From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D041B253351 for ; Fri, 19 Sep 2025 10:08:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758276533; cv=none; b=BAeP0ZWQ2Bt0iYKXdwupnKVS1ccjJYTsR4Al7nqmPUmQ4SCDzm315SQ1sNMyAzgr6RE7ZpKOQm7y3IkVMvino3C61ydW3nMpuFwZWaTebcJghdLLZfD1Sr7XG4e7Y9ojhQD9k6uXSwAUrY366OKpCdxDqEWf7Iz6rcxw0r+NCfo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758276533; c=relaxed/simple; bh=OFXjUK4nxg8Rf6DBYK58/URNLBfNsLJ8MwVo1pSbRGA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Fy7Nro4/cnJyfgYtqjx7R+HVA3pu19uKrTTsa5YlWBnSzNYmvgO9heXXwZ7yLCmu0PkEljVFAHYT8G17rFngYqZ6hBZmlhovjYioVWStBHlB9/jDMoJ9iBWjteThve7In5EKNLTJW/3myCV3kWCIt9XXGJatceZyUastaanRN40= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 20E6D1692; Fri, 19 Sep 2025 03:08:43 -0700 (PDT) Received: from [10.57.95.38] (unknown [10.57.95.38]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D058D3F673; Fri, 19 Sep 2025 03:08:48 -0700 (PDT) Message-ID: Date: Fri, 19 Sep 2025 11:08:47 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 0/5] arm64: support FEAT_BBM level 2 and large block mapping when rodata=full Content-Language: en-GB To: Will Deacon , catalin.marinas@arm.com, akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, ardb@kernel.org, dev.jain@arm.com, scott@os.amperecomputing.com, cl@gentwo.org, Yang Shi Cc: kernel-team@android.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20250917190323.3828347-1-yang@os.amperecomputing.com> <175822779944.710258.10028837182267037801.b4-ty@kernel.org> From: Ryan Roberts In-Reply-To: <175822779944.710258.10028837182267037801.b4-ty@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 18/09/2025 22:10, Will Deacon wrote: > On Wed, 17 Sep 2025 12:02:06 -0700, Yang Shi wrote: >> On systems with BBML2_NOABORT support, it causes the linear map to be mapped >> with large blocks, even when rodata=full, and leads to some nice performance >> improvements. >> >> Ryan tested v7 on an AmpereOne system (a VM with 12G RAM) in all 3 possible >> modes by hacking the BBML2 feature detection code: >> >> [...] > > Applied patches 1 and 3 to arm64 (for-next/mm), thanks! > > [1/5] arm64: Enable permission change on arm64 kernel block mappings > https://git.kernel.org/arm64/c/a660194dd101 > [3/5] arm64: mm: support large block mapping when rodata=full > https://git.kernel.org/arm64/c/a166563e7ec3 > > I also picked up the BBML allow-list addition (second patch) on > for-next/cpufeature. > > The fourth patch ("arm64: mm: split linear mapping if BBML2 unsupported > on secondary CPUs") has some really horrible conflicts. These are partly > due to some of the type cleanups on for-next/mm but I think mainly due > to Kevin's kpti rework that landed after -rc1. Thanks Will, although I'm nervous that without this patch, some platforms might not boot; Wikipedia tells me that there are some Google, Mediatek and Qualcomm SoCs that pair X4 CPUs (which is on the BBML2_NOABORT allow list) with A720 and/or A520 (which are not). See previous mail at [1]. I'd be happy to rebase it if you can let me know the prefered base SHA/tree? [1] https://lore.kernel.org/linux-arm-kernel/11f84d00-8c76-402d-bbad-014a3542992f@arm.com/ Thanks, Ryan > > So I think the best bet might be to leave that one for next time, if > that's ok? > > Cheers,