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

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Date:   Tue, 14 Nov 2017 10:53:12 -0500
From:   Tony Krowiak <akrowiak@...ux.vnet.ibm.com>
To:     Cornelia Huck <cohuck@...hat.com>,
        Christian Borntraeger <borntraeger@...ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, kwankhede@...dia.com,
        bjsdjshi@...ux.vnet.ibm.com, pbonzini@...hat.com,
        alex.williamson@...hat.com, pmorel@...ux.vnet.ibm.com,
        alifm@...ux.vnet.ibm.com, mjrosato@...ux.vnet.ibm.com,
        qemu-s390x@...gnu.org, jjherne@...ux.vnet.ibm.com,
        thuth@...hat.com, pasic@...ux.vnet.ibm.com, david@...hat.com
Subject: Re: [RFC 02/19] KVM: s390: refactor crypto initialization

On 11/14/2017 06:50 AM, Cornelia Huck wrote:
> On Thu, 2 Nov 2017 13:41:18 +0100
> Christian Borntraeger <borntraeger@...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@...ux.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;
>>>