From nobody Sun Apr 19 20:32:04 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14EC6C433EF for ; Mon, 27 Jun 2022 10:28:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232456AbiF0K2e (ORCPT ); Mon, 27 Jun 2022 06:28:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232641AbiF0K2d (ORCPT ); Mon, 27 Jun 2022 06:28:33 -0400 Received: from mail-wm1-x349.google.com (mail-wm1-x349.google.com [IPv6:2a00:1450:4864:20::349]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF596266B for ; Mon, 27 Jun 2022 03:28:31 -0700 (PDT) Received: by mail-wm1-x349.google.com with SMTP id v184-20020a1cacc1000000b0039c7efa3e95so3384874wme.3 for ; Mon, 27 Jun 2022 03:28:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=5yoOjCuxWXXLSKjOheMfZYUlzX6XssbQmvDDk/evZBs=; b=T+ZoH9BiG7ejFpyT99dcXqkAnMFezpeDUaKtR2HF7IBJZ8zeHqiw7fasMX3IbVlgm4 iafSIU9+Ovnl02W+FHqO3dJlLJBfj7NzPULglX5lZci59ht+ts2AQWXJnxRtcdrQ6RQ6 ThhGgkXLP22PuVA+R9GLoy6gN9Y30Z372VCgkc08+RUNXcz+da6cMc1+Rges3239IN/W igToaKzElYxK811q9Pgk0AK8xPBsjoGBJtlA0gO1um7yVEKngx02uOiTJhOPJJx2K40K nZYwqU4FU2ClDWJNieTbbc2Q4JC4bKepV1cUSpl83nSeplccpZjKkAsJm2WalXE4x57N 5uJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=5yoOjCuxWXXLSKjOheMfZYUlzX6XssbQmvDDk/evZBs=; b=Q8quNZeRPF7sn5HKau3H9Axxnm0WIr1rRwOLMLAcCVanQB3e28o5gKbVybdDBKMde+ s8Zx43YZvZCVRkrkkWIAPbpw84Mc6Ih7uAhIzhxLJXwGzYhtz5vBoPVd/crCIt2WGTTU keWUzNsSoQ4woPrtj3ljYX7m5GRHml6RH47bHWlqGa5jFIyo1BFaa/icmpsZc5XN/T7P IYLVDZBGKVkXYmIGxo4EQbmFHUeLqY7BCpqs6uTELuFEK0luDfYzoZwpBPr0rTyo4H0H /Yg8NsbmAJzsfYsd6ekhN0HU/oSCU5KBXWcca9l7ZOmSqjnt71+TXekftxjlfQJAqpq6 FPnA== X-Gm-Message-State: AJIora9sBSHWpi7LALHaTSX3hdKfNk6cq1uDW+rkhDlw8I61lKC6bgZb U/897BbKuMlLggDlQAjBv8QBQJsftWU/6wWgGiM= X-Google-Smtp-Source: AGRyM1uixuGkpvZhhnFWALR4JaK6Q6IadJyqT4NA2OE2UH6hdeMCAfjRfnvN4u20zoYsaffGITCFvRiW7bBHpAH1UuA= X-Received: from sene.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:27c4]) (user=sebastianene job=sendgmr) by 2002:a05:600c:a14c:b0:3a0:4ddc:f710 with SMTP id ib12-20020a05600ca14c00b003a04ddcf710mr1164186wmb.38.1656325710439; Mon, 27 Jun 2022 03:28:30 -0700 (PDT) Date: Mon, 27 Jun 2022 10:28:11 +0000 In-Reply-To: <20220627102810.1811311-1-sebastianene@google.com> Message-Id: <20220627102810.1811311-2-sebastianene@google.com> Mime-Version: 1.0 References: <20220627102810.1811311-1-sebastianene@google.com> X-Mailer: git-send-email 2.37.0.rc0.161.g10f37bed90-goog Subject: [PATCH v8 1/2] dt-bindings: vcpu_stall_detector: Add qemu,vcpu-stall-detector compatible From: Sebastian Ene To: Rob Herring , Greg Kroah-Hartman , Arnd Bergmann , Dragan Cvetic Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, maz@kernel.org, will@kernel.org, vdonnefort@google.com, Guenter Roeck , Sebastian Ene Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The VCPU stall detection mechanism allows to configure the expiration duration and the internal counter clock frequency measured in Hz. Add these properties in the schema. While this is a memory mapped virtual device, it is expected to be loaded when the DT contains the compatible: "qemu,vcpu-stall-detector" node. In a protected VM we trust the generated DT nodes and we don't rely on the host to present the hardware peripherals. Signed-off-by: Sebastian Ene Reviewed-by: Rob Herring --- .../misc/qemu,vcpu-stall-detector.yaml | 51 +++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 Documentation/devicetree/bindings/misc/qemu,vcpu-stall-= detector.yaml diff --git a/Documentation/devicetree/bindings/misc/qemu,vcpu-stall-detecto= r.yaml b/Documentation/devicetree/bindings/misc/qemu,vcpu-stall-detector.ya= ml new file mode 100644 index 000000000000..1aebeb696ee0 --- /dev/null +++ b/Documentation/devicetree/bindings/misc/qemu,vcpu-stall-detector.yaml @@ -0,0 +1,51 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/misc/qemu,vcpu-stall-detector.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: VCPU stall detector + +description: + This binding describes a CPU stall detector mechanism for virtual CPUs + which is accessed through MMIO. + +maintainers: + - Sebastian Ene + +properties: + compatible: + enum: + - qemu,vcpu-stall-detector + + reg: + maxItems: 1 + + clock-frequency: + $ref: /schemas/types.yaml#/definitions/uint32 + description: | + The internal clock of the stall detector peripheral measure in Hz us= ed + to decrement its internal counter register on each tick. + Defaults to 10 if unset. + default: 10 + + timeout-sec: + description: | + The stall detector expiration timeout measured in seconds. + Defaults to 8 if unset. Please note that it also takes into account = the + time spent while the VCPU is not running. + default: 8 + +required: + - compatible + +additionalProperties: false + +examples: + - | + vmwdt@9030000 { + compatible =3D "qemu,vcpu-stall-detector"; + reg =3D <0x9030000 0x10000>; + clock-frequency =3D <10>; + timeout-sec =3D <8>; + }; --=20 2.37.0.rc0.161.g10f37bed90-goog From nobody Sun Apr 19 20:32:04 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3983CC43334 for ; Mon, 27 Jun 2022 10:28:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234240AbiF0K2j (ORCPT ); Mon, 27 Jun 2022 06:28:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36478 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234222AbiF0K2f (ORCPT ); Mon, 27 Jun 2022 06:28:35 -0400 Received: from mail-wm1-x349.google.com (mail-wm1-x349.google.com [IPv6:2a00:1450:4864:20::349]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3484C266B for ; Mon, 27 Jun 2022 03:28:34 -0700 (PDT) Received: by mail-wm1-x349.google.com with SMTP id l17-20020a05600c4f1100b0039c860db521so5406238wmq.5 for ; Mon, 27 Jun 2022 03:28:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=L7aCBCWChRVHjUIcz57p8PugaYxPtPgDPSLCtvALwKM=; b=XdmwCvDkWKy4IXz+yNCPeBO6k3ngsUcN9tx43SKQPQp5HXMDOeiPZs2UlW1tMkB2nA G1P93B5I11GMOrat4weP8m8sVzuc9G8tZA9YNzX5k5zNQBdnNf5uB7JMxYeryFpMiDyx vnn41jGSXQWPGI/Xq7x1GUr51AJuZTa7hrfKGl4Rypq7nWvYop3pxkx0yAZva3HKl5HS mlz/Zdds3efHt2vX/ZFK6x2XCN5wDVnJSPbnMg7E29tVo3wZTdSbxVbdEsyfOa6sOetz mgXu+ERaqzZnSQDkufpL1iOn/aX1IpXyLiZcDuSLOqu5K6wLY8P4+5IiEaZxsJ8ebHXz x40w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=L7aCBCWChRVHjUIcz57p8PugaYxPtPgDPSLCtvALwKM=; b=gUlx43wrwUUOdOL0igT//sbF/6jHzRbLkoWL6LuQe18HotZ9waDWYUSiLV6pKDOkkO jr7E1V8hAI62sGlZ3Pg10FG47Zjcir89cdPqtZz+FavJocTuiE+b/KHA3+F6lzF0DYYX Q8Lw0j+81WDGGSkpLrGtMv/e94gq+tdONLKQMqIUoPPu4kLrForlfP3obIk8T7cn5L0G slT1fdyHf+KqeAFDZPfaLHFGd39GAYXzwANSyvjPGHtyertVtiM4zxX6RzgXak4ZdCmI PQIWkADXErYB+K/AqBQ8gdby4EiuUc+qd+6rd0rdRVprdJ8ouUobk+SDqkSUc8VPU677 CN6A== X-Gm-Message-State: AJIora8dlQvOVbNjrylQBXIMOr/dt4wUuz2xZf7dnkZon97BMDZJPxBN 0+Ndb/bj1RZqwtD789Oc+OktV3fBCr/nxw81Tl4= X-Google-Smtp-Source: AGRyM1vmHrpYiw7SVWxZpVjBQDCOf3VOeNc93006o6tUdV7JtcOFLHuNhZruJidi25GVOyDvcgMk820SWaGRP2rTUyA= X-Received: from sene.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:27c4]) (user=sebastianene job=sendgmr) by 2002:a05:600c:3ca2:b0:3a0:1825:2e6b with SMTP id bg34-20020a05600c3ca200b003a018252e6bmr19193439wmb.132.1656325712826; Mon, 27 Jun 2022 03:28:32 -0700 (PDT) Date: Mon, 27 Jun 2022 10:28:12 +0000 In-Reply-To: <20220627102810.1811311-1-sebastianene@google.com> Message-Id: <20220627102810.1811311-3-sebastianene@google.com> Mime-Version: 1.0 References: <20220627102810.1811311-1-sebastianene@google.com> X-Mailer: git-send-email 2.37.0.rc0.161.g10f37bed90-goog Subject: [PATCH v8 2/2] misc: Add a mechanism to detect stalls on guest vCPUs From: Sebastian Ene To: Rob Herring , Greg Kroah-Hartman , Arnd Bergmann , Dragan Cvetic Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, maz@kernel.org, will@kernel.org, vdonnefort@google.com, Guenter Roeck , Sebastian Ene Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This driver creates per-cpu hrtimers which are required to do the periodic 'pet' operation. On a conventional watchdog-core driver, the userspace is responsible for delivering the 'pet' events by writing to the particular /dev/watchdogN node. In this case we require a strong thread affinity to be able to account for lost time on a per vCPU. This part of the driver is the 'frontend' which is reponsible for delivering the periodic 'pet' events, configuring the virtual peripheral and listening for cpu hotplug events. The other part of the driver handles the peripheral emulation and this part accounts for lost time by looking at the /proc/{}/task/{}/stat entries and is located here: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/354= 8817 Signed-off-by: Sebastian Ene --- drivers/misc/Kconfig | 12 ++ drivers/misc/Makefile | 1 + drivers/misc/vcpu_stall_detector.c | 222 +++++++++++++++++++++++++++++ 3 files changed, 235 insertions(+) create mode 100644 drivers/misc/vcpu_stall_detector.c diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig index 41d2bb0ae23a..e15c85d74c4b 100644 --- a/drivers/misc/Kconfig +++ b/drivers/misc/Kconfig @@ -483,6 +483,18 @@ config OPEN_DICE =20 If unsure, say N. =20 +config VCPU_STALL_DETECTOR + tristate "VCPU stall detector" + select LOCKUP_DETECTOR + help + Detect CPU locks on a kvm virtual machine. This driver relies on + the hrtimers which are CPU-binded to do the 'pet' operation. When a + vCPU has to do a 'pet', it exits the guest through MMIO write and + the backend driver takes into account the lost ticks for this + particular CPU. + To compile this driver as a module, choose M here: the + module will be called vcpu_stall_detector. + source "drivers/misc/c2port/Kconfig" source "drivers/misc/eeprom/Kconfig" source "drivers/misc/cb710/Kconfig" diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile index 70e800e9127f..2be8542616dd 100644 --- a/drivers/misc/Makefile +++ b/drivers/misc/Makefile @@ -60,3 +60,4 @@ obj-$(CONFIG_XILINX_SDFEC) +=3D xilinx_sdfec.o obj-$(CONFIG_HISI_HIKEY_USB) +=3D hisi_hikey_usb.o obj-$(CONFIG_HI6421V600_IRQ) +=3D hi6421v600-irq.o obj-$(CONFIG_OPEN_DICE) +=3D open-dice.o +obj-$(CONFIG_VCPU_STALL_DETECTOR) +=3D vcpu_stall_detector.o \ No newline at end of file diff --git a/drivers/misc/vcpu_stall_detector.c b/drivers/misc/vcpu_stall_d= etector.c new file mode 100644 index 000000000000..8b33f04a9719 --- /dev/null +++ b/drivers/misc/vcpu_stall_detector.c @@ -0,0 +1,222 @@ +// SPDX-License-Identifier: GPL-2.0 +// +// VCPU stall detector. +// Copyright (C) Google, 2022 + +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define REG_STATUS (0x00) +#define REG_LOAD_CNT (0x04) +#define REG_CURRENT_CNT (0x08) +#define REG_CLOCK_FREQ_HZ (0x0C) +#define REG_LEN (0x10) + +#define DEFAULT_CLOCK_HZ (10) +#define DEFAULT_TIMEOT_SEC (8) + +struct vm_stall_detect_s { + void __iomem *membase; + u32 clock_freq; + u32 expiration_sec; + u32 ping_timeout_ms; + struct hrtimer per_cpu_hrtimer; + struct platform_device *dev; +}; + +#define vcpu_stall_detect_reg_write(stall_detect, reg, value) \ + iowrite32((value), (stall_detect)->membase + (reg)) +#define vcpu_stall_detect_reg_read(stall_detect, reg) \ + io32read((stall_detect)->membase + (reg)) + +static struct platform_device *virt_dev; + +static enum hrtimer_restart +vcpu_stall_detect_timer_fn(struct hrtimer *hrtimer) +{ + struct vm_stall_detect_s *cpu_stall_detect; + u32 ticks; + + cpu_stall_detect =3D container_of(hrtimer, struct vm_stall_detect_s, + per_cpu_hrtimer); + ticks =3D cpu_stall_detect->clock_freq * + cpu_stall_detect->expiration_sec; + vcpu_stall_detect_reg_write(cpu_stall_detect, REG_LOAD_CNT, ticks); + hrtimer_forward_now(hrtimer, + ms_to_ktime(cpu_stall_detect->ping_timeout_ms)); + + return HRTIMER_RESTART; +} + +static void vcpu_stall_detect_start(void *arg) +{ + u32 ticks; + struct vm_stall_detect_s *cpu_stall_detect =3D arg; + struct hrtimer *hrtimer =3D &cpu_stall_detect->per_cpu_hrtimer; + + vcpu_stall_detect_reg_write(cpu_stall_detect, REG_CLOCK_FREQ_HZ, + cpu_stall_detect->clock_freq); + + /* Compute the number of ticks required for the stall detector counter + * register based on the internal clock frequency and the timeout + * value given from the device tree. + */ + ticks =3D cpu_stall_detect->clock_freq * + cpu_stall_detect->expiration_sec; + vcpu_stall_detect_reg_write(cpu_stall_detect, REG_LOAD_CNT, ticks); + + /* Enable the internal clock and start the stall detector */ + vcpu_stall_detect_reg_write(cpu_stall_detect, REG_STATUS, 1); + + hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + hrtimer->function =3D vcpu_stall_detect_timer_fn; + hrtimer_start(hrtimer, ms_to_ktime(cpu_stall_detect->ping_timeout_ms), + HRTIMER_MODE_REL_PINNED); +} + +static void vcpu_stall_detect_stop(void *arg) +{ + struct vm_stall_detect_s *cpu_stall_detect =3D arg; + struct hrtimer *hrtimer =3D &cpu_stall_detect->per_cpu_hrtimer; + + hrtimer_cancel(hrtimer); + + /* Disable the stall detector */ + vcpu_stall_detect_reg_write(cpu_stall_detect, REG_STATUS, 0); +} + +static int start_stall_detector_on_cpu(unsigned int cpu) +{ + struct vm_stall_detect_s __percpu *vm_stall_detect; + + vm_stall_detect =3D (struct vm_stall_detect_s __percpu *) + platform_get_drvdata(virt_dev); + vcpu_stall_detect_start(this_cpu_ptr(vm_stall_detect)); + return 0; +} + +static int stop_stall_detector_on_cpu(unsigned int cpu) +{ + struct vm_stall_detect_s __percpu *vm_stall_detect; + + vm_stall_detect =3D (struct vm_stall_detect_s __percpu *) + platform_get_drvdata(virt_dev); + vcpu_stall_detect_stop(this_cpu_ptr(vm_stall_detect)); + return 0; +} + +static int vcpu_stall_detect_probe(struct platform_device *dev) +{ + int cpu, ret, err; + void __iomem *membase; + struct resource *r; + struct vm_stall_detect_s __percpu *vm_stall_detect; + u32 stall_detect_clock, stall_detect_timeout_sec =3D 0; + + r =3D platform_get_resource(dev, IORESOURCE_MEM, 0); + if (r =3D=3D NULL) + return -ENOENT; + + vm_stall_detect =3D alloc_percpu(typeof(struct vm_stall_detect_s)); + if (!vm_stall_detect) + return -ENOMEM; + + membase =3D ioremap(r->start, resource_size(r)); + if (!membase) { + ret =3D -ENXIO; + goto err_withmem; + } + + virt_dev =3D dev; + platform_set_drvdata(dev, vm_stall_detect); + if (of_property_read_u32(dev->dev.of_node, "clock-frequency", + &stall_detect_clock)) + stall_detect_clock =3D DEFAULT_CLOCK_HZ; + + if (of_property_read_u32(dev->dev.of_node, "timeout-sec", + &stall_detect_timeout_sec)) + stall_detect_timeout_sec =3D DEFAULT_TIMEOT_SEC; + + for_each_cpu_and(cpu, cpu_online_mask, &watchdog_cpumask) { + struct vm_stall_detect_s *cpu_stall_detect; + + cpu_stall_detect =3D per_cpu_ptr(vm_stall_detect, cpu); + cpu_stall_detect->membase =3D membase + cpu * REG_LEN; + cpu_stall_detect->clock_freq =3D stall_detect_clock; + cpu_stall_detect->expiration_sec =3D stall_detect_timeout_sec; + cpu_stall_detect->ping_timeout_ms =3D stall_detect_timeout_sec * + MSEC_PER_SEC / 2; + smp_call_function_single(cpu, vcpu_stall_detect_start, + cpu_stall_detect, true); + } + + err =3D cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, + "virt/vcpu_stall_detector:online", + start_stall_detector_on_cpu, + stop_stall_detector_on_cpu); + if (err < 0) { + dev_warn(&dev->dev, "failed to install cpu hotplug"); + ret =3D err; + goto err_withmem; + } + + return 0; + +err_withmem: + free_percpu(vm_stall_detect); + return ret; +} + +static int vcpu_stall_detect_remove(struct platform_device *dev) +{ + int cpu; + struct vm_stall_detect_s __percpu *vm_stall_detect; + + vm_stall_detect =3D (struct vm_stall_detect_s __percpu *) + platform_get_drvdata(dev); + for_each_cpu_and(cpu, cpu_online_mask, &watchdog_cpumask) { + struct vm_stall_detect_s *cpu_stall_detect; + + cpu_stall_detect =3D per_cpu_ptr(vm_stall_detect, cpu); + smp_call_function_single(cpu, vcpu_stall_detect_stop, + cpu_stall_detect, true); + } + + free_percpu(vm_stall_detect); + return 0; +} + +static const struct of_device_id vcpu_stall_detect_of_match[] =3D { + { .compatible =3D "qemu,vcpu-stall-detector", }, + {} +}; + +MODULE_DEVICE_TABLE(of, vcpu_stall_detect_of_match); + +static struct platform_driver vcpu_stall_detect_driver =3D { + .probe =3D vcpu_stall_detect_probe, + .remove =3D vcpu_stall_detect_remove, + .driver =3D { + .name =3D KBUILD_MODNAME, + .of_match_table =3D vcpu_stall_detect_of_match, + }, +}; + +module_platform_driver(vcpu_stall_detect_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Sebastian Ene "); +MODULE_DESCRIPTION("VCPU stall detector"); --=20 2.37.0.rc0.161.g10f37bed90-goog