On 8/23/18 1:21 PM, David Hildenbrand wrote: > On 23.08.2018 13:05, Janosch Frank wrote: >> On 8/23/18 12:25 PM, Pierre Morel wrote: >>> The comment preceding the shadow_crycb function is >>> misleading, we effectively accept FORMAT2 CRYCB in the >>> guest. >> >> I beg to differ: >> >> if (!(crycbd_o & vcpu->arch.sie_block->crycbd & CRYCB_FORMAT1)) >> return 0; > > FORMAT2 includes bit FORMAT1 (backwards compatible)
Right, this check is very misleading because of the constant, we effectively test against Format 0 and Format 2. Can we make this clearer by explicitly ANDing 0x01 or adding a comment? Code makes sense: Reviewed-by: Janosch Frank <fran...@linux.ibm.com> > >> >>> >>> When using FORMAT2 in the host we do not need to or with >>> FORMAT1. >>> >>> Signed-off-by: Pierre Morel <pmo...@linux.ibm.com> >>> --- >>> arch/s390/kvm/vsie.c | 6 +++--- >>> 1 file changed, 3 insertions(+), 3 deletions(-) >>> >>> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c >>> index 38ea5da..e0e6fbf 100644 >>> --- a/arch/s390/kvm/vsie.c >>> +++ b/arch/s390/kvm/vsie.c >>> @@ -140,7 +140,8 @@ static int prepare_cpuflags(struct kvm_vcpu *vcpu, >>> struct vsie_page *vsie_page) >>> * Create a shadow copy of the crycb block and setup key wrapping, if >>> * requested for guest 3 and enabled for guest 2. >>> * >>> - * We only accept format-1 (no AP in g2), but convert it into format-2 >>> + * We accept format-1 or format-2, but we treat it as a format-1 (no AP in >>> g2), >>> + * and we convert it into format-2 in the shadow CRYCB. >>> * There is nothing to do for format-0. >>> * >>> * Returns: - 0 if shadowed or nothing to do >>> @@ -179,8 +180,7 @@ 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; >>> + scb_s->crycbd = ((__u32)(__u64) &vsie_page->crycb) | CRYCB_FORMAT2; >> >> That's purely cosmetic but valid. >> >>> >>> /* xor both blocks in one run */ >>> b1 = (unsigned long *) vsie_page->crycb.dea_wrapping_key_mask; > > Reviewed-by: David Hildenbrand <da...@redhat.com> >
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