diff options
Diffstat (limited to 'arch/x86/kvm/vmx/posted_intr.c')
| -rw-r--r-- | arch/x86/kvm/vmx/posted_intr.c | 35 |
1 files changed, 23 insertions, 12 deletions
diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c index 4db2b14ee7c6..88c53c521094 100644 --- a/arch/x86/kvm/vmx/posted_intr.c +++ b/arch/x86/kvm/vmx/posted_intr.c @@ -34,6 +34,20 @@ static inline struct pi_desc *vcpu_to_pi_desc(struct kvm_vcpu *vcpu) return &(to_vmx(vcpu)->pi_desc); } +static int pi_try_set_control(struct pi_desc *pi_desc, u64 old, u64 new) +{ + /* + * PID.ON can be set at any time by a different vCPU or by hardware, + * e.g. a device. PID.control must be written atomically, and the + * update must be retried with a fresh snapshot an ON change causes + * the cmpxchg to fail. + */ + if (cmpxchg64(&pi_desc->control, old, new) != old) + return -EBUSY; + + return 0; +} + void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu) { struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu); @@ -74,8 +88,7 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu) new.ndst = dest; new.sn = 0; - } while (cmpxchg64(&pi_desc->control, old.control, - new.control) != old.control); + } while (pi_try_set_control(pi_desc, old.control, new.control)); after_clear_sn: @@ -128,17 +141,17 @@ static void __pi_post_block(struct kvm_vcpu *vcpu) if (!x2apic_mode) dest = (dest << 8) & 0xFF00; + WARN(pi_desc->nv != POSTED_INTR_WAKEUP_VECTOR, + "Wakeup handler not enabled while the vCPU was blocking"); + do { old.control = new.control = READ_ONCE(pi_desc->control); - WARN(old.nv != POSTED_INTR_WAKEUP_VECTOR, - "Wakeup handler not enabled while the VCPU is blocked\n"); new.ndst = dest; /* set 'NV' to 'notification vector' */ new.nv = POSTED_INTR_VECTOR; - } while (cmpxchg64(&pi_desc->control, old.control, - new.control) != old.control); + } while (pi_try_set_control(pi_desc, old.control, new.control)); vcpu->pre_pcpu = -1; } @@ -173,17 +186,15 @@ int pi_pre_block(struct kvm_vcpu *vcpu) &per_cpu(blocked_vcpu_on_cpu, vcpu->cpu)); spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->cpu)); + WARN(pi_desc->sn == 1, + "Posted Interrupt Suppress Notification set before blocking"); + do { old.control = new.control = READ_ONCE(pi_desc->control); - WARN((pi_desc->sn == 1), - "Warning: SN field of posted-interrupts " - "is set before blocking\n"); - /* set 'NV' to 'wakeup vector' */ new.nv = POSTED_INTR_WAKEUP_VECTOR; - } while (cmpxchg64(&pi_desc->control, old.control, - new.control) != old.control); + } while (pi_try_set_control(pi_desc, old.control, new.control)); /* We should not block the vCPU if an interrupt is posted for it. */ if (pi_test_on(pi_desc)) |