KVM: s390: Add support for channel I/O instructions.

Add a new capability, KVM_CAP_S390_CSS_SUPPORT, which will pass
intercepts for channel I/O instructions to userspace. Only I/O
instructions interacting with I/O interrupts need to be handled
in-kernel:

- TEST PENDING INTERRUPTION (tpi) dequeues and stores pending
  interrupts entirely in-kernel.
- TEST SUBCHANNEL (tsch) dequeues pending interrupts in-kernel
  and exits via KVM_EXIT_S390_TSCH to userspace for subchannel-
  related processing.

Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

2 files changed, 12 insertions, 1 deletions

diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h
index 7ef9e759f499..a23f47c884cf 100644
--- a/include/trace/events/kvm.h
+++ b/include/trace/events/kvm.h
@@ -14,7 +14,7 @@
         ERSN(SHUTDOWN), ERSN(FAIL_ENTRY), ERSN(INTR), ERSN(SET_TPR),    \
         ERSN(TPR_ACCESS), ERSN(S390_SIEIC), ERSN(S390_RESET), ERSN(DCR),\
         ERSN(NMI), ERSN(INTERNAL_ERROR), ERSN(OSI), ERSN(PAPR_HCALL),   \
-        ERSN(S390_UCONTROL)
+        ERSN(S390_UCONTROL), ERSN(S390_TSCH)
 
 TRACE_EVENT(kvm_userspace_exit,
             TP_PROTO(__u32 reason, int errno),
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 80bb3b801116..8bb0bf83afc5 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -168,6 +168,7 @@ struct kvm_pit_config {
 #define KVM_EXIT_PAPR_HCALL       19
 #define KVM_EXIT_S390_UCONTROL    20
 #define KVM_EXIT_WATCHDOG         21
+#define KVM_EXIT_S390_TSCH        22
 
 /* For KVM_EXIT_INTERNAL_ERROR */
 /* Emulate instruction failed. */
@@ -285,6 +286,15 @@ struct kvm_run {
                         __u64 ret;
                         __u64 args[9];
                 } papr_hcall;
+                /* KVM_EXIT_S390_TSCH */
+                struct {
+                        __u16 subchannel_id;
+                        __u16 subchannel_nr;
+                        __u32 io_int_parm;
+                        __u32 io_int_word;
+                        __u32 ipb;
+                        __u8 dequeued;
+                } s390_tsch;
                 /* Fix the size of the union. */
                 char padding[256];
         };
@@ -645,6 +655,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_IRQFD_RESAMPLE 82
 #define KVM_CAP_PPC_BOOKE_WATCHDOG 83
 #define KVM_CAP_PPC_HTAB_FD 84
+#define KVM_CAP_S390_CSS_SUPPORT 85
 
 #ifdef KVM_CAP_IRQ_ROUTING