KVM: Make KVM_PRIVATE_MEM_SLOTS optional

Seems like everyone copied x86 and defined 4 private memory slots
that never actually get used.  Even x86 only uses 3 of the 4.  These
aren't exposed so there's no need to add padding.
Reviewed-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

arch/ia64/include/asm/kvm_host.h

@@ -24,8 +24,6 @@
 #define __ASM_KVM_HOST_H
 
 #define KVM_USER_MEM_SLOTS 32
-/* memory slots that does not exposed to userspace */
-#define KVM_PRIVATE_MEM_SLOTS 4
 
 #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
 

arch/powerpc/include/asm/kvm_host.h

@@ -38,9 +38,7 @@
 #define KVM_MAX_VCPUS		NR_CPUS
 #define KVM_MAX_VCORES		NR_CPUS
 #define KVM_USER_MEM_SLOTS 32
-/* memory slots that does not exposed to userspace */
-#define KVM_PRIVATE_MEM_SLOTS 4
-#define KVM_MEM_SLOTS_NUM (KVM_USER_MEM_SLOTS + KVM_PRIVATE_MEM_SLOTS)
+#define KVM_MEM_SLOTS_NUM KVM_USER_MEM_SLOTS
 
 #ifdef CONFIG_KVM_MMIO
 #define KVM_COALESCED_MMIO_PAGE_OFFSET 1

arch/s390/include/asm/kvm_host.h

@@ -21,8 +21,6 @@
 
 #define KVM_MAX_VCPUS 64
 #define KVM_USER_MEM_SLOTS 32
-/* memory slots that does not exposed to userspace */
-#define KVM_PRIVATE_MEM_SLOTS 4
 
 struct sca_entry {
 	atomic_t scn;

arch/x86/include/asm/kvm_host.h

@@ -34,8 +34,8 @@
 #define KVM_MAX_VCPUS 254
 #define KVM_SOFT_MAX_VCPUS 160
 #define KVM_USER_MEM_SLOTS 32
-/* memory slots that does not exposed to userspace */
-#define KVM_PRIVATE_MEM_SLOTS 4
+/* 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)
 
 #define KVM_MMIO_SIZE 16

include/linux/kvm_host.h

@@ -313,6 +313,10 @@ struct kvm_irq_routing_table {};
 
 #endif
 
+#ifndef KVM_PRIVATE_MEM_SLOTS
+#define KVM_PRIVATE_MEM_SLOTS 0
+#endif
+
 #ifndef KVM_MEM_SLOTS_NUM
 #define KVM_MEM_SLOTS_NUM (KVM_USER_MEM_SLOTS + KVM_PRIVATE_MEM_SLOTS)
 #endif