[thirdparty/linux.git] / arch / x86 / xen / smp_pv.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Xen SMP support
 *
 * This file implements the Xen versions of smp_ops.  SMP under Xen is
 * very straightforward.  Bringing a CPU up is simply a matter of
 * loading its initial context and setting it running.
 *
 * IPIs are handled through the Xen event mechanism.
 *
 * Because virtual CPUs can be scheduled onto any real CPU, there's no
 * useful topology information for the kernel to make use of.  As a
 * result, all CPUs are treated as if they're single-core and
 * single-threaded.
 */
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/irq_work.h>
#include <linux/tick.h>
#include <linux/nmi.h>
#include <linux/cpuhotplug.h>
#include <linux/stackprotector.h>

#include <asm/paravirt.h>
#include <asm/desc.h>
#include <asm/pgtable.h>
#include <asm/cpu.h>

#include <xen/interface/xen.h>
#include <xen/interface/vcpu.h>
#include <xen/interface/xenpmu.h>

#include <asm/spec-ctrl.h>
#include <asm/xen/interface.h>
#include <asm/xen/hypercall.h>

#include <xen/xen.h>
#include <xen/page.h>
#include <xen/events.h>

#include <xen/hvc-console.h>
#include "xen-ops.h"
#include "mmu.h"
#include "smp.h"
#include "pmu.h"

cpumask_var_t xen_cpu_initialized_map;

static DEFINE_PER_CPU(struct xen_common_irq, xen_irq_work) = { .irq = -1 };
static DEFINE_PER_CPU(struct xen_common_irq, xen_pmu_irq) = { .irq = -1 };

static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id);
void asm_cpu_bringup_and_idle(void);

static void cpu_bringup(void)
{
	int cpu;

	cr4_init();
	cpu_init();
	touch_softlockup_watchdog();
	preempt_disable();

	/* PVH runs in ring 0 and allows us to do native syscalls. Yay! */
	if (!xen_feature(XENFEAT_supervisor_mode_kernel)) {
		xen_enable_sysenter();
		xen_enable_syscall();
	}
	cpu = smp_processor_id();
	smp_store_cpu_info(cpu);
	cpu_data(cpu).x86_max_cores = 1;
	set_cpu_sibling_map(cpu);

	speculative_store_bypass_ht_init();

	xen_setup_cpu_clockevents();

	notify_cpu_starting(cpu);

	set_cpu_online(cpu, true);

	cpu_set_state_online(cpu);  /* Implies full memory barrier. */

	/* We can take interrupts now: we're officially "up". */
	local_irq_enable();
}

asmlinkage __visible void cpu_bringup_and_idle(void)
{
	cpu_bringup();
	boot_init_stack_canary();
	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
	prevent_tail_call_optimization();
}

void xen_smp_intr_free_pv(unsigned int cpu)
{
	if (per_cpu(xen_irq_work, cpu).irq >= 0) {
		unbind_from_irqhandler(per_cpu(xen_irq_work, cpu).irq, NULL);
		per_cpu(xen_irq_work, cpu).irq = -1;
		kfree(per_cpu(xen_irq_work, cpu).name);
		per_cpu(xen_irq_work, cpu).name = NULL;
	}

	if (per_cpu(xen_pmu_irq, cpu).irq >= 0) {
		unbind_from_irqhandler(per_cpu(xen_pmu_irq, cpu).irq, NULL);
		per_cpu(xen_pmu_irq, cpu).irq = -1;
		kfree(per_cpu(xen_pmu_irq, cpu).name);
		per_cpu(xen_pmu_irq, cpu).name = NULL;
	}
}

int xen_smp_intr_init_pv(unsigned int cpu)
{
	int rc;
	char *callfunc_name, *pmu_name;

	callfunc_name = kasprintf(GFP_KERNEL, "irqwork%d", cpu);
	rc = bind_ipi_to_irqhandler(XEN_IRQ_WORK_VECTOR,
				    cpu,
				    xen_irq_work_interrupt,
				    IRQF_PERCPU|IRQF_NOBALANCING,
				    callfunc_name,
				    NULL);
	if (rc < 0)
		goto fail;
	per_cpu(xen_irq_work, cpu).irq = rc;
	per_cpu(xen_irq_work, cpu).name = callfunc_name;

	if (is_xen_pmu(cpu)) {
		pmu_name = kasprintf(GFP_KERNEL, "pmu%d", cpu);
		rc = bind_virq_to_irqhandler(VIRQ_XENPMU, cpu,
					     xen_pmu_irq_handler,
					     IRQF_PERCPU|IRQF_NOBALANCING,
					     pmu_name, NULL);
		if (rc < 0)
			goto fail;
		per_cpu(xen_pmu_irq, cpu).irq = rc;
		per_cpu(xen_pmu_irq, cpu).name = pmu_name;
	}

	return 0;

 fail:
	xen_smp_intr_free_pv(cpu);
	return rc;
}

static void __init xen_fill_possible_map(void)
{
	int i, rc;

	if (xen_initial_domain())
		return;

	for (i = 0; i < nr_cpu_ids; i++) {
		rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
		if (rc >= 0) {
			num_processors++;
			set_cpu_possible(i, true);
		}
	}
}

static void __init xen_filter_cpu_maps(void)
{
	int i, rc;
	unsigned int subtract = 0;

	if (!xen_initial_domain())
		return;

	num_processors = 0;
	disabled_cpus = 0;
	for (i = 0; i < nr_cpu_ids; i++) {
		rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
		if (rc >= 0) {
			num_processors++;
			set_cpu_possible(i, true);
		} else {
			set_cpu_possible(i, false);
			set_cpu_present(i, false);
			subtract++;
		}
	}
#ifdef CONFIG_HOTPLUG_CPU
	/* This is akin to using 'nr_cpus' on the Linux command line.
	 * Which is OK as when we use 'dom0_max_vcpus=X' we can only
	 * have up to X, while nr_cpu_ids is greater than X. This
	 * normally is not a problem, except when CPU hotplugging
	 * is involved and then there might be more than X CPUs
	 * in the guest - which will not work as there is no
	 * hypercall to expand the max number of VCPUs an already
	 * running guest has. So cap it up to X. */
	if (subtract)
		nr_cpu_ids = nr_cpu_ids - subtract;
#endif

}

static void __init xen_pv_smp_prepare_boot_cpu(void)
{
	BUG_ON(smp_processor_id() != 0);
	native_smp_prepare_boot_cpu();

	if (!xen_feature(XENFEAT_writable_page_tables))
		/* We've switched to the "real" per-cpu gdt, so make
		 * sure the old memory can be recycled. */
		make_lowmem_page_readwrite(xen_initial_gdt);

#ifdef CONFIG_X86_32
	/*
	 * Xen starts us with XEN_FLAT_RING1_DS, but linux code
	 * expects __USER_DS
	 */
	loadsegment(ds, __USER_DS);
	loadsegment(es, __USER_DS);
#endif

	xen_filter_cpu_maps();
	xen_setup_vcpu_info_placement();

	/*
	 * The alternative logic (which patches the unlock/lock) runs before
	 * the smp bootup up code is activated. Hence we need to set this up
	 * the core kernel is being patched. Otherwise we will have only
	 * modules patched but not core code.
	 */
	xen_init_spinlocks();
}

static void __init xen_pv_smp_prepare_cpus(unsigned int max_cpus)
{
	unsigned cpu;
	unsigned int i;

	if (skip_ioapic_setup) {
		char *m = (max_cpus == 0) ?
			"The nosmp parameter is incompatible with Xen; " \
			"use Xen dom0_max_vcpus=1 parameter" :
			"The noapic parameter is incompatible with Xen";

		xen_raw_printk(m);
		panic(m);
	}
	xen_init_lock_cpu(0);

	smp_store_boot_cpu_info();
	cpu_data(0).x86_max_cores = 1;

	for_each_possible_cpu(i) {
		zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
		zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
		zalloc_cpumask_var(&per_cpu(cpu_die_map, i), GFP_KERNEL);
		zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
	}
	set_cpu_sibling_map(0);

	speculative_store_bypass_ht_init();

	xen_pmu_init(0);

	if (xen_smp_intr_init(0) || xen_smp_intr_init_pv(0))
		BUG();

	if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL))
		panic("could not allocate xen_cpu_initialized_map\n");

	cpumask_copy(xen_cpu_initialized_map, cpumask_of(0));

	/* Restrict the possible_map according to max_cpus. */
	while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
		for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--)
			continue;
		set_cpu_possible(cpu, false);
	}

	for_each_possible_cpu(cpu)
		set_cpu_present(cpu, true);
}

static int
cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
{
	struct vcpu_guest_context *ctxt;
	struct desc_struct *gdt;
	unsigned long gdt_mfn;

	/* used to tell cpu_init() that it can proceed with initialization */
	cpumask_set_cpu(cpu, cpu_callout_mask);
	if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
		return 0;

	ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
	if (ctxt == NULL)
		return -ENOMEM;

	gdt = get_cpu_gdt_rw(cpu);

#ifdef CONFIG_X86_32
	ctxt->user_regs.fs = __KERNEL_PERCPU;
	ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
#endif
	memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));

	/*
	 * Bring up the CPU in cpu_bringup_and_idle() with the stack
	 * pointing just below where pt_regs would be if it were a normal
	 * kernel entry.
	 */
	ctxt->user_regs.eip = (unsigned long)asm_cpu_bringup_and_idle;
	ctxt->flags = VGCF_IN_KERNEL;
	ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
	ctxt->user_regs.ds = __USER_DS;
	ctxt->user_regs.es = __USER_DS;
	ctxt->user_regs.ss = __KERNEL_DS;
	ctxt->user_regs.cs = __KERNEL_CS;
	ctxt->user_regs.esp = (unsigned long)task_pt_regs(idle);

	xen_copy_trap_info(ctxt->trap_ctxt);

	ctxt->ldt_ents = 0;

	BUG_ON((unsigned long)gdt & ~PAGE_MASK);

	gdt_mfn = arbitrary_virt_to_mfn(gdt);
	make_lowmem_page_readonly(gdt);
	make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));

	ctxt->gdt_frames[0] = gdt_mfn;
	ctxt->gdt_ents      = GDT_ENTRIES;

	/*
	 * Set SS:SP that Xen will use when entering guest kernel mode
	 * from guest user mode.  Subsequent calls to load_sp0() can
	 * change this value.
	 */
	ctxt->kernel_ss = __KERNEL_DS;
	ctxt->kernel_sp = task_top_of_stack(idle);

#ifdef CONFIG_X86_32
	ctxt->event_callback_cs     = __KERNEL_CS;
	ctxt->failsafe_callback_cs  = __KERNEL_CS;
#else
	ctxt->gs_base_kernel = per_cpu_offset(cpu);
#endif
	ctxt->event_callback_eip    =
		(unsigned long)xen_hypervisor_callback;
	ctxt->failsafe_callback_eip =
		(unsigned long)xen_failsafe_callback;
	per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);

	ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_gfn(swapper_pg_dir));
	if (HYPERVISOR_vcpu_op(VCPUOP_initialise, xen_vcpu_nr(cpu), ctxt))
		BUG();

	kfree(ctxt);
	return 0;
}

static int xen_pv_cpu_up(unsigned int cpu, struct task_struct *idle)
{
	int rc;

	rc = common_cpu_up(cpu, idle);
	if (rc)
		return rc;

	xen_setup_runstate_info(cpu);

	/*
	 * PV VCPUs are always successfully taken down (see 'while' loop
	 * in xen_cpu_die()), so -EBUSY is an error.
	 */
	rc = cpu_check_up_prepare(cpu);
	if (rc)
		return rc;

	/* make sure interrupts start blocked */
	per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;

	rc = cpu_initialize_context(cpu, idle);
	if (rc)
		return rc;

	xen_pmu_init(cpu);

	rc = HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL);
	BUG_ON(rc);

	while (cpu_report_state(cpu) != CPU_ONLINE)
		HYPERVISOR_sched_op(SCHEDOP_yield, NULL);

	return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
static int xen_pv_cpu_disable(void)
{
	unsigned int cpu = smp_processor_id();
	if (cpu == 0)
		return -EBUSY;

	cpu_disable_common();

	load_cr3(swapper_pg_dir);
	return 0;
}

static void xen_pv_cpu_die(unsigned int cpu)
{
	while (HYPERVISOR_vcpu_op(VCPUOP_is_up,
				  xen_vcpu_nr(cpu), NULL)) {
		__set_current_state(TASK_UNINTERRUPTIBLE);
		schedule_timeout(HZ/10);
	}

	if (common_cpu_die(cpu) == 0) {
		xen_smp_intr_free(cpu);
		xen_uninit_lock_cpu(cpu);
		xen_teardown_timer(cpu);
		xen_pmu_finish(cpu);
	}
}

static void xen_pv_play_dead(void) /* used only with HOTPLUG_CPU */
{
	play_dead_common();
	HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(smp_processor_id()), NULL);
	cpu_bringup();
	/*
	 * commit 4b0c0f294 (tick: Cleanup NOHZ per cpu data on cpu down)
	 * clears certain data that the cpu_idle loop (which called us
	 * and that we return from) expects. The only way to get that
	 * data back is to call:
	 */
	tick_nohz_idle_enter();
	tick_nohz_idle_stop_tick_protected();

	cpuhp_online_idle(CPUHP_AP_ONLINE_IDLE);
}

#else /* !CONFIG_HOTPLUG_CPU */
static int xen_pv_cpu_disable(void)
{
	return -ENOSYS;
}

static void xen_pv_cpu_die(unsigned int cpu)
{
	BUG();
}

static void xen_pv_play_dead(void)
{
	BUG();
}

#endif
static void stop_self(void *v)
{
	int cpu = smp_processor_id();

	/* make sure we're not pinning something down */
	load_cr3(swapper_pg_dir);
	/* should set up a minimal gdt */

	set_cpu_online(cpu, false);

	HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL);
	BUG();
}

static void xen_pv_stop_other_cpus(int wait)
{
	smp_call_function(stop_self, NULL, wait);
}

static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id)
{
	irq_enter();
	irq_work_run();
	inc_irq_stat(apic_irq_work_irqs);
	irq_exit();

	return IRQ_HANDLED;
}

static const struct smp_ops xen_smp_ops __initconst = {
	.smp_prepare_boot_cpu = xen_pv_smp_prepare_boot_cpu,
	.smp_prepare_cpus = xen_pv_smp_prepare_cpus,
	.smp_cpus_done = xen_smp_cpus_done,

	.cpu_up = xen_pv_cpu_up,
	.cpu_die = xen_pv_cpu_die,
	.cpu_disable = xen_pv_cpu_disable,
	.play_dead = xen_pv_play_dead,

	.stop_other_cpus = xen_pv_stop_other_cpus,
	.smp_send_reschedule = xen_smp_send_reschedule,

	.send_call_func_ipi = xen_smp_send_call_function_ipi,
	.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
};

void __init xen_smp_init(void)
{
	smp_ops = xen_smp_ops;
	xen_fill_possible_map();
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
83b96794 VK	2	/*
	3	* Xen SMP support
	4	*
	5	* This file implements the Xen versions of smp_ops. SMP under Xen is
	6	* very straightforward. Bringing a CPU up is simply a matter of
	7	* loading its initial context and setting it running.
	8	*
	9	* IPIs are handled through the Xen event mechanism.
	10	*
	11	* Because virtual CPUs can be scheduled onto any real CPU, there's no
	12	* useful topology information for the kernel to make use of. As a
	13	* result, all CPUs are treated as if they're single-core and
	14	* single-threaded.
	15	*/
	16	#include <linux/sched.h>
f16b3da1	17	#include <linux/sched/task_stack.h>
83b96794 VK	18	#include <linux/err.h>
	19	#include <linux/slab.h>
	20	#include <linux/smp.h>
	21	#include <linux/irq_work.h>
	22	#include <linux/tick.h>
	23	#include <linux/nmi.h>
c185ddec	24	#include <linux/cpuhotplug.h>
977e4be5	25	#include <linux/stackprotector.h>
83b96794 VK	26
	27	#include <asm/paravirt.h>
	28	#include <asm/desc.h>
	29	#include <asm/pgtable.h>
	30	#include <asm/cpu.h>
	31
	32	#include <xen/interface/xen.h>
	33	#include <xen/interface/vcpu.h>
	34	#include <xen/interface/xenpmu.h>
	35
74899d92	36	#include <asm/spec-ctrl.h>
83b96794 VK	37	#include <asm/xen/interface.h>
	38	#include <asm/xen/hypercall.h>
	39
	40	#include <xen/xen.h>
	41	#include <xen/page.h>
	42	#include <xen/events.h>
	43
	44	#include <xen/hvc-console.h>
	45	#include "xen-ops.h"
	46	#include "mmu.h"
	47	#include "smp.h"
	48	#include "pmu.h"
	49
	50	cpumask_var_t xen_cpu_initialized_map;
	51
	52	static DEFINE_PER_CPU(struct xen_common_irq, xen_irq_work) = { .irq = -1 };
	53	static DEFINE_PER_CPU(struct xen_common_irq, xen_pmu_irq) = { .irq = -1 };
	54
	55	static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id);
c3881eb5	56	void asm_cpu_bringup_and_idle(void);
83b96794 VK	57
	58	static void cpu_bringup(void)
	59	{
	60	int cpu;
	61
7652ac92	62	cr4_init();
83b96794 VK	63	cpu_init();
	64	touch_softlockup_watchdog();
	65	preempt_disable();
	66
	67	/* PVH runs in ring 0 and allows us to do native syscalls. Yay! */
	68	if (!xen_feature(XENFEAT_supervisor_mode_kernel)) {
	69	xen_enable_sysenter();
	70	xen_enable_syscall();
	71	}
	72	cpu = smp_processor_id();
	73	smp_store_cpu_info(cpu);
	74	cpu_data(cpu).x86_max_cores = 1;
	75	set_cpu_sibling_map(cpu);
	76
74899d92 JG	77	speculative_store_bypass_ht_init();
74899d92 JG	78
83b96794 VK	79	xen_setup_cpu_clockevents();
	80
	81	notify_cpu_starting(cpu);
	82
	83	set_cpu_online(cpu, true);
	84
	85	cpu_set_state_online(cpu); /* Implies full memory barrier. */
	86
	87	/* We can take interrupts now: we're officially "up". */
	88	local_irq_enable();
	89	}
	90
	91	asmlinkage __visible void cpu_bringup_and_idle(void)
	92	{
	93	cpu_bringup();
977e4be5	94	boot_init_stack_canary();
83b96794	95	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
a9a3ed1e	96	prevent_tail_call_optimization();
83b96794 VK	97	}
	98
	99	void xen_smp_intr_free_pv(unsigned int cpu)
	100	{
	101	if (per_cpu(xen_irq_work, cpu).irq >= 0) {
	102	unbind_from_irqhandler(per_cpu(xen_irq_work, cpu).irq, NULL);
	103	per_cpu(xen_irq_work, cpu).irq = -1;
	104	kfree(per_cpu(xen_irq_work, cpu).name);
	105	per_cpu(xen_irq_work, cpu).name = NULL;
	106	}
	107
	108	if (per_cpu(xen_pmu_irq, cpu).irq >= 0) {
	109	unbind_from_irqhandler(per_cpu(xen_pmu_irq, cpu).irq, NULL);
	110	per_cpu(xen_pmu_irq, cpu).irq = -1;
	111	kfree(per_cpu(xen_pmu_irq, cpu).name);
	112	per_cpu(xen_pmu_irq, cpu).name = NULL;
	113	}
	114	}
	115
	116	int xen_smp_intr_init_pv(unsigned int cpu)
	117	{
	118	int rc;
	119	char callfunc_name, pmu_name;
	120
	121	callfunc_name = kasprintf(GFP_KERNEL, "irqwork%d", cpu);
	122	rc = bind_ipi_to_irqhandler(XEN_IRQ_WORK_VECTOR,
	123	cpu,
	124	xen_irq_work_interrupt,
	125	IRQF_PERCPU\|IRQF_NOBALANCING,
	126	callfunc_name,
	127	NULL);
	128	if (rc < 0)
	129	goto fail;
	130	per_cpu(xen_irq_work, cpu).irq = rc;
	131	per_cpu(xen_irq_work, cpu).name = callfunc_name;
	132
	133	if (is_xen_pmu(cpu)) {
	134	pmu_name = kasprintf(GFP_KERNEL, "pmu%d", cpu);
	135	rc = bind_virq_to_irqhandler(VIRQ_XENPMU, cpu,
	136	xen_pmu_irq_handler,
	137	IRQF_PERCPU\|IRQF_NOBALANCING,
	138	pmu_name, NULL);
	139	if (rc < 0)
	140	goto fail;
	141	per_cpu(xen_pmu_irq, cpu).irq = rc;
	142	per_cpu(xen_pmu_irq, cpu).name = pmu_name;
	143	}
	144
	145	return 0;
	146
	147	fail:
	148	xen_smp_intr_free_pv(cpu);
	149	return rc;
	150	}
	151
	152	static void __init xen_fill_possible_map(void)
	153	{
	154	int i, rc;
	155
	156	if (xen_initial_domain())
	157	return;
	158
	159	for (i = 0; i < nr_cpu_ids; i++) {
	160	rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
161	if (rc >= 0) {
162	num_processors++;
163	set_cpu_possible(i, true);
164	}
165	}
166	}
167
168	static void __init xen_filter_cpu_maps(void)
169	{
170	int i, rc;
171	unsigned int subtract = 0;
172
173	if (!xen_initial_domain())
174	return;
175
176	num_processors = 0;
177	disabled_cpus = 0;
178	for (i = 0; i < nr_cpu_ids; i++) {
179	rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
180	if (rc >= 0) {
181	num_processors++;
182	set_cpu_possible(i, true);
183	} else {
184	set_cpu_possible(i, false);
185	set_cpu_present(i, false);
186	subtract++;
187	}
188	}
189	#ifdef CONFIG_HOTPLUG_CPU
190	/* This is akin to using 'nr_cpus' on the Linux command line.
191	* Which is OK as when we use 'dom0_max_vcpus=X' we can only
192	* have up to X, while nr_cpu_ids is greater than X. This
193	* normally is not a problem, except when CPU hotplugging
194	* is involved and then there might be more than X CPUs
195	* in the guest - which will not work as there is no
196	* hypercall to expand the max number of VCPUs an already
197	* running guest has. So cap it up to X. */
198	if (subtract)
199	nr_cpu_ids = nr_cpu_ids - subtract;
200	#endif
201
202	}
203
204	static void __init xen_pv_smp_prepare_boot_cpu(void)
205	{
206	BUG_ON(smp_processor_id() != 0);
207	native_smp_prepare_boot_cpu();
208
209	if (!xen_feature(XENFEAT_writable_page_tables))
210	/* We've switched to the "real" per-cpu gdt, so make
211	* sure the old memory can be recycled. */
212	make_lowmem_page_readwrite(xen_initial_gdt);
213
214	#ifdef CONFIG_X86_32
215	/*
216	* Xen starts us with XEN_FLAT_RING1_DS, but linux code
217	* expects __USER_DS
218	*/
219	loadsegment(ds, __USER_DS);
220	loadsegment(es, __USER_DS);
221	#endif
222
223	xen_filter_cpu_maps();
224	xen_setup_vcpu_info_placement();
225
226	/*
227	* The alternative logic (which patches the unlock/lock) runs before
228	* the smp bootup up code is activated. Hence we need to set this up
229	* the core kernel is being patched. Otherwise we will have only
230	* modules patched but not core code.
231	*/
232	xen_init_spinlocks();
233	}
234
8cb6de39	235	static void __init xen_pv_smp_prepare_cpus(unsigned int max_cpus)
83b96794 VK	236	{
	237	unsigned cpu;
	238	unsigned int i;
	239
	240	if (skip_ioapic_setup) {
	241	char *m = (max_cpus == 0) ?
	242	"The nosmp parameter is incompatible with Xen; " \
	243	"use Xen dom0_max_vcpus=1 parameter" :
	244	"The noapic parameter is incompatible with Xen";
	245
	246	xen_raw_printk(m);
	247	panic(m);
	248	}
	249	xen_init_lock_cpu(0);
	250
	251	smp_store_boot_cpu_info();
	252	cpu_data(0).x86_max_cores = 1;
	253
	254	for_each_possible_cpu(i) {
	255	zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
	256	zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
2e4c54da	257	zalloc_cpumask_var(&per_cpu(cpu_die_map, i), GFP_KERNEL);
83b96794 VK	258	zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
	259	}
	260	set_cpu_sibling_map(0);
	261
74899d92 JG	262	speculative_store_bypass_ht_init();
74899d92 JG	263
83b96794 VK	264	xen_pmu_init(0);
83b96794 VK	265
f31b9692	266	if (xen_smp_intr_init(0) \|\| xen_smp_intr_init_pv(0))
83b96794 VK	267	BUG();
	268
	269	if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL))
	270	panic("could not allocate xen_cpu_initialized_map\n");
	271
	272	cpumask_copy(xen_cpu_initialized_map, cpumask_of(0));
	273
	274	/* Restrict the possible_map according to max_cpus. */
	275	while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
	276	for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--)
	277	continue;
	278	set_cpu_possible(cpu, false);
	279	}
	280
	281	for_each_possible_cpu(cpu)
	282	set_cpu_present(cpu, true);
	283	}
	284
	285	static int
	286	cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
	287	{
	288	struct vcpu_guest_context *ctxt;
	289	struct desc_struct *gdt;
	290	unsigned long gdt_mfn;
	291
	292	/* used to tell cpu_init() that it can proceed with initialization */
	293	cpumask_set_cpu(cpu, cpu_callout_mask);
	294	if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
	295	return 0;
	296
	297	ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
	298	if (ctxt == NULL)
	299	return -ENOMEM;
	300
	301	gdt = get_cpu_gdt_rw(cpu);
	302
	303	#ifdef CONFIG_X86_32
	304	ctxt->user_regs.fs = __KERNEL_PERCPU;
	305	ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
	306	#endif
	307	memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
	308
f16b3da1 AL	309	/*
	310	* Bring up the CPU in cpu_bringup_and_idle() with the stack
	311	* pointing just below where pt_regs would be if it were a normal
	312	* kernel entry.
	313	*/
c3881eb5	314	ctxt->user_regs.eip = (unsigned long)asm_cpu_bringup_and_idle;
83b96794 VK	315	ctxt->flags = VGCF_IN_KERNEL;
	316	ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
	317	ctxt->user_regs.ds = __USER_DS;
	318	ctxt->user_regs.es = __USER_DS;
	319	ctxt->user_regs.ss = __KERNEL_DS;
f16b3da1 AL	320	ctxt->user_regs.cs = __KERNEL_CS;
f16b3da1 AL	321	ctxt->user_regs.esp = (unsigned long)task_pt_regs(idle);
83b96794 VK	322
	323	xen_copy_trap_info(ctxt->trap_ctxt);
	324
	325	ctxt->ldt_ents = 0;
	326
	327	BUG_ON((unsigned long)gdt & ~PAGE_MASK);
	328
	329	gdt_mfn = arbitrary_virt_to_mfn(gdt);
	330	make_lowmem_page_readonly(gdt);
	331	make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
	332
	333	ctxt->gdt_frames[0] = gdt_mfn;
	334	ctxt->gdt_ents = GDT_ENTRIES;
	335
f16b3da1 AL	336	/*
	337	* Set SS:SP that Xen will use when entering guest kernel mode
	338	* from guest user mode. Subsequent calls to load_sp0() can
	339	* change this value.
	340	*/
83b96794	341	ctxt->kernel_ss = __KERNEL_DS;
f16b3da1	342	ctxt->kernel_sp = task_top_of_stack(idle);
83b96794 VK	343
	344	#ifdef CONFIG_X86_32
	345	ctxt->event_callback_cs = __KERNEL_CS;
	346	ctxt->failsafe_callback_cs = __KERNEL_CS;
	347	#else
	348	ctxt->gs_base_kernel = per_cpu_offset(cpu);
	349	#endif
	350	ctxt->event_callback_eip =
	351	(unsigned long)xen_hypervisor_callback;
	352	ctxt->failsafe_callback_eip =
	353	(unsigned long)xen_failsafe_callback;
83b96794 VK	354	per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
83b96794 VK	355
83b96794 VK	356	ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_gfn(swapper_pg_dir));
	357	if (HYPERVISOR_vcpu_op(VCPUOP_initialise, xen_vcpu_nr(cpu), ctxt))
	358	BUG();
	359
	360	kfree(ctxt);
	361	return 0;
	362	}
	363
8cb6de39	364	static int xen_pv_cpu_up(unsigned int cpu, struct task_struct *idle)
83b96794 VK	365	{
	366	int rc;
	367
66c7ceb4 TG	368	rc = common_cpu_up(cpu, idle);
	369	if (rc)
	370	return rc;
83b96794 VK	371
	372	xen_setup_runstate_info(cpu);
	373
	374	/*
	375	* PV VCPUs are always successfully taken down (see 'while' loop
	376	* in xen_cpu_die()), so -EBUSY is an error.
	377	*/
	378	rc = cpu_check_up_prepare(cpu);
	379	if (rc)
	380	return rc;
	381
	382	/* make sure interrupts start blocked */
	383	per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
	384
	385	rc = cpu_initialize_context(cpu, idle);
	386	if (rc)
	387	return rc;
	388
	389	xen_pmu_init(cpu);
	390
	391	rc = HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL);
	392	BUG_ON(rc);
	393
	394	while (cpu_report_state(cpu) != CPU_ONLINE)
	395	HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
	396
	397	return 0;
	398	}
	399
83b96794	400	#ifdef CONFIG_HOTPLUG_CPU
8cb6de39	401	static int xen_pv_cpu_disable(void)
83b96794 VK	402	{
	403	unsigned int cpu = smp_processor_id();
	404	if (cpu == 0)
	405	return -EBUSY;
	406
	407	cpu_disable_common();
	408
	409	load_cr3(swapper_pg_dir);
	410	return 0;
	411	}
	412
	413	static void xen_pv_cpu_die(unsigned int cpu)
	414	{
	415	while (HYPERVISOR_vcpu_op(VCPUOP_is_up,
	416	xen_vcpu_nr(cpu), NULL)) {
	417	__set_current_state(TASK_UNINTERRUPTIBLE);
	418	schedule_timeout(HZ/10);
	419	}
	420
	421	if (common_cpu_die(cpu) == 0) {
	422	xen_smp_intr_free(cpu);
	423	xen_uninit_lock_cpu(cpu);
	424	xen_teardown_timer(cpu);
	425	xen_pmu_finish(cpu);
	426	}
	427	}
	428
8cb6de39	429	static void xen_pv_play_dead(void) /* used only with HOTPLUG_CPU */
83b96794 VK	430	{
	431	play_dead_common();
	432	HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(smp_processor_id()), NULL);
	433	cpu_bringup();
	434	/*
	435	* commit 4b0c0f294 (tick: Cleanup NOHZ per cpu data on cpu down)
	436	* clears certain data that the cpu_idle loop (which called us
	437	* and that we return from) expects. The only way to get that
	438	* data back is to call:
	439	*/
	440	tick_nohz_idle_enter();
0e776768	441	tick_nohz_idle_stop_tick_protected();
83b96794	442
c185ddec	443	cpuhp_online_idle(CPUHP_AP_ONLINE_IDLE);
83b96794 VK	444	}
	445
	446	#else /* !CONFIG_HOTPLUG_CPU */
8cb6de39	447	static int xen_pv_cpu_disable(void)
83b96794 VK	448	{
	449	return -ENOSYS;
	450	}
	451
	452	static void xen_pv_cpu_die(unsigned int cpu)
	453	{
	454	BUG();
	455	}
	456
8cb6de39	457	static void xen_pv_play_dead(void)
83b96794 VK	458	{
	459	BUG();
	460	}
	461
	462	#endif
	463	static void stop_self(void *v)
	464	{
	465	int cpu = smp_processor_id();
	466
	467	/* make sure we're not pinning something down */
	468	load_cr3(swapper_pg_dir);
	469	/* should set up a minimal gdt */
	470
	471	set_cpu_online(cpu, false);
	472
	473	HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL);
	474	BUG();
	475	}
	476
8cb6de39	477	static void xen_pv_stop_other_cpus(int wait)
83b96794 VK	478	{
	479	smp_call_function(stop_self, NULL, wait);
	480	}
	481
83b96794 VK	482	static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id)
	483	{
	484	irq_enter();
	485	irq_work_run();
	486	inc_irq_stat(apic_irq_work_irqs);
	487	irq_exit();
	488
	489	return IRQ_HANDLED;
	490	}
	491
	492	static const struct smp_ops xen_smp_ops __initconst = {
	493	.smp_prepare_boot_cpu = xen_pv_smp_prepare_boot_cpu,
8cb6de39	494	.smp_prepare_cpus = xen_pv_smp_prepare_cpus,
ae039001	495	.smp_cpus_done = xen_smp_cpus_done,
83b96794	496
8cb6de39	497	.cpu_up = xen_pv_cpu_up,
83b96794	498	.cpu_die = xen_pv_cpu_die,
8cb6de39 VK	499	.cpu_disable = xen_pv_cpu_disable,
8cb6de39 VK	500	.play_dead = xen_pv_play_dead,
83b96794	501
8cb6de39	502	.stop_other_cpus = xen_pv_stop_other_cpus,
83b96794 VK	503	.smp_send_reschedule = xen_smp_send_reschedule,
	504
	505	.send_call_func_ipi = xen_smp_send_call_function_ipi,
	506	.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
	507	};
	508
	509	void __init xen_smp_init(void)
	510	{
	511	smp_ops = xen_smp_ops;
	512	xen_fill_possible_map();
	513	}