[PATCH] KVM: s390: Pass initialized arg even if unused

Janis Schoetterl-Glausch
2022-08-24T15:31:01Z

This silences smatch warnings reported by kbuild bot:
arch/s390/kvm/gaccess.c:859 guest_range_to_gpas() error: uninitialized symbol 'prot'.
arch/s390/kvm/gaccess.c:1064 access_guest_with_key() error: uninitialized symbol 'prot'.

This is because it cannot tell that the value is not used in this case.
The trans_exc* only examine prot if code is PGM_PROTECTION.
Pass a dummy value for other codes.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
---
arch/s390/kvm/gaccess.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index 082ec5f2c3a5..89186701116a 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -489,6 +489,8 @@ enum prot_type {
PROT_TYPE_ALC = 2,
PROT_TYPE_DAT = 3,
PROT_TYPE_IEP = 4,
+ /* Dummy value for passing an initialized value when code != PGM_PROTECTION */
+ PROT_NONE,
};

static int trans_exc_ending(struct kvm_vcpu *vcpu, int code, unsigned long gva, u8 ar,
@@ -503,6 +505,7 @@ static int trans_exc_ending(struct kvm_vcpu *vcpu, int code, unsigned long gva,

switch (code) {
case PGM_PROTECTION:
+ WARN(unlikely(prot == PROT_NONE), "Invalid prot argument");
switch (prot) {
case PROT_TYPE_IEP:
tec->b61 = 1;
@@ -519,6 +522,8 @@ static int trans_exc_ending(struct kvm_vcpu *vcpu, int code, unsigned long gva,
case PROT_TYPE_DAT:
tec->b61 = 1;
break;
+ case PROT_NONE:
+ /* We should never get here, acts like termination */
}
if (terminate) {
tec->b56 = 0;
@@ -968,8 +973,10 @@ static int guest_range_to_gpas(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
return rc;
} else {
gpa = kvm_s390_real_to_abs(vcpu, ga);
- if (kvm_is_error_gpa(vcpu->kvm, gpa))
+ if (kvm_is_error_gpa(vcpu->kvm, gpa)) {
rc = PGM_ADDRESSING;
+ prot = PROT_NONE;
+ }
}
if (rc)
return trans_exc(vcpu, rc, ga, ar, mode, prot);
@@ -1112,8 +1119,6 @@ int access_guest_with_key(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
if (rc == PGM_PROTECTION && try_storage_prot_override)
rc = access_guest_page_with_key(vcpu->kvm, mode, gpas[idx],
data, fragment_len, PAGE_SPO_ACC);
- if (rc == PGM_PROTECTION)
- prot = PROT_TYPE_KEYC;
if (rc)
break;
len -= fragment_len;
@@ -1123,6 +1128,10 @@ int access_guest_with_key(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
if (rc > 0) {
bool terminate = (mode == GACC_STORE) && (idx > 0);

+ if (rc == PGM_PROTECTION)
+ prot = PROT_TYPE_KEYC;
+ else
+ prot = PROT_NONE;
rc = trans_exc_ending(vcpu, rc, ga, ar, mode, prot, terminate);
}
out_unlock:
--
2.34.1