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

Instead of having huge jump tables for function selection,
let's use normal switch/case statements for the instruction
handlers in priv.c

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

diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index c4c4e157c03631a1d745ccafdfec111a6a08a49e..a74578cdd3f3a8ddd7be14ba9b7e7a234b2f7c91 100644 (file)
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -795,55 +795,60 @@ out:
        return rc;
 }
 
-static const intercept_handler_t b2_handlers[256] = {
-       [0x02] = handle_stidp,
-       [0x04] = handle_set_clock,
-       [0x10] = handle_set_prefix,
-       [0x11] = handle_store_prefix,
-       [0x12] = handle_store_cpu_address,
-       [0x14] = kvm_s390_handle_vsie,
-       [0x21] = handle_ipte_interlock,
-       [0x29] = handle_iske,
-       [0x2a] = handle_rrbe,
-       [0x2b] = handle_sske,
-       [0x2c] = handle_test_block,
-       [0x30] = handle_io_inst,
-       [0x31] = handle_io_inst,
-       [0x32] = handle_io_inst,
-       [0x33] = handle_io_inst,
-       [0x34] = handle_io_inst,
-       [0x35] = handle_io_inst,
-       [0x36] = handle_io_inst,
-       [0x37] = handle_io_inst,
-       [0x38] = handle_io_inst,
-       [0x39] = handle_io_inst,
-       [0x3a] = handle_io_inst,
-       [0x3b] = handle_io_inst,
-       [0x3c] = handle_io_inst,
-       [0x50] = handle_ipte_interlock,
-       [0x56] = handle_sthyi,
-       [0x5f] = handle_io_inst,
-       [0x74] = handle_io_inst,
-       [0x76] = handle_io_inst,
-       [0x7d] = handle_stsi,
-       [0xb1] = handle_stfl,
-       [0xb2] = handle_lpswe,
-};
-
 int kvm_s390_handle_b2(struct kvm_vcpu *vcpu)
 {
-       intercept_handler_t handler;
-
-       /*
-        * A lot of B2 instructions are priviledged. Here we check for
-        * the privileged ones, that we can handle in the kernel.
-        * Anything else goes to userspace.
-        */
-       handler = b2_handlers[vcpu->arch.sie_block->ipa & 0x00ff];
-       if (handler)
-               return handler(vcpu);
-
-       return -EOPNOTSUPP;
+       switch (vcpu->arch.sie_block->ipa & 0x00ff) {
+       case 0x02:
+               return handle_stidp(vcpu);
+       case 0x04:
+               return handle_set_clock(vcpu);
+       case 0x10:
+               return handle_set_prefix(vcpu);
+       case 0x11:
+               return handle_store_prefix(vcpu);
+       case 0x12:
+               return handle_store_cpu_address(vcpu);
+       case 0x14:
+               return kvm_s390_handle_vsie(vcpu);
+       case 0x21:
+       case 0x50:
+               return handle_ipte_interlock(vcpu);
+       case 0x29:
+               return handle_iske(vcpu);
+       case 0x2a:
+               return handle_rrbe(vcpu);
+       case 0x2b:
+               return handle_sske(vcpu);
+       case 0x2c:
+               return handle_test_block(vcpu);
+       case 0x30:
+       case 0x31:
+       case 0x32:
+       case 0x33:
+       case 0x34:
+       case 0x35:
+       case 0x36:
+       case 0x37:
+       case 0x38:
+       case 0x39:
+       case 0x3a:
+       case 0x3b:
+       case 0x3c:
+       case 0x5f:
+       case 0x74:
+       case 0x76:
+               return handle_io_inst(vcpu);
+       case 0x56:
+               return handle_sthyi(vcpu);
+       case 0x7d:
+               return handle_stsi(vcpu);
+       case 0xb1:
+               return handle_stfl(vcpu);
+       case 0xb2:
+               return handle_lpswe(vcpu);
+       default:
+               return -EOPNOTSUPP;
+       }
 }
 
 static int handle_epsw(struct kvm_vcpu *vcpu)
@@ -1105,25 +1110,22 @@ static int handle_essa(struct kvm_vcpu *vcpu)
        return 0;
 }
 
-static const intercept_handler_t b9_handlers[256] = {
-       [0x8a] = handle_ipte_interlock,
-       [0x8d] = handle_epsw,
-       [0x8e] = handle_ipte_interlock,
-       [0x8f] = handle_ipte_interlock,
-       [0xab] = handle_essa,
-       [0xaf] = handle_pfmf,
-};
-
 int kvm_s390_handle_b9(struct kvm_vcpu *vcpu)
 {
-       intercept_handler_t handler;
-
-       /* This is handled just as for the B2 instructions. */
-       handler = b9_handlers[vcpu->arch.sie_block->ipa & 0x00ff];
-       if (handler)
-               return handler(vcpu);
-
-       return -EOPNOTSUPP;
+       switch (vcpu->arch.sie_block->ipa & 0x00ff) {
+       case 0x8a:
+       case 0x8e:
+       case 0x8f:
+               return handle_ipte_interlock(vcpu);
+       case 0x8d:
+               return handle_epsw(vcpu);
+       case 0xab:
+               return handle_essa(vcpu);
+       case 0xaf:
+               return handle_pfmf(vcpu);
+       default:
+               return -EOPNOTSUPP;
+       }
 }
 
 int kvm_s390_handle_lctl(struct kvm_vcpu *vcpu)
@@ -1271,22 +1273,20 @@ static int handle_stctg(struct kvm_vcpu *vcpu)
        return rc ? kvm_s390_inject_prog_cond(vcpu, rc) : 0;
 }
 
-static const intercept_handler_t eb_handlers[256] = {
-       [0x2f] = handle_lctlg,
-       [0x25] = handle_stctg,
-       [0x60] = handle_ri,
-       [0x61] = handle_ri,
-       [0x62] = handle_ri,
-};
-
 int kvm_s390_handle_eb(struct kvm_vcpu *vcpu)
 {
-       intercept_handler_t handler;
-
-       handler = eb_handlers[vcpu->arch.sie_block->ipb & 0xff];
-       if (handler)
-               return handler(vcpu);
-       return -EOPNOTSUPP;
+       switch (vcpu->arch.sie_block->ipb & 0x000000ff) {
+       case 0x25:
+               return handle_stctg(vcpu);
+       case 0x2f:
+               return handle_lctlg(vcpu);
+       case 0x60:
+       case 0x61:
+       case 0x62:
+               return handle_ri(vcpu);
+       default:
+               return -EOPNOTSUPP;
+       }
 }
 
 static int handle_tprot(struct kvm_vcpu *vcpu)
@@ -1346,10 +1346,12 @@ out_unlock:
 
 int kvm_s390_handle_e5(struct kvm_vcpu *vcpu)
 {
-       /* For e5xx... instructions we only handle TPROT */
-       if ((vcpu->arch.sie_block->ipa & 0x00ff) == 0x01)
+       switch (vcpu->arch.sie_block->ipa & 0x00ff) {
+       case 0x01:
                return handle_tprot(vcpu);
-       return -EOPNOTSUPP;
+       default:
+               return -EOPNOTSUPP;
+       }
 }
 
 static int handle_sckpf(struct kvm_vcpu *vcpu)
@@ -1380,17 +1382,14 @@ static int handle_ptff(struct kvm_vcpu *vcpu)
        return 0;
 }
 
-static const intercept_handler_t x01_handlers[256] = {
-       [0x04] = handle_ptff,
-       [0x07] = handle_sckpf,
-};
-
 int kvm_s390_handle_01(struct kvm_vcpu *vcpu)
 {
-       intercept_handler_t handler;
-
-       handler = x01_handlers[vcpu->arch.sie_block->ipa & 0x00ff];
-       if (handler)
-               return handler(vcpu);
-       return -EOPNOTSUPP;
+       switch (vcpu->arch.sie_block->ipa & 0x00ff) {
+       case 0x04:
+               return handle_ptff(vcpu);
+       case 0x07:
+               return handle_sckpf(vcpu);
+       default:
+               return -EOPNOTSUPP;
+       }
 }