Re: [PATCH v1] KVM: s390: vsie: fix Do the CRYCB validation first

From: Pierre Morel
Date: Fri Feb 01 2019 - 08:36:18 EST

On 01/02/2019 11:50, Cornelia Huck wrote:
On Fri, 1 Feb 2019 10:52:05 +0100
Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:

The case when the SIE for guest3 is not setup for using
encryption keys nor Adjunct processor but the guest2
does use these features was not properly handled.

This leads SIE entry for guest3 to crash with validity intercept
because the guest2, not having the use of encryption keys nor
Adjunct Processor did not initialize the CRYCB designation.

In the case where none of ECA_APIE, ECB3_AES or ECB3_DEA
are set in guest3 a format 0 CRYCB is allowed for guest3
and the CRYCB designation in the SIE for guest3 is not checked
on SIE entry.

Let's allow the CRYCD designation to be ignored when the


SIE for guest3 is not initialized for encryption key usage
nor AP.

Fixup: d6f6959 (KVM: s390: vsie: Do the CRYCB validation first)

I think the canonical format is

Fixes: d6f6959ac587 ("KVM: s390: vsie: Do the CRYCB validation first")

CC: stable@xxxxxxxxxxxxxxx # 4.20+

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
Reported-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
arch/s390/kvm/vsie.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index a153257..a748f76 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -300,6 +300,9 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
if (!apie_h && !key_msk)
return 0;
+ if (!(scb_o->eca & ECA_APIE) && !(scb_o->ecb3 & (ECB3_AES | ECB3_DEA)))
+ return 0;
if (!crycb_addr)
return set_validity_icpt(scb_s, 0x0039U);

Looks sane to me, but I'll let vsie experts comment.


Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany