Re: [qemu-s390x] [RFC 02/19] KVM: s390: refactor crypto initialization

[Cornelia Huck]

On Thu, 2 Nov 2017 13:41:18 +0100
Christian Borntraeger <address@hidden> wrote:

> 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---

So, we need this so userspace can add the appropriate flags, right?

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

Did you manage to find out?

> 
> 
> 
> > 
> > Signed-off-by: Tony Krowiak <address@hidden>
> > ---
> >  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;
> >   
>