From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- arch/x86/xen/smp_pv.c | 470 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 470 insertions(+) create mode 100644 arch/x86/xen/smp_pv.c (limited to 'arch/x86/xen/smp_pv.c') diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c new file mode 100644 index 000000000..e97bab7b0 --- /dev/null +++ b/arch/x86/xen/smp_pv.c @@ -0,0 +1,470 @@ +// 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +#include +#include +#include + +#include +#include +#include + +#include +#include +#include + +#include +#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(); + fpu__init_cpu(); + touch_softlockup_watchdog(); + + /* 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(); + cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); +} + +void xen_smp_intr_free_pv(unsigned int cpu) +{ + kfree(per_cpu(xen_irq_work, cpu).name); + per_cpu(xen_irq_work, cpu).name = NULL; + 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_pmu_irq, cpu).name); + per_cpu(xen_pmu_irq, 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; + } +} + +int xen_smp_intr_init_pv(unsigned int cpu) +{ + int rc; + char *callfunc_name, *pmu_name; + + callfunc_name = kasprintf(GFP_KERNEL, "irqwork%d", cpu); + per_cpu(xen_irq_work, cpu).name = callfunc_name; + 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; + + if (is_xen_pmu) { + pmu_name = kasprintf(GFP_KERNEL, "pmu%d", cpu); + per_cpu(xen_pmu_irq, cpu).name = pmu_name; + 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; + } + + return 0; + + fail: + xen_smp_intr_free_pv(cpu); + return rc; +} + +static void __init _get_smp_config(unsigned int early) +{ + int i, rc; + unsigned int subtract = 0; + + if (early) + 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) + set_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); + + 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; + + 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_prepare_cpus_common(); + + cpu_data(0).x86_max_cores = 1; + + 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) { + cpumask_clear_cpu(cpu, xen_cpu_initialized_map); + cpumask_clear_cpu(cpu, cpu_callout_mask); + return -ENOMEM; + } + + gdt = get_cpu_gdt_rw(cpu); + + /* + * 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); + + 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); + + ctxt->gs_base_kernel = per_cpu_offset(cpu); + ctxt->event_callback_eip = + (unsigned long)xen_asm_exc_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_work_run(); + inc_irq_stat(apic_irq_work_irqs); + + 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; + + /* Avoid searching for BIOS MP tables */ + x86_init.mpparse.find_smp_config = x86_init_noop; + x86_init.mpparse.get_smp_config = _get_smp_config; +} -- cgit v1.2.3