KVM: x86: avoid logical_map when it is invalid

We want to support mixed modes and the easiest solution is to avoid
optimizing those weird and unlikely scenarios.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Message-Id: <1423766494-26150-4-git-send-email-rkrcmar@redhat.com>
[Add comment above KVM_APIC_MODE_* defines. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5b1bc97a258a..9477b27e8e1e 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -548,8 +548,20 @@ struct kvm_arch_memory_slot {
 	struct kvm_lpage_info *lpage_info[KVM_NR_PAGE_SIZES - 1];
 };
 
+/*
+ * We use as the mode the number of bits allocated in the LDR for the
+ * logical processor ID.  It happens that these are all powers of two.
+ * This makes it is very easy to detect cases where the APICs are
+ * configured for multiple modes; in that case, we cannot use the map and
+ * hence cannot use kvm_irq_delivery_to_apic_fast either.
+ */
+#define KVM_APIC_MODE_XAPIC_CLUSTER          4
+#define KVM_APIC_MODE_XAPIC_FLAT             8
+#define KVM_APIC_MODE_X2APIC                16
+
 struct kvm_apic_map {
 	struct rcu_head rcu;
+	u8 mode;
 	u8 ldr_bits;
 	/* fields bellow are used to decode ldr values in different modes */
 	u32 cid_shift, cid_mask, lid_mask;