From patchwork Wed Mar 20 08:56:01 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarkko Sakkinen X-Patchwork-Id: 13597602 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 AB2113BB35; Wed, 20 Mar 2024 08:56:06 +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=1710924966; cv=none; b=qpxnyAyD/C4aylWnwPZR8fEtcKttWMEDwTunLdqv7UpcjV0myUuYWpPb2hpODmkWEdYrL3OXiZHmyT/wMyJoDWAMg1m89TR0C+dnoQK/5IvhZXKr7kZAcBgR7AfrdAWVe5oX3krz69cJIqh+kHCN0SkgOXT4ETNq0tqlLXdp0Hk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710924966; c=relaxed/simple; bh=LGyKYM8XcN8nBnrxBDrb0mYgitWNCQAUDnZ3X2WeWo8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=K/kN/j2pNY5PYFjcIYqUTSmVTk9TnB//XlqkIHUvM1moNUk5T0dewB+VWom3VginEdYfb8ITV/Zdx13oihkPQFu+gZT53LCNocPvsfH6ZYy2gGKxi0gckArNZQ+FEQWh4l6JjuQ2lhXZcR5xNzcU9RFxiDBna6UGAHRKogw7SR0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LDzu7bX+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LDzu7bX+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D61EBC433F1; Wed, 20 Mar 2024 08:56:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1710924966; bh=LGyKYM8XcN8nBnrxBDrb0mYgitWNCQAUDnZ3X2WeWo8=; h=From:To:Cc:Subject:Date:From; b=LDzu7bX+x9PSrTH6Xd7JrdDYEcfYLME/QLFo1J+0xPMv1zNhFevPQCPqnFR9nv8p6 pYlxrN1Ua9lqNZOrbuqcybpYY+DZyMZ2QJM2eny/cWSGT0NCr8ch6Z/yeW8XZ926VK e/iyuMLZyuy113N3ksFxYvrYulgE/baZWZNXi54QFIERh8b7I/LN4Fho2GZ4n0fsQv 7TI9FByBBJ5jo6k+SRty5qb9gQ6cdYZ3LcJM2wWlT5jps1tzc6uu12swfzlwIm9atN m54GlPIVXAJEh4iFU0V9uZ4aZee8AUBymlPH44qBB5mKnqAOAg6YT/z9/8fK22sQ0x PVQ2dDa7BgSiQ== From: Jarkko Sakkinen To: linux-integrity@vger.kernel.org Cc: Jarkko Sakkinen , Jonathan Corbet , "Daniel P . Smith" , Lino Sanfilippo , Jason Gunthorpe , Peter Huewe , James Bottomley , Alexander Steffen , keyrings@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Randy Dunlap Subject: [PATCH v2] Documentation: tpm_tis Date: Wed, 20 Mar 2024 10:56:01 +0200 Message-ID: <20240320085601.40450-1-jarkko@kernel.org> X-Mailer: git-send-email 2.44.0 Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Based recent discussions on LKML, provide preliminary bits of tpm_tis_core dependent drivers. Includes only bare essentials but can be extended later on case by case. This way some people may even want to read it later on. Cc: Jonathan Corbet CC: Daniel P. Smith Cc: Lino Sanfilippo Cc: Jason Gunthorpe Cc: Peter Huewe Cc: James Bottomley Cc: Alexander Steffen Cc: keyrings@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-integrity@vger.kernel.org Cc: Randy Dunlap Signed-off-by: Jarkko Sakkinen Reviewed-by: Randy Dunlap --- v2: - Fixed errors reported by Randy: https://lore.kernel.org/all/aed28265-d677-491a-a045-24b351854b24@infradead.org/ - Improved the text a bit to have a better presentation. --- Documentation/security/tpm/index.rst | 1 + Documentation/security/tpm/tpm_tis.rst | 30 ++++++++++++++++++++++++++ 2 files changed, 31 insertions(+) create mode 100644 Documentation/security/tpm/tpm_tis.rst diff --git a/Documentation/security/tpm/index.rst b/Documentation/security/tpm/index.rst index fc40e9f23c85..f27a17f60a96 100644 --- a/Documentation/security/tpm/index.rst +++ b/Documentation/security/tpm/index.rst @@ -5,6 +5,7 @@ Trusted Platform Module documentation .. toctree:: tpm_event_log + tpm_tis tpm_vtpm_proxy xen-tpmfront tpm_ftpm_tee diff --git a/Documentation/security/tpm/tpm_tis.rst b/Documentation/security/tpm/tpm_tis.rst new file mode 100644 index 000000000000..b331813b3c45 --- /dev/null +++ b/Documentation/security/tpm/tpm_tis.rst @@ -0,0 +1,30 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================= +TPM FIFO interface Driver +========================= + +FIFO (First-In-First-Out) is the name of the hardware interface used by the +tpm_tis_core dependent drivers. The prefix "tis" comes from the TPM Interface +Specification, which is the hardware interface specification for TPM 1.x chips. + +Communication is based on a 5 KiB buffer shared by the TPM chip through a +hardware bus or memory map, depending on the physical wiring. The buffer is +further split into five equal-size buffers, which provide equivalent sets of +registers for communication between the CPU and TPM. These communication +endpoints are called localities in the TCG terminology. + +When the kernel wants to send commands to the TPM chip, it first reserves +locality 0 by setting the requestUse bit in the TPM_ACCESS register. The bit is +cleared by the chip when the access is granted. Once it completes its +communication, the kernel writes the TPM_ACCESS.activeLocality bit. This +informs the chip that the locality has been relinquished. + +Pending localities are served in order by the chip in descending order, one at +a time: + +- Locality 0 has the lowest priority. +- Locality 5 has the highest priority. + +Further information on the purpose and meaning of the localities can be found +in section 3.2 of the TCG PC Client Platform TPM Profile Specification.