s390/kvm: remove explicit -EFAULT return code checking on guest access

Let's change to the paradigm that every return code from guest memory
access functions that is not zero translates to -EFAULT and do not
explictly compare.
Explictly comparing the return value with -EFAULT has already shown to
be a bit fragile. In addition this is closer to the handling of
copy_to/from_user functions, which imho is in general a good idea.

Also shorten the return code handling in interrupt.c a bit.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index f26ff1e..9b22047 100644 (file)
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -45,7 +45,7 @@ static int handle_lctlg(struct kvm_vcpu *vcpu)
        do {
                rc = get_guest_u64(vcpu, useraddr,
                                   &vcpu->arch.sie_block->gcr[reg]);
-               if (rc == -EFAULT) {
+               if (rc) {
                        kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
                        break;
                }
@@ -79,7 +79,7 @@ static int handle_lctl(struct kvm_vcpu *vcpu)
        reg = reg1;
        do {
                rc = get_guest_u32(vcpu, useraddr, &val);
-               if (rc == -EFAULT) {
+               if (rc) {
                        kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
                        break;
                }

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 37116a7..5afa931 100644 (file)
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -180,7 +180,7 @@ static void __do_deliver_interrupt(struct kvm_vcpu *vcpu,
                                   struct kvm_s390_interrupt_info *inti)
 {
        const unsigned short table[] = { 2, 4, 4, 6 };
-       int rc, exception = 0;
+       int rc = 0;
 
        switch (inti->type) {
        case KVM_S390_INT_EMERGENCY:
@@ -188,74 +188,38 @@ static void __do_deliver_interrupt(struct kvm_vcpu *vcpu,
                vcpu->stat.deliver_emergency_signal++;
                trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id, inti->type,
                                                 inti->emerg.code, 0);
-               rc = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x1201);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = put_guest_u16(vcpu, __LC_EXT_CPU_ADDR, inti->emerg.code);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
-                        &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
-                       __LC_EXT_NEW_PSW, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
+               rc  = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x1201);
+               rc |= put_guest_u16(vcpu, __LC_EXT_CPU_ADDR, inti->emerg.code);
+               rc |= copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
+                                   &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
+               rc |= copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
+                                     __LC_EXT_NEW_PSW, sizeof(psw_t));
                break;
-
        case KVM_S390_INT_EXTERNAL_CALL:
                VCPU_EVENT(vcpu, 4, "%s", "interrupt: sigp ext call");
                vcpu->stat.deliver_external_call++;
                trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id, inti->type,
                                                 inti->extcall.code, 0);
-               rc = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x1202);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = put_guest_u16(vcpu, __LC_EXT_CPU_ADDR, inti->extcall.code);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
-                        &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
-                       __LC_EXT_NEW_PSW, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
+               rc  = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x1202);
+               rc |= put_guest_u16(vcpu, __LC_EXT_CPU_ADDR, inti->extcall.code);
+               rc |= copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
+                                   &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
+               rc |= copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
+                                     __LC_EXT_NEW_PSW, sizeof(psw_t));
                break;
-
        case KVM_S390_INT_SERVICE:
                VCPU_EVENT(vcpu, 4, "interrupt: sclp parm:%x",
                           inti->ext.ext_params);
                vcpu->stat.deliver_service_signal++;
                trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id, inti->type,
                                                 inti->ext.ext_params, 0);
-               rc = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x2401);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
-                        &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
-                       __LC_EXT_NEW_PSW, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = put_guest_u32(vcpu, __LC_EXT_PARAMS, inti->ext.ext_params);
-               if (rc == -EFAULT)
-                       exception = 1;
+               rc  = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x2401);
+               rc |= copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
+                                   &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
+               rc |= copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
+                                     __LC_EXT_NEW_PSW, sizeof(psw_t));
+               rc |= put_guest_u32(vcpu, __LC_EXT_PARAMS, inti->ext.ext_params);
                break;
-
        case KVM_S390_INT_VIRTIO:
                VCPU_EVENT(vcpu, 4, "interrupt: virtio parm:%x,parm64:%llx",
                           inti->ext.ext_params, inti->ext.ext_params2);
@@ -263,34 +227,16 @@ static void __do_deliver_interrupt(struct kvm_vcpu *vcpu,
                trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id, inti->type,
                                                 inti->ext.ext_params,
                                                 inti->ext.ext_params2);
-               rc = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x2603);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = put_guest_u16(vcpu, __LC_EXT_CPU_ADDR, 0x0d00);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
-                        &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
-                       __LC_EXT_NEW_PSW, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = put_guest_u32(vcpu, __LC_EXT_PARAMS, inti->ext.ext_params);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = put_guest_u64(vcpu, __LC_EXT_PARAMS2,
-                                  inti->ext.ext_params2);
-               if (rc == -EFAULT)
-                       exception = 1;
+               rc  = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x2603);
+               rc |= put_guest_u16(vcpu, __LC_EXT_CPU_ADDR, 0x0d00);
+               rc |= copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
+                                   &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
+               rc |= copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
+                                     __LC_EXT_NEW_PSW, sizeof(psw_t));
+               rc |= put_guest_u32(vcpu, __LC_EXT_PARAMS, inti->ext.ext_params);
+               rc |= put_guest_u64(vcpu, __LC_EXT_PARAMS2,
+                                   inti->ext.ext_params2);
                break;
-
        case KVM_S390_SIGP_STOP:
                VCPU_EVENT(vcpu, 4, "%s", "interrupt: cpu stop");
                vcpu->stat.deliver_stop_signal++;
@@ -313,18 +259,14 @@ static void __do_deliver_interrupt(struct kvm_vcpu *vcpu,
                vcpu->stat.deliver_restart_signal++;
                trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id, inti->type,
                                                 0, 0);
-               rc = copy_to_guest(vcpu, offsetof(struct _lowcore,
-                 restart_old_psw), &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
-                       offsetof(struct _lowcore, restart_psw), sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
+               rc  = copy_to_guest(vcpu,
+                                   offsetof(struct _lowcore, restart_old_psw),
+                                   &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
+               rc |= copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
+                                     offsetof(struct _lowcore, restart_psw),
+                                     sizeof(psw_t));
                atomic_clear_mask(CPUSTAT_STOPPED, &vcpu->arch.sie_block->cpuflags);
                break;
-
        case KVM_S390_PROGRAM_INT:
                VCPU_EVENT(vcpu, 4, "interrupt: pgm check code:%x, ilc:%x",
                           inti->pgm.code,
@@ -332,24 +274,13 @@ static void __do_deliver_interrupt(struct kvm_vcpu *vcpu,
                vcpu->stat.deliver_program_int++;
                trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id, inti->type,
                                                 inti->pgm.code, 0);
-               rc = put_guest_u16(vcpu, __LC_PGM_INT_CODE, inti->pgm.code);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = put_guest_u16(vcpu, __LC_PGM_ILC,
-                       table[vcpu->arch.sie_block->ipa >> 14]);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_to_guest(vcpu, __LC_PGM_OLD_PSW,
-                        &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
-                       __LC_PGM_NEW_PSW, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
+               rc  = put_guest_u16(vcpu, __LC_PGM_INT_CODE, inti->pgm.code);
+               rc |= put_guest_u16(vcpu, __LC_PGM_ILC,
+                                   table[vcpu->arch.sie_block->ipa >> 14]);
+               rc |= copy_to_guest(vcpu, __LC_PGM_OLD_PSW,
+                                   &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
+               rc |= copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
+                                     __LC_PGM_NEW_PSW, sizeof(psw_t));
                break;
 
        case KVM_S390_MCHK:
@@ -358,24 +289,13 @@ static void __do_deliver_interrupt(struct kvm_vcpu *vcpu,
                trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id, inti->type,
                                                 inti->mchk.cr14,
                                                 inti->mchk.mcic);
-               rc = kvm_s390_vcpu_store_status(vcpu,
-                                               KVM_S390_STORE_STATUS_PREFIXED);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = put_guest_u64(vcpu, __LC_MCCK_CODE, inti->mchk.mcic);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_to_guest(vcpu, __LC_MCK_OLD_PSW,
-                                  &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
-                                    __LC_MCK_NEW_PSW, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
+               rc  = kvm_s390_vcpu_store_status(vcpu,
+                                                KVM_S390_STORE_STATUS_PREFIXED);
+               rc |= put_guest_u64(vcpu, __LC_MCCK_CODE, inti->mchk.mcic);
+               rc |= copy_to_guest(vcpu, __LC_MCK_OLD_PSW,
+                                   &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
+               rc |= copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
+                                     __LC_MCK_NEW_PSW, sizeof(psw_t));
                break;
 
        case KVM_S390_INT_IO_MIN...KVM_S390_INT_IO_MAX:
@@ -388,67 +308,44 @@ static void __do_deliver_interrupt(struct kvm_vcpu *vcpu,
                vcpu->stat.deliver_io_int++;
                trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id, inti->type,
                                                 param0, param1);
-               rc = put_guest_u16(vcpu, __LC_SUBCHANNEL_ID,
-                                  inti->io.subchannel_id);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = put_guest_u16(vcpu, __LC_SUBCHANNEL_NR,
-                                  inti->io.subchannel_nr);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = put_guest_u32(vcpu, __LC_IO_INT_PARM,
-                                  inti->io.io_int_parm);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = put_guest_u32(vcpu, __LC_IO_INT_WORD,
-                                  inti->io.io_int_word);
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_to_guest(vcpu, __LC_IO_OLD_PSW,
-                                  &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
-
-               rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
-                                    __LC_IO_NEW_PSW, sizeof(psw_t));
-               if (rc == -EFAULT)
-                       exception = 1;
+               rc  = put_guest_u16(vcpu, __LC_SUBCHANNEL_ID,
+                                   inti->io.subchannel_id);
+               rc |= put_guest_u16(vcpu, __LC_SUBCHANNEL_NR,
+                                   inti->io.subchannel_nr);
+               rc |= put_guest_u32(vcpu, __LC_IO_INT_PARM,
+                                   inti->io.io_int_parm);
+               rc |= put_guest_u32(vcpu, __LC_IO_INT_WORD,
+                                   inti->io.io_int_word);
+               rc |= copy_to_guest(vcpu, __LC_IO_OLD_PSW,
+                                   &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
+               rc |= copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
+                                     __LC_IO_NEW_PSW, sizeof(psw_t));
                break;
        }
        default:
                BUG();
        }
-       if (exception) {
+       if (rc) {
                printk("kvm: The guest lowcore is not mapped during interrupt "
-                       "delivery, killing userspace\n");
+                      "delivery, killing userspace\n");
                do_exit(SIGKILL);
        }
 }
 
 static int __try_deliver_ckc_interrupt(struct kvm_vcpu *vcpu)
 {
-       int rc, exception = 0;
+       int rc;
 
        if (psw_extint_disabled(vcpu))
                return 0;
        if (!(vcpu->arch.sie_block->gcr[0] & 0x800ul))
                return 0;
-       rc = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x1004);
-       if (rc == -EFAULT)
-               exception = 1;
-       rc = copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
-                &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
-       if (rc == -EFAULT)
-               exception = 1;
-       rc = copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
-               __LC_EXT_NEW_PSW, sizeof(psw_t));
-       if (rc == -EFAULT)
-               exception = 1;
-       if (exception) {
+       rc  = put_guest_u16(vcpu, __LC_EXT_INT_CODE, 0x1004);
+       rc |= copy_to_guest(vcpu, __LC_EXT_OLD_PSW,
+                           &vcpu->arch.sie_block->gpsw, sizeof(psw_t));
+       rc |= copy_from_guest(vcpu, &vcpu->arch.sie_block->gpsw,
+                             __LC_EXT_NEW_PSW, sizeof(psw_t));
+       if (rc) {
                printk("kvm: The guest lowcore is not mapped during interrupt "
                        "delivery, killing userspace\n");
                do_exit(SIGKILL);

diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 75ad91e..34b42dc 100644 (file)
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -108,7 +108,7 @@ static int handle_store_cpu_address(struct kvm_vcpu *vcpu)
        }
 
        rc = put_guest_u16(vcpu, useraddr, vcpu->vcpu_id);
-       if (rc == -EFAULT) {
+       if (rc) {
                kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
                goto out;
        }
@@ -230,7 +230,7 @@ static int handle_stfl(struct kvm_vcpu *vcpu)
 
        rc = copy_to_guest(vcpu, offsetof(struct _lowcore, stfl_fac_list),
                           &facility_list, sizeof(facility_list));
-       if (rc == -EFAULT)
+       if (rc)
                kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
        else {
                VCPU_EVENT(vcpu, 5, "store facility list value %x",
@@ -348,7 +348,7 @@ static int handle_stidp(struct kvm_vcpu *vcpu)
        }
 
        rc = put_guest_u64(vcpu, operand2, vcpu->arch.stidp_data);
-       if (rc == -EFAULT) {
+       if (rc) {
                kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
                goto out;
        }