KVM: s390: interprocessor communication via sigp

This patch introduces in-kernel handling of _some_ sigp interprocessor
signals (similar to ipi).
kvm_s390_handle_sigp() decodes the sigp instruction and calls individual
handlers depending on the operation requested:
- sigp sense tries to retrieve information such as existence or running state
  of the remote cpu
- sigp emergency sends an external interrupt to the remove cpu
- sigp stop stops a remove cpu
- sigp stop store status stops a remote cpu, and stores its entire internal
  state to the cpus lowcore
- sigp set arch sets the architecture mode of the remote cpu. setting to
  ESAME (s390x 64bit) is accepted, setting to ESA/S390 (s390, 31 or 24 bit) is
  denied, all others are passed to userland
- sigp set prefix sets the prefix register of a remote cpu

For implementation of this, the stop intercept indication starts to get reused
on purpose: a set of action bits defines what to do once a cpu gets stopped:
ACTION_STOP_ON_STOP  really stops the cpu when a stop intercept is recognized
ACTION_STORE_ON_STOP stores the cpu status to lowcore when a stop intercept is
                     recognized

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/asm-s390/kvm_host.h b/include/asm-s390/kvm_host.h
index 2eaf6fede025..1c829bdf5889 100644
--- a/include/asm-s390/kvm_host.h
+++ b/include/asm-s390/kvm_host.h
@@ -128,6 +128,12 @@ struct kvm_vcpu_stat {
 	u32 instruction_chsc;
 	u32 instruction_stsi;
 	u32 instruction_stfl;
+	u32 instruction_sigp_sense;
+	u32 instruction_sigp_emergency;
+	u32 instruction_sigp_stop;
+	u32 instruction_sigp_arch;
+	u32 instruction_sigp_prefix;
+	u32 instruction_sigp_restart;
 };
 
 struct io_info {
@@ -169,6 +175,10 @@ struct interrupt_info {
 	};
 };
 
+/* for local_interrupt.action_flags */
+#define ACTION_STORE_ON_STOP 1
+#define ACTION_STOP_ON_STOP  2
+
 struct local_interrupt {
 	spinlock_t lock;
 	struct list_head list;
@@ -176,6 +186,8 @@ struct local_interrupt {
 	struct float_interrupt *float_int;
 	int timer_due; /* event indicator for waitqueue below */
 	wait_queue_head_t wq;
+	atomic_t *cpuflags;
+	unsigned int action_bits;
 };
 
 struct float_interrupt {