kvm: x86: increase user memory slots to 509

With the 3 private slots, this gives us 512 slots total.
Motivation for this is in addition to assigned devices
support more memory hotplug slots, where 1 slot is
used by a hotplugged memory stick.
It will allow to support upto 256 hotplug memory
slots and leave 253 slots for assigned devices and
other devices that use them.
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -33,7 +33,7 @@
 
 #define KVM_MAX_VCPUS 255
 #define KVM_SOFT_MAX_VCPUS 160
-#define KVM_USER_MEM_SLOTS 125
+#define KVM_USER_MEM_SLOTS 509
 /* memory slots that are not exposed to userspace */
 #define KVM_PRIVATE_MEM_SLOTS 3
 #define KVM_MEM_SLOTS_NUM (KVM_USER_MEM_SLOTS + KVM_PRIVATE_MEM_SLOTS)