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Diffstat (limited to 'arch/x86/include/asm/kvm_host.h')
-rw-r--r--arch/x86/include/asm/kvm_host.h14
1 files changed, 13 insertions, 1 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0532f4e84308..59da1fbf5248 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -39,7 +39,19 @@
#define KVM_MAX_VCPUS 288
#define KVM_SOFT_MAX_VCPUS 240
-#define KVM_MAX_VCPU_ID 1023
+
+/*
+ * In x86, the VCPU ID corresponds to the APIC ID, and APIC IDs
+ * might be larger than the actual number of VCPUs because the
+ * APIC ID encodes CPU topology information.
+ *
+ * In the worst case, we'll need less than one extra bit for the
+ * Core ID, and less than one extra bit for the Package (Die) ID,
+ * so ratio of 4 should be enough.
+ */
+#define KVM_VCPU_ID_RATIO 4
+#define KVM_MAX_VCPU_ID (KVM_MAX_VCPUS * KVM_VCPU_ID_RATIO)
+
/* memory slots that are not exposed to userspace */
#define KVM_PRIVATE_MEM_SLOTS 3