KVM: s390: use switch vs jump table in intercept.c

Instead of having huge jump tables for function selection,
let's use normal switch/case statements for the instruction
handlers in intercept.c We can now also get rid of
intercept_handler_t.

This allows the compiler to make the right decision depending
on the situation (e.g. avoid jump-tables for thunks).

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

2 files changed, 29 insertions, 24 deletions

diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 9c7d70715862..07c6e81163bf 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -22,22 +22,6 @@
 #include "trace.h"
 #include "trace-s390.h"
 
-
-static const intercept_handler_t instruction_handlers[256] = {
-        [0x01] = kvm_s390_handle_01,
-        [0x82] = kvm_s390_handle_lpsw,
-        [0x83] = kvm_s390_handle_diag,
-        [0xaa] = kvm_s390_handle_aa,
-        [0xae] = kvm_s390_handle_sigp,
-        [0xb2] = kvm_s390_handle_b2,
-        [0xb6] = kvm_s390_handle_stctl,
-        [0xb7] = kvm_s390_handle_lctl,
-        [0xb9] = kvm_s390_handle_b9,
-        [0xe3] = kvm_s390_handle_e3,
-        [0xe5] = kvm_s390_handle_e5,
-        [0xeb] = kvm_s390_handle_eb,
-};
-
 u8 kvm_s390_get_ilen(struct kvm_vcpu *vcpu)
 {
         struct kvm_s390_sie_block *sie_block = vcpu->arch.sie_block;
@@ -129,16 +113,39 @@ static int handle_validity(struct kvm_vcpu *vcpu)
 
 static int handle_instruction(struct kvm_vcpu *vcpu)
 {
-        intercept_handler_t handler;
-
         vcpu->stat.exit_instruction++;
         trace_kvm_s390_intercept_instruction(vcpu,
                                              vcpu->arch.sie_block->ipa,
                                              vcpu->arch.sie_block->ipb);
-        handler = instruction_handlers[vcpu->arch.sie_block->ipa >> 8];
-        if (handler)
-                return handler(vcpu);
-        return -EOPNOTSUPP;
+
+        switch (vcpu->arch.sie_block->ipa >> 8) {
+        case 0x01:
+                return kvm_s390_handle_01(vcpu);
+        case 0x82:
+                return kvm_s390_handle_lpsw(vcpu);
+        case 0x83:
+                return kvm_s390_handle_diag(vcpu);
+        case 0xaa:
+                return kvm_s390_handle_aa(vcpu);
+        case 0xae:
+                return kvm_s390_handle_sigp(vcpu);
+        case 0xb2:
+                return kvm_s390_handle_b2(vcpu);
+        case 0xb6:
+                return kvm_s390_handle_stctl(vcpu);
+        case 0xb7:
+                return kvm_s390_handle_lctl(vcpu);
+        case 0xb9:
+                return kvm_s390_handle_b9(vcpu);
+        case 0xe3:
+                return kvm_s390_handle_e3(vcpu);
+        case 0xe5:
+                return kvm_s390_handle_e5(vcpu);
+        case 0xeb:
+                return kvm_s390_handle_eb(vcpu);
+        default:
+                return -EOPNOTSUPP;
+        }
 }
 
 static int inject_prog_on_prog_intercept(struct kvm_vcpu *vcpu)
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index bd31b37b0e6f..3c0a975c2477 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -19,8 +19,6 @@
 #include <asm/processor.h>
 #include <asm/sclp.h>
 
-typedef int (*intercept_handler_t)(struct kvm_vcpu *vcpu);
-
 /* Transactional Memory Execution related macros */
 #define IS_TE_ENABLED(vcpu)     ((vcpu->arch.sie_block->ecb & ECB_TE))
 #define TDB_FORMAT1             1