From patchwork Thu Mar 21 16:43:07 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarkko Sakkinen X-Patchwork-Id: 13599238 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 6B956130E54; Thu, 21 Mar 2024 16:45:38 +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=1711039538; cv=none; b=GlbNprUdKcZ5mIV5WYfG5Tbq2xzz3bnv7MnY2h6u6jWPuM5pNk1nbg0PPmJ9c+w7sAPqWW+x1Hoye4aNprxXMt3Lme24S1tQ566+cbdsaZcFohI0A/E5Gi6ntu9efqhpDjpMkphCv6HOkzlGGpnYFxiFiWL24n3oDpBMcWfhOA4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711039538; c=relaxed/simple; bh=nPVWYcFVife9z6PvN7CZBdrGkGPDFZARTn8Jlbi06jo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=k8Y0fuyQKSLoVwiPVSRFhns/kEWUOlQrcZsVrNTeBslGvIRj0ZhudE3aRvjEPj63D0USUfKZJ8c787auZgXKxbXe2pOkp0y7evzfh6OHM6nFgsK1W+vOtNafWajWbIXCBU8L7vNvNIEgaDCpYmsrA/L41o6KzgjgP+nBi0F7r0k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=p0QhQBUf; 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="p0QhQBUf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6728AC433C7; Thu, 21 Mar 2024 16:45:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711039538; bh=nPVWYcFVife9z6PvN7CZBdrGkGPDFZARTn8Jlbi06jo=; h=From:To:Cc:Subject:Date:From; b=p0QhQBUfqBhYa0QHOFz2qzWrrtUZmGwvBVc1ven3CagVdge1xOMt6mi5/CAbFumaG lLVDLvYdAJA48kGHY0T3BLbfFR0xuoLsnMHIvmvK+RlZKfNqM+eAuExhhPfqxdTUdW K4KYpS+aA4PRgIzSJ7zbsuxC93sUc0oZPMVS0Jbj65Ggwgq39IW/tsLsnZdokrIHwP 05WBoKY82KPsnR8Gm04ENhFBmDSCPkGSDQM8sWRJxszfcvRE1feRkX1PHWWWcrNagA 6S8wF9mdknt7/Y2QlcfwFarDDJBf9FEVbz8iqHNBI0iVCjMzQR9u1osUuDF4tmuENu GByjFZx4UYAgQ== 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 v3] Documentation: tpm_tis Date: Thu, 21 Mar 2024 18:43:07 +0200 Message-ID: <20240321164314.14732-1-jarkko@kernel.org> X-Mailer: git-send-email 2.43.0 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 Reviewed-by: Randy Dunlap Signed-off-by: Jarkko Sakkinen --- v3: - Fixed incorrect buffer size: https://lore.kernel.org/linux-integrity/d957dbd3-4975-48d7-abc5-1a01c0959ea3@linux.ibm.com/ 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..078b75666086 --- /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 20 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 4 KiB 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.