Re: [PATCH v2 4/7] KVM: s390: enable MSA9 keywrapping functions depending on cpu model

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On 18.04.19 12:17, Christian Borntraeger wrote:
> 
> 
> On 18.04.19 11:13, David Hildenbrand wrote:
>> On 18.04.19 10:58, Christian Borntraeger wrote:
>>>
>>>
>>> On 18.04.19 09:54, David Hildenbrand wrote:
>>>> On 17.04.19 20:29, Christian Borntraeger wrote:
>>>>> Instead of adding a new machine option to disable/enable the keywrapping
>>>>> options of pckmo (like for AES and DEA) we can now use the CPU model to
>>>>> decide.
>>>>>
>>>>> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
>>>>> Reviewed-by: Collin Walling <walling@xxxxxxxxxxxxx>
>>>>> ---
>>>>> v1->v2: - enable vsie
>>>>> 	- also check if the host has the pckmo functions
>>>>>  arch/s390/include/asm/kvm_host.h | 1 +
>>>>>  arch/s390/kvm/kvm-s390.c         | 7 +++++++
>>>>>  arch/s390/kvm/vsie.c             | 5 ++++-
>>>>>  3 files changed, 12 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
>>>>> index c47e22bba87fa..e224246ff93c6 100644
>>>>> --- a/arch/s390/include/asm/kvm_host.h
>>>>> +++ b/arch/s390/include/asm/kvm_host.h
>>>>> @@ -278,6 +278,7 @@ struct kvm_s390_sie_block {
>>>>>  #define ECD_HOSTREGMGMT	0x20000000
>>>>>  #define ECD_MEF		0x08000000
>>>>>  #define ECD_ETOKENF	0x02000000
>>>>> +#define ECD_ECC		0x00200000
>>>>>  	__u32	ecd;			/* 0x01c8 */
>>>>>  	__u8	reserved1cc[18];	/* 0x01cc */
>>>>>  	__u64	pp;			/* 0x01de */
>>>>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>>>>> index 0dad61ccde3d6..9869d785677f1 100644
>>>>> --- a/arch/s390/kvm/kvm-s390.c
>>>>> +++ b/arch/s390/kvm/kvm-s390.c
>>>>> @@ -2933,6 +2933,13 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
>>>>>  		VCPU_EVENT(vcpu, 3, "AIV gisa format-%u enabled for cpu %03u",
>>>>>  			   vcpu->arch.sie_block->gd & 0x3, vcpu->vcpu_id);
>>>>>  	}
>>>>> +	/*
>>>>> +	 * if any of 32,33,34,40,41 is active in host AND guest,
>>>>> +	 * we enable pckmo for ecc
>>>>> +	 */
>>>>> +	if ((vcpu->kvm->arch.model.subfuncs.pckmo[4] & kvm_s390_available_subfunc.pckmo[4] & 0xe0) ||
>>>>> +	    (vcpu->kvm->arch.model.subfuncs.pckmo[5] & kvm_s390_available_subfunc.pckmo[5] & 0xc0))
>>>>
>>>> Maybe some helper like
>>>>
>>>> bool kvm_has_pckmo_subfunc(kvm, nr)
>>>> {
>>>> 	/* magic for one number */
>>>> }
>>>> ...
>>>>
>>>> if (kvm_has_pckmo_subfunc(kvm, 32) || kvm_has_pckmo_subfunc(kvm, 33))
>>>> ...
>>>>
>>>> then you can also get rid of the comment.
>>>
>>> Will give it a try.
>>>>
>>>>> +		vcpu->arch.sie_block->ecd |= ECD_ECC;
>>>>>  	vcpu->arch.sie_block->sdnxo = ((unsigned long) &vcpu->run->s.regs.sdnx)
>>>>>  					| SDNXC;
>>>>>  	vcpu->arch.sie_block->riccbd = (unsigned long) &vcpu->run->s.regs.riccb;
>>>>> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
>>>>> index d62fa148558b9..c6983d962abfd 100644
>>>>> --- a/arch/s390/kvm/vsie.c
>>>>> +++ b/arch/s390/kvm/vsie.c
>>>>> @@ -288,6 +288,7 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
>>>>>  	const u32 crycb_addr = crycbd_o & 0x7ffffff8U;
>>>>>  	unsigned long *b1, *b2;
>>>>>  	u8 ecb3_flags;
>>>>> +	u32 ecd_flags;
>>>>>  	int apie_h;
>>>>>  	int key_msk = test_kvm_facility(vcpu->kvm, 76);
>>>>>  	int fmt_o = crycbd_o & CRYCB_FORMAT_MASK;
>>>>> @@ -320,7 +321,8 @@ static int shadow_crycb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
>>>>>  	/* we may only allow it if enabled for guest 2 */
>>>>>  	ecb3_flags = scb_o->ecb3 & vcpu->arch.sie_block->ecb3 &
>>>>>  		     (ECB3_AES | ECB3_DEA);
>>>>> -	if (!ecb3_flags)
>>>>> +	ecd_flags = scb_o->ecd & vcpu->arch.sie_block->ecd & ECD_ECC;
>>>>> +	if (!ecb3_flags && !ecd_flags)
>>>>>  		goto end;
>>>>
>>>> Just so I get it right, there are no *new* wrapping keys? Which wrapping
>>>> keys are used then?
>>>
>>> Yes, AES.
>>>
>>
>> Hmmmm, so if user space doesn't call KVM_S390_VM_CRYPTO_ENABLE_AES_KW,
>> the wrapping key is basically uninitialized (kvm_s390_vm_set_crypto()),
>> but will be used.
>>
>> I guess you should also check against kvm->arch.crypto.aes_kw before
>> turning the ecd bit on, just to be sure.
> 
> We should rather initialize the aes value when ecc wrapping is enabled.
> 

If you don't glue this to KVM_S390_VM_CRYPTO_ENABLE_AES_KW, you will
have to find another way to reset AES keys during resets.

-- 

Thanks,

David / dhildenb



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