Re: [RFC 02/19] KVM: s390: refactor crypto initialization

[Christian Borntraeger]

On 10/13/2017 07:38 PM, Tony Krowiak wrote:
> This patch introduces the following changes to crypto initialization.
> 
> * For key management operations support, the crypto control block
>   (CRYCB) referenced by the KVM guest's SIE state description is
>   formatted only if the Message-Security-Assist (MSA) extension 3
>   facility is installed (STFLE.76 is set). Virtualization of AP
>   facilities, however; requires that a CRYCB of the appropriate
>   format be made available to SIE regardless of the value of STFLE.76.
> 
> * The Execution Controls A (ECA) field bit 28 in the SIE block needs
>   to be set to enable interpretive execution mode of adjunct processor (AP)
>   instructions.

We should fence setting ECA to cases where we have virtualization capability 
for crypto. In addition we need to bind this somehow to the CPU model, so
I guess we need to add some CRYPTO feature e.g. add KVM_S390_VM_CPU_FEAT_AP to the
list of know features
(see arch/s390/include/uapi/asm/kvm.h)
---snip---
#define KVM_S390_VM_CPU_FEAT_ESOP       0
#define KVM_S390_VM_CPU_FEAT_SIEF2      1
#define KVM_S390_VM_CPU_FEAT_64BSCAO    2
#define KVM_S390_VM_CPU_FEAT_SIIF       3
#define KVM_S390_VM_CPU_FEAT_GPERE      4
#define KVM_S390_VM_CPU_FEAT_GSLS       5
#define KVM_S390_VM_CPU_FEAT_IB         6
#define KVM_S390_VM_CPU_FEAT_CEI        7
#define KVM_S390_VM_CPU_FEAT_IBS        8
#define KVM_S390_VM_CPU_FEAT_SKEY       9
#define KVM_S390_VM_CPU_FEAT_CMMA       10
#define KVM_S390_VM_CPU_FEAT_PFMFI      11
#define KVM_S390_VM_CPU_FEAT_SIGPIF     12
#define KVM_S390_VM_CPU_FEAT_KSS        13
---snip---


I will try to find out a way to properly detect that.



> 
> Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx>
> ---
>  arch/s390/include/asm/kvm_host.h |    1 +
>  arch/s390/kvm/kvm-s390.c         |   17 +++++++++++++----
>  2 files changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index 50a6b25..5683f18 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -188,6 +188,7 @@ struct kvm_s390_sie_block {
>  #define ECA_MVPGI	0x01000000
>  #define ECA_VX		0x00020000
>  #define ECA_PROTEXCI	0x00002000
> +#define ECA_AP		0x00000008
>  #define ECA_SII		0x00000001
>  	__u32	eca;			/* 0x004c */
>  #define ICPT_INST	0x04
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 40d0a1a..e57fc9b 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -1819,7 +1819,9 @@ static void kvm_s390_set_crycb_format(struct kvm *kvm)
>  {
>  	kvm->arch.crypto.crycbd = (__u32)(unsigned long) kvm->arch.crypto.crycb;
> 
> -	if (kvm_s390_apxa_installed())
> +	if (!test_kvm_facility(kvm, 76))
> +		kvm->arch.crypto.crycbd &= ~(CRYCB_FORMAT2); /* format 0 */
> +	else if (kvm_s390_apxa_installed())
>  		kvm->arch.crypto.crycbd |= CRYCB_FORMAT2;
>  	else
>  		kvm->arch.crypto.crycbd |= CRYCB_FORMAT1;
> @@ -1836,12 +1838,12 @@ static u64 kvm_s390_get_initial_cpuid(void)
> 
>  static void kvm_s390_crypto_init(struct kvm *kvm)
>  {
> -	if (!test_kvm_facility(kvm, 76))
> -		return;
> -
>  	kvm->arch.crypto.crycb = &kvm->arch.sie_page2->crycb;
>  	kvm_s390_set_crycb_format(kvm);
> 
> +	if (!test_kvm_facility(kvm, 76))
> +		return;
> +
>  	/* Enable AES/DEA protected key functions by default */
>  	kvm->arch.crypto.aes_kw = 1;
>  	kvm->arch.crypto.dea_kw = 1;
> @@ -2366,8 +2368,15 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
>  	vcpu->arch.enabled_gmap = vcpu->arch.gmap;
>  }
> 
> +static void kvm_s390_vcpu_set_crypto_exec_mode(struct kvm_vcpu *vcpu)
> +{
> +	vcpu->arch.sie_block->eca |= ECA_AP;
> +}
> +
>  static void kvm_s390_vcpu_crypto_setup(struct kvm_vcpu *vcpu)
>  {
> +	kvm_s390_vcpu_set_crypto_exec_mode(vcpu);
> +
>  	if (!test_kvm_facility(vcpu->kvm, 76))
>  		return;
>