summaryrefslogtreecommitdiffstats
path: root/drivers/misc/vcpu_stall_detector.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /drivers/misc/vcpu_stall_detector.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'drivers/misc/vcpu_stall_detector.c')
-rw-r--r--drivers/misc/vcpu_stall_detector.c223
1 files changed, 223 insertions, 0 deletions
diff --git a/drivers/misc/vcpu_stall_detector.c b/drivers/misc/vcpu_stall_detector.c
new file mode 100644
index 000000000..53b550608
--- /dev/null
+++ b/drivers/misc/vcpu_stall_detector.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// VCPU stall detector.
+// Copyright (C) Google, 2022
+
+#include <linux/cpu.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/nmi.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/param.h>
+#include <linux/percpu.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define VCPU_STALL_REG_STATUS (0x00)
+#define VCPU_STALL_REG_LOAD_CNT (0x04)
+#define VCPU_STALL_REG_CURRENT_CNT (0x08)
+#define VCPU_STALL_REG_CLOCK_FREQ_HZ (0x0C)
+#define VCPU_STALL_REG_LEN (0x10)
+
+#define VCPU_STALL_DEFAULT_CLOCK_HZ (10)
+#define VCPU_STALL_MAX_CLOCK_HZ (100)
+#define VCPU_STALL_DEFAULT_TIMEOUT_SEC (8)
+#define VCPU_STALL_MAX_TIMEOUT_SEC (600)
+
+struct vcpu_stall_detect_config {
+ u32 clock_freq_hz;
+ u32 stall_timeout_sec;
+
+ void __iomem *membase;
+ struct platform_device *dev;
+ enum cpuhp_state hp_online;
+};
+
+struct vcpu_stall_priv {
+ struct hrtimer vcpu_hrtimer;
+ bool is_initialized;
+};
+
+/* The vcpu stall configuration structure which applies to all the CPUs */
+static struct vcpu_stall_detect_config vcpu_stall_config;
+
+#define vcpu_stall_reg_write(vcpu, reg, value) \
+ writel_relaxed((value), \
+ (void __iomem *)(vcpu_stall_config.membase + \
+ (vcpu) * VCPU_STALL_REG_LEN + (reg)))
+
+
+static struct vcpu_stall_priv __percpu *vcpu_stall_detectors;
+
+static enum hrtimer_restart
+vcpu_stall_detect_timer_fn(struct hrtimer *hrtimer)
+{
+ u32 ticks, ping_timeout_ms;
+
+ /* Reload the stall detector counter register every
+ * `ping_timeout_ms` to prevent the virtual device
+ * from decrementing it to 0. The virtual device decrements this
+ * register at 'clock_freq_hz' frequency.
+ */
+ ticks = vcpu_stall_config.clock_freq_hz *
+ vcpu_stall_config.stall_timeout_sec;
+ vcpu_stall_reg_write(smp_processor_id(),
+ VCPU_STALL_REG_LOAD_CNT, ticks);
+
+ ping_timeout_ms = vcpu_stall_config.stall_timeout_sec *
+ MSEC_PER_SEC / 2;
+ hrtimer_forward_now(hrtimer,
+ ms_to_ktime(ping_timeout_ms));
+
+ return HRTIMER_RESTART;
+}
+
+static int start_stall_detector_cpu(unsigned int cpu)
+{
+ u32 ticks, ping_timeout_ms;
+ struct vcpu_stall_priv *vcpu_stall_detector =
+ this_cpu_ptr(vcpu_stall_detectors);
+ struct hrtimer *vcpu_hrtimer = &vcpu_stall_detector->vcpu_hrtimer;
+
+ vcpu_stall_reg_write(cpu, VCPU_STALL_REG_CLOCK_FREQ_HZ,
+ vcpu_stall_config.clock_freq_hz);
+
+ /* 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 = vcpu_stall_config.clock_freq_hz *
+ vcpu_stall_config.stall_timeout_sec;
+ vcpu_stall_reg_write(cpu, VCPU_STALL_REG_LOAD_CNT, ticks);
+
+ /* Enable the internal clock and start the stall detector */
+ vcpu_stall_reg_write(cpu, VCPU_STALL_REG_STATUS, 1);
+
+ /* Pet the stall detector at half of its expiration timeout
+ * to prevent spurious resets.
+ */
+ ping_timeout_ms = vcpu_stall_config.stall_timeout_sec *
+ MSEC_PER_SEC / 2;
+
+ hrtimer_init(vcpu_hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ vcpu_hrtimer->function = vcpu_stall_detect_timer_fn;
+ vcpu_stall_detector->is_initialized = true;
+
+ hrtimer_start(vcpu_hrtimer, ms_to_ktime(ping_timeout_ms),
+ HRTIMER_MODE_REL_PINNED);
+
+ return 0;
+}
+
+static int stop_stall_detector_cpu(unsigned int cpu)
+{
+ struct vcpu_stall_priv *vcpu_stall_detector =
+ per_cpu_ptr(vcpu_stall_detectors, cpu);
+
+ if (!vcpu_stall_detector->is_initialized)
+ return 0;
+
+ /* Disable the stall detector for the current CPU */
+ hrtimer_cancel(&vcpu_stall_detector->vcpu_hrtimer);
+ vcpu_stall_reg_write(cpu, VCPU_STALL_REG_STATUS, 0);
+ vcpu_stall_detector->is_initialized = false;
+
+ return 0;
+}
+
+static int vcpu_stall_detect_probe(struct platform_device *pdev)
+{
+ int ret;
+ struct resource *r;
+ void __iomem *membase;
+ u32 clock_freq_hz = VCPU_STALL_DEFAULT_CLOCK_HZ;
+ u32 stall_timeout_sec = VCPU_STALL_DEFAULT_TIMEOUT_SEC;
+ struct device_node *np = pdev->dev.of_node;
+
+ vcpu_stall_detectors = devm_alloc_percpu(&pdev->dev,
+ typeof(struct vcpu_stall_priv));
+ if (!vcpu_stall_detectors)
+ return -ENOMEM;
+
+ membase = devm_platform_get_and_ioremap_resource(pdev, 0, &r);
+ if (IS_ERR(membase)) {
+ dev_err(&pdev->dev, "Failed to get memory resource\n");
+ return PTR_ERR(membase);
+ }
+
+ if (!of_property_read_u32(np, "clock-frequency", &clock_freq_hz)) {
+ if (!(clock_freq_hz > 0 &&
+ clock_freq_hz < VCPU_STALL_MAX_CLOCK_HZ)) {
+ dev_warn(&pdev->dev, "clk out of range\n");
+ clock_freq_hz = VCPU_STALL_DEFAULT_CLOCK_HZ;
+ }
+ }
+
+ if (!of_property_read_u32(np, "timeout-sec", &stall_timeout_sec)) {
+ if (!(stall_timeout_sec > 0 &&
+ stall_timeout_sec < VCPU_STALL_MAX_TIMEOUT_SEC)) {
+ dev_warn(&pdev->dev, "stall timeout out of range\n");
+ stall_timeout_sec = VCPU_STALL_DEFAULT_TIMEOUT_SEC;
+ }
+ }
+
+ vcpu_stall_config = (struct vcpu_stall_detect_config) {
+ .membase = membase,
+ .clock_freq_hz = clock_freq_hz,
+ .stall_timeout_sec = stall_timeout_sec
+ };
+
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
+ "virt/vcpu_stall_detector:online",
+ start_stall_detector_cpu,
+ stop_stall_detector_cpu);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to install cpu hotplug");
+ goto err;
+ }
+
+ vcpu_stall_config.hp_online = ret;
+ return 0;
+err:
+ return ret;
+}
+
+static int vcpu_stall_detect_remove(struct platform_device *pdev)
+{
+ int cpu;
+
+ cpuhp_remove_state(vcpu_stall_config.hp_online);
+
+ for_each_possible_cpu(cpu)
+ stop_stall_detector_cpu(cpu);
+
+ return 0;
+}
+
+static const struct of_device_id vcpu_stall_detect_of_match[] = {
+ { .compatible = "qemu,vcpu-stall-detector", },
+ {}
+};
+
+MODULE_DEVICE_TABLE(of, vcpu_stall_detect_of_match);
+
+static struct platform_driver vcpu_stall_detect_driver = {
+ .probe = vcpu_stall_detect_probe,
+ .remove = vcpu_stall_detect_remove,
+ .driver = {
+ .name = KBUILD_MODNAME,
+ .of_match_table = vcpu_stall_detect_of_match,
+ },
+};
+
+module_platform_driver(vcpu_stall_detect_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sebastian Ene <sebastianene@google.com>");
+MODULE_DESCRIPTION("VCPU stall detector");