From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
sthyi should only generate a specification exception if the function
code is zero and the response buffer is not on a 4k boundary.
The current code would also test for unknown function codes if the
response buffer, that is currently only defined for function code 0,
is not on a 4k boundary and incorrectly inject a specification
exception instead of returning with condition code 3 and return code 4
(unsupported function code).
Fix this by moving the boundary check.
Fixes: 95ca2cb57985 ("KVM: s390: Add sthyi emulation")
Cc: <stable@xxxxxxxxxxxxxxx> # 4.8+
Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
arch/s390/kvm/sthyi.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/s390/kvm/sthyi.c b/arch/s390/kvm/sthyi.c
index 2773a2f..a2e5c24 100644
--- a/arch/s390/kvm/sthyi.c
+++ b/arch/s390/kvm/sthyi.c
@@ -425,7 +425,7 @@ int handle_sthyi(struct kvm_vcpu *vcpu)
VCPU_EVENT(vcpu, 3, "STHYI: fc: %llu addr: 0x%016llx", code, addr);
trace_kvm_s390_handle_sthyi(vcpu, code, addr);
- if (reg1 == reg2 || reg1 & 1 || reg2 & 1 || addr & ~PAGE_MASK)
+ if (reg1 == reg2 || reg1 & 1 || reg2 & 1)
return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
if (code & 0xffff) {
@@ -433,6 +433,9 @@ int handle_sthyi(struct kvm_vcpu *vcpu)
goto out;
}
+ if (addr & ~PAGE_MASK)
+ return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
+
/*
* If the page has not yet been faulted in, we want to do that
* now and not after all the expensive calculations.
--
2.7.4
