On 08/21/2017 02:43 PM, David Hildenbrand wrote: > On 21.08.2017 14:27, Christian Borntraeger wrote: >> 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> >> 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. >> > > Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> > > Just wondering if this is really worth stable? (only function code 0 is > defined, so this should not happen in sane environments. or is this used > to test for support for new function codes (which would be strange but > possible)?) I think it is a safety net if we ever implement new function codes. So yes we want software being able to test for the new codes without having to handle a program check. -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html