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 C7142247295; Wed, 8 Oct 2025 06:21:24 +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=1759904484; cv=none; b=DIo7HFuTCmDfOI3ndM9s3huhfXsCx22yfX1+jAaFV4KoCbHXT0VKufrKZRYx7fDDXyxeJ1rTiIOrhABnBxWQ8Hah/0rzWsbd9+7rpNTiV6qCK5n175NDPUA+bLpURNOrH8yOxWKozckg4+Qna3WGD1w3vI4Kohq313SGFS5kkrc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759904484; c=relaxed/simple; bh=zftFoY2NW42CeV+u2LtWYiPyCxMvkvvCeKwoDsOpq1I=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=e3o6k7vQ5Ofz86bKQACrswTPasWm9LERj5qfG0xpglLAzZ68jK60D8Eq5y4phxgOkdPIOZB7PhxdqbL0MB0RGhfrjNNcbFzmPy+vGDV248BWtluZRhKD47fgsxXPyDYwRVq/NQ6eozOY8RFV4VEwdzTekqqPYutmrAUNYXwzPwc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=H3DcyU/X; 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="H3DcyU/X" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AFFB8C4CEF4; Wed, 8 Oct 2025 06:21:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1759904484; bh=zftFoY2NW42CeV+u2LtWYiPyCxMvkvvCeKwoDsOpq1I=; h=From:Subject:Date:To:Cc:From; b=H3DcyU/XACgbUcA0UFao8srliyrovizXB20FA1HoYEJUBUh+k2jqIUrJN94uKoCzD OImKMUfzcqZV0B0fQwad4kB1WZxVyNrMC2vGFaORO0j4/06gudMRbJHzHVNJ3w6SyA aVQaKExMNWjAkOdKxEurAL/+nWeRFvoCwLVuGdPMekvmd9ActOZiA92BjudkbbLaxu KdeGDvEitVcMKXqrQ7TA1eTRLzG2DkrmxotLcH/xnvB/xjwJh6ytVNx63cREHVrAGV 0VL9tgDCJt3LiOFTO63iopHnGQ4T33gS6djVgV42jILMHAOIavIQCX7AslvlO3woij 6DU7WzLfQOyeA== From: Drew Fustini Subject: [PATCH v4 0/3] RISC-V: Detect Ssqosid extension and handle srmcfg CSR Date: Tue, 07 Oct 2025 23:21:09 -0700 Message-Id: <20251007-ssqosid-v4-0-e8b57e59d812@kernel.org> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIANUC5mgC/6tWKk4tykwtVrJSqFYqSi3LLM7MzwNyTHQUlJIzE vPSU3UzU4B8JSMDI1NDAwNz3eLiwvzizBTdlJRkC3NLM4skoxRLJaDqgqLUtMwKsEnRsbW1AIf xr0JZAAAA X-Change-ID: 20251007-ssqosid-ddc87968b2d9 To: Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: =?utf-8?q?Kornel_Dul=C4=99ba?= , Adrien Ricciardi , James Morse , Atish Kumar Patra , Atish Patra , Vasudevan Srinivasan , Conor Dooley , guo.wenjia23@zte.com.cn, liu.qingtao2@zte.com.cn, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Drew Fustini X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=5432; i=fustini@kernel.org; h=from:subject:message-id; bh=zftFoY2NW42CeV+u2LtWYiPyCxMvkvvCeKwoDsOpq1I=; b=owGbwMvMwCF2+43O4ZsaG3kYT6slMWQ8Y3q87G3P9ic//k6xnhvqVc27gMe22e3xgi9h+7U+F jQF258S7ChlYRDjYJAVU2TZ9CHvwhKv0K8L5r/YBjOHlQlkCAMXpwBMROkrw//q1IMdtQwf/fcw /DBV7p13THmebdzsG0t1Jlwtf+shUnKFkaHre9saqdeblHdMqdN7wjJ5q8z04K6w2hfvnFfKc4U w/ucFAA== X-Developer-Key: i=fustini@kernel.org; a=openpgp; fpr=1B6F948213EA489734F3997035D5CD577C1E6010 This series adds support for the RISC-V Quality-of-Service Identifiers (Ssqosid) extension [1] which adds the srmcfg register. This CSR configures a hart with two identifiers: a Resource Control ID (RCID) and a Monitoring Counter ID (MCID). These identifiers accompany each request issued by the hart to shared resource controllers. Background on RISC-V QoS: The Ssqosid extension is used by the RISC-V Capacity and Bandwidth Controller QoS Register Interface (CBQRI) specification [2]. QoS in this context is concerned with shared resources on an SoC such as cache capacity and memory bandwidth. Intel and AMD already have QoS features on x86 and ARM has MPAM. There is an existing user interface in Linux: the resctrl virtual filesystem [3]. The srmcfg CSR provides a mechanism by which a software workload (e.g. a process or a set of processes) can be associated with an RCID and an MCID. CBQRI defines operations to configure resource usage limits, in the form of capacity or bandwidth. CBQRI also defines operations to configure counters to track the resource utilization. Goal for this series: These patches are taken from the implementation of resctrl support for RISC-V CBQRI. Please refer to the proof-of-concept RFC [4] for details on the resctrl implementation. More recently, I have rebased the CBQRI support on mainline [5]. Big thanks to James Morse for the tireless work to extract resctrl from arch/x86 and make it available to all architectures. I think it makes sense to first focus on the detection of Ssqosid and handling of srmcfg when switching tasks. It has been tested against a QEMU branch that implements Ssqosid and CBQRI [6]. A test driver [7] was used to set srmcfg for the current process. This allows switch_to to be tested without resctrl. [1] https://github.com/riscv/riscv-ssqosid/releases/tag/v1.0 [2] https://github.com/riscv-non-isa/riscv-cbqri/releases/tag/v1.0 [3] https://docs.kernel.org/filesystems/resctrl.html [4] https://lore.kernel.org/linux-riscv/20230419111111.477118-1-dfustini@baylibre.com/ [5] https://git.kernel.org/pub/scm/linux/kernel/git/fustini/linux.git/log/?h=b4/cbqri [6] https://github.com/tt-fustini/qemu/tree/riscv-cbqri-rqsc-pptt [7] https://git.kernel.org/pub/scm/linux/kernel/git/fustini/linux.git/log/?h=b4/ssqosid-debug Changes in v4: - Rebase on riscv/for-next as of riscv-for-linus-6.18-mw2 - Add Conor's Acked-by to the yaml patch - Link to v3: https://lore.kernel.org/all/20250920-ssqosid-v6-17-rc5-v3-0-5093162922d8@kernel.org/ Changes in v3: - Fix parameter in __switch_to_srmcfg() when CONFIG_RISCV_ISA_SSQOSID is not set to avoid error in clang. This does trigger checkpatch warning about "Argument '__next' is not used in function-like macro" but it seems that '__switch_to_srmcfg(__next)' is needed to avoid the error that LKP reported. '__switch_to_srmcfg()' will trigger a build error in clang. https://lore.kernel.org/oe-kbuild-all/202509162355.wByessnb-lkp@intel.com/ - Improve description of ssqosid in extensions.xml - Link to v2: https://lore.kernel.org/linux-riscv/20250915-ssqosid-v6-17-rc5-v2-0-2d4b0254dfd6@kernel.org/ Changes in v2: - Restore the per-cpu fix from RFC v2 that was missed in v1: change DEFINE_PER_CPU to DECLARE_PER_CPU in qos.h and move DEFINE_PER_CPU to qos.c - Introduce a patch that adds Ssqosid to riscv/extensions.yaml - Link to v1: https://lore.kernel.org/r/20250910-ssqosid-v6-17-rc5-v1-0-72cb8f144615@kernel.org Changes in v1: - Rename all instances of the sqoscfg CSR to srmcfg to match the ratified Ssqosid spec - Link RFC v2: https://lore.kernel.org/linux-riscv/20230430-riscv-cbqri-rfc-v2-v2-0-8e3725c4a473@baylibre.com/ Changes in RFC v2: - change DEFINE_PER_CPU to DECLARE_PER_CPU for cpu_sqoscfg in qos.h to prevent linking error about multiple definition. Move DEFINE_PER_CPU for cpu_sqoscfg into qos.c - renamed qos prefix in function names to sqoscfg to be less generic - handle sqoscfg the same way has_vector and has_fpu are handled in the vector patch series - Link to RFC v1: https://lore.kernel.org/linux-riscv/20230410043646.3138446-1-dfustini@baylibre.com/ Signed-off-by: Drew Fustini --- Drew Fustini (3): dt-bindings: riscv: Add Ssqosid extension description RISC-V: Detect the Ssqosid extension RISC-V: Add support for srmcfg CSR from Ssqosid ext .../devicetree/bindings/riscv/extensions.yaml | 6 ++++ MAINTAINERS | 7 ++++ arch/riscv/Kconfig | 17 +++++++++ arch/riscv/include/asm/csr.h | 8 +++++ arch/riscv/include/asm/hwcap.h | 1 + arch/riscv/include/asm/processor.h | 3 ++ arch/riscv/include/asm/qos.h | 41 ++++++++++++++++++++++ arch/riscv/include/asm/switch_to.h | 3 ++ arch/riscv/kernel/Makefile | 2 ++ arch/riscv/kernel/cpufeature.c | 1 + arch/riscv/kernel/qos/Makefile | 2 ++ arch/riscv/kernel/qos/qos.c | 5 +++ 12 files changed, 96 insertions(+) --- base-commit: 68247d45c045bb7dda923cf2c8d0937ce0e16394 change-id: 20251007-ssqosid-ddc87968b2d9 Best regards, -- Drew Fustini