From nobody Mon Jun 15 12:20:21 2026 Received: from canpmsgout01.his.huawei.com (canpmsgout01.his.huawei.com [113.46.200.216]) (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 546EE2F7445; Fri, 10 Apr 2026 09:41:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.216 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775814113; cv=none; b=nP1qtwzOUir3iWJv0oO8H+YRPlAu1nqllDqH+Q07ogYcDO0KfItvcDD6nMCMxhb3KKglYRLahTTlKyJTF3OqR37i3tS2Bb0Gv0uJzeyofy+a/cp4zk11IGoRqGmbkvEPTX/1rI3MzOwRhFAfBOFCEAH7tSf+pcn8g3FlOY9kFXE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775814113; c=relaxed/simple; bh=eJq/ip+RnCQ7nVrtbXpBQJA1u5yrmRxSgRtTeuONu4Y=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=inhmK9MHeOC/uTV0RK4DrJo7RT90xBD8BCfTHA0ePPY+t/eynJcFP8XsfgElHXbG7ei/MNeI1K0RWPpztAzeUf6QY0v/6XPETmccTfXP2+s+j1C4fEb6cSB34MxZ1cFc4WADN/ZTikVGJmLoao60hoj8AaU1/0EQQZJnfTGNFkg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=aQ8pixy5; arc=none smtp.client-ip=113.46.200.216 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="aQ8pixy5" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=7w8y8miPjLI8+H+UgNwPJIYCDw9RNOhgOGxRWFDonsU=; b=aQ8pixy5Dnci6R2bR1/8odw2eQxaQci0KFq4E4PYFZI5L1YKDjrIchIhmtK6Dyi2n/UmGdXGS h0UMMPrMKLwGyrIJ0W3HwaijhEy+Yu8FudonilIRPkaX7zsBoE/T0cVVh9OV1py5+C8ipTV9DAt Tju3oZQQ3gbAkck0R54hMyk= Received: from mail.maildlp.com (unknown [172.19.162.197]) by canpmsgout01.his.huawei.com (SkyGuard) with ESMTPS id 4fsWrV2FZ9z1T4Fk; Fri, 10 Apr 2026 17:35:54 +0800 (CST) Received: from kwepemr200004.china.huawei.com (unknown [7.202.195.241]) by mail.maildlp.com (Postfix) with ESMTPS id DD27D40569; Fri, 10 Apr 2026 17:41:47 +0800 (CST) Received: from huawei.com (10.50.163.32) by kwepemr200004.china.huawei.com (7.202.195.241) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 10 Apr 2026 17:41:46 +0800 From: Pengjie Zhang To: , , , , , , , , , CC: , , , , , , , , , , , , Subject: [PATCH 1/2] ACPI: CPPC: add paired FFH feedback-counter read hook Date: Fri, 10 Apr 2026 17:41:44 +0800 Message-ID: <20260410094145.4132082-2-zhangpengjie2@huawei.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20260410094145.4132082-1-zhangpengjie2@huawei.com> References: <20260410094145.4132082-1-zhangpengjie2@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: kwepems500001.china.huawei.com (7.221.188.70) To kwepemr200004.china.huawei.com (7.202.195.241) Content-Type: text/plain; charset="utf-8" cppc_get_perf_ctrs() reads the delivered and reference performance counters one at a time. Allow architectures to provide both FFH feedback counters in one operation when that either narrows the sampling window or avoids extra cross-CPU reads. Add a small FFH-specific hook for that case and fall back to the existing per-register reads when unsupported. Signed-off-by: Pengjie Zhang --- drivers/acpi/cppc_acpi.c | 58 ++++++++++++++++++++++++++++++++++++---- include/acpi/cppc_acpi.h | 7 +++++ 2 files changed, 60 insertions(+), 5 deletions(-) diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index 2e91c5a97761..7b3e8b0597dc 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -988,6 +988,23 @@ int __weak cpc_read_ffh(int cpunum, struct cpc_reg *re= g, u64 *val) return -ENOTSUPP; } =20 +/** + * cpc_read_ffh_fb_ctrs() - Read FFH feedback counters together + * @cpunum: CPU number to read + * @reg1: first CPPC register information + * @val1: place holder for first return value + * @reg2: second CPPC register information + * @val2: place holder for second return value + * + * Return: 0 for success and error code + */ +int __weak cpc_read_ffh_fb_ctrs(int cpunum, struct cpc_reg *reg1, + u64 *val1, struct cpc_reg *reg2, u64 *val2) +{ + return -EOPNOTSUPP; +} + + /** * cpc_write_ffh() - Write FFH register * @cpunum: CPU number to write @@ -1504,6 +1521,40 @@ bool cppc_perf_ctrs_in_pcc(void) } EXPORT_SYMBOL_GPL(cppc_perf_ctrs_in_pcc); =20 +static int cppc_read_perf_fb_ctrs(int cpunum, + struct cpc_register_resource *delivered_reg, + struct cpc_register_resource *reference_reg, + u64 *delivered, u64 *reference) +{ + int ret; + + /* + * For FFH feedback counters, try a paired read first to reduce + * sampling skew between delivered and reference counters. Fall + * back to the existing per-register reads if unsupported. + */ + if (CPC_IN_FFH(delivered_reg) && CPC_IN_FFH(reference_reg)) { + ret =3D cpc_read_ffh_fb_ctrs(cpunum, + &delivered_reg->cpc_entry.reg, delivered, + &reference_reg->cpc_entry.reg, reference); + if (!ret) + return 0; + + if (ret !=3D -EOPNOTSUPP) + return ret; + } + + ret =3D cpc_read(cpunum, delivered_reg, delivered); + if (ret) + return ret; + + ret =3D cpc_read(cpunum, reference_reg, reference); + if (ret) + return ret; + + return 0; +} + /** * cppc_get_perf_ctrs - Read a CPU's performance feedback counters. * @cpunum: CPU from which to read counters. @@ -1547,11 +1598,8 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_= fb_ctrs *perf_fb_ctrs) } } =20 - ret =3D cpc_read(cpunum, delivered_reg, &delivered); - if (ret) - goto out_err; - - ret =3D cpc_read(cpunum, reference_reg, &reference); + ret =3D cppc_read_perf_fb_ctrs(cpunum, delivered_reg, reference_reg, + &delivered, &reference); if (ret) goto out_err; =20 diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h index d1f02ceec4f9..006b42dbbd4b 100644 --- a/include/acpi/cppc_acpi.h +++ b/include/acpi/cppc_acpi.h @@ -172,6 +172,8 @@ extern int cppc_get_transition_latency(int cpu); extern bool cpc_ffh_supported(void); extern bool cpc_supported_by_cpu(void); extern int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val); +extern int cpc_read_ffh_fb_ctrs(int cpu, struct cpc_reg *reg1, u64 *val1, + struct cpc_reg *reg2, u64 *val2); extern int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val); extern int cppc_get_epp_perf(int cpunum, u64 *epp_perf); extern int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, = bool enable); @@ -246,6 +248,11 @@ static inline int cpc_read_ffh(int cpunum, struct cpc_= reg *reg, u64 *val) { return -EOPNOTSUPP; } +static inline int cpc_read_ffh_fb_ctrs(int cpu, struct cpc_reg *reg1, u64 = *val1, + struct cpc_reg *reg2, u64 *val2) +{ + return -EOPNOTSUPP; +} static inline int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val) { return -EOPNOTSUPP; --=20 2.33.0 From nobody Mon Jun 15 12:20:21 2026 Received: from canpmsgout11.his.huawei.com (canpmsgout11.his.huawei.com [113.46.200.226]) (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 7715C33263F; 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Fri, 10 Apr 2026 17:41:47 +0800 From: Pengjie Zhang To: , , , , , , , , , CC: , , , , , , , , , , , , Subject: [PATCH 2/2] arm64: topology: read CPPC FFH feedback counters in one operation Date: Fri, 10 Apr 2026 17:41:45 +0800 Message-ID: <20260410094145.4132082-3-zhangpengjie2@huawei.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20260410094145.4132082-1-zhangpengjie2@huawei.com> References: <20260410094145.4132082-1-zhangpengjie2@huawei.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: kwepems500001.china.huawei.com (7.221.188.70) To kwepemr200004.china.huawei.com (7.202.195.241) Content-Type: text/plain; charset="utf-8" arm64 implements CPPC FFH feedback-counter reads using AMU counters. Because those counters must be sampled on the target CPU, reading the delivered and reference counters separately widens the observation window between them. Implement the paired FFH feedback-counter read hook on arm64 and sample both AMU counters together before decoding the requested CPC register values. Also factor the FFH bitfield extraction logic into a helper and reuse it from the existing single-counter FFH read path. Signed-off-by: Pengjie Zhang --- arch/arm64/kernel/topology.c | 75 ++++++++++++++++++++++++++++++++---- 1 file changed, 67 insertions(+), 8 deletions(-) diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index b32f13358fbb..b90a767b2a1f 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -50,6 +50,16 @@ struct amu_cntr_sample { unsigned long last_scale_update; }; =20 +struct amu_ffh_ctrs { + u64 corecnt; + u64 constcnt; +}; + +enum cpc_ffh_ctr_id { + CPC_FFH_CTR_CORE =3D 0x0, + CPC_FFH_CTR_CONST =3D 0x1, +}; + static DEFINE_PER_CPU_SHARED_ALIGNED(struct amu_cntr_sample, cpu_amu_sampl= es); =20 void update_freq_counters_refs(void) @@ -397,7 +407,7 @@ static void cpu_read_constcnt(void *val) } =20 static inline -int counters_read_on_cpu(int cpu, smp_call_func_t func, u64 *val) +int counters_read_on_cpu(int cpu, smp_call_func_t func, void *val) { /* * Abort call on counterless CPU. @@ -447,24 +457,73 @@ bool cpc_ffh_supported(void) return true; } =20 +static void amu_read_core_const_ctrs(void *val) +{ + struct amu_ffh_ctrs *ctrs =3D val; + + cpu_read_constcnt(&ctrs->constcnt); + cpu_read_corecnt(&ctrs->corecnt); +} + +static u64 cpc_ffh_extract_bits(const struct cpc_reg *reg, u64 val) +{ + val &=3D GENMASK_ULL(reg->bit_offset + reg->bit_width - 1, + reg->bit_offset); + val >>=3D reg->bit_offset; + + return val; +} + +static bool cpc_ffh_ctr_value(const struct cpc_reg *reg, + const struct amu_ffh_ctrs *ctrs, u64 *val) +{ + switch ((u64)reg->address) { + case CPC_FFH_CTR_CORE: + *val =3D ctrs->corecnt; + break; + case CPC_FFH_CTR_CONST: + *val =3D ctrs->constcnt; + break; + default: + return false; + } + + *val =3D cpc_ffh_extract_bits(reg, *val); + return true; +} + +int cpc_read_ffh_fb_ctrs(int cpu, struct cpc_reg *reg1, u64 *val1, + struct cpc_reg *reg2, u64 *val2) +{ + struct amu_ffh_ctrs ctrs; + int ret; + + ret =3D counters_read_on_cpu(cpu, amu_read_core_const_ctrs, &ctrs); + if (ret) + return ret; + + if (!cpc_ffh_ctr_value(reg1, &ctrs, val1) || + !cpc_ffh_ctr_value(reg2, &ctrs, val2)) + return -EOPNOTSUPP; + + return 0; +} + int cpc_read_ffh(int cpu, struct cpc_reg *reg, u64 *val) { int ret =3D -EOPNOTSUPP; =20 switch ((u64)reg->address) { - case 0x0: + case CPC_FFH_CTR_CORE: ret =3D counters_read_on_cpu(cpu, cpu_read_corecnt, val); break; - case 0x1: + case CPC_FFH_CTR_CONST: ret =3D counters_read_on_cpu(cpu, cpu_read_constcnt, val); break; } =20 - if (!ret) { - *val &=3D GENMASK_ULL(reg->bit_offset + reg->bit_width - 1, - reg->bit_offset); - *val >>=3D reg->bit_offset; - } + if (!ret) + *val =3D cpc_ffh_extract_bits(reg, *val); =20 return ret; } --=20 2.33.0