From: Suzuki K Poulose <suzuki.poulose@arm.com>
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: 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>,
Will Deacon <will@kernel.org>,
Steven Price <steven.price@arm.com>,
Andre Przywara <andre.przywara@arm.com>
Subject: Re: [PATCH v8 6/6] coco: guest: arm64: Replace dummy CCA device with sysfs ABI
Date: Wed, 15 Jul 2026 13:19:37 +0100 [thread overview]
Message-ID: <ba85df41-4858-44aa-9bd3-d503518fe107@arm.com> (raw)
In-Reply-To: <20260707081351.1680209-7-aneesh.kumar@kernel.org>
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) <aneesh.kumar@kernel.org>
Acked-by: Suzuki K Poulose <suzuki.poulose@arm.com>
next prev parent reply other threads:[~2026-07-15 12:19 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-07 8:13 [PATCH v8 0/6] Switch Arm SMCCC firmware services to an SMCCC bus Aneesh Kumar K.V (Arm)
2026-07-07 8:13 ` [PATCH v8 1/6] firmware: smccc: Add an Arm " Aneesh Kumar K.V (Arm)
2026-07-09 8:12 ` Sudeep Holla
2026-07-07 8:13 ` [PATCH v8 2/6] firmware: hwrng: arm_smccc_trng: Register as an SMCCC device Aneesh Kumar K.V (Arm)
2026-07-07 8:13 ` [PATCH v8 3/6] firmware: smccc: Move RSI definitions to include/linux Aneesh Kumar K.V (Arm)
2026-07-07 8:13 ` [PATCH v8 4/6] virt: coco: arm-cca-guest: Rename TSM report source file Aneesh Kumar K.V (Arm)
2026-07-07 12:37 ` Suzuki K Poulose
2026-07-07 8:13 ` [PATCH v8 5/6] firmware: smccc: arm-cca-guest: Bind the TSM provider to an SMCCC device Aneesh Kumar K.V (Arm)
2026-07-07 12:41 ` Suzuki K Poulose
2026-07-07 8:13 ` [PATCH v8 6/6] coco: guest: arm64: Replace dummy CCA device with sysfs ABI Aneesh Kumar K.V (Arm)
2026-07-15 12:19 ` Suzuki K Poulose [this message]
2026-07-23 7:55 ` [PATCH v8 0/6] Switch Arm SMCCC firmware services to an SMCCC bus Aneesh Kumar K.V
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