The driver is mainly used with the back-end watchdog device of qemu.

Signed-off-by: zhanghao1 <zhanghao1@kylinos.cn>
---
 drivers/virtio/Kconfig                      |   9 +
 drivers/virtio/Makefile                     |   1 +
 drivers/virtio/virtio_vcpu_stall_detector.c | 299 ++++++++++++++++++++
 3 files changed, 309 insertions(+)
 create mode 100644 drivers/virtio/virtio_vcpu_stall_detector.c

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 0a53a61231c2..869323e345a1 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -173,4 +173,13 @@ config VIRTIO_DMA_SHARED_BUFFER
 	 This option adds a flavor of dma buffers that are backed by
 	 virtio resources.
 
+config VIRTIO_VCPU_WATCHDOG
+	tristate "Virtio vcpu watchdog driver"
+	depends on VIRTIO_PCI
+	help
+	 When this driver is bound inside a KVM guest, it will
+	 periodically "pet" an PCI virtio watchdog device from each vCPU
+	 and allow the host to detect vCPU stalls.
+
+	 If you do not intend to run this kernel as a guest, say N.
 endif # VIRTIO_MENU
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index 8e98d24917cc..c7341f078a34 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -12,3 +12,4 @@ obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o
 obj-$(CONFIG_VIRTIO_VDPA) += virtio_vdpa.o
 obj-$(CONFIG_VIRTIO_MEM) += virtio_mem.o
 obj-$(CONFIG_VIRTIO_DMA_SHARED_BUFFER) += virtio_dma_buf.o
+obj-$(CONFIG_VIRTIO_VCPU_WATCHDOG) += virtio_vcpu_stall_detector.o
diff --git a/drivers/virtio/virtio_vcpu_stall_detector.c b/drivers/virtio/virtio_vcpu_stall_detector.c
new file mode 100644
index 000000000000..58344ca528be
--- /dev/null
+++ b/drivers/virtio/virtio_vcpu_stall_detector.c
@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// VCPU stall detector.
+// Copyright (C) Kylin Software, 2023
+
+#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 <uapi/linux/virtio_ids.h>
+#include <linux/virtio_config.h>
+#include <linux/param.h>
+#include <linux/percpu.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_REG_TIMEOUT_SEC	(0x14)
+
+#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;
+
+	enum cpuhp_state hp_online;
+};
+
+struct vcpu_stall_priv {
+	struct hrtimer vcpu_hrtimer;
+	struct virtio_device *vdev;
+	u32 cpu_id;
+};
+
+struct vcpu_stall {
+	struct vcpu_stall_priv *priv;
+	struct virtqueue *vq;
+	spinlock_t lock;
+	struct pet_event {
+		u32 cpu_id;
+		bool is_initialized;
+		u32 ticks;
+	} pet_event;
+};
+
+static const struct virtio_device_id vcpu_stall_id_table[] = {
+	{ VIRTIO_ID_WATCHDOG, VIRTIO_DEV_ANY_ID },
+	{ 0, },
+};
+
+/* The vcpu stall configuration structure which applies to all the CPUs */
+static struct vcpu_stall_detect_config vcpu_stall_config;
+static struct vcpu_stall *vcpu_stall;
+
+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;
+	struct scatterlist sg;
+	int unused, err = 0;
+
+	struct vcpu_stall_priv *vcpu_stall_detector =
+		this_cpu_ptr(vcpu_stall->priv);
+
+	/* 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;
+
+	spin_lock(&vcpu_stall->lock);
+	while (virtqueue_get_buf(vcpu_stall->vq, &unused))
+		;
+	vcpu_stall->pet_event.ticks = cpu_to_virtio32(vcpu_stall_detector->vdev, ticks);
+	vcpu_stall->pet_event.is_initialized = true;
+	vcpu_stall->pet_event.cpu_id = vcpu_stall_detector->cpu_id;
+
+	sg_init_one(&sg, &vcpu_stall->pet_event, sizeof(vcpu_stall->pet_event));
+	err = virtqueue_add_outbuf(vcpu_stall->vq, &sg, 1, vcpu_stall, GFP_ATOMIC);
+	if (!err)
+		virtqueue_kick(vcpu_stall->vq);
+	else
+		pr_err("cpu:%d failed to add outbuf, err:%d\n", vcpu_stall_detector->cpu_id, err);
+
+	spin_unlock(&vcpu_stall->lock);
+
+	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 scatterlist sg;
+	struct hrtimer *vcpu_hrtimer;
+	int err = 0;
+
+	struct vcpu_stall_priv *vcpu_stall_detector =
+		this_cpu_ptr(vcpu_stall->priv);
+
+	vcpu_stall_detector->cpu_id = cpu;
+
+	vcpu_hrtimer = &vcpu_stall_detector->vcpu_hrtimer;
+
+	/* 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->pet_event.ticks = cpu_to_virtio32(vcpu_stall_detector->vdev, ticks);
+
+	/* 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->pet_event.is_initialized = true;
+
+	spin_lock(&vcpu_stall->lock);
+	vcpu_stall->pet_event.cpu_id = cpu;
+	sg_init_one(&sg, &vcpu_stall->pet_event, sizeof(vcpu_stall->pet_event));
+	err = virtqueue_add_outbuf(vcpu_stall->vq, &sg, 1, vcpu_stall, GFP_ATOMIC);
+	if (!err)
+		virtqueue_kick(vcpu_stall->vq);
+
+	spin_unlock(&vcpu_stall->lock);
+
+	hrtimer_start(vcpu_hrtimer, ms_to_ktime(ping_timeout_ms),
+		      HRTIMER_MODE_REL_PINNED);
+	return err;
+}
+
+static int stop_stall_detector_cpu(unsigned int cpu)
+{
+	int err = 0;
+	struct scatterlist sg;
+
+	struct vcpu_stall_priv *vcpu_stall_detector =
+		per_cpu_ptr(vcpu_stall_detectors, cpu);
+
+	/* Disable the stall detector for the current CPU */
+	hrtimer_cancel(&vcpu_stall_detector->vcpu_hrtimer);
+	vcpu_stall->pet_event.is_initialized = false;
+	vcpu_stall->pet_event.cpu_id = cpu;
+
+	spin_lock(&vcpu_stall->lock);
+	sg_init_one(&sg, &vcpu_stall->pet_event, sizeof(vcpu_stall->pet_event));
+	err = virtqueue_add_outbuf(vcpu_stall->vq, &sg, 1, vcpu_stall, GFP_ATOMIC);
+	if (!err)
+		virtqueue_kick(vcpu_stall->vq);
+
+	spin_unlock(&vcpu_stall->lock);
+
+	return err;
+}
+
+static int vcpu_stall_detect_probe(struct virtio_device *vdev)
+{
+	int ret, cpu;
+	u32 clock_freq_hz = VCPU_STALL_DEFAULT_CLOCK_HZ;
+	u32 stall_timeout_sec = VCPU_STALL_DEFAULT_TIMEOUT_SEC;
+
+	vcpu_stall = kzalloc(sizeof(struct vcpu_stall), GFP_KERNEL);
+	if (!vcpu_stall) {
+		ret = -ENOMEM;
+		goto err;
+	}
+	vdev->priv = vcpu_stall;
+
+	vcpu_stall->priv = devm_alloc_percpu(&vdev->dev,
+					typeof(struct vcpu_stall_priv));
+	if (!vcpu_stall->priv) {
+		ret = -ENOMEM;
+		goto failed_priv;
+	}
+
+	for_each_possible_cpu(cpu) {
+		struct vcpu_stall_priv *priv;
+
+		priv = per_cpu_ptr(vcpu_stall->priv, cpu);
+		priv->vdev = vdev;
+	}
+
+	ret = virtio_cread_feature(vdev, VCPU_STALL_REG_CLOCK_FREQ_HZ,
+						struct vcpu_stall_detect_config, clock_freq_hz,
+						&clock_freq_hz);
+	if (ret || !clock_freq_hz) {
+		if (!(clock_freq_hz > 0 &&
+		      clock_freq_hz < VCPU_STALL_MAX_CLOCK_HZ)) {
+			dev_warn(&vdev->dev, "clk out of range\n");
+			clock_freq_hz = VCPU_STALL_DEFAULT_CLOCK_HZ;
+		}
+	}
+	ret = virtio_cread_feature(vdev, VCPU_STALL_REG_TIMEOUT_SEC,
+						struct vcpu_stall_detect_config, stall_timeout_sec,
+						&stall_timeout_sec);
+	if (ret || !stall_timeout_sec) {
+		if (!(stall_timeout_sec > 0 &&
+		      stall_timeout_sec < VCPU_STALL_MAX_TIMEOUT_SEC)) {
+			dev_warn(&vdev->dev, "stall timeout out of range\n");
+			stall_timeout_sec = VCPU_STALL_DEFAULT_TIMEOUT_SEC;
+		}
+	}
+
+	vcpu_stall_config = (struct vcpu_stall_detect_config) {
+		.clock_freq_hz		= clock_freq_hz,
+		.stall_timeout_sec	= stall_timeout_sec
+	};
+
+	/* find virtqueue for guest to send pet event to host */
+	vcpu_stall->vq = virtio_find_single_vq(vdev, NULL, "pet-event");
+	if (IS_ERR(vcpu_stall->vq)) {
+		dev_err(&vdev->dev, "failed to find vq\n");
+		goto failed_priv;
+	}
+
+	spin_lock_init(&vcpu_stall->lock);
+
+	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(&vdev->dev, "failed to install cpu hotplug\n");
+		goto failed_priv;
+	}
+
+	vcpu_stall_config.hp_online = ret;
+	return 0;
+
+
+failed_priv:
+	kfree(vcpu_stall);
+err:
+	return ret;
+}
+
+static void vcpu_stall_detect_remove(struct virtio_device *vdev)
+{
+	int cpu;
+
+	cpuhp_remove_state(vcpu_stall_config.hp_online);
+
+	for_each_possible_cpu(cpu)
+		stop_stall_detector_cpu(cpu);
+}
+
+static unsigned int features_legacy[] = {
+	VCPU_STALL_REG_STATUS, VCPU_STALL_REG_LOAD_CNT, VCPU_STALL_REG_CURRENT_CNT,
+	VCPU_STALL_REG_CLOCK_FREQ_HZ, VCPU_STALL_REG_LEN, VCPU_STALL_REG_TIMEOUT_SEC
+};
+
+
+static unsigned int features[] = {
+	VCPU_STALL_REG_STATUS, VCPU_STALL_REG_LOAD_CNT, VCPU_STALL_REG_CURRENT_CNT,
+	VCPU_STALL_REG_CLOCK_FREQ_HZ, VCPU_STALL_REG_LEN, VCPU_STALL_REG_TIMEOUT_SEC
+};
+
+static struct virtio_driver vcpu_stall_detect_driver = {
+	.feature_table	= features,
+	.feature_table_size = ARRAY_SIZE(features),
+	.feature_table_legacy	= features_legacy,
+	.feature_table_size_legacy	= ARRAY_SIZE(features_legacy),
+	.driver.name	= KBUILD_MODNAME,
+	.driver.owner	= THIS_MODULE,
+	.id_table =	vcpu_stall_id_table,
+	.probe  = vcpu_stall_detect_probe,
+	.remove = vcpu_stall_detect_remove,
+};
+
+module_virtio_driver(vcpu_stall_detect_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(virtio, vcpu_stall_id_table);
+MODULE_AUTHOR("zhanghao1 <zhanghao1@kylinos.cn>");
+MODULE_DESCRIPTION("VCPU stall detector");
-- 
2.25.1


No virus found
		Checked by Hillstone Network AntiVirus

Hi zhanghao1,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.5-rc5 next-20230809]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/zhanghao1/A-new-virtio-pci-driver-is-added-for-listening-to-vcpus-inside-guest-Each-vcpu-creates-a-corresponding-thread-to-periodi/20230731-092546
base:   linus/master
patch link:    https://lore.kernel.org/r/20230731012405.234611-1-zhanghao1%40kylinos.cn
patch subject: [PATCH] A new virtio pci driver is added for listening to vcpus inside guest. Each vcpu creates a corresponding thread to periodically send data to qemu's back-end watchdog device.
config: sparc64-randconfig-r071-20230811 (https://download.01.org/0day-ci/archive/20230811/202308110442.0tXLNEKs-lkp@intel.com/config)
compiler: sparc64-linux-gcc (GCC) 12.3.0
reproduce: (https://download.01.org/0day-ci/archive/20230811/202308110442.0tXLNEKs-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202308110442.0tXLNEKs-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/virtio/virtio_vcpu_stall_detector.c:76:17: sparse: sparse: incorrect type in initializer (different address spaces) @@     expected void const [noderef] __percpu *__vpp_verify @@     got struct vcpu_stall_priv * @@
   drivers/virtio/virtio_vcpu_stall_detector.c:76:17: sparse:     expected void const [noderef] __percpu *__vpp_verify
   drivers/virtio/virtio_vcpu_stall_detector.c:76:17: sparse:     got struct vcpu_stall_priv *
>> drivers/virtio/virtio_vcpu_stall_detector.c:89:37: sparse: sparse: incorrect type in assignment (different base types) @@     expected unsigned int [usertype] ticks @@     got restricted __virtio32 @@
   drivers/virtio/virtio_vcpu_stall_detector.c:89:37: sparse:     expected unsigned int [usertype] ticks
   drivers/virtio/virtio_vcpu_stall_detector.c:89:37: sparse:     got restricted __virtio32
   drivers/virtio/virtio_vcpu_stall_detector.c:117:17: sparse: sparse: incorrect type in initializer (different address spaces) @@     expected void const [noderef] __percpu *__vpp_verify @@     got struct vcpu_stall_priv * @@
   drivers/virtio/virtio_vcpu_stall_detector.c:117:17: sparse:     expected void const [noderef] __percpu *__vpp_verify
   drivers/virtio/virtio_vcpu_stall_detector.c:117:17: sparse:     got struct vcpu_stall_priv *
   drivers/virtio/virtio_vcpu_stall_detector.c:129:37: sparse: sparse: incorrect type in assignment (different base types) @@     expected unsigned int [usertype] ticks @@     got restricted __virtio32 @@
   drivers/virtio/virtio_vcpu_stall_detector.c:129:37: sparse:     expected unsigned int [usertype] ticks
   drivers/virtio/virtio_vcpu_stall_detector.c:129:37: sparse:     got restricted __virtio32
>> drivers/virtio/virtio_vcpu_stall_detector.c:193:26: sparse: sparse: incorrect type in assignment (different address spaces) @@     expected struct vcpu_stall_priv *priv @@     got struct vcpu_stall_priv [noderef] __percpu * @@
   drivers/virtio/virtio_vcpu_stall_detector.c:193:26: sparse:     expected struct vcpu_stall_priv *priv
   drivers/virtio/virtio_vcpu_stall_detector.c:193:26: sparse:     got struct vcpu_stall_priv [noderef] __percpu *
   drivers/virtio/virtio_vcpu_stall_detector.c:203:24: sparse: sparse: incorrect type in initializer (different address spaces) @@     expected void const [noderef] __percpu *__vpp_verify @@     got struct vcpu_stall_priv * @@
   drivers/virtio/virtio_vcpu_stall_detector.c:203:24: sparse:     expected void const [noderef] __percpu *__vpp_verify
   drivers/virtio/virtio_vcpu_stall_detector.c:203:24: sparse:     got struct vcpu_stall_priv *
>> drivers/virtio/virtio_vcpu_stall_detector.c:207:15: sparse: sparse: no generic selection for 'unsigned int virtio_cread_v'
>> drivers/virtio/virtio_vcpu_stall_detector.c:207:15: sparse: sparse: incompatible types in comparison expression (different base types):
>> drivers/virtio/virtio_vcpu_stall_detector.c:207:15: sparse:    bad type *
>> drivers/virtio/virtio_vcpu_stall_detector.c:207:15: sparse:    unsigned int *
>> drivers/virtio/virtio_vcpu_stall_detector.c:207:15: sparse: sparse: no generic selection for 'unsigned int [addressable] virtio_cread_v'
   drivers/virtio/virtio_vcpu_stall_detector.c:217:15: sparse: sparse: no generic selection for 'unsigned int virtio_cread_v'
   drivers/virtio/virtio_vcpu_stall_detector.c:217:15: sparse: sparse: incompatible types in comparison expression (different base types):
   drivers/virtio/virtio_vcpu_stall_detector.c:217:15: sparse:    bad type *
   drivers/virtio/virtio_vcpu_stall_detector.c:217:15: sparse:    unsigned int *
   drivers/virtio/virtio_vcpu_stall_detector.c:217:15: sparse: sparse: no generic selection for 'unsigned int [addressable] virtio_cread_v'

vim +76 drivers/virtio/virtio_vcpu_stall_detector.c

    67	
    68	static enum hrtimer_restart
    69	vcpu_stall_detect_timer_fn(struct hrtimer *hrtimer)
    70	{
    71		u32 ticks, ping_timeout_ms;
    72		struct scatterlist sg;
    73		int unused, err = 0;
    74	
    75		struct vcpu_stall_priv *vcpu_stall_detector =
  > 76			this_cpu_ptr(vcpu_stall->priv);
    77	
    78		/* Reload the stall detector counter register every
    79		 * `ping_timeout_ms` to prevent the virtual device
    80		 * from decrementing it to 0. The virtual device decrements this
    81		 * register at 'clock_freq_hz' frequency.
    82		 */
    83		ticks = vcpu_stall_config.clock_freq_hz *
    84					vcpu_stall_config.stall_timeout_sec;
    85	
    86		spin_lock(&vcpu_stall->lock);
    87		while (virtqueue_get_buf(vcpu_stall->vq, &unused))
    88			;
  > 89		vcpu_stall->pet_event.ticks = cpu_to_virtio32(vcpu_stall_detector->vdev, ticks);
    90		vcpu_stall->pet_event.is_initialized = true;
    91		vcpu_stall->pet_event.cpu_id = vcpu_stall_detector->cpu_id;
    92	
    93		sg_init_one(&sg, &vcpu_stall->pet_event, sizeof(vcpu_stall->pet_event));
    94		err = virtqueue_add_outbuf(vcpu_stall->vq, &sg, 1, vcpu_stall, GFP_ATOMIC);
    95		if (!err)
    96			virtqueue_kick(vcpu_stall->vq);
    97		else
    98			pr_err("cpu:%d failed to add outbuf, err:%d\n", vcpu_stall_detector->cpu_id, err);
    99	
   100		spin_unlock(&vcpu_stall->lock);
   101	
   102		ping_timeout_ms = vcpu_stall_config.stall_timeout_sec *
   103				  MSEC_PER_SEC / 2;
   104		hrtimer_forward_now(hrtimer,
   105				    ms_to_ktime(ping_timeout_ms));
   106		return HRTIMER_RESTART;
   107	}
   108	
   109	static int start_stall_detector_cpu(unsigned int cpu)
   110	{
   111		u32 ticks, ping_timeout_ms;
   112		struct scatterlist sg;
   113		struct hrtimer *vcpu_hrtimer;
   114		int err = 0;
   115	
   116		struct vcpu_stall_priv *vcpu_stall_detector =
   117			this_cpu_ptr(vcpu_stall->priv);
   118	
   119		vcpu_stall_detector->cpu_id = cpu;
   120	
   121		vcpu_hrtimer = &vcpu_stall_detector->vcpu_hrtimer;
   122	
   123		/* Compute the number of ticks required for the stall detector
   124		 * counter register based on the internal clock frequency and the
   125		 * timeout value given from the device tree.
   126		 */
   127		ticks = vcpu_stall_config.clock_freq_hz *
   128			vcpu_stall_config.stall_timeout_sec;
   129		vcpu_stall->pet_event.ticks = cpu_to_virtio32(vcpu_stall_detector->vdev, ticks);
   130	
   131		/* Pet the stall detector at half of its expiration timeout
   132		 * to prevent spurious resets.
   133		 */
   134		ping_timeout_ms = vcpu_stall_config.stall_timeout_sec *
   135				  MSEC_PER_SEC / 2;
   136	
   137		hrtimer_init(vcpu_hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
   138		vcpu_hrtimer->function = vcpu_stall_detect_timer_fn;
   139	
   140		vcpu_stall->pet_event.is_initialized = true;
   141	
   142		spin_lock(&vcpu_stall->lock);
   143		vcpu_stall->pet_event.cpu_id = cpu;
   144		sg_init_one(&sg, &vcpu_stall->pet_event, sizeof(vcpu_stall->pet_event));
   145		err = virtqueue_add_outbuf(vcpu_stall->vq, &sg, 1, vcpu_stall, GFP_ATOMIC);
   146		if (!err)
   147			virtqueue_kick(vcpu_stall->vq);
   148	
   149		spin_unlock(&vcpu_stall->lock);
   150	
   151		hrtimer_start(vcpu_hrtimer, ms_to_ktime(ping_timeout_ms),
   152			      HRTIMER_MODE_REL_PINNED);
   153		return err;
   154	}
   155	
   156	static int stop_stall_detector_cpu(unsigned int cpu)
   157	{
   158		int err = 0;
   159		struct scatterlist sg;
   160	
   161		struct vcpu_stall_priv *vcpu_stall_detector =
   162			per_cpu_ptr(vcpu_stall_detectors, cpu);
   163	
   164		/* Disable the stall detector for the current CPU */
   165		hrtimer_cancel(&vcpu_stall_detector->vcpu_hrtimer);
   166		vcpu_stall->pet_event.is_initialized = false;
   167		vcpu_stall->pet_event.cpu_id = cpu;
   168	
   169		spin_lock(&vcpu_stall->lock);
   170		sg_init_one(&sg, &vcpu_stall->pet_event, sizeof(vcpu_stall->pet_event));
   171		err = virtqueue_add_outbuf(vcpu_stall->vq, &sg, 1, vcpu_stall, GFP_ATOMIC);
   172		if (!err)
   173			virtqueue_kick(vcpu_stall->vq);
   174	
   175		spin_unlock(&vcpu_stall->lock);
   176	
   177		return err;
   178	}
   179	
   180	static int vcpu_stall_detect_probe(struct virtio_device *vdev)
   181	{
   182		int ret, cpu;
   183		u32 clock_freq_hz = VCPU_STALL_DEFAULT_CLOCK_HZ;
   184		u32 stall_timeout_sec = VCPU_STALL_DEFAULT_TIMEOUT_SEC;
   185	
   186		vcpu_stall = kzalloc(sizeof(struct vcpu_stall), GFP_KERNEL);
   187		if (!vcpu_stall) {
   188			ret = -ENOMEM;
   189			goto err;
   190		}
   191		vdev->priv = vcpu_stall;
   192	
 > 193		vcpu_stall->priv = devm_alloc_percpu(&vdev->dev,
   194						typeof(struct vcpu_stall_priv));
   195		if (!vcpu_stall->priv) {
   196			ret = -ENOMEM;
   197			goto failed_priv;
   198		}
   199	
   200		for_each_possible_cpu(cpu) {
   201			struct vcpu_stall_priv *priv;
   202	
   203			priv = per_cpu_ptr(vcpu_stall->priv, cpu);
   204			priv->vdev = vdev;
   205		}
   206	
 > 207		ret = virtio_cread_feature(vdev, VCPU_STALL_REG_CLOCK_FREQ_HZ,
   208							struct vcpu_stall_detect_config, clock_freq_hz,
   209							&clock_freq_hz);
   210		if (ret || !clock_freq_hz) {
   211			if (!(clock_freq_hz > 0 &&
   212			      clock_freq_hz < VCPU_STALL_MAX_CLOCK_HZ)) {
   213				dev_warn(&vdev->dev, "clk out of range\n");
   214				clock_freq_hz = VCPU_STALL_DEFAULT_CLOCK_HZ;
   215			}
   216		}
   217		ret = virtio_cread_feature(vdev, VCPU_STALL_REG_TIMEOUT_SEC,
   218							struct vcpu_stall_detect_config, stall_timeout_sec,
   219							&stall_timeout_sec);
   220		if (ret || !stall_timeout_sec) {
   221			if (!(stall_timeout_sec > 0 &&
   222			      stall_timeout_sec < VCPU_STALL_MAX_TIMEOUT_SEC)) {
   223				dev_warn(&vdev->dev, "stall timeout out of range\n");
   224				stall_timeout_sec = VCPU_STALL_DEFAULT_TIMEOUT_SEC;
   225			}
   226		}
   227	
   228		vcpu_stall_config = (struct vcpu_stall_detect_config) {
   229			.clock_freq_hz		= clock_freq_hz,
   230			.stall_timeout_sec	= stall_timeout_sec
   231		};
   232	
   233		/* find virtqueue for guest to send pet event to host */
   234		vcpu_stall->vq = virtio_find_single_vq(vdev, NULL, "pet-event");
   235		if (IS_ERR(vcpu_stall->vq)) {
   236			dev_err(&vdev->dev, "failed to find vq\n");
   237			goto failed_priv;
   238		}
   239	
   240		spin_lock_init(&vcpu_stall->lock);
   241	
   242		ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
   243					"virt/vcpu_stall_detector:online",
   244					start_stall_detector_cpu,
   245					stop_stall_detector_cpu);
   246		if (ret < 0) {
   247			dev_err(&vdev->dev, "failed to install cpu hotplug\n");
   248			goto failed_priv;
   249		}
   250	
   251		vcpu_stall_config.hp_online = ret;
   252		return 0;
   253	
   254	
   255	failed_priv:
   256		kfree(vcpu_stall);
   257	err:
   258		return ret;
   259	}
   260	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki