KVM: ppc: Add DCR access information to struct kvm_run

Device Control Registers are essentially another address space found on PowerPC
4xx processors, analogous to PIO on x86. DCRs are always 32 bits, and can be
identified by a 32-bit number. We forward most DCR accesses to userspace for
emulation (with the exception of CPR0 registers, which can be read directly
for simplicity in timebase frequency determination).

Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

include/linux/kvm.h

@@ -82,6 +82,7 @@ struct kvm_irqchip {
 #define KVM_EXIT_TPR_ACCESS       12
 #define KVM_EXIT_S390_SIEIC       13
 #define KVM_EXIT_S390_RESET       14
+#define KVM_EXIT_DCR              15
 
 /* for KVM_RUN, returned by mmap(vcpu_fd, offset=0) */
 struct kvm_run {
@@ -161,6 +162,12 @@ struct kvm_run {
 #define KVM_S390_RESET_CPU_INIT  8
 #define KVM_S390_RESET_IPL       16
 		__u64 s390_reset_flags;
+		/* KVM_EXIT_DCR */
+		struct {
+			__u32 dcrn;
+			__u32 data;
+			__u8  is_write;
+		} dcr;
 		/* Fix the size of the union. */
 		char padding[256];
 	};