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

Tony Krowiak
2017-11-14T15:53:12Z

On 11/14/2017 06:50 AM, Cornelia Huck wrote:
> On Thu, 2 Nov 2017 13:41:18 +0100
> Christian Borntraeger <borntraeger@de.ibm.com> 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
The AP bus (drivers/s390/crypto/ap_bus.c) calls
ap_instructions_available() function in drivers/s390/crypto/ap_asm.c
to determine whether AP instructions are installed. This function
executes the PQAP(TAPQ) function and incorporates
exception table to catch the operation exception if the AP instructions
are not installed. I propose externalizing
that function so it can be called from KVM.
>
>>
>>
>>> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>
>>> ---
>>> 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;
>>>