From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 7BC57265CA7; Thu, 13 Mar 2025 10:43:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741862597; cv=none; b=d3qEA5BOEhLndQHeHB1Kxo5GhxqVUtV9dksF0E7TQmIYByPmcQILzAFRCK8PdrnPRUghlpMFadtMLpjmr7G2ojMRCMhQ7jnQmCioeQGRLEbg3NA++6JxWpgN21eUuZX19Dk3UpUPonDAxneOTVpdVI4SAPttg2i1M9HF/PZFMAo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741862597; c=relaxed/simple; bh=IVeYqcQ7mMJgmqLGzL+8J1PV9CdWuhC7wLLbzMbjGWw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=kiINjyK/ipBO/PHoAWi6mxXlZ8rBAS34JsSES6z3GtXObT5iBs3znbTx4aiVZttoErUekfNVnxfj17JioBtFZF3fqXv+JpQ3li7Wh3/ZS8fzhwF4w61X7gPIBK39rCqL6z83oqooHUApMGFwPellEHr+PqvoRE8HVg8sCEc8Kl4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 319561516; Thu, 13 Mar 2025 03:43:25 -0700 (PDT) Received: from mazurka.cambridge.arm.com (mazurka.cambridge.arm.com [10.2.80.18]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 987113F694; Thu, 13 Mar 2025 03:43:10 -0700 (PDT) From: =?UTF-8?q?Miko=C5=82aj=20Lenczewski?= To: ryan.roberts@arm.com, suzuki.poulose@arm.com, yang@os.amperecomputing.com, corbet@lwn.net, catalin.marinas@arm.com, will@kernel.org, jean-philippe@linaro.org, robin.murphy@arm.com, joro@8bytes.org, akpm@linux-foundation.org, mark.rutland@arm.com, joey.gouly@arm.com, maz@kernel.org, james.morse@arm.com, broonie@kernel.org, anshuman.khandual@arm.com, oliver.upton@linux.dev, ioworker0@gmail.com, baohua@kernel.org, david@redhat.com, jgg@ziepe.ca, shameerali.kolothum.thodi@huawei.com, nicolinc@nvidia.com, mshavit@google.com, jsnitsel@redhat.com, smostafa@google.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev Cc: =?UTF-8?q?Miko=C5=82aj=20Lenczewski?= Subject: [PATCH v3 0/3] Initial BBML2 support for contpte_convert() Date: Thu, 13 Mar 2025 10:41:09 +0000 Message-ID: <20250313104111.24196-2-miko.lenczewski@arm.com> X-Mailer: git-send-email 2.48.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi All, This patch series adds adding initial support for eliding break-before-make requirements on systems that support BBML2 and additionally guarantee to never raise a conflict abort. This support elides a TLB invalidation in contpte_convert(). This leads to a 12% improvement when executing a microbenchmark designed to force the pathological path where contpte_convert() gets called. This represents an 80% reduction in the cost of calling contpte_convert(). This series is based on v6.14-rc4 (d082ecbc71e9). Patch 1 implements an allow-list of cpus that support BBML2, but with the additional constraint of never causing TLB conflict aborts. We settled on this constraint because we will use the feature for kernel mappings in the future, for which we cannot handle conflict aborts safely. Yang Shi has a series at [1] that aims to use BBML2 to enable splitting the linear map at runtime. This series partially overlaps with it to add the cpu feature. We believe this series is fully compatible with Yang's requirements and could go first. [1]: https://lore.kernel.org/linux-arm-kernel/20250304222018.615808-1-yang@os.amperecomputing.com/ MikoĊ‚aj Lenczewski (3): arm64: Add BBM Level 2 cpu feature iommu/arm: Add BBM Level 2 smmu feature arm64/mm: Elide tlbi in contpte_convert() under BBML2 .../admin-guide/kernel-parameters.txt | 3 + arch/arm64/Kconfig | 11 +++ arch/arm64/include/asm/cpucaps.h | 2 + arch/arm64/include/asm/cpufeature.h | 6 ++ arch/arm64/kernel/cpufeature.c | 76 +++++++++++++++++++ arch/arm64/kernel/pi/idreg-override.c | 2 + arch/arm64/mm/contpte.c | 3 +- arch/arm64/tools/cpucaps | 1 + .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 3 + drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 + drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 4 + 11 files changed, 113 insertions(+), 1 deletion(-) -- 2.48.1