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

Janosch Frank
2018-08-09T05:58:13Z

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On 08.08.2018 16:44, Tony Krowiak wrote:
> From: Tony Krowiak <akrowiak@linux.ibm.com>
>
> 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@linux.ibm.com>
> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Tested-by: Michael Mueller <mimu@linux.ibm.com>
> Tested-by: Farhan Ali <alifm@linux.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

Acked-by: Janosch Frank <frankja@linux.ibm.com>

> ---
> 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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