lkml.org 
[lkml]   [2018]   [Apr]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] KVM: s390: reset crypto attributes for all vcpus
From
Date
On 04/20/2018 08:26 AM, David Hildenbrand wrote:
> On 19.04.2018 23:13, Tony Krowiak wrote:
>> Introduces a new function to reset the crypto attributes for all
>> vcpus whether they are running or not. Each vcpu in KVM will
>> be removed from SIE prior to resetting the crypto attributes in its
>> SIE state description. After all vcpus have had their crypto attributes
>> reset the vcpus will be restored to SIE.
>>
>> This function is incorporated into the kvm_s390_vm_set_crypto(kvm)
>> function to fix a reported issue whereby the crypto key wrapping
>> attributes could potentially get out of synch for running vcpus.
>>
>> Reported-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> A reported-by for a code refactoring is strange.

I was asked to include this.

>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>
>> ---
>> arch/s390/kvm/kvm-s390.c | 18 ++++++++++++++----
>> arch/s390/kvm/kvm-s390.h | 13 +++++++++++++
>> 2 files changed, 27 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index fa355a6..4fa3037 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -789,6 +789,19 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att
>> return ret;
>> }
>>
>> +void kvm_s390_vcpu_crypto_reset_all(struct kvm *kvm)
>> + {
>> + int i;
>> + struct kvm_vcpu *vcpu;
>> +
>> + kvm_s390_vcpu_block_all(kvm);
>> +
>> + kvm_for_each_vcpu(i, vcpu, kvm)
>> + kvm_s390_vcpu_crypto_setup(vcpu);
>> +
>> + kvm_s390_vcpu_unblock_all(kvm);
> This code has to be protected by kvm->lock. Can that be guaranteed by
> the caller?

I can hold the kvm->lock in this function, but if you look at the
function from which it
is called, kvm_s390_vm_set_crypto(vcpu) below, the kvm->lock is already
held by that
function to do other work. I suppose the kvm_s390_vm_set_crypto(vcpu)
instruction could
have released the lock prior to calling
kvm_s390_vcpu_crypto_reset_all(kvm), but since
this function is called within a block of crypto work, it made sense to
me to place
the responsibility for locking in the caller and include a comment in
the comments for
the function definition:

Note: The kvm->lock must be held while calling this function



>
>> +}
>> +
>> static void kvm_s390_vcpu_crypto_setup(struct kvm_vcpu *vcpu);
>>
>> static int kvm_s390_vm_set_crypto(struct kvm *kvm, struct kvm_device_attr *attr)
>> @@ -832,10 +845,7 @@ static int kvm_s390_vm_set_crypto(struct kvm *kvm, struct kvm_device_attr *attr)
>> return -ENXIO;
>> }
>>
>> - kvm_for_each_vcpu(i, vcpu, kvm) {
>> - kvm_s390_vcpu_crypto_setup(vcpu);
>> - exit_sie(vcpu);
>> - }
>> + kvm_s390_vcpu_crypto_reset_all(kvm);
>> mutex_unlock(&kvm->lock);
>> return 0;
>> }
>> diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
>> index 1b5621f..981e3ba 100644
>> --- a/arch/s390/kvm/kvm-s390.h
>> +++ b/arch/s390/kvm/kvm-s390.h
>> @@ -410,4 +410,17 @@ static inline int kvm_s390_use_sca_entries(void)
>> }
>> void kvm_s390_reinject_machine_check(struct kvm_vcpu *vcpu,
>> struct mcck_volatile_info *mcck_info);
>> +
>> +/**
>> + * kvm_s390_vcpu_crypto_reset_all
>> + *
>> + * Reset the crypto attributes for each vcpu. This can be done while the vcpus
>> + * are running as each vcpu will be removed from SIE before resetting the crypt
>> + * attributes and restored to SIE afterward.
>> + *
>> + * Note: The kvm->lock must be held while calling this function
>> + *
>> + * @kvm: the KVM guest
>> + */
>> +void kvm_s390_vcpu_crypto_reset_all(struct kvm *kvm);
>> #endif
>>
>

\
 
 \ /
  Last update: 2018-04-22 17:08    [W:0.211 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site