| /* |
| * KVM paravirt_ops implementation |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| * |
| * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com> |
| * Copyright IBM Corporation, 2007 |
| * Authors: Anthony Liguori <aliguori@us.ibm.com> |
| */ |
| |
| #include <linux/context_tracking.h> |
| #include <linux/init.h> |
| #include <linux/kernel.h> |
| #include <linux/kvm_para.h> |
| #include <linux/cpu.h> |
| #include <linux/mm.h> |
| #include <linux/highmem.h> |
| #include <linux/hardirq.h> |
| #include <linux/notifier.h> |
| #include <linux/reboot.h> |
| #include <linux/hash.h> |
| #include <linux/sched.h> |
| #include <linux/slab.h> |
| #include <linux/kprobes.h> |
| #include <linux/debugfs.h> |
| #include <linux/nmi.h> |
| #include <linux/swait.h> |
| #include <asm/timer.h> |
| #include <asm/cpu.h> |
| #include <asm/traps.h> |
| #include <asm/desc.h> |
| #include <asm/tlbflush.h> |
| #include <asm/apic.h> |
| #include <asm/apicdef.h> |
| #include <asm/hypervisor.h> |
| #include <asm/kvm_guest.h> |
| |
| static int kvmapf = 1; |
| |
| static int parse_no_kvmapf(char *arg) |
| { |
| kvmapf = 0; |
| return 0; |
| } |
| |
| early_param("no-kvmapf", parse_no_kvmapf); |
| |
| static int steal_acc = 1; |
| static int parse_no_stealacc(char *arg) |
| { |
| steal_acc = 0; |
| return 0; |
| } |
| |
| early_param("no-steal-acc", parse_no_stealacc); |
| |
| static int kvmclock_vsyscall = 1; |
| static int parse_no_kvmclock_vsyscall(char *arg) |
| { |
| kvmclock_vsyscall = 0; |
| return 0; |
| } |
| |
| early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall); |
| |
| static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64); |
| static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64); |
| static int has_steal_clock = 0; |
| |
| /* |
| * No need for any "IO delay" on KVM |
| */ |
| static void kvm_io_delay(void) |
| { |
| } |
| |
| #define KVM_TASK_SLEEP_HASHBITS 8 |
| #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS) |
| |
| struct kvm_task_sleep_node { |
| struct hlist_node link; |
| struct swait_queue_head wq; |
| u32 token; |
| int cpu; |
| bool halted; |
| }; |
| |
| static struct kvm_task_sleep_head { |
| raw_spinlock_t lock; |
| struct hlist_head list; |
| } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE]; |
| |
| static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b, |
| u32 token) |
| { |
| struct hlist_node *p; |
| |
| hlist_for_each(p, &b->list) { |
| struct kvm_task_sleep_node *n = |
| hlist_entry(p, typeof(*n), link); |
| if (n->token == token) |
| return n; |
| } |
| |
| return NULL; |
| } |
| |
| void kvm_async_pf_task_wait(u32 token) |
| { |
| u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); |
| struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; |
| struct kvm_task_sleep_node n, *e; |
| DECLARE_SWAITQUEUE(wait); |
| |
| rcu_irq_enter(); |
| |
| raw_spin_lock(&b->lock); |
| e = _find_apf_task(b, token); |
| if (e) { |
| /* dummy entry exist -> wake up was delivered ahead of PF */ |
| hlist_del(&e->link); |
| kfree(e); |
| raw_spin_unlock(&b->lock); |
| |
| rcu_irq_exit(); |
| return; |
| } |
| |
| n.token = token; |
| n.cpu = smp_processor_id(); |
| n.halted = is_idle_task(current) || preempt_count() > 1; |
| init_swait_queue_head(&n.wq); |
| hlist_add_head(&n.link, &b->list); |
| raw_spin_unlock(&b->lock); |
| |
| for (;;) { |
| if (!n.halted) |
| prepare_to_swait(&n.wq, &wait, TASK_UNINTERRUPTIBLE); |
| if (hlist_unhashed(&n.link)) |
| break; |
| |
| rcu_irq_exit(); |
| |
| if (!n.halted) { |
| local_irq_enable(); |
| schedule(); |
| local_irq_disable(); |
| } else { |
| /* |
| * We cannot reschedule. So halt. |
| */ |
| native_safe_halt(); |
| local_irq_disable(); |
| } |
| |
| rcu_irq_enter(); |
| } |
| if (!n.halted) |
| finish_swait(&n.wq, &wait); |
| |
| rcu_irq_exit(); |
| return; |
| } |
| EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait); |
| |
| static void apf_task_wake_one(struct kvm_task_sleep_node *n) |
| { |
| hlist_del_init(&n->link); |
| if (n->halted) |
| smp_send_reschedule(n->cpu); |
| else if (swq_has_sleeper(&n->wq)) |
| swake_up(&n->wq); |
| } |
| |
| static void apf_task_wake_all(void) |
| { |
| int i; |
| |
| for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) { |
| struct hlist_node *p, *next; |
| struct kvm_task_sleep_head *b = &async_pf_sleepers[i]; |
| raw_spin_lock(&b->lock); |
| hlist_for_each_safe(p, next, &b->list) { |
| struct kvm_task_sleep_node *n = |
| hlist_entry(p, typeof(*n), link); |
| if (n->cpu == smp_processor_id()) |
| apf_task_wake_one(n); |
| } |
| raw_spin_unlock(&b->lock); |
| } |
| } |
| |
| void kvm_async_pf_task_wake(u32 token) |
| { |
| u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS); |
| struct kvm_task_sleep_head *b = &async_pf_sleepers[key]; |
| struct kvm_task_sleep_node *n; |
| |
| if (token == ~0) { |
| apf_task_wake_all(); |
| return; |
| } |
| |
| again: |
| raw_spin_lock(&b->lock); |
| n = _find_apf_task(b, token); |
| if (!n) { |
| /* |
| * async PF was not yet handled. |
| * Add dummy entry for the token. |
| */ |
| n = kzalloc(sizeof(*n), GFP_ATOMIC); |
| if (!n) { |
| /* |
| * Allocation failed! Busy wait while other cpu |
| * handles async PF. |
| */ |
| raw_spin_unlock(&b->lock); |
| cpu_relax(); |
| goto again; |
| } |
| n->token = token; |
| n->cpu = smp_processor_id(); |
| init_swait_queue_head(&n->wq); |
| hlist_add_head(&n->link, &b->list); |
| } else |
| apf_task_wake_one(n); |
| raw_spin_unlock(&b->lock); |
| return; |
| } |
| EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake); |
| |
| u32 kvm_read_and_reset_pf_reason(void) |
| { |
| u32 reason = 0; |
| |
| if (__this_cpu_read(apf_reason.enabled)) { |
| reason = __this_cpu_read(apf_reason.reason); |
| __this_cpu_write(apf_reason.reason, 0); |
| } |
| |
| return reason; |
| } |
| EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason); |
| NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason); |
| |
| dotraplinkage void |
| do_async_page_fault(struct pt_regs *regs, unsigned long error_code) |
| { |
| enum ctx_state prev_state; |
| |
| switch (kvm_read_and_reset_pf_reason()) { |
| default: |
| do_page_fault(regs, error_code); |
| break; |
| case KVM_PV_REASON_PAGE_NOT_PRESENT: |
| /* page is swapped out by the host. */ |
| prev_state = exception_enter(); |
| kvm_async_pf_task_wait((u32)read_cr2()); |
| exception_exit(prev_state); |
| break; |
| case KVM_PV_REASON_PAGE_READY: |
| rcu_irq_enter(); |
| kvm_async_pf_task_wake((u32)read_cr2()); |
| rcu_irq_exit(); |
| break; |
| } |
| } |
| NOKPROBE_SYMBOL(do_async_page_fault); |
| |
| static void __init paravirt_ops_setup(void) |
| { |
| pv_info.name = "KVM"; |
| |
| if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY)) |
| pv_cpu_ops.io_delay = kvm_io_delay; |
| |
| #ifdef CONFIG_X86_IO_APIC |
| no_timer_check = 1; |
| #endif |
| } |
| |
| static void kvm_register_steal_time(void) |
| { |
| int cpu = smp_processor_id(); |
| struct kvm_steal_time *st = &per_cpu(steal_time, cpu); |
| |
| if (!has_steal_clock) |
| return; |
| |
| wrmsrl(MSR_KVM_STEAL_TIME, (slow_virt_to_phys(st) | KVM_MSR_ENABLED)); |
| pr_info("kvm-stealtime: cpu %d, msr %llx\n", |
| cpu, (unsigned long long) slow_virt_to_phys(st)); |
| } |
| |
| static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED; |
| |
| static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val) |
| { |
| /** |
| * This relies on __test_and_clear_bit to modify the memory |
| * in a way that is atomic with respect to the local CPU. |
| * The hypervisor only accesses this memory from the local CPU so |
| * there's no need for lock or memory barriers. |
| * An optimization barrier is implied in apic write. |
| */ |
| if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi))) |
| return; |
| apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK); |
| } |
| |
| static void kvm_guest_cpu_init(void) |
| { |
| if (!kvm_para_available()) |
| return; |
| |
| if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) { |
| u64 pa = slow_virt_to_phys(this_cpu_ptr(&apf_reason)); |
| |
| #ifdef CONFIG_PREEMPT |
| pa |= KVM_ASYNC_PF_SEND_ALWAYS; |
| #endif |
| pa |= KVM_ASYNC_PF_ENABLED; |
| |
| /* Async page fault support for L1 hypervisor is optional */ |
| if (wrmsr_safe(MSR_KVM_ASYNC_PF_EN, |
| (pa | KVM_ASYNC_PF_DELIVERY_AS_PF_VMEXIT) & 0xffffffff, pa >> 32) < 0) |
| wrmsrl(MSR_KVM_ASYNC_PF_EN, pa); |
| __this_cpu_write(apf_reason.enabled, 1); |
| printk(KERN_INFO"KVM setup async PF for cpu %d\n", |
| smp_processor_id()); |
| } |
| |
| if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) { |
| unsigned long pa; |
| /* Size alignment is implied but just to make it explicit. */ |
| BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4); |
| __this_cpu_write(kvm_apic_eoi, 0); |
| pa = slow_virt_to_phys(this_cpu_ptr(&kvm_apic_eoi)) |
| | KVM_MSR_ENABLED; |
| wrmsrl(MSR_KVM_PV_EOI_EN, pa); |
| } |
| |
| if (has_steal_clock) |
| kvm_register_steal_time(); |
| } |
| |
| static void kvm_pv_disable_apf(void) |
| { |
| if (!__this_cpu_read(apf_reason.enabled)) |
| return; |
| |
| wrmsrl(MSR_KVM_ASYNC_PF_EN, 0); |
| __this_cpu_write(apf_reason.enabled, 0); |
| |
| printk(KERN_INFO"Unregister pv shared memory for cpu %d\n", |
| smp_processor_id()); |
| } |
| |
| static void kvm_pv_guest_cpu_reboot(void *unused) |
| { |
| /* |
| * We disable PV EOI before we load a new kernel by kexec, |
| * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory. |
| * New kernel can re-enable when it boots. |
| */ |
| if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) |
| wrmsrl(MSR_KVM_PV_EOI_EN, 0); |
| kvm_pv_disable_apf(); |
| kvm_disable_steal_time(); |
| } |
| |
| static int kvm_pv_reboot_notify(struct notifier_block *nb, |
| unsigned long code, void *unused) |
| { |
| if (code == SYS_RESTART) |
| on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1); |
| return NOTIFY_DONE; |
| } |
| |
| static struct notifier_block kvm_pv_reboot_nb = { |
| .notifier_call = kvm_pv_reboot_notify, |
| }; |
| |
| static u64 kvm_steal_clock(int cpu) |
| { |
| u64 steal; |
| struct kvm_steal_time *src; |
| int version; |
| |
| src = &per_cpu(steal_time, cpu); |
| do { |
| version = src->version; |
| virt_rmb(); |
| steal = src->steal; |
| virt_rmb(); |
| } while ((version & 1) || (version != src->version)); |
| |
| return steal; |
| } |
| |
| void kvm_disable_steal_time(void) |
| { |
| if (!has_steal_clock) |
| return; |
| |
| wrmsr(MSR_KVM_STEAL_TIME, 0, 0); |
| } |
| |
| #ifdef CONFIG_SMP |
| static void __init kvm_smp_prepare_boot_cpu(void) |
| { |
| kvm_guest_cpu_init(); |
| native_smp_prepare_boot_cpu(); |
| kvm_spinlock_init(); |
| } |
| |
| static void kvm_guest_cpu_offline(void) |
| { |
| kvm_disable_steal_time(); |
| if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) |
| wrmsrl(MSR_KVM_PV_EOI_EN, 0); |
| kvm_pv_disable_apf(); |
| apf_task_wake_all(); |
| } |
| |
| static int kvm_cpu_online(unsigned int cpu) |
| { |
| local_irq_disable(); |
| kvm_guest_cpu_init(); |
| local_irq_enable(); |
| return 0; |
| } |
| |
| static int kvm_cpu_down_prepare(unsigned int cpu) |
| { |
| local_irq_disable(); |
| kvm_guest_cpu_offline(); |
| local_irq_enable(); |
| return 0; |
| } |
| #endif |
| |
| static void __init kvm_apf_trap_init(void) |
| { |
| update_intr_gate(X86_TRAP_PF, async_page_fault); |
| } |
| |
| void __init kvm_guest_init(void) |
| { |
| int i; |
| |
| if (!kvm_para_available()) |
| return; |
| |
| paravirt_ops_setup(); |
| register_reboot_notifier(&kvm_pv_reboot_nb); |
| for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) |
| raw_spin_lock_init(&async_pf_sleepers[i].lock); |
| if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF)) |
| x86_init.irqs.trap_init = kvm_apf_trap_init; |
| |
| if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { |
| has_steal_clock = 1; |
| pv_time_ops.steal_clock = kvm_steal_clock; |
| } |
| |
| if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) |
| apic_set_eoi_write(kvm_guest_apic_eoi_write); |
| |
| if (kvmclock_vsyscall) |
| kvm_setup_vsyscall_timeinfo(); |
| |
| #ifdef CONFIG_SMP |
| smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu; |
| if (cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "x86/kvm:online", |
| kvm_cpu_online, kvm_cpu_down_prepare) < 0) |
| pr_err("kvm_guest: Failed to install cpu hotplug callbacks\n"); |
| #else |
| kvm_guest_cpu_init(); |
| #endif |
| |
| /* |
| * Hard lockup detection is enabled by default. Disable it, as guests |
| * can get false positives too easily, for example if the host is |
| * overcommitted. |
| */ |
| hardlockup_detector_disable(); |
| } |
| |
| static noinline uint32_t __kvm_cpuid_base(void) |
| { |
| if (boot_cpu_data.cpuid_level < 0) |
| return 0; /* So we don't blow up on old processors */ |
| |
| if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) |
| return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0); |
| |
| return 0; |
| } |
| |
| static inline uint32_t kvm_cpuid_base(void) |
| { |
| static int kvm_cpuid_base = -1; |
| |
| if (kvm_cpuid_base == -1) |
| kvm_cpuid_base = __kvm_cpuid_base(); |
| |
| return kvm_cpuid_base; |
| } |
| |
| bool kvm_para_available(void) |
| { |
| return kvm_cpuid_base() != 0; |
| } |
| EXPORT_SYMBOL_GPL(kvm_para_available); |
| |
| unsigned int kvm_arch_para_features(void) |
| { |
| return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES); |
| } |
| |
| static uint32_t __init kvm_detect(void) |
| { |
| return kvm_cpuid_base(); |
| } |
| |
| const struct hypervisor_x86 x86_hyper_kvm __refconst = { |
| .name = "KVM", |
| .detect = kvm_detect, |
| .x2apic_available = kvm_para_available, |
| }; |
| EXPORT_SYMBOL_GPL(x86_hyper_kvm); |
| |
| static __init int activate_jump_labels(void) |
| { |
| if (has_steal_clock) { |
| static_key_slow_inc(¶virt_steal_enabled); |
| if (steal_acc) |
| static_key_slow_inc(¶virt_steal_rq_enabled); |
| } |
| |
| return 0; |
| } |
| arch_initcall(activate_jump_labels); |
| |
| #ifdef CONFIG_PARAVIRT_SPINLOCKS |
| |
| /* Kick a cpu by its apicid. Used to wake up a halted vcpu */ |
| static void kvm_kick_cpu(int cpu) |
| { |
| int apicid; |
| unsigned long flags = 0; |
| |
| apicid = per_cpu(x86_cpu_to_apicid, cpu); |
| kvm_hypercall2(KVM_HC_KICK_CPU, flags, apicid); |
| } |
| |
| #include <asm/qspinlock.h> |
| |
| static void kvm_wait(u8 *ptr, u8 val) |
| { |
| unsigned long flags; |
| |
| if (in_nmi()) |
| return; |
| |
| local_irq_save(flags); |
| |
| if (READ_ONCE(*ptr) != val) |
| goto out; |
| |
| /* |
| * halt until it's our turn and kicked. Note that we do safe halt |
| * for irq enabled case to avoid hang when lock info is overwritten |
| * in irq spinlock slowpath and no spurious interrupt occur to save us. |
| */ |
| if (arch_irqs_disabled_flags(flags)) |
| halt(); |
| else |
| safe_halt(); |
| |
| out: |
| local_irq_restore(flags); |
| } |
| |
| #ifdef CONFIG_X86_32 |
| __visible bool __kvm_vcpu_is_preempted(long cpu) |
| { |
| struct kvm_steal_time *src = &per_cpu(steal_time, cpu); |
| |
| return !!src->preempted; |
| } |
| PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted); |
| |
| #else |
| |
| #include <asm/asm-offsets.h> |
| |
| extern bool __raw_callee_save___kvm_vcpu_is_preempted(long); |
| |
| /* |
| * Hand-optimize version for x86-64 to avoid 8 64-bit register saving and |
| * restoring to/from the stack. |
| */ |
| asm( |
| ".pushsection .text;" |
| ".global __raw_callee_save___kvm_vcpu_is_preempted;" |
| ".type __raw_callee_save___kvm_vcpu_is_preempted, @function;" |
| "__raw_callee_save___kvm_vcpu_is_preempted:" |
| "movq __per_cpu_offset(,%rdi,8), %rax;" |
| "cmpb $0, " __stringify(KVM_STEAL_TIME_preempted) "+steal_time(%rax);" |
| "setne %al;" |
| "ret;" |
| ".popsection"); |
| |
| #endif |
| |
| /* |
| * Setup pv_lock_ops to exploit KVM_FEATURE_PV_UNHALT if present. |
| */ |
| void __init kvm_spinlock_init(void) |
| { |
| if (!kvm_para_available()) |
| return; |
| /* Does host kernel support KVM_FEATURE_PV_UNHALT? */ |
| if (!kvm_para_has_feature(KVM_FEATURE_PV_UNHALT)) |
| return; |
| |
| __pv_init_lock_hash(); |
| pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath; |
| pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock); |
| pv_lock_ops.wait = kvm_wait; |
| pv_lock_ops.kick = kvm_kick_cpu; |
| |
| if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) { |
| pv_lock_ops.vcpu_is_preempted = |
| PV_CALLEE_SAVE(__kvm_vcpu_is_preempted); |
| } |
| } |
| |
| #endif /* CONFIG_PARAVIRT_SPINLOCKS */ |