Re: [PATCH v8 07/22] KVM: s390: refactor crypto initialization

[Janosch Frank]

On 08.08.2018 16:44, Tony Krowiak wrote:
> From: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> 
> This patch refactors the code that initializes and sets up the
> crypto configuration for a guest. The following changes are
> implemented via this patch:
> 
> 1. Prior to the introduction of AP device virtualization, it
>    was not necessary to provide guest access to the CRYCB
>    unless the MSA extension 3 (MSAX3) facility was installed
>    on the host system. With the introduction of AP device
>    virtualization, the CRYCB must be made accessible to the
>    guest if the AP instructions are installed on the host
>    and are to be provided to the guest.
> 
> 2. Introduces a flag indicating AP instructions executed on
>    the guest shall be interpreted by the firmware. It is
>    initialized to indicate AP instructions are to be
>    to be interpreted and is used to set the SIE bit for
>    each vcpu during vcpu setup.
> 
> Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
> Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxx>
> Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> Tested-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
> Tested-by: Farhan Ali <alifm@xxxxxxxxxxxxx>
> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>

Acked-by: Janosch Frank <frankja@xxxxxxxxxxxxx>

> ---
>  arch/s390/include/asm/kvm_host.h |    3 +
>  arch/s390/include/uapi/asm/kvm.h |    1 +
>  arch/s390/kvm/kvm-s390.c         |   86 ++++++++++++++++++++------------------
>  3 files changed, 49 insertions(+), 41 deletions(-)
> 
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index af39561..0c13f61 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -187,6 +187,7 @@ struct kvm_s390_sie_block {
>  #define ECA_AIV		0x00200000
>  #define ECA_VX		0x00020000
>  #define ECA_PROTEXCI	0x00002000
> +#define ECA_APIE	0x00000008
>  #define ECA_SII		0x00000001
>  	__u32	eca;			/* 0x004c */
>  #define ICPT_INST	0x04
> @@ -256,6 +257,7 @@ struct kvm_s390_sie_block {
>  	__u8	reservede4[4];		/* 0x00e4 */
>  	__u64	tecmc;			/* 0x00e8 */
>  	__u8	reservedf0[12];		/* 0x00f0 */
> +#define CRYCB_FORMAT_MASK 0x00000003
>  #define CRYCB_FORMAT1 0x00000001
>  #define CRYCB_FORMAT2 0x00000003
>  	__u32	crycbd;			/* 0x00fc */
> @@ -714,6 +716,7 @@ struct kvm_s390_crypto {
>  	__u32 crycbd;
>  	__u8 aes_kw;
>  	__u8 dea_kw;
> +	__u8 apie;

In the last review I wanted a comment here to know what they do.

>  static void kvm_s390_vcpu_crypto_setup(struct kvm_vcpu *vcpu)
>  {
> -	if (!test_kvm_facility(vcpu->kvm, 76))
> +	/*
> +	 * If neither the AP instructions nor the MSAX3 facility are installed
> +	 * on the host, then there is no need for a CRYCB in SIE because the
> +	 * they will not be installed on the guest either.

the they

> +	 */
> +	if (ap_instructions_available() && !test_facility(76))
>  		return;

I know you're not responsible for that one :) but 0 being the wanted
value here is a bit counter-intuitive.

>  
> -	vcpu->arch.sie_block->ecb3 &= ~(ECB3_AES | ECB3_DEA);
> +	vcpu->arch.sie_block->crycbd = vcpu->kvm->arch.crypto.crycbd;
> +
> +	vcpu->arch.sie_block->eca &= ~ECA_APIE;

The scb is zero allocated, are the ECA and the ECB3s set somewhere
in-between, or is that your way of making sure the controls are
definitely gone for good?

> +	if (vcpu->kvm->arch.crypto.apie &&
> +	    test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_AP))
> +		vcpu->arch.sie_block->eca |= ECA_APIE;
>  
> -	if (vcpu->kvm->arch.crypto.aes_kw)
> -		vcpu->arch.sie_block->ecb3 |= ECB3_AES;
> -	if (vcpu->kvm->arch.crypto.dea_kw)
> -		vcpu->arch.sie_block->ecb3 |= ECB3_DEA;
> +	/* If MSAX3 is installed on the guest, set up protected key support */
> +	if (test_kvm_facility(vcpu->kvm, 76)) {
> +		vcpu->arch.sie_block->ecb3 &= ~(ECB3_AES | ECB3_DEA);
>  
> -	vcpu->arch.sie_block->crycbd = vcpu->kvm->arch.crypto.crycbd;
> +		if (vcpu->kvm->arch.crypto.aes_kw)
> +			vcpu->arch.sie_block->ecb3 |= ECB3_AES;
> +		if (vcpu->kvm->arch.crypto.dea_kw)
> +			vcpu->arch.sie_block->ecb3 |= ECB3_DEA;
> +	}
>  }
>  
>  void kvm_s390_vcpu_unsetup_cmma(struct kvm_vcpu *vcpu)
>

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