Re: [PATCH v4 06/18] nitro_enclaves: Handle out-of-band PCI device events

["Paraschiv, Andra-Irina" <andraprs@amazon.com>]

On 02/07/2020 18:24, Alexander Graf wrote:
>
>
> On 22.06.20 22:03, Andra Paraschiv wrote:
>> In addition to the replies sent by the Nitro Enclaves PCI device in
>> response to command requests, out-of-band enclave events can happen e.g.
>> an enclave crashes. In this case, the Nitro Enclaves driver needs to be
>> aware of the event and notify the corresponding user space process that
>> abstracts the enclave.
>>
>> Register an MSI-X interrupt vector to be used for this kind of
>> out-of-band events. The interrupt notifies that the state of an enclave
>> changed and the driver logic scans the state of each running enclave to
>> identify for which this notification is intended.
>>
>> Create an workqueue to handle the out-of-band events. Notify user space
>> enclave process that is using a polling mechanism on the enclave fd.
>>
>> Signed-off-by: Alexandru-Catalin Vasile <lexnv@amazon.com>
>> Signed-off-by: Andra Paraschiv <andraprs@amazon.com>
>> ---
>> Changelog
>>
>> v3 -> v4
>>
>> * Use dev_err instead of custom NE log pattern.
>> * Return IRQ_NONE when interrupts are not handled.
>>
>> v2 -> v3
>>
>> * Remove the WARN_ON calls.
>> * Update static calls sanity checks.
>> * Remove "ratelimited" from the logs that are not in the ioctl call
>>    paths.
>>
>> v1 -> v2
>>
>> * Add log pattern for NE.
>> * Update goto labels to match their purpose.
>> ---
>>   drivers/virt/nitro_enclaves/ne_pci_dev.c | 122 +++++++++++++++++++++++
>>   1 file changed, 122 insertions(+)
>>
>> diff --git a/drivers/virt/nitro_enclaves/ne_pci_dev.c 
>> b/drivers/virt/nitro_enclaves/ne_pci_dev.c
>> index c24230cfe7c0..9a137862cade 100644
>> --- a/drivers/virt/nitro_enclaves/ne_pci_dev.c
>> +++ b/drivers/virt/nitro_enclaves/ne_pci_dev.c
>> @@ -239,6 +239,93 @@ static irqreturn_t ne_reply_handler(int irq, 
>> void *args)
>>       return IRQ_HANDLED;
>>   }
>>   +/**
>> + * ne_event_work_handler - Work queue handler for notifying enclaves on
>> + * a state change received by the event interrupt handler.
>> + *
>> + * An out-of-band event is being issued by the Nitro Hypervisor when 
>> at least
>> + * one enclave is changing state without client interaction.
>> + *
>> + * @work: item containing the Nitro Enclaves PCI device for which a
>> + *      out-of-band event was issued.
>> + */
>> +static void ne_event_work_handler(struct work_struct *work)
>> +{
>> +    struct ne_pci_dev_cmd_reply cmd_reply = {};
>> +    struct ne_enclave *ne_enclave = NULL;
>> +    struct ne_pci_dev *ne_pci_dev =
>> +        container_of(work, struct ne_pci_dev, notify_work);
>> +    int rc = -EINVAL;
>> +    struct slot_info_req slot_info_req = {};
>> +
>> +    if (!ne_pci_dev)
>> +        return;
>
> How?

Removed this check and the one below. Thank you.

Andra

>
>> +
>> +    mutex_lock(&ne_pci_dev->enclaves_list_mutex);
>> +
>> +    /*
>> +     * Iterate over all enclaves registered for the Nitro Enclaves
>> +     * PCI device and determine for which enclave(s) the out-of-band 
>> event
>> +     * is corresponding to.
>> +     */
>> +    list_for_each_entry(ne_enclave, &ne_pci_dev->enclaves_list,
>> +                enclave_list_entry) {
>> +        mutex_lock(&ne_enclave->enclave_info_mutex);
>> +
>> +        /*
>> +         * Enclaves that were never started cannot receive out-of-band
>> +         * events.
>> +         */
>> +        if (ne_enclave->state != NE_STATE_RUNNING)
>> +            goto unlock;
>> +
>> +        slot_info_req.slot_uid = ne_enclave->slot_uid;
>> +
>> +        rc = ne_do_request(ne_enclave->pdev, SLOT_INFO, &slot_info_req,
>> +                   sizeof(slot_info_req), &cmd_reply,
>> +                   sizeof(cmd_reply));
>> +        if (rc < 0)
>> +            dev_err(&ne_enclave->pdev->dev,
>> +                "Error in slot info [rc=%d]\n", rc);
>> +
>> +        /* Notify enclave process that the enclave state changed. */
>> +        if (ne_enclave->state != cmd_reply.state) {
>> +            ne_enclave->state = cmd_reply.state;
>> +
>> +            ne_enclave->has_event = true;
>> +
>> +            wake_up_interruptible(&ne_enclave->eventq);
>> +        }
>> +
>> +unlock:
>> +         mutex_unlock(&ne_enclave->enclave_info_mutex);
>> +    }
>> +
>> +    mutex_unlock(&ne_pci_dev->enclaves_list_mutex);
>> +}
>> +
>> +/**
>> + * ne_event_handler - Interrupt handler for PCI device out-of-band
>> + * events. This interrupt does not supply any data in the MMIO region.
>> + * It notifies a change in the state of any of the launched enclaves.
>> + *
>> + * @irq: received interrupt for an out-of-band event.
>> + * @args: PCI device private data structure.
>> + *
>> + * @returns: IRQ_HANDLED on handled interrupt, IRQ_NONE otherwise.
>> + */
>> +static irqreturn_t ne_event_handler(int irq, void *args)
>> +{
>> +    struct ne_pci_dev *ne_pci_dev = (struct ne_pci_dev *)args;
>> +
>> +    if (!ne_pci_dev)
>> +        return IRQ_NONE;
>
> How can this happen?
>
>
> Alex
>
>> +
>> +    queue_work(ne_pci_dev->event_wq, &ne_pci_dev->notify_work);
>> +
>> +    return IRQ_HANDLED;
>> +}
>> +
>>   /**
>>    * ne_setup_msix - Setup MSI-X vectors for the PCI device.
>>    *
>> @@ -284,8 +371,37 @@ static int ne_setup_msix(struct pci_dev *pdev)
>>           goto free_irq_vectors;
>>       }
>>   +    ne_pci_dev->event_wq = 
>> create_singlethread_workqueue("ne_pci_dev_wq");
>> +    if (!ne_pci_dev->event_wq) {
>> +        rc = -ENOMEM;
>> +
>> +        dev_err(&pdev->dev, "Cannot get wq for dev events [rc=%d]\n",
>> +            rc);
>> +
>> +        goto free_reply_irq_vec;
>> +    }
>> +
>> +    INIT_WORK(&ne_pci_dev->notify_work, ne_event_work_handler);
>> +
>> +    /*
>> +     * This IRQ gets triggered every time any enclave's state 
>> changes. Its
>> +     * handler then scans for the changes and propagates them to the 
>> user
>> +     * space.
>> +     */
>> +    rc = request_irq(pci_irq_vector(pdev, NE_VEC_EVENT),
>> +             ne_event_handler, 0, "enclave_evt", ne_pci_dev);
>> +    if (rc < 0) {
>> +        dev_err(&pdev->dev, "Error in request irq event [rc=%d]\n", 
>> rc);
>> +
>> +        goto destroy_wq;
>> +    }
>> +
>>       return 0;
>>   +destroy_wq:
>> +    destroy_workqueue(ne_pci_dev->event_wq);
>> +free_reply_irq_vec:
>> +    free_irq(pci_irq_vector(pdev, NE_VEC_REPLY), ne_pci_dev);
>>   free_irq_vectors:
>>       pci_free_irq_vectors(pdev);
>>   @@ -304,6 +420,12 @@ static void ne_teardown_msix(struct pci_dev 
>> *pdev)
>>       if (!ne_pci_dev)
>>           return;
>>   +    free_irq(pci_irq_vector(pdev, NE_VEC_EVENT), ne_pci_dev);
>> +
>> +    flush_work(&ne_pci_dev->notify_work);
>> +    flush_workqueue(ne_pci_dev->event_wq);
>> +    destroy_workqueue(ne_pci_dev->event_wq);
>> +
>>       free_irq(pci_irq_vector(pdev, NE_VEC_REPLY), ne_pci_dev);
>>         pci_free_irq_vectors(pdev);
>>




Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania. Registration number J22/2621/2005.