KVM: Accelerated apic support

This adds a mechanism for exposing the virtual apic tpr to the guest, and a
protocol for letting the guest update the tpr without causing a vmexit if
conditions allow (e.g. there is no interrupt pending with a higher priority
than the new tpr).

Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c2b80884447e..e7eac27adb7f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1173,6 +1173,19 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
                 r = 0;
                 break;
         };
+        case KVM_SET_VAPIC_ADDR: {
+                struct kvm_vapic_addr va;
+
+                r = -EINVAL;
+                if (!irqchip_in_kernel(vcpu->kvm))
+                        goto out;
+                r = -EFAULT;
+                if (copy_from_user(&va, argp, sizeof va))
+                        goto out;
+                r = 0;
+                kvm_lapic_set_vapic_addr(vcpu, va.vapic_addr);
+                break;
+        }
         default:
                 r = -EINVAL;
         }
@@ -2214,6 +2227,9 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
         }
 
         switch (nr) {
+        case KVM_HC_VAPIC_POLL_IRQ:
+                ret = 0;
+                break;
         default:
                 ret = -KVM_ENOSYS;
                 break;
@@ -2421,6 +2437,29 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu,
                                          vcpu->arch.irq_summary == 0);
 }
 
+static void vapic_enter(struct kvm_vcpu *vcpu)
+{
+        struct kvm_lapic *apic = vcpu->arch.apic;
+        struct page *page;
+
+        if (!apic || !apic->vapic_addr)
+                return;
+
+        page = gfn_to_page(vcpu->kvm, apic->vapic_addr >> PAGE_SHIFT);
+        vcpu->arch.apic->vapic_page = page;
+}
+
+static void vapic_exit(struct kvm_vcpu *vcpu)
+{
+        struct kvm_lapic *apic = vcpu->arch.apic;
+
+        if (!apic || !apic->vapic_addr)
+                return;
+
+        kvm_release_page_dirty(apic->vapic_page);
+        mark_page_dirty(vcpu->kvm, apic->vapic_addr >> PAGE_SHIFT);
+}
+
 static int __vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
         int r;
@@ -2435,6 +2474,8 @@ static int __vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
                 vcpu->arch.mp_state = VCPU_MP_STATE_RUNNABLE;
         }
 
+        vapic_enter(vcpu);
+
 preempted:
         if (vcpu->guest_debug.enabled)
                 kvm_x86_ops->guest_debug_pre(vcpu);
@@ -2444,6 +2485,14 @@ again:
         if (unlikely(r))
                 goto out;
 
+        if (vcpu->requests)
+                if (test_and_clear_bit(KVM_REQ_REPORT_TPR_ACCESS,
+                                       &vcpu->requests)) {
+                        kvm_run->exit_reason = KVM_EXIT_TPR_ACCESS;
+                        r = 0;
+                        goto out;
+                }
+
         kvm_inject_pending_timer_irqs(vcpu);
 
         preempt_disable();
@@ -2469,6 +2518,8 @@ again:
         else
                 kvm_x86_ops->inject_pending_vectors(vcpu, kvm_run);
 
+        kvm_lapic_sync_to_vapic(vcpu);
+
         vcpu->guest_mode = 1;
         kvm_guest_enter();
 
@@ -2506,6 +2557,8 @@ again:
         if (vcpu->arch.exception.pending && kvm_x86_ops->exception_injected(vcpu))
                 vcpu->arch.exception.pending = false;
 
+        kvm_lapic_sync_from_vapic(vcpu);
+
         r = kvm_x86_ops->handle_exit(kvm_run, vcpu);
 
         if (r > 0) {
@@ -2527,6 +2580,8 @@ out:
 
         post_kvm_run_save(vcpu, kvm_run);
 
+        vapic_exit(vcpu);
+
         return r;
 }