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 DF2C44432F2 for ; Wed, 15 Jul 2026 12:19:41 +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=1784117984; cv=none; b=MNh1pgUeDf033vRB/DubVhtqXRD689kpDPQmExb1ztkbdEodQ5MN5kaCKBJLo4ckZSO8iIfuFqetiNqCLrXyQrWJ9o+5wKt6nZ8OQuEQbt3HJkbyzQDjccKj3tB2t/BxwAddPxX2h6qDmFpVJA8XMC74Cb7Q4FyL6G5GeQqgc/4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784117984; c=relaxed/simple; bh=1Tt0MZGEStJa1QvPCBaLpbX+2rLiZ4I/VM9Ny/bJNBE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Xp6+KDkjjYV7kR8mABfuL0lzYAIOd1p3OwSUbZ8CJUV7Ub8k1Lu0bt8VHMosMQMXW71bxPo1hn4Nv4GdAMMOqx+XbPdpcE0Fwqv/htWEwQiY4pIiGx/k/efZmY4h3i2pv/vVqc3/JN/Oh0y/0TozvC2zLA43NzvvWnrTht+TWk8= 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; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=U1mfcg9Q; 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="U1mfcg9Q" 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 068432F; Wed, 15 Jul 2026 05:19:37 -0700 (PDT) Received: from [10.1.39.37] (unknown [10.1.39.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5640F3F7B4; Wed, 15 Jul 2026 05:19:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784117981; bh=1Tt0MZGEStJa1QvPCBaLpbX+2rLiZ4I/VM9Ny/bJNBE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=U1mfcg9QIS5BoO/4wu//17ztJSflgRoB9KQjRjBikCmilifzyw6nVovS43XmGPDtn 4cMHAPRhcRgkMscJR0+GbCwtD5Vw65ifrz/ECvQ6Q7ZrvDfG/DJH6/Wich4aXymhWI 21sLyoTBBqddcTDUvDNaVr+eHAlRJRLMnW87X+w8= Message-ID: Date: Wed, 15 Jul 2026 13:19:37 +0100 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: [PATCH v8 6/6] coco: guest: arm64: Replace dummy CCA device with sysfs ABI Content-Language: en-GB To: "Aneesh Kumar K.V (Arm)" , linux-coco@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Catalin Marinas , Greg KH , Jeremy Linton , Jonathan Cameron , Lorenzo Pieralisi , Mark Rutland , Sudeep Holla , Will Deacon , Steven Price , Andre Przywara References: <20260707081351.1680209-1-aneesh.kumar@kernel.org> <20260707081351.1680209-7-aneesh.kumar@kernel.org> From: Suzuki K Poulose In-Reply-To: <20260707081351.1680209-7-aneesh.kumar@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 07/07/2026 09:13, Aneesh Kumar K.V (Arm) wrote: > The SMCCC firmware driver now creates the arm-smccc platform device and > instantiates the CCA RSI auxiliary devices once the RSI ABI is discovered. > The arm64-specific arm-cca-dev platform device stub is therefore no longer > needed. > > However, userspace has used the arm-cca-dev platform device to detect Arm > CCA Realm guests [1]. Removing it without a replacement would break that > detection and would also leave userspace depending on kernel device-model > details. > > Add /sys/firmware/cca/realm_guest as a stable, architecture-provided ABI > for detecting whether the kernel is running as an Arm CCA Realm guest. The > file returns 1 in Realm world and 0 otherwise, similar to the existing s390 > /sys/firmware/uv/prot_virt_guest interface for protected virtualization > guests. > > Remove the dummy arm-cca-dev registration now that userspace has a > dedicated CCA Realm guest indicator, and document the new ABI in > Documentation/ABI/testing/sysfs-firmware-cca. > > [1] https://lore.kernel.org/all/4a7d84b2-2ec4-4773-a2d5-7b63d5c683cf@arm.com > > Signed-off-by: Aneesh Kumar K.V (Arm) Acked-by: Suzuki K Poulose