From mboxrd@z Thu Jan 1 00:00:00 1970 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 16C7510E4 for ; Thu, 15 May 2025 00:09:47 +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=1747267787; cv=none; b=eLXiO3ygrzz+hpewrSnR+y/Apo3W4v9W5wRSyjOgGIrOP/rSN1MeX/Iq9NfaP0EkdLwi8AUH5uTI1jguKDOv17N/waORAWlneGPFz0kz/Vbhc8e4fADM8FpnNk5C0XJPJBdOcZFq3ZiJyxdd/o5kd9wf/CzLLQmtKAWq37LR57c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747267787; c=relaxed/simple; bh=RizAUUkKxsQrjyQa28rDw0JbPSPSjmeFS2QuK7QRjAQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rgI+Rv+3TL8TWiFRPHptgqsEBUNpokgj+4kvCJKP4QYJcKtAfgJ77eoC81vnfelXYRxI4ZxtxatAZ8lmrLB28b8mhFn3E6ZXWuh12jpu2dARGQmuPQEIl6JoRgn8+2uZ8wzMpDY9XSJQT0M0ezlDANN0CT0/QgYG+2BzdAeezQs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id CDBEDC4CEED; Thu, 15 May 2025 00:09:46 +0000 (UTC) From: Dave Jiang To: linux-cxl@vger.kernel.org Cc: dave@stgolabs.net, jonathan.cameron@huawei.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com, gourry@gourry.net Subject: [PATCH v2 2/3] cxl: docs/platform/acpi/srat Add generic target documentation Date: Wed, 14 May 2025 17:09:22 -0700 Message-ID: <20250515000923.2590820-3-dave.jiang@intel.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250515000923.2590820-1-dave.jiang@intel.com> References: <20250515000923.2590820-1-dave.jiang@intel.com> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add description in the SRAT document to descript the Generic Port Affinity sub-table. Reviewed-by: Gregory Price Signed-off-by: Dave Jiang --- v2: - Clarify sentence in usage description. (Gregory) - Added association of SRAT to HMAT. --- .../driver-api/cxl/platform/acpi/srat.rst | 27 +++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/Documentation/driver-api/cxl/platform/acpi/srat.rst b/Documentation/driver-api/cxl/platform/acpi/srat.rst index 56d7bbb18c3b..cc98ca0e508e 100644 --- a/Documentation/driver-api/cxl/platform/acpi/srat.rst +++ b/Documentation/driver-api/cxl/platform/acpi/srat.rst @@ -42,3 +42,30 @@ Example :: Enabled : 1 Hot Pluggable : 1 Non-Volatile : 0 + + +Generic Port Affinity +===================== +The Generic Port Affinity subtable provides an association between a proximity +domain and a device handle representing a Generic Port such as a CXL host +bridge. With the association, latency and bandwidth numbers can be retrieved +from the SRAT for the path between CPU(s) (initiator) and the Generic Port. +This is used to construct performance coordinates for hotplugged CXL DEVICES, +which cannot be enumerated at boot by platform firmware. + +Example :: + + Subtable Type : 06 [Generic Port Affinity] + Length : 20 <- 32d, length of table + Reserved : 00 + Device Handle Type : 00 <- 0 - ACPI, 1 - PCI + Proximity Domain : 00000001 + Device Handle : ACPI0016:01 + Flags : 00000001 <- Bit 0 (Enabled) + Reserved : 00000000 + +The Proximity Domain is matched up to the :doc:`HMAT ` SSLBI Target +Proximity Domain List for the related latency or bandwidth numbers. Those +performance numbers are tied to a CXL host bridge via the Device Handle. +The driver uses the association to retrieve the Generic Port performance +numbers for the whole CXL path access coordinates calculation. -- 2.49.0