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Message-ID: <c8819aea-d0a2-45ea-a4dc-54e2f9aa2df8@arm.com>
Date: Wed, 23 Sep 2026 16:08:24 +0100
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Subject: Re: [PATCH v13 7/8] coco: guest: arm64: Add sysfs ABI for CCA Realm
 guests
Content-Language: en-GB
To: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>,
 linux-coco@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
 linux-kernel@vger.kernel.org
Cc: Jason Gunthorpe <jgg@nvidia.com>,
 Catalin Marinas <catalin.marinas@arm.com>,
 Greg KH <gregkh@linuxfoundation.org>, Jeremy Linton <jeremy.linton@arm.com>,
 Jonathan Cameron <jic23@kernel.org>,
 Lorenzo Pieralisi <lpieralisi@kernel.org>,
 Mark Rutland <mark.rutland@arm.com>, Sudeep Holla <sudeep.holla@arm.com>,
 Sudeep Holla <sudeep.holla@kernel.org>, Will Deacon <will@kernel.org>,
 Steven Price <steven.price@arm.com>, Andre Przywara
 <andre.przywara@arm.com>, Herbert Xu <herbert@gondor.apana.org.au>,
 Nathan Chancellor <nathan@kernel.org>, Nicolas Schier <nsc@kernel.org>,
 Olivia Mackall <olivia@selenic.com>, Russell King <linux@armlinux.org.uk>,
 Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
References: <20260923140405.1111554-1-aneesh.kumar@kernel.org>
 <20260923140405.1111554-8-aneesh.kumar@kernel.org>
From: Suzuki K Poulose <suzuki.poulose@arm.com>
In-Reply-To: <20260923140405.1111554-8-aneesh.kumar@kernel.org>
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On 23/09/2026 15:04, Aneesh Kumar K.V (Arm) wrote:
> Userspace has used the arm-cca-dev platform device to detect Arm CCA
> Realm guests. 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 ABI for detecting whether
> the kernel is running as an Arm CCA Realm guest. Create the file only in
> Realm world, where it reads 1.
> 
> Document the new ABI in Documentation/ABI/testing/sysfs-firmware-cca.
> 
> Link: https://lore.kernel.org/all/4a7d84b2-2ec4-4773-a2d5-7b63d5c683cf@arm.com
> Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>