1 // SPDX-License-Identifier: GPL-2.0
3 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
4 #include <linux/memblock.h>
7 #include <linux/kexec.h>
8 #include <linux/slab.h>
11 #include <xen/features.h>
14 #include <asm/xen/hypercall.h>
15 #include <asm/xen/hypervisor.h>
17 #include <asm/e820/api.h>
23 EXPORT_SYMBOL_GPL(hypercall_page
);
26 * Pointer to the xen_vcpu_info structure or
27 * &HYPERVISOR_shared_info->vcpu_info[cpu]. See xen_hvm_init_shared_info
28 * and xen_vcpu_setup for details. By default it points to share_info->vcpu_info
29 * but if the hypervisor supports VCPUOP_register_vcpu_info then it can point
30 * to xen_vcpu_info. The pointer is used in __xen_evtchn_do_upcall to
31 * acknowledge pending events.
32 * Also more subtly it is used by the patched version of irq enable/disable
33 * e.g. xen_irq_enable_direct and xen_iret in PV mode.
35 * The desire to be able to do those mask/unmask operations as a single
36 * instruction by using the per-cpu offset held in %gs is the real reason
37 * vcpu info is in a per-cpu pointer and the original reason for this
41 DEFINE_PER_CPU(struct vcpu_info
*, xen_vcpu
);
44 * Per CPU pages used if hypervisor supports VCPUOP_register_vcpu_info
45 * hypercall. This can be used both in PV and PVHVM mode. The structure
46 * overrides the default per_cpu(xen_vcpu, cpu) value.
48 DEFINE_PER_CPU(struct vcpu_info
, xen_vcpu_info
);
50 /* Linux <-> Xen vCPU id mapping */
51 DEFINE_PER_CPU(uint32_t, xen_vcpu_id
);
52 EXPORT_PER_CPU_SYMBOL(xen_vcpu_id
);
54 enum xen_domain_type xen_domain_type
= XEN_NATIVE
;
55 EXPORT_SYMBOL_GPL(xen_domain_type
);
57 unsigned long *machine_to_phys_mapping
= (void *)MACH2PHYS_VIRT_START
;
58 EXPORT_SYMBOL(machine_to_phys_mapping
);
59 unsigned long machine_to_phys_nr
;
60 EXPORT_SYMBOL(machine_to_phys_nr
);
62 struct start_info
*xen_start_info
;
63 EXPORT_SYMBOL_GPL(xen_start_info
);
65 struct shared_info xen_dummy_shared_info
;
67 __read_mostly
int xen_have_vector_callback
;
68 EXPORT_SYMBOL_GPL(xen_have_vector_callback
);
71 * NB: needs to live in .data because it's used by xen_prepare_pvh which runs
72 * before clearing the bss.
74 uint32_t xen_start_flags
__section(".data") = 0;
75 EXPORT_SYMBOL(xen_start_flags
);
78 * Point at some empty memory to start with. We map the real shared_info
79 * page as soon as fixmap is up and running.
81 struct shared_info
*HYPERVISOR_shared_info
= &xen_dummy_shared_info
;
84 * Flag to determine whether vcpu info placement is available on all
85 * VCPUs. We assume it is to start with, and then set it to zero on
86 * the first failure. This is because it can succeed on some VCPUs
87 * and not others, since it can involve hypervisor memory allocation,
88 * or because the guest failed to guarantee all the appropriate
89 * constraints on all VCPUs (ie buffer can't cross a page boundary).
91 * Note that any particular CPU may be using a placed vcpu structure,
92 * but we can only optimise if the all are.
94 * 0: not available, 1: available
96 int xen_have_vcpu_info_placement
= 1;
98 static int xen_cpu_up_online(unsigned int cpu
)
100 xen_init_lock_cpu(cpu
);
104 int xen_cpuhp_setup(int (*cpu_up_prepare_cb
)(unsigned int),
105 int (*cpu_dead_cb
)(unsigned int))
109 rc
= cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE
,
110 "x86/xen/guest:prepare",
111 cpu_up_prepare_cb
, cpu_dead_cb
);
113 rc
= cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN
,
114 "x86/xen/guest:online",
115 xen_cpu_up_online
, NULL
);
117 cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE
);
120 return rc
>= 0 ? 0 : rc
;
123 static int xen_vcpu_setup_restore(int cpu
)
127 /* Any per_cpu(xen_vcpu) is stale, so reset it */
128 xen_vcpu_info_reset(cpu
);
131 * For PVH and PVHVM, setup online VCPUs only. The rest will
132 * be handled by hotplug.
134 if (xen_pv_domain() ||
135 (xen_hvm_domain() && cpu_online(cpu
))) {
136 rc
= xen_vcpu_setup(cpu
);
143 * On restore, set the vcpu placement up again.
144 * If it fails, then we're in a bad state, since
145 * we can't back out from using it...
147 void xen_vcpu_restore(void)
151 for_each_possible_cpu(cpu
) {
152 bool other_cpu
= (cpu
!= smp_processor_id());
155 if (xen_vcpu_nr(cpu
) == XEN_VCPU_ID_INVALID
)
158 /* Only Xen 4.5 and higher support this. */
159 is_up
= HYPERVISOR_vcpu_op(VCPUOP_is_up
,
160 xen_vcpu_nr(cpu
), NULL
) > 0;
162 if (other_cpu
&& is_up
&&
163 HYPERVISOR_vcpu_op(VCPUOP_down
, xen_vcpu_nr(cpu
), NULL
))
166 if (xen_pv_domain() || xen_feature(XENFEAT_hvm_safe_pvclock
))
167 xen_setup_runstate_info(cpu
);
169 rc
= xen_vcpu_setup_restore(cpu
);
171 pr_emerg_once("vcpu restore failed for cpu=%d err=%d. "
172 "System will hang.\n", cpu
, rc
);
174 * In case xen_vcpu_setup_restore() fails, do not bring up the
175 * VCPU. This helps us avoid the resulting OOPS when the VCPU
176 * accesses pvclock_vcpu_time via xen_vcpu (which is NULL.)
177 * Note that this does not improve the situation much -- now the
178 * VM hangs instead of OOPSing -- with the VCPUs that did not
179 * fail, spinning in stop_machine(), waiting for the failed
182 if (other_cpu
&& is_up
&& (rc
== 0) &&
183 HYPERVISOR_vcpu_op(VCPUOP_up
, xen_vcpu_nr(cpu
), NULL
))
188 void xen_vcpu_info_reset(int cpu
)
190 if (xen_vcpu_nr(cpu
) < MAX_VIRT_CPUS
) {
191 per_cpu(xen_vcpu
, cpu
) =
192 &HYPERVISOR_shared_info
->vcpu_info
[xen_vcpu_nr(cpu
)];
194 /* Set to NULL so that if somebody accesses it we get an OOPS */
195 per_cpu(xen_vcpu
, cpu
) = NULL
;
199 int xen_vcpu_setup(int cpu
)
201 struct vcpu_register_vcpu_info info
;
203 struct vcpu_info
*vcpup
;
205 BUG_ON(HYPERVISOR_shared_info
== &xen_dummy_shared_info
);
208 * This path is called on PVHVM at bootup (xen_hvm_smp_prepare_boot_cpu)
209 * and at restore (xen_vcpu_restore). Also called for hotplugged
210 * VCPUs (cpu_init -> xen_hvm_cpu_prepare_hvm).
211 * However, the hypercall can only be done once (see below) so if a VCPU
212 * is offlined and comes back online then let's not redo the hypercall.
214 * For PV it is called during restore (xen_vcpu_restore) and bootup
215 * (xen_setup_vcpu_info_placement). The hotplug mechanism does not
218 if (xen_hvm_domain()) {
219 if (per_cpu(xen_vcpu
, cpu
) == &per_cpu(xen_vcpu_info
, cpu
))
223 if (xen_have_vcpu_info_placement
) {
224 vcpup
= &per_cpu(xen_vcpu_info
, cpu
);
225 info
.mfn
= arbitrary_virt_to_mfn(vcpup
);
226 info
.offset
= offset_in_page(vcpup
);
229 * Check to see if the hypervisor will put the vcpu_info
230 * structure where we want it, which allows direct access via
232 * N.B. This hypercall can _only_ be called once per CPU.
233 * Subsequent calls will error out with -EINVAL. This is due to
234 * the fact that hypervisor has no unregister variant and this
235 * hypercall does not allow to over-write info.mfn and
238 err
= HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info
,
239 xen_vcpu_nr(cpu
), &info
);
242 pr_warn_once("register_vcpu_info failed: cpu=%d err=%d\n",
244 xen_have_vcpu_info_placement
= 0;
247 * This cpu is using the registered vcpu info, even if
248 * later ones fail to.
250 per_cpu(xen_vcpu
, cpu
) = vcpup
;
254 if (!xen_have_vcpu_info_placement
)
255 xen_vcpu_info_reset(cpu
);
257 return ((per_cpu(xen_vcpu
, cpu
) == NULL
) ? -ENODEV
: 0);
260 void xen_reboot(int reason
)
262 struct sched_shutdown r
= { .reason
= reason
};
265 for_each_online_cpu(cpu
)
268 if (HYPERVISOR_sched_op(SCHEDOP_shutdown
, &r
))
272 static int reboot_reason
= SHUTDOWN_reboot
;
273 static bool xen_legacy_crash
;
274 void xen_emergency_restart(void)
276 xen_reboot(reboot_reason
);
280 xen_panic_event(struct notifier_block
*this, unsigned long event
, void *ptr
)
282 if (!kexec_crash_loaded()) {
283 if (xen_legacy_crash
)
284 xen_reboot(SHUTDOWN_crash
);
286 reboot_reason
= SHUTDOWN_crash
;
289 * If panic_timeout==0 then we are supposed to wait forever.
290 * However, to preserve original dom0 behavior we have to drop
291 * into hypervisor. (domU behavior is controlled by its
294 if (panic_timeout
== 0)
300 static int __init
parse_xen_legacy_crash(char *arg
)
302 xen_legacy_crash
= true;
305 early_param("xen_legacy_crash", parse_xen_legacy_crash
);
307 static struct notifier_block xen_panic_block
= {
308 .notifier_call
= xen_panic_event
,
312 int xen_panic_handler_init(void)
314 atomic_notifier_chain_register(&panic_notifier_list
, &xen_panic_block
);
318 void xen_pin_vcpu(int cpu
)
320 static bool disable_pinning
;
321 struct sched_pin_override pin_override
;
327 pin_override
.pcpu
= cpu
;
328 ret
= HYPERVISOR_sched_op(SCHEDOP_pin_override
, &pin_override
);
330 /* Ignore errors when removing override. */
336 pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
338 disable_pinning
= true;
341 WARN(1, "Trying to pin vcpu without having privilege to do so\n");
342 disable_pinning
= true;
346 pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
352 WARN(1, "rc %d while trying to pin vcpu\n", ret
);
353 disable_pinning
= true;
357 #ifdef CONFIG_HOTPLUG_CPU
358 void xen_arch_register_cpu(int num
)
360 arch_register_cpu(num
);
362 EXPORT_SYMBOL(xen_arch_register_cpu
);
364 void xen_arch_unregister_cpu(int num
)
366 arch_unregister_cpu(num
);
368 EXPORT_SYMBOL(xen_arch_unregister_cpu
);