diff options
Diffstat (limited to 'arch/x86/kvm/vmx/vmx.c')
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 26 |
1 files changed, 11 insertions, 15 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index c39f1c38b878..c81dc632464a 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1193,21 +1193,6 @@ static void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu) if (!pi_test_sn(pi_desc) && vcpu->cpu == cpu) return; - /* - * First handle the simple case where no cmpxchg is necessary; just - * allow posting non-urgent interrupts. - * - * If the 'nv' field is POSTED_INTR_WAKEUP_VECTOR, do not change - * PI.NDST: pi_post_block will do it for us and the wakeup_handler - * expects the VCPU to be on the blocked_vcpu_list that matches - * PI.NDST. - */ - if (pi_desc->nv == POSTED_INTR_WAKEUP_VECTOR || - vcpu->cpu == cpu) { - pi_clear_sn(pi_desc); - return; - } - /* The full case. */ do { old.control = new.control = pi_desc->control; @@ -1222,6 +1207,17 @@ static void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu) new.sn = 0; } while (cmpxchg64(&pi_desc->control, old.control, new.control) != old.control); + + /* + * Clear SN before reading the bitmap; this ensures that any + * interrupt that comes after the bitmap is read sets ON. The + * VT-d firmware * writes the bitmap and reads SN atomically (5.2.3 + * in the spec), so it doesn't really have a memory barrier that + * pairs with this. However, we cannot do that and we need one. + */ + smp_mb__after_atomic(); + if (!bitmap_empty((unsigned long *)pi_desc->pir, NR_VECTORS)) + pi_set_on(pi_desc); } /* |