linux-kernel - Re: [PATCH v10 02/26] KVM: s390: introduce and use KVM_REQ_VSIE

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Date:   Mon, 24 Sep 2018 12:48:35 -0400
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     Christian Borntraeger <borntraeger@...ibm.com>,
        Tony Krowiak <akrowiak@...ux.vnet.ibm.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, cohuck@...hat.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,
        jjherne@...ux.vnet.ibm.com, thuth@...hat.com,
        pasic@...ux.vnet.ibm.com, berrange@...hat.com,
        fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com,
        frankja@...ux.ibm.com, David Hildenbrand <david@...hat.com>
Subject: Re: [PATCH v10 02/26] KVM: s390: introduce and use
 KVM_REQ_VSIE_RESTART

On 09/24/2018 06:49 AM, Christian Borntraeger wrote:
> On 09/12/2018 09:42 PM, Tony Krowiak wrote:
>> From: David Hildenbrand <david@...hat.com>
>>
>> When we change the crycb (or execution controls), we also have to make sure
>> that the vSIE shadow datastructures properly consider the changed
>> values before rerunning the vSIE. We can achieve that by simply using a
>> VCPU request now.
>>
>> This has to be a synchronous request (== handled before entering the
>> (v)SIE again).
>>
>> The request will make sure that the vSIE handler is left, and that the
>> request will be processed (NOP), therefore forcing a reload of all
>> vSIE data (including rebuilding the crycb) when re-entering the vSIE
>> interception handler the next time.
>>
>> Reviewed-by: Pierre Morel <pmorel@...ux.ibm.com>
>> Reviewed-by: Cornelia Huck <cohuck@...hat.com>
>> Reviewed-by: Janosch Frank <frankja@...ux.ibm.com>
>> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
>> Signed-off-by: David Hildenbrand <david@...hat.com>
> 
> 
> same here? First David then Tomy?

Will do.

> 
> otherwise
> Reviewed-by: Christian Borntraeger <borntraeger@...ibm.com>
> 
> 
>> ---
>>   arch/s390/include/asm/kvm_host.h |    1 +
>>   arch/s390/kvm/kvm-s390.c         |    7 ++++++-
>>   2 files changed, 7 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
>> index 29c940b..75d3962 100644
>> --- a/arch/s390/include/asm/kvm_host.h
>> +++ b/arch/s390/include/asm/kvm_host.h
>> @@ -44,6 +44,7 @@
>>   #define KVM_REQ_ICPT_OPEREXC	KVM_ARCH_REQ(2)
>>   #define KVM_REQ_START_MIGRATION KVM_ARCH_REQ(3)
>>   #define KVM_REQ_STOP_MIGRATION  KVM_ARCH_REQ(4)
>> +#define KVM_REQ_VSIE_RESTART	KVM_ARCH_REQ(5)
>>   
>>   #define SIGP_CTRL_C		0x80
>>   #define SIGP_CTRL_SCN_MASK	0x3f
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index 0b5aff0..876fbb2 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -844,8 +844,11 @@ void kvm_s390_vcpu_crypto_reset_all(struct kvm *kvm)
>>   
>>   	kvm_s390_vcpu_block_all(kvm);
>>   
>> -	kvm_for_each_vcpu(i, vcpu, kvm)
>> +	kvm_for_each_vcpu(i, vcpu, kvm) {
>>   		kvm_s390_vcpu_crypto_setup(vcpu);
>> +		/* recreate the shadow crycb by leaving the VSIE handler */
>> +		kvm_s390_sync_request(KVM_REQ_VSIE_RESTART, vcpu);
>> +	}
>>   
>>   	kvm_s390_vcpu_unblock_all(kvm);
>>   }
>> @@ -3203,6 +3206,8 @@ static int kvm_s390_handle_requests(struct kvm_vcpu *vcpu)
>>   
>>   	/* nothing to do, just clear the request */
>>   	kvm_clear_request(KVM_REQ_UNHALT, vcpu);
>> +	/* we left the vsie handler, nothing to do, just clear the request */
>> +	kvm_clear_request(KVM_REQ_VSIE_RESTART, vcpu);
>>   
>>   	return 0;
>>   }
>>