KVM: x86: bump KVM_MAX_VCPU_ID to 1023

kzalloc was replaced with kvm_kvzalloc to allow non-contiguous areas and
rcu had to be modified to cope with it.

The practical limit for KVM_MAX_VCPU_ID right now is INT_MAX, but lower
value was chosen in case there were bugs.  1023 is sufficient maximum
APIC ID for 288 VCPUs.

Signed-off-by: Radim Krčmář <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

Author: rkrcmar

arch/x86/include/asm/kvm_host.h

@@ -36,6 +36,7 @@
 
 #define KVM_MAX_VCPUS 288
 #define KVM_SOFT_MAX_VCPUS 240
+#define KVM_MAX_VCPU_ID 1023
 #define KVM_USER_MEM_SLOTS 509
 /* memory slots that are not exposed to userspace */
 #define KVM_PRIVATE_MEM_SLOTS 3

arch/x86/kvm/lapic.c

@@ -147,6 +147,13 @@ static inline bool kvm_apic_map_get_logical_dest(struct kvm_apic_map *map,
 	}
 }
 
+static void kvm_apic_map_free(struct rcu_head *rcu)
+{
+	struct kvm_apic_map *map = container_of(rcu, struct kvm_apic_map, rcu);
+
+	kvfree(map);
+}
+
 static void recalculate_apic_map(struct kvm *kvm)
 {
 	struct kvm_apic_map *new, *old = NULL;
@@ -160,8 +167,8 @@ static void recalculate_apic_map(struct kvm *kvm)
 		if (kvm_apic_present(vcpu))
 			max_id = max(max_id, kvm_apic_id(vcpu->arch.apic));
 
-	new = kzalloc(sizeof(struct kvm_apic_map) +
-	              sizeof(struct kvm_lapic *) * (max_id + 1), GFP_KERNEL);
+	new = kvm_kvzalloc(sizeof(struct kvm_apic_map) +
+	                   sizeof(struct kvm_lapic *) * ((u64)max_id + 1));
 
 	if (!new)
 		goto out;
@@ -206,7 +213,7 @@ static void recalculate_apic_map(struct kvm *kvm)
 	mutex_unlock(&kvm->arch.apic_map_lock);
 
 	if (old)
-		kfree_rcu(old, rcu);
+		call_rcu(&old->rcu, kvm_apic_map_free);
 
 	kvm_make_scan_ioapic_request(kvm);
 }

arch/x86/kvm/x86.c

@@ -7927,7 +7927,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 	kfree(kvm->arch.vpic);
 	kfree(kvm->arch.vioapic);
 	kvm_free_vcpus(kvm);
-	kfree(rcu_dereference_check(kvm->arch.apic_map, 1));
+	kvfree(rcu_dereference_check(kvm->arch.apic_map, 1));
 	kvm_mmu_uninit_vm(kvm);
 }