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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /drivers/xen/cpu_hotplug.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'drivers/xen/cpu_hotplug.c')
-rw-r--r-- | drivers/xen/cpu_hotplug.c | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/drivers/xen/cpu_hotplug.c b/drivers/xen/cpu_hotplug.c new file mode 100644 index 000000000..b96b11e2b --- /dev/null +++ b/drivers/xen/cpu_hotplug.c @@ -0,0 +1,121 @@ +// SPDX-License-Identifier: GPL-2.0 +#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt + +#include <linux/notifier.h> + +#include <xen/xen.h> +#include <xen/xenbus.h> + +#include <asm/xen/hypervisor.h> +#include <asm/cpu.h> + +static void enable_hotplug_cpu(int cpu) +{ + if (!cpu_present(cpu)) + xen_arch_register_cpu(cpu); + + set_cpu_present(cpu, true); +} + +static void disable_hotplug_cpu(int cpu) +{ + if (!cpu_is_hotpluggable(cpu)) + return; + lock_device_hotplug(); + if (cpu_online(cpu)) + device_offline(get_cpu_device(cpu)); + if (!cpu_online(cpu) && cpu_present(cpu)) { + xen_arch_unregister_cpu(cpu); + set_cpu_present(cpu, false); + } + unlock_device_hotplug(); +} + +static int vcpu_online(unsigned int cpu) +{ + int err; + char dir[16], state[16]; + + sprintf(dir, "cpu/%u", cpu); + err = xenbus_scanf(XBT_NIL, dir, "availability", "%15s", state); + if (err != 1) { + if (!xen_initial_domain()) + pr_err("Unable to read cpu state\n"); + return err; + } + + if (strcmp(state, "online") == 0) + return 1; + else if (strcmp(state, "offline") == 0) + return 0; + + pr_err("unknown state(%s) on CPU%d\n", state, cpu); + return -EINVAL; +} +static void vcpu_hotplug(unsigned int cpu) +{ + if (cpu >= nr_cpu_ids || !cpu_possible(cpu)) + return; + + switch (vcpu_online(cpu)) { + case 1: + enable_hotplug_cpu(cpu); + break; + case 0: + disable_hotplug_cpu(cpu); + break; + default: + break; + } +} + +static void handle_vcpu_hotplug_event(struct xenbus_watch *watch, + const char *path, const char *token) +{ + unsigned int cpu; + char *cpustr; + + cpustr = strstr(path, "cpu/"); + if (cpustr != NULL) { + sscanf(cpustr, "cpu/%u", &cpu); + vcpu_hotplug(cpu); + } +} + +static int setup_cpu_watcher(struct notifier_block *notifier, + unsigned long event, void *data) +{ + int cpu; + static struct xenbus_watch cpu_watch = { + .node = "cpu", + .callback = handle_vcpu_hotplug_event}; + + (void)register_xenbus_watch(&cpu_watch); + + for_each_possible_cpu(cpu) { + if (vcpu_online(cpu) == 0) + disable_hotplug_cpu(cpu); + } + + return NOTIFY_DONE; +} + +static int __init setup_vcpu_hotplug_event(void) +{ + static struct notifier_block xsn_cpu = { + .notifier_call = setup_cpu_watcher }; + +#ifdef CONFIG_X86 + if (!xen_pv_domain() && !xen_pvh_domain()) +#else + if (!xen_domain()) +#endif + return -ENODEV; + + register_xenstore_notifier(&xsn_cpu); + + return 0; +} + +late_initcall(setup_vcpu_hotplug_event); + |