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)?)
--
Thanks,
David
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