From: Tony Krowiak <akrowiak@linux.ibm.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: cohuck@redhat.com, pasic@linux.vnet.ibm.com,
jjherne@linux.ibm.com, jgg@nvidia.com,
alex.williamson@redhat.com, kwankhede@nvidia.com,
david@redhat.com
Subject: Re: [PATCH 1/2] s390/vfio-ap: r/w lock for PQAP interception handler function pointer
Date: Thu, 19 Aug 2021 09:20:28 -0400 [thread overview]
Message-ID: <358b1052-c751-7417-1263-308b133325b6@linux.ibm.com> (raw)
In-Reply-To: <1a9f15d7-0f4d-00a0-0a8b-f1c08aa52eeb@de.ibm.com>
On 8/18/21 1:03 PM, Christian Borntraeger wrote:
> On 19.07.21 21:35, Tony Krowiak wrote:
>> The function pointer to the interception handler for the PQAP
>> instruction
>> can get changed during the interception process. Let's add a
>> semaphore to struct kvm_s390_crypto to control read/write access to the
>> function pointer contained therein.
>>
>> The semaphore must be locked for write access by the vfio_ap device
>> driver
>> when notified that the KVM pointer has been set or cleared. It must be
>> locked for read access by the interception framework when the PQAP
>> instruction is intercepted.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
>> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
>> ---
>> arch/s390/include/asm/kvm_host.h | 8 +++-----
>> arch/s390/kvm/kvm-s390.c | 1 +
>> arch/s390/kvm/priv.c | 10 ++++++----
>> drivers/s390/crypto/vfio_ap_ops.c | 23 +++++++++++++++++------
>> drivers/s390/crypto/vfio_ap_private.h | 2 +-
>> 5 files changed, 28 insertions(+), 16 deletions(-)
>>
>> diff --git a/arch/s390/include/asm/kvm_host.h
>> b/arch/s390/include/asm/kvm_host.h
>> index 9b4473f76e56..f18849d259e6 100644
>> --- a/arch/s390/include/asm/kvm_host.h
>> +++ b/arch/s390/include/asm/kvm_host.h
>> @@ -798,14 +798,12 @@ struct kvm_s390_cpu_model {
>> unsigned short ibc;
>> };
>> -struct kvm_s390_module_hook {
>> - int (*hook)(struct kvm_vcpu *vcpu);
>> - struct module *owner;
>> -};
>> +typedef int (*crypto_hook)(struct kvm_vcpu *vcpu);
>> struct kvm_s390_crypto {
>> struct kvm_s390_crypto_cb *crycb;
>> - struct kvm_s390_module_hook *pqap_hook;
>> + struct rw_semaphore pqap_hook_rwsem;
>> + crypto_hook *pqap_hook;
>> __u32 crycbd;
>> __u8 aes_kw;
>> __u8 dea_kw;
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index b655a7d82bf0..a08f242a9f27 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -2630,6 +2630,7 @@ static void kvm_s390_crypto_init(struct kvm *kvm)
>> {
>> kvm->arch.crypto.crycb = &kvm->arch.sie_page2->crycb;
>> kvm_s390_set_crycb_format(kvm);
>> + init_rwsem(&kvm->arch.crypto.pqap_hook_rwsem);
>> if (!test_kvm_facility(kvm, 76))
>> return;
>> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
>> index 9928f785c677..6bed9406c1f3 100644
>> --- a/arch/s390/kvm/priv.c
>> +++ b/arch/s390/kvm/priv.c
>> @@ -610,6 +610,7 @@ static int handle_io_inst(struct kvm_vcpu *vcpu)
>> static int handle_pqap(struct kvm_vcpu *vcpu)
>> {
>> struct ap_queue_status status = {};
>> + crypto_hook pqap_hook;
>> unsigned long reg0;
>> int ret;
>> uint8_t fc;
>> @@ -657,15 +658,16 @@ static int handle_pqap(struct kvm_vcpu *vcpu)
>> * Verify that the hook callback is registered, lock the owner
>> * and call the hook.
>> */
>> + down_read(&vcpu->kvm->arch.crypto.pqap_hook_rwsem);
>> if (vcpu->kvm->arch.crypto.pqap_hook) {
>> - if (!try_module_get(vcpu->kvm->arch.crypto.pqap_hook->owner))
>> - return -EOPNOTSUPP;
>> - ret = vcpu->kvm->arch.crypto.pqap_hook->hook(vcpu);
>> - module_put(vcpu->kvm->arch.crypto.pqap_hook->owner);
>> + pqap_hook = *vcpu->kvm->arch.crypto.pqap_hook;
>
> Dont we have to check for NULL here? If not can you add a comment why?
Take a look above the removed lines: if (vcpu->kvm->arch.crypto.pqap_hook)
>
> Otherwise this looks good.
Also, in the cover letter I said this patch was already queued and was
included here because it pre-reqs the second patch. Is this patch not
already in Alex's tree?
>
>
>> + ret = pqap_hook(vcpu);
> [...]
next prev parent reply other threads:[~2021-08-19 13:20 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-19 19:35 [PATCH 0/2] s390/vfio-ap: do not open code locks for VFIO_GROUP_NOTIFY_SET_KVM notification Tony Krowiak
2021-07-19 19:35 ` [PATCH 1/2] s390/vfio-ap: r/w lock for PQAP interception handler function pointer Tony Krowiak
2021-08-18 17:03 ` Christian Borntraeger
2021-08-18 23:25 ` Halil Pasic
2021-08-19 6:56 ` Christian Borntraeger
2021-08-19 13:36 ` Tony Krowiak
2021-08-19 21:42 ` Halil Pasic
2021-08-23 13:08 ` Tony Krowiak
2021-08-19 13:20 ` Tony Krowiak [this message]
2021-08-19 17:54 ` Alex Williamson
2021-08-19 17:58 ` Jason Gunthorpe
2021-08-20 15:59 ` Tony Krowiak
2021-08-20 22:05 ` Tony Krowiak
2021-08-20 22:30 ` Jason Gunthorpe
2021-08-23 15:17 ` Tony Krowiak
2021-08-20 22:41 ` Alex Williamson
2021-08-23 20:51 ` Tony Krowiak
2021-07-19 19:35 ` [PATCH 2/2] s390/vfio-ap: replace open coded locks for VFIO_GROUP_NOTIFY_SET_KVM notification Tony Krowiak
2021-07-21 14:45 ` Halil Pasic
2021-07-22 13:09 ` Tony Krowiak
2021-07-23 14:26 ` Halil Pasic
2021-07-23 21:24 ` Tony Krowiak
2021-07-26 20:36 ` Halil Pasic
2021-07-26 22:03 ` Jason Gunthorpe
2021-07-26 22:43 ` Halil Pasic
2021-07-28 13:43 ` Tony Krowiak
2021-07-28 19:42 ` Halil Pasic
2021-07-30 13:33 ` Tony Krowiak
2021-07-27 6:54 ` Christoph Hellwig
2021-07-21 19:37 ` Jason J. Herne
2021-07-22 13:16 ` Tony Krowiak
2021-08-02 13:10 ` [PATCH 0/2] s390/vfio-ap: do not open code " Tony Krowiak
2021-08-02 13:53 ` Halil Pasic
2021-08-02 16:32 ` Tony Krowiak
2021-08-03 13:08 ` Jason Gunthorpe
2021-08-03 13:34 ` Tony Krowiak
2021-08-18 15:59 ` Christian Borntraeger
2021-08-18 16:39 ` Alex Williamson
2021-08-18 16:50 ` Christian Borntraeger
2021-08-18 22:52 ` Halil Pasic
2021-08-19 15:30 ` Cornelia Huck
2021-08-20 14:24 ` Tony Krowiak
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