diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 7 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 82 |
2 files changed, 51 insertions, 38 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 8b16fa504cd4..68ac06fef4fa 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1086,6 +1086,11 @@ struct kvm_arch { unsigned long irq_sources_bitmap; s64 kvmclock_offset; + + /* + * This also protects nr_vcpus_matched_tsc which is read from a + * preemption-disabled region, so it must be a raw spinlock. + */ raw_spinlock_t tsc_write_lock; u64 last_tsc_nsec; u64 last_tsc_write; @@ -1096,7 +1101,7 @@ struct kvm_arch { u64 cur_tsc_generation; int nr_vcpus_matched_tsc; - spinlock_t pvclock_gtod_sync_lock; + seqcount_raw_spinlock_t pvclock_sc; bool use_master_clock; u64 master_kernel_ns; u64 master_cycle_now; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d3631d149187..d7588f6c90c8 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2521,9 +2521,7 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 data) vcpu->arch.this_tsc_write = kvm->arch.cur_tsc_write; kvm_vcpu_write_tsc_offset(vcpu, offset); - raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags); - spin_lock_irqsave(&kvm->arch.pvclock_gtod_sync_lock, flags); if (!matched) { kvm->arch.nr_vcpus_matched_tsc = 0; } else if (!already_matched) { @@ -2531,7 +2529,7 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 data) } kvm_track_tsc_matching(vcpu); - spin_unlock_irqrestore(&kvm->arch.pvclock_gtod_sync_lock, flags); + raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags); } static inline void adjust_tsc_offset_guest(struct kvm_vcpu *vcpu, @@ -2719,6 +2717,7 @@ static void pvclock_update_vm_gtod_copy(struct kvm *kvm) int vclock_mode; bool host_tsc_clocksource, vcpus_matched; + lockdep_assert_held(&kvm->arch.tsc_write_lock); vcpus_matched = (ka->nr_vcpus_matched_tsc + 1 == atomic_read(&kvm->online_vcpus)); @@ -2748,14 +2747,18 @@ static void kvm_make_mclock_inprogress_request(struct kvm *kvm) kvm_make_all_cpus_request(kvm, KVM_REQ_MCLOCK_INPROGRESS); } -static void kvm_start_pvclock_update(struct kvm *kvm) +static void __kvm_start_pvclock_update(struct kvm *kvm) { - struct kvm_arch *ka = &kvm->arch; + raw_spin_lock_irq(&kvm->arch.tsc_write_lock); + write_seqcount_begin(&kvm->arch.pvclock_sc); +} +static void kvm_start_pvclock_update(struct kvm *kvm) +{ kvm_make_mclock_inprogress_request(kvm); /* no guest entries from this point */ - spin_lock_irq(&ka->pvclock_gtod_sync_lock); + __kvm_start_pvclock_update(kvm); } static void kvm_end_pvclock_update(struct kvm *kvm) @@ -2764,7 +2767,8 @@ static void kvm_end_pvclock_update(struct kvm *kvm) struct kvm_vcpu *vcpu; int i; - spin_unlock_irq(&ka->pvclock_gtod_sync_lock); + write_seqcount_end(&ka->pvclock_sc); + raw_spin_unlock_irq(&ka->tsc_write_lock); kvm_for_each_vcpu(i, vcpu, kvm) kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); @@ -2781,29 +2785,17 @@ static void kvm_update_masterclock(struct kvm *kvm) kvm_end_pvclock_update(kvm); } -static void get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data) +/* Called within read_seqcount_begin/retry for kvm->pvclock_sc. */ +static void __get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data) { struct kvm_arch *ka = &kvm->arch; struct pvclock_vcpu_time_info hv_clock; - unsigned long flags; - - data->flags = 0; - spin_lock_irqsave(&ka->pvclock_gtod_sync_lock, flags); - if (!ka->use_master_clock) { - spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags); - data->clock = get_kvmclock_base_ns() + ka->kvmclock_offset; - return; - } - - data->flags |= KVM_CLOCK_TSC_STABLE; - hv_clock.tsc_timestamp = ka->master_cycle_now; - hv_clock.system_time = ka->master_kernel_ns + ka->kvmclock_offset; - spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags); /* both __this_cpu_read() and rdtsc() should be on the same cpu */ get_cpu(); - if (__this_cpu_read(cpu_tsc_khz)) { + data->flags = 0; + if (ka->use_master_clock && __this_cpu_read(cpu_tsc_khz)) { #ifdef CONFIG_X86_64 struct timespec64 ts; @@ -2814,6 +2806,9 @@ static void get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data) #endif data->host_tsc = rdtsc(); + data->flags |= KVM_CLOCK_TSC_STABLE; + hv_clock.tsc_timestamp = ka->master_cycle_now; + hv_clock.system_time = ka->master_kernel_ns + ka->kvmclock_offset; kvm_get_time_scale(NSEC_PER_SEC, __this_cpu_read(cpu_tsc_khz) * 1000LL, &hv_clock.tsc_shift, &hv_clock.tsc_to_system_mul); @@ -2825,6 +2820,17 @@ static void get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data) put_cpu(); } +static void get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data) +{ + struct kvm_arch *ka = &kvm->arch; + unsigned seq; + + do { + seq = read_seqcount_begin(&ka->pvclock_sc); + __get_kvmclock(kvm, data); + } while (read_seqcount_retry(&ka->pvclock_sc, seq)); +} + u64 get_kvmclock_ns(struct kvm *kvm) { struct kvm_clock_data data; @@ -2895,6 +2901,7 @@ static void kvm_setup_pvclock_page(struct kvm_vcpu *v, static int kvm_guest_time_update(struct kvm_vcpu *v) { unsigned long flags, tgt_tsc_khz; + unsigned seq; struct kvm_vcpu_arch *vcpu = &v->arch; struct kvm_arch *ka = &v->kvm->arch; s64 kernel_ns; @@ -2909,13 +2916,14 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) * If the host uses TSC clock, then passthrough TSC as stable * to the guest. */ - spin_lock_irqsave(&ka->pvclock_gtod_sync_lock, flags); - use_master_clock = ka->use_master_clock; - if (use_master_clock) { - host_tsc = ka->master_cycle_now; - kernel_ns = ka->master_kernel_ns; - } - spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags); + do { + seq = read_seqcount_begin(&ka->pvclock_sc); + use_master_clock = ka->use_master_clock; + if (use_master_clock) { + host_tsc = ka->master_cycle_now; + kernel_ns = ka->master_kernel_ns; + } + } while (read_seqcount_retry(&ka->pvclock_sc, seq)); /* Keep irq disabled to prevent changes to the clock */ local_irq_save(flags); @@ -5838,9 +5846,8 @@ int kvm_arch_pm_notifier(struct kvm *kvm, unsigned long state) static int kvm_vm_ioctl_get_clock(struct kvm *kvm, void __user *argp) { - struct kvm_clock_data data; + struct kvm_clock_data data = { 0 }; - memset(&data, 0, sizeof(data)); get_kvmclock(kvm, &data); if (copy_to_user(argp, &data, sizeof(data))) return -EFAULT; @@ -8153,9 +8160,7 @@ static void kvm_hyperv_tsc_notifier(void) kvm_max_guest_tsc_khz = tsc_khz; list_for_each_entry(kvm, &vm_list, vm_list) { - struct kvm_arch *ka = &kvm->arch; - - spin_lock_irq(&ka->pvclock_gtod_sync_lock); + __kvm_start_pvclock_update(kvm); pvclock_update_vm_gtod_copy(kvm); kvm_end_pvclock_update(kvm); } @@ -11156,6 +11161,7 @@ void kvm_arch_free_vm(struct kvm *kvm) int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) { int ret; + unsigned long flags; if (type) return -EINVAL; @@ -11179,10 +11185,12 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) raw_spin_lock_init(&kvm->arch.tsc_write_lock); mutex_init(&kvm->arch.apic_map_lock); - spin_lock_init(&kvm->arch.pvclock_gtod_sync_lock); - + seqcount_raw_spinlock_init(&kvm->arch.pvclock_sc, &kvm->arch.tsc_write_lock); kvm->arch.kvmclock_offset = -get_kvmclock_base_ns(); + + raw_spin_lock_irqsave(&kvm->arch.tsc_write_lock, flags); pvclock_update_vm_gtod_copy(kvm); + raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags); kvm->arch.guest_can_read_msr_platform_info = true; |