__end_of_ram_pfn() * PAGE_SIZE, > > > + PMD_SIZE * BITS_PER_BYTE); > > > + memblock_reserve(boot_params.unaccepted_memory, size); > > > + } > > > + > > > > Hmm, I don't like how this is dropped right in the middle of a unrelated > > function. > > > > You're adding arch/x86/mm/unaccepted_memory.c later. Why don't you put > > that chunk in a function there which is called by early_reserve_memory() > > which does exactly what you want - reserve memory early, before memblock > > allocations? > > early_reserve_memory() specifically called before e820__memory_setup() > (see comment in setup_arch()), so we don't have e820_table finalized and > we need it to get correct RAM size from e820__end_of_ram_pfn(). > > I guess we can hide the chunk in a function in unaccepted_memory.c and > call it from here, but it would require #ifdeffery in a header file as the > .c is only compiled for CONFIG_UNACCEPTED_MEMORY=y. > > Looks like an overkill to me, no? Agree. Can we just extend the comment to explain why we reserve the bitmap at e820__memblock_setup() rather than in early_reserve_memory(), pretty much with the explanation above? > -- > Kiryl Shutsemau / Kirill A. Shutemov -- Sincerely yours, Mike.