Re: [PATCH v2 5/5] KVM: s390: vsie: Do the CRYCB validation first

David Hildenbrand
2018-08-22T17:15:49Z

On 22.08.2018 18:51, Pierre Morel wrote:
> When entering the SIE the CRYCB validation better
> be done independently of the instruction's
> availability.
>
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
> arch/s390/kvm/vsie.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index 7ee4329..fca25aa 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -164,17 +164,18 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
> /* format-1 is supported with message-security-assist extension 3 */
> if (!test_kvm_facility(vcpu->kvm, 76))
> return 0;
> - /* we may only allow it if enabled for guest 2 */
> - ecb3_flags = scb_o->ecb3 & vcpu->arch.sie_block->ecb3 &
> - (ECB3_AES | ECB3_DEA);
> - if (!ecb3_flags)
> - return 0;
>
> if ((crycb_addr & PAGE_MASK) != ((crycb_addr + 128) & PAGE_MASK))
> return set_validity_icpt(scb_s, 0x003CU);
> if (!crycb_addr)
> return set_validity_icpt(scb_s, 0x0039U);
>
> + /* we may only allow it if enabled for guest 2 */
> + ecb3_flags = scb_o->ecb3 & vcpu->arch.sie_block->ecb3 &
> + (ECB3_AES | ECB3_DEA);
> + if (!ecb3_flags)
> + return 0;
> +
> /* copy only the wrapping keys */
> if (read_guest_real(vcpu, crycb_addr + 72,
> vsie_page->crycb.dea_wrapping_key_mask, 56))
>

That makes sense, especially if ECB3_AES is used but effectively turned
off by us.

What is the expected behavior if ECB3_AES | ECB3_DEA are not set by g2
for g3?

--

Thanks,

David / dhildenb