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 <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0cb35ef26ab38bb87586a7bc358538bd87851e25..069e75288514b5bdc147e157db668c6c8763dc34 100644 (file)
--- 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 c028ff7d6fb989fda7b6f636de8dcd493bf1f60c..759ba849e10b5e3f809d8dcafbccff825ae72867 100644 (file)
--- 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)) {