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 4201F1DF25A; Wed, 30 Apr 2025 12:05:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746014743; cv=none; b=DVgb04W31Q62MQegTDvgTMjgxzUyx8AWTAG37VeWm5QI66ZqHtl7YfxEr0OUJCwceVP8h2hYRJ6BS2y/HmILx/Vs1fYmzGuu8aUDmybIPnTo/dc5r8TZzUHv3hKh9xnQWzo4WyvnYqvIDPfnDc5hoW7jiGD77KyLNoxtCVE2LXU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746014743; c=relaxed/simple; bh=WgsIZBnKrOUXlHWyHteBatYQrkxyacAFYb8soNIONAQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=EGZDvu1VWjjet5K+ds06b8sZ7bDQxpT8zAezQ6Mu3f1/c6Bhjj/ZLS4/q3fW+TQPl7AFUBnKRrh0kY4qj6/PP/o/Za08jzewrHW7PwLhIquwIE65mVoUIu0Nj/jldGZYzRUtXTj4yqFBiQsqI/UACho77zz26vlOa7hu3OnFfR0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=OVjzrAzX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="OVjzrAzX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 644ADC4CEE9; Wed, 30 Apr 2025 12:05:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1746014743; bh=WgsIZBnKrOUXlHWyHteBatYQrkxyacAFYb8soNIONAQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OVjzrAzXTVvSHGWlOIPuVzuwrY02hbg+25DrO/iLoej4dIOMEL1IM8g+OZgwHbVf+ s9FC2tlPvpI0TWPWjhQkmoJxnFku+k/36BH60uT1vSHNDTGj9tf1LDXoD19X1r9YIj PxT+vba369KabXRIGDRF9zZBt/3x7X8aDjoga/U8= Date: Wed, 30 Apr 2025 09:19:54 +0200 From: Greg Kroah-Hartman To: Dan Williams Cc: dave.hansen@linux.intel.com, Arnd Bergmann , Ingo Molnar , Kees Cook , Kirill Shutemov , Michael Ellerman , Naveen N Rao , Nikolay Borisov , stable@vger.kernel.org, Suzuki K Poulose , Vishal Annapurve , x86@kernel.org, linux-coco@lists.linux.dev Subject: Re: [PATCH v5] x86/devmem: Remove duplicate range_is_allowed() definition Message-ID: <2025043043-disinfect-cosigner-db50@gregkh> References: <20250430024622.1134277-1-dan.j.williams@intel.com> <20250430024622.1134277-2-dan.j.williams@intel.com> 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: <20250430024622.1134277-2-dan.j.williams@intel.com> On Tue, Apr 29, 2025 at 07:46:21PM -0700, Dan Williams wrote: > 17 years ago, Venki suggested [1] "A future improvement would be to > avoid the range_is_allowed duplication". > > The only thing preventing a common implementation is that > phys_mem_access_prot_allowed() expects the range check to exit > immediately when PAT is disabled [2]. I.e. there is no cache conflict to > manage in that case. This cleanup was noticed on the path to > considering changing range_is_allowed() policy to blanket deny /dev/mem > for private (confidential computing) memory. > > Note, however that phys_mem_access_prot_allowed() has long since stopped > being relevant for managing cache-type validation due to [3], and [4]. > > Commit 0124cecfc85a ("x86, PAT: disable /dev/mem mmap RAM with PAT") [1] > Commit 9e41bff2708e ("x86: fix /dev/mem mmap breakage when PAT is disabled") [2] > Commit 1886297ce0c8 ("x86/mm/pat: Fix BUG_ON() in mmap_mem() on QEMU/i386") [3] > Commit 0c3c8a18361a ("x86, PAT: Remove duplicate memtype reserve in devmem mmap") [4] > > Cc: Dave Hansen > Cc: Ingo Molnar > Cc: "Naveen N Rao" > Reviewed-by: Nikolay Borisov > Signed-off-by: Dan Williams > --- > arch/x86/mm/pat/memtype.c | 31 ++++--------------------------- > drivers/char/mem.c | 18 ------------------ > include/linux/io.h | 21 +++++++++++++++++++++ > 3 files changed, 25 insertions(+), 45 deletions(-) Reviewed-by: Greg Kroah-Hartman