Re: [PATCH v2 3/5] KVM: s390: vsie: Allow support for a host without AP

David Hildenbrand
2018-08-22T17:06:09Z

On 22.08.2018 18:51, Pierre Morel wrote:
> Currently the CRYCB format used in the host for the
> shadowed CRYCB is FORMAT2 while no check is done if
> AP instructions are supported in the host.
>
> We better use the format the host calculated for the
> guest 1 as the host already tested it against its
> facility set.
>
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
> arch/s390/kvm/vsie.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index 56a9d47..0b12916 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -154,6 +154,7 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
> const u32 crycb_addr = crycbd_o & 0x7ffffff8U;
> unsigned long *b1, *b2;
> u8 ecb3_flags;
> + unsigned long g1_fmt;
>
> scb_s->crycbd = 0;
> if (!(crycbd_o == CRYCB_FORMAT1))
> @@ -180,8 +181,8 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
> return set_validity_icpt(scb_s, 0x0035U);
>
> scb_s->ecb3 |= ecb3_flags;
> - scb_s->crycbd = ((__u32)(__u64) &vsie_page->crycb) | CRYCB_FORMAT1 |
> - CRYCB_FORMAT2;
> + g1_fmt = vcpu->arch.sie_block->crycbd & 0x03;
> + scb_s->crycbd = ((__u32)(__u64) &vsie_page->crycb) | g1_fmt;
>
> /* xor both blocks in one run */
> b1 = (unsigned long *) vsie_page->crycb.dea_wrapping_key_mask;
>

This is wrong. I remember that with APXA, if FORMAT2 is available, we
should always use FORMAT2. That's why we explicitly convert it here.

--

Thanks,

David / dhildenb