enlighten.c

  1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <linux/console.h>
  4#include <linux/cpu.h>
  5#include <linux/instrumentation.h>
  6#include <linux/kexec.h>
  7#include <linux/memblock.h>
  8#include <linux/slab.h>
  9#include <linux/panic_notifier.h>
 10
 11#include <xen/xen.h>
 12#include <xen/features.h>
 13#include <xen/interface/sched.h>
 14#include <xen/interface/version.h>
 15#include <xen/page.h>
 16
 17#include <asm/xen/hypercall.h>
 18#include <asm/xen/hypervisor.h>
 19#include <asm/cpu.h>
 20#include <asm/e820/api.h> 
 21#include <asm/setup.h>
 22
 23#include "xen-ops.h"
 24
 25DEFINE_STATIC_CALL(xen_hypercall, xen_hypercall_hvm);
 26EXPORT_STATIC_CALL_TRAMP(xen_hypercall);
 27
 28/*
 29 * Pointer to the xen_vcpu_info structure or
 30 * &HYPERVISOR_shared_info->vcpu_info[cpu]. See xen_hvm_init_shared_info
 31 * and xen_vcpu_setup for details. By default it points to share_info->vcpu_info
 32 * but during boot it is switched to point to xen_vcpu_info.
 33 * The pointer is used in xen_evtchn_do_upcall to acknowledge pending events.
 34 * Make sure that xen_vcpu_info doesn't cross a page boundary by making it
 35 * cache-line aligned (the struct is guaranteed to have a size of 64 bytes,
 36 * which matches the cache line size of 64-bit x86 processors).
 37 */
 38DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
 39DEFINE_PER_CPU_ALIGNED(struct vcpu_info, xen_vcpu_info);
 40
 41/* Linux <-> Xen vCPU id mapping */
 42DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
 43EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);
 44
 45unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
 46EXPORT_SYMBOL(machine_to_phys_mapping);
 47unsigned long  machine_to_phys_nr;
 48EXPORT_SYMBOL(machine_to_phys_nr);
 49
 50struct start_info *xen_start_info;
 51EXPORT_SYMBOL_GPL(xen_start_info);
 52
 53struct shared_info xen_dummy_shared_info;
 54
 55__read_mostly bool xen_have_vector_callback = true;
 56EXPORT_SYMBOL_GPL(xen_have_vector_callback);
 57
 58/*
 59 * NB: These need to live in .data or alike because they're used by
 60 * xen_prepare_pvh() which runs before clearing the bss.
 61 */
 62enum xen_domain_type __ro_after_init xen_domain_type = XEN_NATIVE;
 63EXPORT_SYMBOL_GPL(xen_domain_type);
 64uint32_t __ro_after_init xen_start_flags;
 65EXPORT_SYMBOL(xen_start_flags);
 66
 67/*
 68 * Point at some empty memory to start with. We map the real shared_info
 69 * page as soon as fixmap is up and running.
 70 */
 71struct shared_info *HYPERVISOR_shared_info = &xen_dummy_shared_info;
 72
 73/* Number of pages released from the initial allocation. */
 74unsigned long xen_released_pages;
 75
 76static __ref void xen_get_vendor(void)
 77{
 78	init_cpu_devs();
 79	cpu_detect(&boot_cpu_data);
 80	get_cpu_vendor(&boot_cpu_data);
 81}
 82
 83void xen_hypercall_setfunc(void)
 84{
 85	if (static_call_query(xen_hypercall) != xen_hypercall_hvm)
 86		return;
 87
 88	if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
 89	     boot_cpu_data.x86_vendor == X86_VENDOR_HYGON))
 90		static_call_update(xen_hypercall, xen_hypercall_amd);
 91	else
 92		static_call_update(xen_hypercall, xen_hypercall_intel);
 93}
 94
 95/*
 96 * Evaluate processor vendor in order to select the correct hypercall
 97 * function for HVM/PVH guests.
 98 * Might be called very early in boot before vendor has been set by
 99 * early_cpu_init().
100 */
101noinstr void *__xen_hypercall_setfunc(void)
102{
103	void (*func)(void);
104
105	/*
106	 * Note that __xen_hypercall_setfunc() is noinstr only due to a nasty
107	 * dependency chain: it is being called via the xen_hypercall static
108	 * call when running as a PVH or HVM guest. Hypercalls need to be
109	 * noinstr due to PV guests using hypercalls in noinstr code. So we
110	 * can safely tag the function body as "instrumentation ok", since
111	 * the PV guest requirement is not of interest here (xen_get_vendor()
112	 * calls noinstr functions, and static_call_update_early() might do
113	 * so, too).
114	 */
115	instrumentation_begin();
116
117	xen_get_vendor();
118
119	if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
120	     boot_cpu_data.x86_vendor == X86_VENDOR_HYGON))
121		func = xen_hypercall_amd;
122	else
123		func = xen_hypercall_intel;
124
125	static_call_update_early(xen_hypercall, func);
126
127	instrumentation_end();
128
129	return func;
130}
131
132static int xen_cpu_up_online(unsigned int cpu)
133{
134	xen_init_lock_cpu(cpu);
135	return 0;
136}
137
138int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int),
139		    int (*cpu_dead_cb)(unsigned int))
140{
141	int rc;
142
143	rc = cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE,
144				       "x86/xen/guest:prepare",
145				       cpu_up_prepare_cb, cpu_dead_cb);
146	if (rc >= 0) {
147		rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
148					       "x86/xen/guest:online",
149					       xen_cpu_up_online, NULL);
150		if (rc < 0)
151			cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE);
152	}
153
154	return rc >= 0 ? 0 : rc;
155}
156
157static void xen_vcpu_setup_restore(int cpu)
158{
159	/* Any per_cpu(xen_vcpu) is stale, so reset it */
160	xen_vcpu_info_reset(cpu);
161
162	/*
163	 * For PVH and PVHVM, setup online VCPUs only. The rest will
164	 * be handled by hotplug.
165	 */
166	if (xen_pv_domain() ||
167	    (xen_hvm_domain() && cpu_online(cpu)))
168		xen_vcpu_setup(cpu);
169}
170
171/*
172 * On restore, set the vcpu placement up again.
173 * If it fails, then we're in a bad state, since
174 * we can't back out from using it...
175 */
176void xen_vcpu_restore(void)
177{
178	int cpu;
179
180	for_each_possible_cpu(cpu) {
181		bool other_cpu = (cpu != smp_processor_id());
182		bool is_up;
183
184		if (xen_vcpu_nr(cpu) == XEN_VCPU_ID_INVALID)
185			continue;
186
187		/* Only Xen 4.5 and higher support this. */
188		is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up,
189					   xen_vcpu_nr(cpu), NULL) > 0;
190
191		if (other_cpu && is_up &&
192		    HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL))
193			BUG();
194
195		if (xen_pv_domain() || xen_feature(XENFEAT_hvm_safe_pvclock))
196			xen_setup_runstate_info(cpu);
197
198		xen_vcpu_setup_restore(cpu);
199
200		if (other_cpu && is_up &&
201		    HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL))
202			BUG();
203	}
204}
205
206void xen_vcpu_info_reset(int cpu)
207{
208	if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) {
209		per_cpu(xen_vcpu, cpu) =
210			&HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)];
211	} else {
212		/* Set to NULL so that if somebody accesses it we get an OOPS */
213		per_cpu(xen_vcpu, cpu) = NULL;
214	}
215}
216
217void xen_vcpu_setup(int cpu)
218{
219	struct vcpu_register_vcpu_info info;
220	int err;
221	struct vcpu_info *vcpup;
222
223	BUILD_BUG_ON(sizeof(*vcpup) > SMP_CACHE_BYTES);
224	BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
225
226	/*
227	 * This path is called on PVHVM at bootup (xen_hvm_smp_prepare_boot_cpu)
228	 * and at restore (xen_vcpu_restore). Also called for hotplugged
229	 * VCPUs (cpu_init -> xen_hvm_cpu_prepare_hvm).
230	 * However, the hypercall can only be done once (see below) so if a VCPU
231	 * is offlined and comes back online then let's not redo the hypercall.
232	 *
233	 * For PV it is called during restore (xen_vcpu_restore) and bootup
234	 * (xen_setup_vcpu_info_placement). The hotplug mechanism does not
235	 * use this function.
236	 */
237	if (xen_hvm_domain()) {
238		if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu))
239			return;
240	}
241
242	vcpup = &per_cpu(xen_vcpu_info, cpu);
243	info.mfn = arbitrary_virt_to_mfn(vcpup);
244	info.offset = offset_in_page(vcpup);
245
246	/*
247	 * N.B. This hypercall can _only_ be called once per CPU.
248	 * Subsequent calls will error out with -EINVAL. This is due to
249	 * the fact that hypervisor has no unregister variant and this
250	 * hypercall does not allow to over-write info.mfn and
251	 * info.offset.
252	 */
253	err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, xen_vcpu_nr(cpu),
254				 &info);
255	if (err)
256		panic("register_vcpu_info failed: cpu=%d err=%d\n", cpu, err);
257
258	per_cpu(xen_vcpu, cpu) = vcpup;
259}
260
261void __init xen_banner(void)
262{
263	unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL);
264	struct xen_extraversion extra;
265
266	HYPERVISOR_xen_version(XENVER_extraversion, &extra);
267
268	pr_info("Booting kernel on %s\n", pv_info.name);
269	pr_info("Xen version: %u.%u%s%s\n",
270		version >> 16, version & 0xffff, extra.extraversion,
271		xen_feature(XENFEAT_mmu_pt_update_preserve_ad)
272		? " (preserve-AD)" : "");
273}
274
275/* Check if running on Xen version (major, minor) or later */
276bool xen_running_on_version_or_later(unsigned int major, unsigned int minor)
277{
278	unsigned int version;
279
280	if (!xen_domain())
281		return false;
282
283	version = HYPERVISOR_xen_version(XENVER_version, NULL);
284	if ((((version >> 16) == major) && ((version & 0xffff) >= minor)) ||
285		((version >> 16) > major))
286		return true;
287	return false;
288}
289
290void __init xen_add_preferred_consoles(void)
291{
292	add_preferred_console("xenboot", 0, NULL);
293	if (!boot_params.screen_info.orig_video_isVGA)
294		add_preferred_console("tty", 0, NULL);
295	add_preferred_console("hvc", 0, NULL);
296	if (boot_params.screen_info.orig_video_isVGA)
297		add_preferred_console("tty", 0, NULL);
298}
299
300void xen_reboot(int reason)
301{
302	struct sched_shutdown r = { .reason = reason };
303	int cpu;
304
305	for_each_online_cpu(cpu)
306		xen_pmu_finish(cpu);
307
308	if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
309		BUG();
310}
311
312static int reboot_reason = SHUTDOWN_reboot;
313static bool xen_legacy_crash;
314void xen_emergency_restart(void)
315{
316	xen_reboot(reboot_reason);
317}
318
319static int
320xen_panic_event(struct notifier_block *this, unsigned long event, void *ptr)
321{
322	if (!kexec_crash_loaded()) {
323		if (xen_legacy_crash)
324			xen_reboot(SHUTDOWN_crash);
325
326		reboot_reason = SHUTDOWN_crash;
327
328		/*
329		 * If panic_timeout==0 then we are supposed to wait forever.
330		 * However, to preserve original dom0 behavior we have to drop
331		 * into hypervisor. (domU behavior is controlled by its
332		 * config file)
333		 */
334		if (panic_timeout == 0)
335			panic_timeout = -1;
336	}
337	return NOTIFY_DONE;
338}
339
340static int __init parse_xen_legacy_crash(char *arg)
341{
342	xen_legacy_crash = true;
343	return 0;
344}
345early_param("xen_legacy_crash", parse_xen_legacy_crash);
346
347static struct notifier_block xen_panic_block = {
348	.notifier_call = xen_panic_event,
349	.priority = INT_MIN
350};
351
352int xen_panic_handler_init(void)
353{
354	atomic_notifier_chain_register(&panic_notifier_list, &xen_panic_block);
355	return 0;
356}
357
358void xen_pin_vcpu(int cpu)
359{
360	static bool disable_pinning;
361	struct sched_pin_override pin_override;
362	int ret;
363
364	if (disable_pinning)
365		return;
366
367	pin_override.pcpu = cpu;
368	ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);
369
370	/* Ignore errors when removing override. */
371	if (cpu < 0)
372		return;
373
374	switch (ret) {
375	case -ENOSYS:
376		pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
377			cpu);
378		disable_pinning = true;
379		break;
380	case -EPERM:
381		WARN(1, "Trying to pin vcpu without having privilege to do so\n");
382		disable_pinning = true;
383		break;
384	case -EINVAL:
385	case -EBUSY:
386		pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
387			cpu);
388		break;
389	case 0:
390		break;
391	default:
392		WARN(1, "rc %d while trying to pin vcpu\n", ret);
393		disable_pinning = true;
394	}
395}
396
397#ifdef CONFIG_HOTPLUG_CPU
398void xen_arch_register_cpu(int num)
399{
400	arch_register_cpu(num);
401}
402EXPORT_SYMBOL(xen_arch_register_cpu);
403
404void xen_arch_unregister_cpu(int num)
405{
406	arch_unregister_cpu(num);
407}
408EXPORT_SYMBOL(xen_arch_unregister_cpu);
409#endif
410
411/* Amount of extra memory space we add to the e820 ranges */
412struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
413
414void __init xen_add_extra_mem(unsigned long start_pfn, unsigned long n_pfns)
415{
416	unsigned int i;
417
418	/*
419	 * No need to check for zero size, should happen rarely and will only
420	 * write a new entry regarded to be unused due to zero size.
421	 */
422	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
423		/* Add new region. */
424		if (xen_extra_mem[i].n_pfns == 0) {
425			xen_extra_mem[i].start_pfn = start_pfn;
426			xen_extra_mem[i].n_pfns = n_pfns;
427			break;
428		}
429		/* Append to existing region. */
430		if (xen_extra_mem[i].start_pfn + xen_extra_mem[i].n_pfns ==
431		    start_pfn) {
432			xen_extra_mem[i].n_pfns += n_pfns;
433			break;
434		}
435	}
436	if (i == XEN_EXTRA_MEM_MAX_REGIONS)
437		printk(KERN_WARNING "Warning: not enough extra memory regions\n");
438
439	memblock_reserve(PFN_PHYS(start_pfn), PFN_PHYS(n_pfns));
440}
441
442#ifdef CONFIG_XEN_UNPOPULATED_ALLOC
443int __init arch_xen_unpopulated_init(struct resource **res)
444{
445	unsigned int i;
446
447	if (!xen_domain())
448		return -ENODEV;
449
450	/* Must be set strictly before calling xen_free_unpopulated_pages(). */
451	*res = &iomem_resource;
452
453	/*
454	 * Initialize with pages from the extra memory regions (see
455	 * arch/x86/xen/setup.c).
456	 */
457	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
458		unsigned int j;
459
460		for (j = 0; j < xen_extra_mem[i].n_pfns; j++) {
461			struct page *pg =
462				pfn_to_page(xen_extra_mem[i].start_pfn + j);
463
464			xen_free_unpopulated_pages(1, &pg);
465		}
466
467		/*
468		 * Account for the region being in the physmap but unpopulated.
469		 * The value in xen_released_pages is used by the balloon
470		 * driver to know how much of the physmap is unpopulated and
471		 * set an accurate initial memory target.
472		 */
473		xen_unpopulated_pages += xen_extra_mem[i].n_pfns;
474		/* Zero so region is not also added to the balloon driver. */
475		xen_extra_mem[i].n_pfns = 0;
476	}
477
478	return 0;
479}
480#endif