kvm: x86: vmx: NULL out hwapic_isr_update() in case of !enable_apicv

In most cases calling hwapic_isr_update(), we always check if
kvm_apic_vid_enabled() == 1, but actually,
kvm_apic_vid_enabled()
    -> kvm_x86_ops->vm_has_apicv()
        -> vmx_vm_has_apicv() or '0' in svm case
            -> return enable_apicv && irqchip_in_kernel(kvm)

So its a little cost to recall vmx_vm_has_apicv() inside
hwapic_isr_update(), here just NULL out hwapic_isr_update() in
case of !enable_apicv inside hardware_setup() then make all
related stuffs follow this. Note we don't check this under that
condition of irqchip_in_kernel() since we should make sure
definitely any caller don't work  without in-kernel irqchip.

Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 4f0c0b954686cbf5e980f761b5b9bd4f7bc2df9a..fe8bae511e99fddcacb3ab511af178508c807e6f 100644 (file)
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -402,7 +402,7 @@ static inline void apic_set_isr(int vec, struct kvm_lapic *apic)
         * because the processor can modify ISR under the hood.  Instead
         * just set SVI.
         */
-       if (unlikely(kvm_apic_vid_enabled(vcpu->kvm)))
+       if (unlikely(kvm_x86_ops->hwapic_isr_update))
                kvm_x86_ops->hwapic_isr_update(vcpu->kvm, vec);
        else {
                ++apic->isr_count;
@@ -450,7 +450,7 @@ static inline void apic_clear_isr(int vec, struct kvm_lapic *apic)
         * on the other hand isr_count and highest_isr_cache are unused
         * and must be left alone.
         */
-       if (unlikely(kvm_apic_vid_enabled(vcpu->kvm)))
+       if (unlikely(kvm_x86_ops->hwapic_isr_update))
                kvm_x86_ops->hwapic_isr_update(vcpu->kvm,
                                               apic_find_highest_isr(apic));
        else {
@@ -1742,7 +1742,9 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
        if (kvm_x86_ops->hwapic_irr_update)
                kvm_x86_ops->hwapic_irr_update(vcpu,
                                apic_find_highest_irr(apic));
-       kvm_x86_ops->hwapic_isr_update(vcpu->kvm, apic_find_highest_isr(apic));
+       if (unlikely(kvm_x86_ops->hwapic_isr_update))
+               kvm_x86_ops->hwapic_isr_update(vcpu->kvm,
+                               apic_find_highest_isr(apic));
        kvm_make_request(KVM_REQ_EVENT, vcpu);
        kvm_rtc_eoi_tracking_restore_one(vcpu);
 }

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e14c96e574ff649724142f3453f1f707467b2cc9..6e71fac27d4eea41cf3f580b3b5f721ab948ff66 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5895,6 +5895,7 @@ static __init int hardware_setup(void)
                kvm_x86_ops->update_cr8_intercept = NULL;
        else {
                kvm_x86_ops->hwapic_irr_update = NULL;
+               kvm_x86_ops->hwapic_isr_update = NULL;
                kvm_x86_ops->deliver_posted_interrupt = NULL;
                kvm_x86_ops->sync_pir_to_irr = vmx_sync_pir_to_irr_dummy;
        }
@@ -7478,9 +7479,6 @@ static void vmx_hwapic_isr_update(struct kvm *kvm, int isr)
        u16 status;
        u8 old;
 
-       if (!vmx_vm_has_apicv(kvm))
-               return;
-
        if (isr == -1)
                isr = 0;