linux-kernel - Re: [PATCH v8 19/22] KVM: s390: Clear Crypto Control Block when using vSIE

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Date:   Thu, 9 Aug 2018 10:10:45 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Tony Krowiak <akrowiak@...ux.vnet.ibm.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, borntraeger@...ibm.com,
        cohuck@...hat.com, kwankhede@...dia.com,
        bjsdjshi@...ux.vnet.ibm.com, pbonzini@...hat.com,
        alex.williamson@...hat.com, pmorel@...ux.vnet.ibm.com,
        alifm@...ux.vnet.ibm.com, mjrosato@...ux.vnet.ibm.com,
        jjherne@...ux.vnet.ibm.com, thuth@...hat.com,
        pasic@...ux.vnet.ibm.com, berrange@...hat.com,
        fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com,
        frankja@...ux.ibm.com, Pierre Morel <pmorel@...ux.ibm.com>
Subject: Re: [PATCH v8 19/22] KVM: s390: Clear Crypto Control Block when using
 vSIE

On 08.08.2018 16:44, Tony Krowiak wrote:
> From: Pierre Morel <pmorel@...ux.ibm.com>
> 
> When we clear the Crypto Control Block (CRYCB) used by a guest
> level 2, the vSIE shadow CRYCB for guest level 3 must be updated
> before the guest uses it.
> 
> We achieve this by using the KVM_REQ_VSIE_RESTART synchronous
> request for each vCPU belonging to the guest to force the reload
> of the shadow CRYCB before rerunning the guest level 3.
> 
> Signed-off-by: Pierre Morel <pmorel@...ux.ibm.com>
> ---
>  arch/s390/kvm/kvm-s390.c |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 0d03249..9203f0b 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -1921,6 +1921,9 @@ static void kvm_s390_set_crycb_format(struct kvm *kvm)
>  
>  void kvm_arch_crypto_clear_masks(struct kvm *kvm)
>  {
> +	int i;
> +	struct kvm_vcpu *vcpu;
> +
>  	mutex_lock(&kvm->lock);
>  	kvm_s390_vcpu_block_all(kvm);
>  
> @@ -1929,6 +1932,10 @@ void kvm_arch_crypto_clear_masks(struct kvm *kvm)
>  	memset(&kvm->arch.crypto.crycb->apcb1, 0,
>  	       sizeof(kvm->arch.crypto.crycb->apcb1));
>  
> +	/* recreate the shadow crycb for each vcpu */
> +	kvm_for_each_vcpu(i, vcpu, kvm)
> +		kvm_s390_sync_request(KVM_REQ_VSIE_RESTART, vcpu);

We have kvm_s390_sync_request_broadcast(), which should boil down to a
one-liner

> +
>  	kvm_s390_vcpu_unblock_all(kvm);
>  	mutex_unlock(&kvm->lock);
>  }
> 


-- 

Thanks,

David / dhildenb