From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3CB3BF4BB6C for ; Tue, 24 Feb 2026 17:59:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=5m43AA6kWyGBLy2vEOWIWcMN87g94iGuxkh+tLjfCCk=; b=gXP6981HQVUFMc1AEOdCYGhydv 1zz3mZXevW5hb0JbZCIy/igzplSWxlBdWHnPzXwLQ8WH7PA9zKB1Y8aO3Cdi3Gnzl6WcZan8dOSlb c6tMITuF7sfCiEwq2JcTWsgKKoOoikjixl1Uzndxa2EKl49noUYDcSVKyoG8LRlhTmFo4faYdJ81m u8EenZPVNpuA1rjgfZG+W4knrMtrdTaegI694nmJnnURKCqXtUbygGkSlNiPrG1vN1vdu9wNZnEvU GdJzIv/msxSob5HnP8HV0sRy+H40s48A98Ieg1u/iApWRlLgKOVcqEhRjyY9dqNS6WCfojhuJLgZf qjr+R66w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vuwh5-00000002YWb-1QqU; Tue, 24 Feb 2026 17:59:35 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vuwh0-00000002YNE-2Mvg for linux-arm-kernel@bombadil.infradead.org; Tue, 24 Feb 2026 17:59:30 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:MIME-Version :References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=5m43AA6kWyGBLy2vEOWIWcMN87g94iGuxkh+tLjfCCk=; b=TTo9YdlHhxz8FzxO1gEMyOTfN/ ughFi4GYm1TM/TnImGR7IbIXmR1MmhF4LJyKmpbRJP5OOwPYXM8e8mIXI5KdCvzN/9xBdSTdSFufE RoplZcr5+ezy8kk1RaLmxX74nEXZpSy2gs+oE/bfVW0bQPj8WjIbsasDG5cvVtfe0RS+2NR/NZ4Hl aW+90sncLrBShoJpBdVGbhzT+fbRh7hR26OgZE93k8dUu3C3wh3xG2FsbTzT7uUzDWbDHb3Jur3TQ 642YdtVYmW8dQlKAORF4q0d8sCQbnSiEcSe+mLwqqPpEzIDg/wuCW/gfO2ghDQePYiy+w4jPIKGdg En6tGUAA==; Received: from foss.arm.com ([217.140.110.172]) by desiato.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vuwgv-00000007dvz-0RM2 for linux-arm-kernel@lists.infradead.org; Tue, 24 Feb 2026 17:59:27 +0000 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 8F3E51595; Tue, 24 Feb 2026 09:59:17 -0800 (PST) Received: from e134344.cambridge.arm.com (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id CF9303F59E; Tue, 24 Feb 2026 09:59:18 -0800 (PST) From: Ben Horgan To: ben.horgan@arm.com Cc: amitsinght@marvell.com, baisheng.gao@unisoc.com, baolin.wang@linux.alibaba.com, carl@os.amperecomputing.com, dave.martin@arm.com, david@kernel.org, dfustini@baylibre.com, fenghuay@nvidia.com, gshan@redhat.com, james.morse@arm.com, jonathan.cameron@huawei.com, kobak@nvidia.com, lcherian@marvell.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, peternewman@google.com, punit.agrawal@oss.qualcomm.com, quic_jiles@quicinc.com, reinette.chatre@intel.com, rohit.mathew@arm.com, scott@os.amperecomputing.com, sdonthineni@nvidia.com, tan.shaopeng@fujitsu.com, xhao@linux.alibaba.com, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, kvmarm@lists.linux.dev, zengheng4@huawei.com, linux-doc@vger.kernel.org, Dave Martin , Shaopeng Tan Subject: [PATCH v5 21/41] arm_mpam: resctrl: Add kunit test for control format conversions Date: Tue, 24 Feb 2026 17:57:00 +0000 Message-ID: <20260224175720.2663924-22-ben.horgan@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260224175720.2663924-1-ben.horgan@arm.com> References: <20260224175720.2663924-1-ben.horgan@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260224_175925_531378_89350311 X-CRM114-Status: GOOD ( 25.17 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Dave Martin resctrl specifies the format of the control schemes, and these don't match the hardware. Some of the conversions are a bit hairy - add some kunit tests. Tested-by: Gavin Shan Tested-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Zeng Heng Reviewed-by: Shaopeng Tan Reviewed-by: Jonathan Cameron Signed-off-by: Dave Martin [morse: squashed enough of Dave's fixes in here that it's his patch now!] Signed-off-by: James Morse Signed-off-by: Ben Horgan --- Changes since v2: Include additional values from the latest spec --- drivers/resctrl/mpam_resctrl.c | 4 + drivers/resctrl/test_mpam_resctrl.c | 315 ++++++++++++++++++++++++++++ 2 files changed, 319 insertions(+) create mode 100644 drivers/resctrl/test_mpam_resctrl.c diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index 38d1b7f48ecf..ded18a9d4cd4 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -764,3 +764,7 @@ int mpam_resctrl_setup(void) return 0; } + +#ifdef CONFIG_MPAM_KUNIT_TEST +#include "test_mpam_resctrl.c" +#endif diff --git a/drivers/resctrl/test_mpam_resctrl.c b/drivers/resctrl/test_mpam_resctrl.c new file mode 100644 index 000000000000..b93d6ad87e43 --- /dev/null +++ b/drivers/resctrl/test_mpam_resctrl.c @@ -0,0 +1,315 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (C) 2025 Arm Ltd. +/* This file is intended to be included into mpam_resctrl.c */ + +#include +#include +#include +#include +#include + +struct percent_value_case { + u8 pc; + u8 width; + u16 value; +}; + +/* + * Mysterious inscriptions taken from the union of ARM DDI 0598D.b, + * "Arm Architecture Reference Manual Supplement - Memory System + * Resource Partitioning and Monitoring (MPAM), for A-profile + * architecture", Section 9.8, "About the fixed-point fractional + * format" (exact percentage entries only) and ARM IHI0099B.a + * "MPAM system component specification", Section 9.3, + * "The fixed-point fractional format": + */ +static const struct percent_value_case percent_value_cases[] = { + /* Architectural cases: */ + { 1, 8, 1 }, { 1, 12, 0x27 }, { 1, 16, 0x28e }, + { 25, 8, 0x3f }, { 25, 12, 0x3ff }, { 25, 16, 0x3fff }, + { 33, 8, 0x53 }, { 33, 12, 0x546 }, { 33, 16, 0x5479 }, + { 35, 8, 0x58 }, { 35, 12, 0x598 }, { 35, 16, 0x5998 }, + { 45, 8, 0x72 }, { 45, 12, 0x732 }, { 45, 16, 0x7332 }, + { 50, 8, 0x7f }, { 50, 12, 0x7ff }, { 50, 16, 0x7fff }, + { 52, 8, 0x84 }, { 52, 12, 0x850 }, { 52, 16, 0x851d }, + { 55, 8, 0x8b }, { 55, 12, 0x8cb }, { 55, 16, 0x8ccb }, + { 58, 8, 0x93 }, { 58, 12, 0x946 }, { 58, 16, 0x9479 }, + { 75, 8, 0xbf }, { 75, 12, 0xbff }, { 75, 16, 0xbfff }, + { 80, 8, 0xcb }, { 80, 12, 0xccb }, { 80, 16, 0xcccb }, + { 88, 8, 0xe0 }, { 88, 12, 0xe13 }, { 88, 16, 0xe146 }, + { 95, 8, 0xf2 }, { 95, 12, 0xf32 }, { 95, 16, 0xf332 }, + { 100, 8, 0xff }, { 100, 12, 0xfff }, { 100, 16, 0xffff }, +}; + +static void test_percent_value_desc(const struct percent_value_case *param, + char *desc) +{ + snprintf(desc, KUNIT_PARAM_DESC_SIZE, + "pc=%d, width=%d, value=0x%.*x\n", + param->pc, param->width, + DIV_ROUND_UP(param->width, 4), param->value); +} + +KUNIT_ARRAY_PARAM(test_percent_value, percent_value_cases, + test_percent_value_desc); + +struct percent_value_test_info { + u32 pc; /* result of value-to-percent conversion */ + u32 value; /* result of percent-to-value conversion */ + u32 max_value; /* maximum raw value allowed by test params */ + unsigned int shift; /* promotes raw testcase value to 16 bits */ +}; + +/* + * Convert a reference percentage to a fixed-point MAX value and + * vice-versa, based on param (not test->param_value!) + */ +static void __prepare_percent_value_test(struct kunit *test, + struct percent_value_test_info *res, + const struct percent_value_case *param) +{ + struct mpam_props fake_props = { }; + + /* Reject bogus test parameters that would break the tests: */ + KUNIT_ASSERT_GE(test, param->width, 1); + KUNIT_ASSERT_LE(test, param->width, 16); + KUNIT_ASSERT_LT(test, param->value, 1 << param->width); + + mpam_set_feature(mpam_feat_mbw_max, &fake_props); + fake_props.bwa_wd = param->width; + + res->shift = 16 - param->width; + res->max_value = GENMASK_U32(param->width - 1, 0); + res->value = percent_to_mbw_max(param->pc, &fake_props); + res->pc = mbw_max_to_percent(param->value << res->shift, &fake_props); +} + +static void test_get_mba_granularity(struct kunit *test) +{ + int ret; + struct mpam_props fake_props = { }; + + /* Use MBW_MAX */ + mpam_set_feature(mpam_feat_mbw_max, &fake_props); + + fake_props.bwa_wd = 0; + KUNIT_EXPECT_FALSE(test, mba_class_use_mbw_max(&fake_props)); + + fake_props.bwa_wd = 1; + KUNIT_EXPECT_TRUE(test, mba_class_use_mbw_max(&fake_props)); + + /* Architectural maximum: */ + fake_props.bwa_wd = 16; + KUNIT_EXPECT_TRUE(test, mba_class_use_mbw_max(&fake_props)); + + /* No usable control... */ + fake_props.bwa_wd = 0; + ret = get_mba_granularity(&fake_props); + KUNIT_EXPECT_EQ(test, ret, 0); + + fake_props.bwa_wd = 1; + ret = get_mba_granularity(&fake_props); + KUNIT_EXPECT_EQ(test, ret, 50); /* DIV_ROUND_UP(100, 1 << 1)% = 50% */ + + fake_props.bwa_wd = 2; + ret = get_mba_granularity(&fake_props); + KUNIT_EXPECT_EQ(test, ret, 25); /* DIV_ROUND_UP(100, 1 << 2)% = 25% */ + + fake_props.bwa_wd = 3; + ret = get_mba_granularity(&fake_props); + KUNIT_EXPECT_EQ(test, ret, 13); /* DIV_ROUND_UP(100, 1 << 3)% = 13% */ + + fake_props.bwa_wd = 6; + ret = get_mba_granularity(&fake_props); + KUNIT_EXPECT_EQ(test, ret, 2); /* DIV_ROUND_UP(100, 1 << 6)% = 2% */ + + fake_props.bwa_wd = 7; + ret = get_mba_granularity(&fake_props); + KUNIT_EXPECT_EQ(test, ret, 1); /* DIV_ROUND_UP(100, 1 << 7)% = 1% */ + + /* Granularity saturates at 1% */ + fake_props.bwa_wd = 16; /* architectural maximum */ + ret = get_mba_granularity(&fake_props); + KUNIT_EXPECT_EQ(test, ret, 1); /* DIV_ROUND_UP(100, 1 << 16)% = 1% */ +} + +static void test_mbw_max_to_percent(struct kunit *test) +{ + const struct percent_value_case *param = test->param_value; + struct percent_value_test_info res; + + /* + * Since the reference values in percent_value_cases[] all + * correspond to exact percentages, round-to-nearest will + * always give the exact percentage back when the MPAM max + * value has precision of 0.5% or finer. (Always true for the + * reference data, since they all specify 8 bits or more of + * precision. + * + * So, keep it simple and demand an exact match: + */ + __prepare_percent_value_test(test, &res, param); + KUNIT_EXPECT_EQ(test, res.pc, param->pc); +} + +static void test_percent_to_mbw_max(struct kunit *test) +{ + const struct percent_value_case *param = test->param_value; + struct percent_value_test_info res; + + __prepare_percent_value_test(test, &res, param); + + KUNIT_EXPECT_GE(test, res.value, param->value << res.shift); + KUNIT_EXPECT_LE(test, res.value, (param->value + 1) << res.shift); + KUNIT_EXPECT_LE(test, res.value, res.max_value << res.shift); + + /* No flexibility allowed for 0% and 100%! */ + + if (param->pc == 0) + KUNIT_EXPECT_EQ(test, res.value, 0); + + if (param->pc == 100) + KUNIT_EXPECT_EQ(test, res.value, res.max_value << res.shift); +} + +static const void *test_all_bwa_wd_gen_params(struct kunit *test, const void *prev, + char *desc) +{ + uintptr_t param = (uintptr_t)prev; + + if (param > 15) + return NULL; + + param++; + + snprintf(desc, KUNIT_PARAM_DESC_SIZE, "wd=%u\n", (unsigned int)param); + + return (void *)param; +} + +static unsigned int test_get_bwa_wd(struct kunit *test) +{ + uintptr_t param = (uintptr_t)test->param_value; + + KUNIT_ASSERT_GE(test, param, 1); + KUNIT_ASSERT_LE(test, param, 16); + + return param; +} + +static void test_mbw_max_to_percent_limits(struct kunit *test) +{ + struct mpam_props fake_props = {0}; + u32 max_value; + + mpam_set_feature(mpam_feat_mbw_max, &fake_props); + fake_props.bwa_wd = test_get_bwa_wd(test); + max_value = GENMASK(15, 16 - fake_props.bwa_wd); + + KUNIT_EXPECT_EQ(test, mbw_max_to_percent(max_value, &fake_props), + MAX_MBA_BW); + KUNIT_EXPECT_EQ(test, mbw_max_to_percent(0, &fake_props), + get_mba_min(&fake_props)); + + /* + * Rounding policy dependent 0% sanity-check: + * With round-to-nearest, the minimum mbw_max value really + * should map to 0% if there are at least 200 steps. + * (100 steps may be enough for some other rounding policies.) + */ + if (fake_props.bwa_wd >= 8) + KUNIT_EXPECT_EQ(test, mbw_max_to_percent(0, &fake_props), 0); + + if (fake_props.bwa_wd < 8 && + mbw_max_to_percent(0, &fake_props) == 0) + kunit_warn(test, "wd=%d: Testsuite/driver Rounding policy mismatch?", + fake_props.bwa_wd); +} + +/* + * Check that converting a percentage to mbw_max and back again (or, as + * appropriate, vice-versa) always restores the original value: + */ +static void test_percent_max_roundtrip_stability(struct kunit *test) +{ + struct mpam_props fake_props = {0}; + unsigned int shift; + u32 pc, max, pc2, max2; + + mpam_set_feature(mpam_feat_mbw_max, &fake_props); + fake_props.bwa_wd = test_get_bwa_wd(test); + shift = 16 - fake_props.bwa_wd; + + /* + * Converting a valid value from the coarser scale to the finer + * scale and back again must yield the original value: + */ + if (fake_props.bwa_wd >= 7) { + /* More than 100 steps: only test exact pc values: */ + for (pc = get_mba_min(&fake_props); pc <= MAX_MBA_BW; pc++) { + max = percent_to_mbw_max(pc, &fake_props); + pc2 = mbw_max_to_percent(max, &fake_props); + KUNIT_EXPECT_EQ(test, pc2, pc); + } + } else { + /* Fewer than 100 steps: only test exact mbw_max values: */ + for (max = 0; max < 1 << 16; max += 1 << shift) { + pc = mbw_max_to_percent(max, &fake_props); + max2 = percent_to_mbw_max(pc, &fake_props); + KUNIT_EXPECT_EQ(test, max2, max); + } + } +} + +static void test_percent_to_max_rounding(struct kunit *test) +{ + const struct percent_value_case *param = test->param_value; + unsigned int num_rounded_up = 0, total = 0; + struct percent_value_test_info res; + + for (param = percent_value_cases, total = 0; + param < &percent_value_cases[ARRAY_SIZE(percent_value_cases)]; + param++, total++) { + __prepare_percent_value_test(test, &res, param); + if (res.value > param->value << res.shift) + num_rounded_up++; + } + + /* + * The MPAM driver applies a round-to-nearest policy, whereas a + * round-down policy seems to have been applied in the + * reference table from which the test vectors were selected. + * + * For a large and well-distributed suite of test vectors, + * about half should be rounded up and half down compared with + * the reference table. The actual test vectors are few in + * number and probably not very well distributed however, so + * tolerate a round-up rate of between 1/4 and 3/4 before + * crying foul: + */ + + kunit_info(test, "Round-up rate: %u%% (%u/%u)\n", + DIV_ROUND_CLOSEST(num_rounded_up * 100, total), + num_rounded_up, total); + + KUNIT_EXPECT_GE(test, 4 * num_rounded_up, 1 * total); + KUNIT_EXPECT_LE(test, 4 * num_rounded_up, 3 * total); +} + +static struct kunit_case mpam_resctrl_test_cases[] = { + KUNIT_CASE(test_get_mba_granularity), + KUNIT_CASE_PARAM(test_mbw_max_to_percent, test_percent_value_gen_params), + KUNIT_CASE_PARAM(test_percent_to_mbw_max, test_percent_value_gen_params), + KUNIT_CASE_PARAM(test_mbw_max_to_percent_limits, test_all_bwa_wd_gen_params), + KUNIT_CASE(test_percent_to_max_rounding), + KUNIT_CASE_PARAM(test_percent_max_roundtrip_stability, + test_all_bwa_wd_gen_params), + {} +}; + +static struct kunit_suite mpam_resctrl_test_suite = { + .name = "mpam_resctrl_test_suite", + .test_cases = mpam_resctrl_test_cases, +}; + +kunit_test_suites(&mpam_resctrl_test_suite); -- 2.43.0