linux-kernel - Re: [PATCH] KVM: s390: vsie: Do not shadow CRYCB when no AP and no keys

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Date:   Fri, 26 Apr 2019 11:04:01 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Pierre Morel <pmorel@...ux.ibm.com>
Cc:     linux-kernel@...r.kernel.org, cohuck@...hat.com,
        linux-s390@...r.kernel.org, kvm@...r.kernel.org,
        frankja@...ux.ibm.com, akrowiak@...ux.ibm.com,
        borntraeger@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com
Subject: Re: [PATCH] KVM: s390: vsie: Do not shadow CRYCB when no AP and no
 keys

On 26.04.19 10:56, Pierre Morel wrote:
> When the guest do not have AP instructions nor Key management
> we should return without shadowing the CRYCB.
> 
> We did not check correctly in the past.
> 
> Fixes: b10bd9a256ae ("s390: vsie: Use effective CRYCBD.31 to check CRYCBD
> validity")

We should really try to pay more attention, commit b10bd9a256ae already
was supposed to fix 6ee74098201b.

Unfortunately, I don't have access to documentation and can't verify.

Acked-by: David Hildenbrand <david@...hat.com>

> Fixes: 6ee74098201b ("KVM: s390: vsie: allow CRYCB FORMAT-0")
> 
> Signed-off-by: Pierre Morel <pmorel@...ux.ibm.com>
> Reported-by: Christian Borntraeger <borntraeger@...ibm.com>
> ---
>  arch/s390/kvm/vsie.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index c6983d9..ac411e9 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -290,6 +290,7 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
>  	u8 ecb3_flags;
>  	u32 ecd_flags;
>  	int apie_h;
> +	int apie_s;
>  	int key_msk = test_kvm_facility(vcpu->kvm, 76);
>  	int fmt_o = crycbd_o & CRYCB_FORMAT_MASK;
>  	int fmt_h = vcpu->arch.sie_block->crycbd & CRYCB_FORMAT_MASK;
> @@ -298,7 +299,8 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
>  	scb_s->crycbd = 0;
>  
>  	apie_h = vcpu->arch.sie_block->eca & ECA_APIE;
> -	if (!apie_h && (!key_msk || fmt_o == CRYCB_FORMAT0))
> +	apie_s = apie_h & scb_o->eca;
> +	if (!apie_s && (!key_msk || (fmt_o == CRYCB_FORMAT0)))
>  		return 0;
>  
>  	if (!crycb_addr)
> @@ -309,7 +311,7 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
>  		    ((crycb_addr + 128) & PAGE_MASK))
>  			return set_validity_icpt(scb_s, 0x003CU);
>  
> -	if (apie_h && (scb_o->eca & ECA_APIE)) {
> +	if (apie_s) {
>  		ret = setup_apcb(vcpu, &vsie_page->crycb, crycb_addr,
>  				 vcpu->kvm->arch.crypto.crycb,
>  				 fmt_o, fmt_h);
> 


-- 

Thanks,

David / dhildenb