From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.8bytes.org (mail.8bytes.org [85.214.250.239]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4379F1DA636 for ; Fri, 24 Jan 2025 07:58:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=85.214.250.239 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737705523; cv=none; b=FabRoJAz7rTaW0GrFCUemv8sP9QjRRIQFxp8XurABneImOL1nbK0qSvljxNG9Ql1LerBLCrebQcuSbct8o3piW6cCVlUftnXXqaydLFnRV7zEIsZzLP4FjFiFQrXdj3ugGVZxS0X8tHA2I7YT12hzfwqWpN5uVpK2SUKEdhnhTY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737705523; c=relaxed/simple; bh=MVetvB9K1iImHrM4hQvY0TY3WvPAvKZ0ME9INSigEqM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gwv5un0Jp4RY68Sq8jCbEmGYh9Uxs5Oqq77pYdmXci9hmplGxTIq1bp6KPbANOAEvA0mITuXJB2ICHRlzez2HGwNSIJFOyZqfW6LV3rKhgq6I+GGzLsm/0KsX3ARNmDO8I0ecTV9fGF7eSTNgcduJp0Itz5GAJGrECQoH9slgcc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=8bytes.org; spf=pass smtp.mailfrom=8bytes.org; dkim=pass (2048-bit key) header.d=8bytes.org header.i=@8bytes.org header.b=UJIHFiwO; arc=none smtp.client-ip=85.214.250.239 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=8bytes.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=8bytes.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=8bytes.org header.i=@8bytes.org header.b="UJIHFiwO" Received: from 8bytes.org (p54921e31.dip0.t-ipconnect.de [84.146.30.49]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mail.8bytes.org (Postfix) with ESMTPSA id 1C00D4071A; Fri, 24 Jan 2025 08:58:34 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=8bytes.org; s=default; t=1737705514; bh=MVetvB9K1iImHrM4hQvY0TY3WvPAvKZ0ME9INSigEqM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UJIHFiwOBoTto2BPnbbZUWp0j2Qv9Uco0rIhiY6a7+G8Enl4OCcCMWre5ENzz2stF fuXdYKfnmVu8xsZdBpKbz2Twnb2T9pYJRqZLIcB2muo8mhe2SqHDspMak8/dcE5RaW fhmS2jrpdPuUYxrehNBsG67ybA1d1dsgchtyHxN7/Rol2EgsL1GpFje/9bGjtLXD3s jCAuhpMAEiwIAyrgpGGxpEppC/4JERKg6mVrMioIbQK+ZpvB0pdrYbauSv0Gj+8XYR mq3RMswiygAlZm3uddlwkYQ5bkzO4hy7m37mke3JE9VR30fwQrYFmfOyZBXD58Ytrf WHQV2f0OTQSoA== Date: Fri, 24 Jan 2025 08:58:32 +0100 From: Joerg Roedel To: Dave Hansen Cc: Peter Zijlstra , Dave Hansen , linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de, bp@alien8.de, luto@kernel.org, kirill.shutemov@linux.intel.com, rick.p.edgecombe@intel.com, jgross@suse.com Subject: Re: [RFC][PATCH 0/8] x86/mm: Simplify PAE page table handling Message-ID: References: <20250123172428.D6D8C8D9@davehans-spike.ostc.intel.com> <20250123214911.GB969@noisy.programming.kicks-ass.net> <6c1785c8-e74e-4912-95bb-88b6e94f544f@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6c1785c8-e74e-4912-95bb-88b6e94f544f@intel.com> On Thu, Jan 23, 2025 at 03:06:26PM -0800, Dave Hansen wrote: > 32-bit+PTI or 32-bit in general? ;) +1 for removing x86-32 bit support alltogether. > I'm curious what Joerg and the other folks that worked on 32-bit PTI > think about it in retrospect. The 32 vs. 64-bit security gap was > probably modest in 2018 and it can only have grown since then. I think the decision to keep and maintain 32-bit support only makes sense if it can be kept on-par with x86-64 security-wise, otherwise we are lying to our users about the 'supported' part. Back in the day when I did the 32-bit PTI support it made sense, but that was 7 years ago. When was the last 32-bit only x86 CPU sold? > I definitely haven't seen a lot of 32-bit PTI bug reports. That's because the 32-bit PTI support is a well crafted piece of beauty, which was merged with almost no bugs ;-) Regards, Joerg