From 6b6fcd2804a2dcc86068859188708ee57c7ca19f Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 16 Sep 2021 18:15:32 +0000 Subject: [PATCH] kvm: x86: abstract locking around pvclock_update_vm_gtod_copy Updates to the kvmclock parameters needs to do a complicated dance of KVM_REQ_MCLOCK_INPROGRESS and KVM_REQ_CLOCK_UPDATE in addition to taking pvclock_gtod_sync_lock. Place that in two functions that can be called on all of master clock update, KVM_SET_CLOCK, and Hyper-V reenlightenment. Reviewed-by: Marcelo Tosatti Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 1 - arch/x86/kvm/x86.c | 62 +++++++++++++++++++---------------------- 2 files changed, 29 insertions(+), 34 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 0cb35ef..069e752 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1862,7 +1862,6 @@ u64 kvm_calc_nested_tsc_multiplier(u64 l1_multiplier, u64 l2_multiplier); unsigned long kvm_get_linear_rip(struct kvm_vcpu *vcpu); bool kvm_is_linear_rip(struct kvm_vcpu *vcpu, unsigned long linear_rip); -void kvm_make_mclock_inprogress_request(struct kvm *kvm); void kvm_make_scan_ioapic_request(struct kvm *kvm); void kvm_make_scan_ioapic_request_mask(struct kvm *kvm, unsigned long *vcpu_bitmap); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c028ff7..759ba84 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2743,35 +2743,42 @@ static void pvclock_update_vm_gtod_copy(struct kvm *kvm) #endif } -void kvm_make_mclock_inprogress_request(struct kvm *kvm) +static void kvm_make_mclock_inprogress_request(struct kvm *kvm) { kvm_make_all_cpus_request(kvm, KVM_REQ_MCLOCK_INPROGRESS); } -static void kvm_gen_update_masterclock(struct kvm *kvm) +static void kvm_start_pvclock_update(struct kvm *kvm) { -#ifdef CONFIG_X86_64 - int i; - struct kvm_vcpu *vcpu; struct kvm_arch *ka = &kvm->arch; - unsigned long flags; - - kvm_hv_invalidate_tsc_page(kvm); kvm_make_mclock_inprogress_request(kvm); /* no guest entries from this point */ - spin_lock_irqsave(&ka->pvclock_gtod_sync_lock, flags); - pvclock_update_vm_gtod_copy(kvm); - spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags); + spin_lock_irq(&ka->pvclock_gtod_sync_lock); +} +static void kvm_end_pvclock_update(struct kvm *kvm) +{ + struct kvm_arch *ka = &kvm->arch; + struct kvm_vcpu *vcpu; + int i; + + spin_unlock_irq(&ka->pvclock_gtod_sync_lock); kvm_for_each_vcpu(i, vcpu, kvm) kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); /* guest entries allowed */ kvm_for_each_vcpu(i, vcpu, kvm) kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu); -#endif +} + +static void kvm_update_masterclock(struct kvm *kvm) +{ + kvm_hv_invalidate_tsc_page(kvm); + kvm_start_pvclock_update(kvm); + pvclock_update_vm_gtod_copy(kvm); + kvm_end_pvclock_update(kvm); } u64 get_kvmclock_ns(struct kvm *kvm) @@ -6067,12 +6074,10 @@ set_pit2_out: goto out; r = 0; - /* - * TODO: userspace has to take care of races with VCPU_RUN, so - * kvm_gen_update_masterclock() can be cut down to locked - * pvclock_update_vm_gtod_copy(). - */ - kvm_gen_update_masterclock(kvm); + + kvm_hv_invalidate_tsc_page(kvm); + kvm_start_pvclock_update(kvm); + pvclock_update_vm_gtod_copy(kvm); /* * This pairs with kvm_guest_time_update(): when masterclock is @@ -6081,15 +6086,12 @@ set_pit2_out: * is slightly ahead) here we risk going negative on unsigned * 'system_time' when 'user_ns.clock' is very small. */ - spin_lock_irq(&ka->pvclock_gtod_sync_lock); if (kvm->arch.use_master_clock) now_ns = ka->master_kernel_ns; else now_ns = get_kvmclock_base_ns(); ka->kvmclock_offset = user_ns.clock - now_ns; - spin_unlock_irq(&ka->pvclock_gtod_sync_lock); - - kvm_make_all_cpus_request(kvm, KVM_REQ_CLOCK_UPDATE); + kvm_end_pvclock_update(kvm); break; } case KVM_GET_CLOCK: { @@ -8102,14 +8104,13 @@ static void tsc_khz_changed(void *data) static void kvm_hyperv_tsc_notifier(void) { struct kvm *kvm; - struct kvm_vcpu *vcpu; int cpu; - unsigned long flags; mutex_lock(&kvm_lock); list_for_each_entry(kvm, &vm_list, vm_list) kvm_make_mclock_inprogress_request(kvm); + /* no guest entries from this point */ hyperv_stop_tsc_emulation(); /* TSC frequency always matches when on Hyper-V */ @@ -8120,16 +8121,11 @@ static void kvm_hyperv_tsc_notifier(void) list_for_each_entry(kvm, &vm_list, vm_list) { struct kvm_arch *ka = &kvm->arch; - spin_lock_irqsave(&ka->pvclock_gtod_sync_lock, flags); + spin_lock_irq(&ka->pvclock_gtod_sync_lock); pvclock_update_vm_gtod_copy(kvm); - spin_unlock_irqrestore(&ka->pvclock_gtod_sync_lock, flags); - - kvm_for_each_vcpu(cpu, vcpu, kvm) - kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); - - kvm_for_each_vcpu(cpu, vcpu, kvm) - kvm_clear_request(KVM_REQ_MCLOCK_INPROGRESS, vcpu); + kvm_end_pvclock_update(kvm); } + mutex_unlock(&kvm_lock); } #endif @@ -9406,7 +9402,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) if (kvm_check_request(KVM_REQ_MIGRATE_TIMER, vcpu)) __kvm_migrate_timers(vcpu); if (kvm_check_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu)) - kvm_gen_update_masterclock(vcpu->kvm); + kvm_update_masterclock(vcpu->kvm); if (kvm_check_request(KVM_REQ_GLOBAL_CLOCK_UPDATE, vcpu)) kvm_gen_kvmclock_update(vcpu); if (kvm_check_request(KVM_REQ_CLOCK_UPDATE, vcpu)) { -- 2.7.4