From patchwork Sat Jan 27 00:43:15 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Dai X-Patchwork-Id: 13533861 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 31F443FF1 for ; Sat, 27 Jan 2024 00:43:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706316215; cv=none; b=Rl0iIQnM8mgY/Oj1SRilBmLvAipMqOKl3OJCcJiV9GTrnHFx0NeP3Pvc6MtGOXW5RAq1K5MQMFjHuCW6fEWm9UMOzviAeHqFzVnKvxcicP1SWe0jN7GcMD5G+US+aL6B5VqzroBQCuI8359yQin1wHQuDNnkRYAWYtUzEx9o1FY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706316215; c=relaxed/simple; bh=FLh37MtrGgxAZbOEtksVIMPeDxGh9lhShCJV0PP9zsA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=e7aIf/Y4IsjolX3GY6R2pPof3MhKIt0AaviBtbaqg7zjsho8kUJqIEXGhkRt3VQ2ZtbYeZ7iWSZC9yLebuufCq8dbNQ3CBl1E1KgsA+5nRpUCIsRCMbVU7bMqprR4TiPztuy70w7j3cBPw0rZUcvljd5lBKYXQ4+LpeRssEhpFo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--davidai.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=g8rS4Tr6; arc=none smtp.client-ip=209.85.219.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--davidai.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="g8rS4Tr6" Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-dc64b659a9cso1495064276.3 for ; Fri, 26 Jan 2024 16:43:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1706316213; x=1706921013; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=vWcySjj6Okvs9yBn0W41qrIqSKP3wnCoOn0mL6uTY9k=; b=g8rS4Tr6cxN0qQ6y2ez5wRpJwQe8CttNRVm8XTSa/Umc4aDOOTPUN7qfMQv6kGqeyF VcEK/H8W8zYzVMNsfCMOIwWgVA0mZrXu+hMIMYEuB2Ern+20nIfXgGBDtUCLCJJWkWMm 0RcnpUK/KTHP42JFjErPSzBILCte7CdafjxK+vZopc3e8HrWT/H/6bK6lTJ4QkXDffXh WD20W+vXe6KP0V8VhqiNlvEQgWxAsyZU/gesJvNKOXhOrtNJpzioM9vI1izRyZUlJgwM jX6hoANKrCMuaVTuCVy6xtWX70XBDOMdl5dKfi66YDcPTRU5NoPy2OwTXoQcxSEvzPkx J+eQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706316213; x=1706921013; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=vWcySjj6Okvs9yBn0W41qrIqSKP3wnCoOn0mL6uTY9k=; b=OT6b56KZc5ZrQ68lwFPeJ1P5c/o91yOMAogCkn2YRW7Db51nGDMZnyYnehVjDBHFEe M/hb7OZhSeIQHv/eiFPGdsiDl8xE0K7N1CpMSmD0+3obzQUrpycBL8RcgUhTjTBmz0Bn M7nnqK7iZYpqYZDAtlThj1KLnZBBGSehkxpqDJ/s+nO0I2uaMDx64NOAuokKWIUa1es/ 34p34MHWf9XdJ9ndMlq/1OSl/JqBkUEzv9MPiPjahYzrxrPTk0WORdX7LFy5x6u4jOxL ydK0BEGTQUgFO16NzS5UggM7TQ0+OcUw/jIxURho5YwB5IyV2/idpKHX8I1dbNVea2IT oCYQ== X-Gm-Message-State: AOJu0Yw5FI6i6ms7FFfibV53gkSQSsWcUdksPlVnf++RosyfQcA3uNUH gMShPFU/grNwYUDrLYsK2c4NtbNAn0K5T1s0M9iwt5lsOYaHx5IVEpMkm4/raHo9L6RW7uR07os r4NESnw== X-Google-Smtp-Source: AGHT+IHE75xRExeRW8631Xw+f5EC+Wzp3aOn5SVy5OmK0nm2p16TAsb9X9xJgRY4CGuHCaB1HiVAMZrps4aD X-Received: from davidai2.mtv.corp.google.com ([2620:15c:211:201:d621:88fa:6f6:1b46]) (user=davidai job=sendgmr) by 2002:a05:6902:2489:b0:dc2:2d2c:962a with SMTP id ds9-20020a056902248900b00dc22d2c962amr348609ybb.8.1706316213251; Fri, 26 Jan 2024 16:43:33 -0800 (PST) Date: Fri, 26 Jan 2024 16:43:15 -0800 In-Reply-To: <20240127004321.1902477-1-davidai@google.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240127004321.1902477-1-davidai@google.com> X-Mailer: git-send-email 2.43.0.429.g432eaa2c6b-goog Message-ID: <20240127004321.1902477-2-davidai@google.com> Subject: [PATCH v5 1/2] dt-bindings: cpufreq: add virtual cpufreq device From: David Dai To: "Rafael J. Wysocki" , Viresh Kumar , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Sudeep Holla , David Dai , Saravana Kannan Cc: Quentin Perret , Masami Hiramatsu , Will Deacon , Peter Zijlstra , Vincent Guittot , Marc Zyngier , Oliver Upton , Dietmar Eggemann , Pavan Kondeti , Gupta Pankaj , Mel Gorman , kernel-team@android.com, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Adding bindings to represent a virtual cpufreq device. Virtual machines may expose MMIO regions for a virtual cpufreq device for guests to read frequency information or to request frequency selection. The virtual cpufreq device has an individual controller for each frequency domain. Performance points for a given domain can be normalized across all domains for ease of allowing for virtual machines to migrate between hosts. Co-developed-by: Saravana Kannan Signed-off-by: Saravana Kannan Signed-off-by: David Dai --- .../cpufreq/qemu,cpufreq-virtual.yaml | 110 ++++++++++++++++++ 1 file changed, 110 insertions(+) create mode 100644 Documentation/devicetree/bindings/cpufreq/qemu,cpufreq-virtual.yaml diff --git a/Documentation/devicetree/bindings/cpufreq/qemu,cpufreq-virtual.yaml b/Documentation/devicetree/bindings/cpufreq/qemu,cpufreq-virtual.yaml new file mode 100644 index 000000000000..cd617baf75e7 --- /dev/null +++ b/Documentation/devicetree/bindings/cpufreq/qemu,cpufreq-virtual.yaml @@ -0,0 +1,110 @@ +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/cpufreq/qemu,cpufreq-virtual.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Virtual CPUFreq + +maintainers: + - David Dai + - Saravana Kannan + +description: + Virtual CPUFreq is a virtualized driver in guest kernels that sends frequency + selection of its vCPUs as a hint to the host through MMIO regions. Each vCPU + is associated with a frequency domain which can be shared with other vCPUs. + Each frequency domain has its own set of registers for frequency controls. + +properties: + compatible: + const: qemu,virtual-cpufreq + + reg: + maxItems: 1 + description: + Address and size of region containing frequency controls for each of the + frequency domains. Regions for each frequency domain is placed + contiguously and contain registers for controlling DVFS(Dynamic Frequency + and Voltage) characteristics. The size of the region is proportional to + total number of frequency domains. This device also needs the CPUs to + list their OPPs using operating-points-v2 tables. The OPP tables for the + CPUs should use normalized "frequency" values where the OPP with the + highest performance among all the vCPUs is listed as 1024 KHz. The rest + of the frequencies of all the vCPUs should be normalized based on their + performance relative to that 1024 KHz OPP. This makes it much easier to + migrate the VM across systems which might have different physical CPU + OPPs. + +required: + - compatible + - reg + +additionalProperties: false + +examples: + - | + // This example shows a two CPU configuration with a frequency domain + // for each CPU showing normalized performance points. + cpus { + #address-cells = <1>; + #size-cells = <0>; + + cpu@0 { + compatible = "arm,armv8"; + device_type = "cpu"; + reg = <0x0>; + operating-points-v2 = <&opp_table0>; + }; + + cpu@1 { + compatible = "arm,armv8"; + device_type = "cpu"; + reg = <0x0>; + operating-points-v2 = <&opp_table1>; + }; + }; + + opp_table0: opp-table-0 { + compatible = "operating-points-v2"; + + opp64000 { opp-hz = /bits/ 64 <64000>; }; + opp128000 { opp-hz = /bits/ 64 <128000>; }; + opp192000 { opp-hz = /bits/ 64 <192000>; }; + opp256000 { opp-hz = /bits/ 64 <256000>; }; + opp320000 { opp-hz = /bits/ 64 <320000>; }; + opp384000 { opp-hz = /bits/ 64 <384000>; }; + opp425000 { opp-hz = /bits/ 64 <425000>; }; + }; + + opp_table1: opp-table-1 { + compatible = "operating-points-v2"; + + opp64000 { opp-hz = /bits/ 64 <64000>; }; + opp128000 { opp-hz = /bits/ 64 <128000>; }; + opp192000 { opp-hz = /bits/ 64 <192000>; }; + opp256000 { opp-hz = /bits/ 64 <256000>; }; + opp320000 { opp-hz = /bits/ 64 <320000>; }; + opp384000 { opp-hz = /bits/ 64 <384000>; }; + opp448000 { opp-hz = /bits/ 64 <448000>; }; + opp512000 { opp-hz = /bits/ 64 <512000>; }; + opp576000 { opp-hz = /bits/ 64 <576000>; }; + opp640000 { opp-hz = /bits/ 64 <640000>; }; + opp704000 { opp-hz = /bits/ 64 <704000>; }; + opp768000 { opp-hz = /bits/ 64 <768000>; }; + opp832000 { opp-hz = /bits/ 64 <832000>; }; + opp896000 { opp-hz = /bits/ 64 <896000>; }; + opp960000 { opp-hz = /bits/ 64 <960000>; }; + opp1024000 { opp-hz = /bits/ 64 <1024000>; }; + + }; + + soc { + #address-cells = <1>; + #size-cells = <1>; + + cpufreq@1040000 { + compatible = "qemu,virtual-cpufreq"; + reg = <0x1040000 0x10>; + }; + }; From patchwork Sat Jan 27 00:43:16 2024 Content-Type: text/plain; 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Fri, 26 Jan 2024 16:43:37 -0800 (PST) Date: Fri, 26 Jan 2024 16:43:16 -0800 In-Reply-To: <20240127004321.1902477-1-davidai@google.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240127004321.1902477-1-davidai@google.com> X-Mailer: git-send-email 2.43.0.429.g432eaa2c6b-goog Message-ID: <20240127004321.1902477-3-davidai@google.com> Subject: [PATCH v5 2/2] cpufreq: add virtual-cpufreq driver From: David Dai To: "Rafael J. Wysocki" , Viresh Kumar , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Sudeep Holla , David Dai , Saravana Kannan Cc: Quentin Perret , Masami Hiramatsu , Will Deacon , Peter Zijlstra , Vincent Guittot , Marc Zyngier , Oliver Upton , Dietmar Eggemann , Pavan Kondeti , Gupta Pankaj , Mel Gorman , kernel-team@android.com, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Introduce a virtualized cpufreq driver for guest kernels to improve performance and power of workloads within VMs. This driver does two main things: 1. Sends the frequency of vCPUs as a hint to the host. The host uses the hint to schedule the vCPU threads and decide physical CPU frequency. 2. If a VM does not support a virtualized FIE(like AMUs), it queries the host CPU frequency by reading a MMIO region of a virtual cpufreq device to update the guest's frequency scaling factor periodically. This enables accurate Per-Entity Load Tracking for tasks running in the guest. Co-developed-by: Saravana Kannan Signed-off-by: Saravana Kannan Signed-off-by: David Dai --- drivers/cpufreq/Kconfig | 15 +++ drivers/cpufreq/Makefile | 1 + drivers/cpufreq/virtual-cpufreq.c | 209 ++++++++++++++++++++++++++++++ include/linux/arch_topology.h | 1 + 4 files changed, 226 insertions(+) create mode 100644 drivers/cpufreq/virtual-cpufreq.c diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig index 35efb53d5492..f2d37075aa10 100644 --- a/drivers/cpufreq/Kconfig +++ b/drivers/cpufreq/Kconfig @@ -217,6 +217,21 @@ config CPUFREQ_DT If in doubt, say N. +config CPUFREQ_VIRT + tristate "Virtual cpufreq driver" + depends on OF + select PM_OPP + help + This adds a virtualized cpufreq driver for guest kernels that + read/writes to a MMIO region for a virtualized cpufreq device to + communicate with the host. It sends frequency updates to the host + which gets used as a hint to schedule vCPU threads and select CPU + frequency. If a VM does not support a virtualized FIE such as AMUs, + it updates the frequency scaling factor by polling host CPU frequency + to enable accurate Per-Entity Load Tracking for tasks running in the guest. + + If in doubt, say N. + config CPUFREQ_DT_PLATDEV tristate "Generic DT based cpufreq platdev driver" depends on OF diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile index 8d141c71b016..eb72ecdc24db 100644 --- a/drivers/cpufreq/Makefile +++ b/drivers/cpufreq/Makefile @@ -16,6 +16,7 @@ obj-$(CONFIG_CPU_FREQ_GOV_ATTR_SET) += cpufreq_governor_attr_set.o obj-$(CONFIG_CPUFREQ_DT) += cpufreq-dt.o obj-$(CONFIG_CPUFREQ_DT_PLATDEV) += cpufreq-dt-platdev.o +obj-$(CONFIG_CPUFREQ_VIRT) += virtual-cpufreq.o # Traces CFLAGS_amd-pstate-trace.o := -I$(src) diff --git a/drivers/cpufreq/virtual-cpufreq.c b/drivers/cpufreq/virtual-cpufreq.c new file mode 100644 index 000000000000..0132f430a13e --- /dev/null +++ b/drivers/cpufreq/virtual-cpufreq.c @@ -0,0 +1,209 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2023 Google LLC + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define REG_CUR_FREQ_KHZ_OFFSET 0x0 +#define REG_SET_FREQ_KHZ_OFFSET 0x4 +#define PER_CPU_OFFSET 0x8 + +static void __iomem *base; + +static void virt_scale_freq_tick(void) +{ + int cpu = smp_processor_id(); + u32 max_freq = (u32)cpufreq_get_hw_max_freq(cpu); + u64 cur_freq; + unsigned long scale; + + cur_freq = (u64)readl_relaxed(base + cpu * PER_CPU_OFFSET + + REG_CUR_FREQ_KHZ_OFFSET); + + cur_freq <<= SCHED_CAPACITY_SHIFT; + scale = (unsigned long)div_u64(cur_freq, max_freq); + scale = min(scale, SCHED_CAPACITY_SCALE); + + this_cpu_write(arch_freq_scale, scale); +} + +static struct scale_freq_data virt_sfd = { + .source = SCALE_FREQ_SOURCE_VIRT, + .set_freq_scale = virt_scale_freq_tick, +}; + +static unsigned int virt_cpufreq_set_perf(struct cpufreq_policy *policy, + unsigned int target_freq) +{ + writel_relaxed(target_freq, + base + policy->cpu * PER_CPU_OFFSET + REG_SET_FREQ_KHZ_OFFSET); + return 0; +} + +static unsigned int virt_cpufreq_fast_switch(struct cpufreq_policy *policy, + unsigned int target_freq) +{ + virt_cpufreq_set_perf(policy, target_freq); + return target_freq; +} + +static int virt_cpufreq_target_index(struct cpufreq_policy *policy, + unsigned int index) +{ + return virt_cpufreq_set_perf(policy, + policy->freq_table[index].frequency); +} + +static int virt_cpufreq_cpu_init(struct cpufreq_policy *policy) +{ + struct cpufreq_frequency_table *table; + struct device *cpu_dev; + int ret; + + cpu_dev = get_cpu_device(policy->cpu); + if (!cpu_dev) + return -ENODEV; + + ret = dev_pm_opp_of_add_table(cpu_dev); + if (ret) + return ret; + + ret = dev_pm_opp_get_opp_count(cpu_dev); + if (ret <= 0) { + dev_err(cpu_dev, "OPP table can't be empty\n"); + return -ENODEV; + } + + ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &table); + if (ret) { + dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret); + return ret; + } + + policy->freq_table = table; + + /* + * To simplify and improve latency of handling frequency requests on + * the host side, this ensures that the vCPU thread triggering the MMIO + * abort is the same thread whose performance constraints (Ex. uclamp + * settings) need to be updated. This simplifies the VMM (Virtual + * Machine Manager) having to find the correct vCPU thread and/or + * facing permission issues when configuring other threads. + */ + policy->dvfs_possible_from_any_cpu = false; + policy->fast_switch_possible = true; + + /* + * Using the default SCALE_FREQ_SOURCE_CPUFREQ is insufficient since + * the actual physical CPU frequency may not match requested frequency + * from the vCPU thread due to frequency update latencies or other + * inputs to the physical CPU frequency selection. This additional FIE + * source allows for more accurate freq_scale updates and only takes + * effect if another FIE source such as AMUs have not been registered. + */ + topology_set_scale_freq_source(&virt_sfd, policy->cpus); + + return 0; +} + +static int virt_cpufreq_cpu_exit(struct cpufreq_policy *policy) +{ + struct device *cpu_dev; + + cpu_dev = get_cpu_device(policy->cpu); + if (!cpu_dev) + return -ENODEV; + + topology_clear_scale_freq_source(SCALE_FREQ_SOURCE_VIRT, policy->related_cpus); + dev_pm_opp_free_cpufreq_table(cpu_dev, &policy->freq_table); + return 0; +} + +static int virt_cpufreq_online(struct cpufreq_policy *policy) +{ + /* Nothing to restore. */ + return 0; +} + +static int virt_cpufreq_offline(struct cpufreq_policy *policy) +{ + /* Dummy offline() to avoid exit() being called and freeing resources. */ + return 0; +} + +static struct cpufreq_driver cpufreq_virt_driver = { + .name = "virt-cpufreq", + .init = virt_cpufreq_cpu_init, + .exit = virt_cpufreq_cpu_exit, + .online = virt_cpufreq_online, + .offline = virt_cpufreq_offline, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = virt_cpufreq_target_index, + .fast_switch = virt_cpufreq_fast_switch, + .attr = cpufreq_generic_attr, +}; + +static int virt_cpufreq_driver_probe(struct platform_device *pdev) +{ + int ret; + + base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(base)) + return PTR_ERR(base); + + ret = cpufreq_register_driver(&cpufreq_virt_driver); + if (ret) { + dev_err(&pdev->dev, "Virtual CPUFreq driver failed to register: %d\n", ret); + return ret; + } + + dev_dbg(&pdev->dev, "Virtual CPUFreq driver initialized\n"); + return 0; +} + +static int virt_cpufreq_driver_remove(struct platform_device *pdev) +{ + cpufreq_unregister_driver(&cpufreq_virt_driver); + return 0; +} + +static const struct of_device_id virt_cpufreq_match[] = { + { .compatible = "qemu,virtual-cpufreq", .data = NULL}, + {} +}; +MODULE_DEVICE_TABLE(of, virt_cpufreq_match); + +static struct platform_driver virt_cpufreq_driver = { + .probe = virt_cpufreq_driver_probe, + .remove = virt_cpufreq_driver_remove, + .driver = { + .name = "virt-cpufreq", + .of_match_table = virt_cpufreq_match, + }, +}; + +static int __init virt_cpufreq_init(void) +{ + return platform_driver_register(&virt_cpufreq_driver); +} +postcore_initcall(virt_cpufreq_init); + +static void __exit virt_cpufreq_exit(void) +{ + platform_driver_unregister(&virt_cpufreq_driver); +} +module_exit(virt_cpufreq_exit); + +MODULE_DESCRIPTION("Virtual cpufreq driver"); +MODULE_LICENSE("GPL"); diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h index a63d61ca55af..fb272b4bf7b1 100644 --- a/include/linux/arch_topology.h +++ b/include/linux/arch_topology.h @@ -49,6 +49,7 @@ enum scale_freq_source { SCALE_FREQ_SOURCE_CPUFREQ = 0, SCALE_FREQ_SOURCE_ARCH, SCALE_FREQ_SOURCE_CPPC, + SCALE_FREQ_SOURCE_VIRT, }; struct scale_freq_data {