KVM: Introduce bitmask for apic attention reasons

The patch introduces a bitmap that will hold reasons apic should be
checked during vmexit. This is in a preparation for vp eoi patch
that will add one more check on vmexit. With the bitmap we can do
if(apic_attention) to check everything simultaneously which will
add zero overhead on the fast path.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

2 files changed, 11 insertions, 5 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index f624ca72ea24..69e39bc7e36f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -172,6 +172,9 @@ enum {
 #define DR7_FIXED_1     0x00000400
 #define DR7_VOLATILE    0xffff23ff
 
+/* apic attention bits */
+#define KVM_APIC_CHECK_VAPIC    0
+
 /*
  * We don't want allocation failures within the mmu code, so we preallocate
  * enough memory for a single page fault in a cache.
@@ -337,6 +340,7 @@ struct kvm_vcpu_arch {
         u64 efer;
         u64 apic_base;
         struct kvm_lapic *apic;    /* kernel irqchip context */
+        unsigned long apic_attention;
         int32_t apic_arb_prio;
         int mp_state;
         int sipi_vector;
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 992b4eaae684..93c15743f1ee 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1088,6 +1088,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu)
         apic_update_ppr(apic);
 
         vcpu->arch.apic_arb_prio = 0;
+        vcpu->arch.apic_attention = 0;
 
         apic_debug(KERN_INFO "%s: vcpu=%p, id=%d, base_msr="
                    "0x%016" PRIx64 ", base_address=0x%0lx.\n", __func__,
@@ -1287,7 +1288,7 @@ void kvm_lapic_sync_from_vapic(struct kvm_vcpu *vcpu)
         u32 data;
         void *vapic;
 
-        if (!irqchip_in_kernel(vcpu->kvm) || !vcpu->arch.apic->vapic_addr)
+        if (!test_bit(KVM_APIC_CHECK_VAPIC, &vcpu->arch.apic_attention))
                 return;
 
         vapic = kmap_atomic(vcpu->arch.apic->vapic_page);
@@ -1304,7 +1305,7 @@ void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu)
         struct kvm_lapic *apic;
         void *vapic;
 
-        if (!irqchip_in_kernel(vcpu->kvm) || !vcpu->arch.apic->vapic_addr)
+        if (!test_bit(KVM_APIC_CHECK_VAPIC, &vcpu->arch.apic_attention))
                 return;
 
         apic = vcpu->arch.apic;
@@ -1324,10 +1325,11 @@ void kvm_lapic_sync_to_vapic(struct kvm_vcpu *vcpu)
 
 void kvm_lapic_set_vapic_addr(struct kvm_vcpu *vcpu, gpa_t vapic_addr)
 {
-        if (!irqchip_in_kernel(vcpu->kvm))
-                return;
-
         vcpu->arch.apic->vapic_addr = vapic_addr;
+        if (vapic_addr)
+                __set_bit(KVM_APIC_CHECK_VAPIC, &vcpu->arch.apic_attention);
+        else
+                __clear_bit(KVM_APIC_CHECK_VAPIC, &vcpu->arch.apic_attention);
 }
 
 int kvm_x2apic_msr_write(struct kvm_vcpu *vcpu, u32 msr, u64 data)