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    Subject[PATCH v4 05/18] nitro_enclaves: Handle PCI device command requests
    Date
    The Nitro Enclaves PCI device exposes a MMIO space that this driver
    uses to submit command requests and to receive command replies e.g. for
    enclave creation / termination or setting enclave resources.

    Add logic for handling PCI device command requests based on the given
    command type.

    Register an MSI-X interrupt vector for command reply notifications to
    handle this type of communication events.

    Signed-off-by: Alexandru-Catalin Vasile <lexnv@amazon.com>
    Signed-off-by: Andra Paraschiv <andraprs@amazon.com>

    Fix issue reported in:
    https://lore.kernel.org/lkml/202004231644.xTmN4Z1z%25lkp@intel.com/

    Reported-by: kbuild test robot <lkp@intel.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.
    * Remove the BUG_ON calls.
    * Update goto labels to match their purpose.
    * Add fix for kbuild report.
    ---
    drivers/virt/nitro_enclaves/ne_pci_dev.c | 232 +++++++++++++++++++++++
    1 file changed, 232 insertions(+)

    diff --git a/drivers/virt/nitro_enclaves/ne_pci_dev.c b/drivers/virt/nitro_enclaves/ne_pci_dev.c
    index 235fa3ecbee2..c24230cfe7c0 100644
    --- a/drivers/virt/nitro_enclaves/ne_pci_dev.c
    +++ b/drivers/virt/nitro_enclaves/ne_pci_dev.c
    @@ -27,6 +27,218 @@ static const struct pci_device_id ne_pci_ids[] = {

    MODULE_DEVICE_TABLE(pci, ne_pci_ids);

    +/**
    + * ne_submit_request - Submit command request to the PCI device based on the
    + * command type.
    + *
    + * This function gets called with the ne_pci_dev mutex held.
    + *
    + * @pdev: PCI device to send the command to.
    + * @cmd_type: command type of the request sent to the PCI device.
    + * @cmd_request: command request payload.
    + * @cmd_request_size: size of the command request payload.
    + *
    + * @returns: 0 on success, negative return value on failure.
    + */
    +static int ne_submit_request(struct pci_dev *pdev,
    + enum ne_pci_dev_cmd_type cmd_type,
    + void *cmd_request, size_t cmd_request_size)
    +{
    + struct ne_pci_dev *ne_pci_dev = pci_get_drvdata(pdev);
    +
    + if (!ne_pci_dev || !ne_pci_dev->iomem_base)
    + return -EINVAL;
    +
    + memcpy_toio(ne_pci_dev->iomem_base + NE_SEND_DATA, cmd_request,
    + cmd_request_size);
    +
    + iowrite32(cmd_type, ne_pci_dev->iomem_base + NE_COMMAND);
    +
    + return 0;
    +}
    +
    +/**
    + * ne_retrieve_reply - Retrieve reply from the PCI device.
    + *
    + * This function gets called with the ne_pci_dev mutex held.
    + *
    + * @pdev: PCI device to receive the reply from.
    + * @cmd_reply: command reply payload.
    + * @cmd_reply_size: size of the command reply payload.
    + *
    + * @returns: 0 on success, negative return value on failure.
    + */
    +static int ne_retrieve_reply(struct pci_dev *pdev,
    + struct ne_pci_dev_cmd_reply *cmd_reply,
    + size_t cmd_reply_size)
    +{
    + struct ne_pci_dev *ne_pci_dev = pci_get_drvdata(pdev);
    +
    + if (!ne_pci_dev || !ne_pci_dev->iomem_base)
    + return -EINVAL;
    +
    + memcpy_fromio(cmd_reply, ne_pci_dev->iomem_base + NE_RECV_DATA,
    + cmd_reply_size);
    +
    + return 0;
    +}
    +
    +/**
    + * ne_wait_for_reply - Wait for a reply of a PCI command.
    + *
    + * This function gets called with the ne_pci_dev mutex held.
    + *
    + * @pdev: PCI device for which a reply is waited.
    + *
    + * @returns: 0 on success, negative return value on failure.
    + */
    +static int ne_wait_for_reply(struct pci_dev *pdev)
    +{
    + struct ne_pci_dev *ne_pci_dev = pci_get_drvdata(pdev);
    + int rc = -EINVAL;
    +
    + if (!ne_pci_dev)
    + return -EINVAL;
    +
    + /*
    + * TODO: Update to _interruptible and handle interrupted wait event
    + * e.g. -ERESTARTSYS, incoming signals + add / update timeout.
    + */
    + rc = wait_event_timeout(ne_pci_dev->cmd_reply_wait_q,
    + atomic_read(&ne_pci_dev->cmd_reply_avail) != 0,
    + msecs_to_jiffies(NE_DEFAULT_TIMEOUT_MSECS));
    + if (!rc)
    + return -ETIMEDOUT;
    +
    + return 0;
    +}
    +
    +int ne_do_request(struct pci_dev *pdev, enum ne_pci_dev_cmd_type cmd_type,
    + void *cmd_request, size_t cmd_request_size,
    + struct ne_pci_dev_cmd_reply *cmd_reply, size_t cmd_reply_size)
    +{
    + struct ne_pci_dev *ne_pci_dev = NULL;
    + int rc = -EINVAL;
    +
    + if (!pdev)
    + return -ENODEV;
    +
    + ne_pci_dev = pci_get_drvdata(pdev);
    + if (!ne_pci_dev || !ne_pci_dev->iomem_base)
    + return -EINVAL;
    +
    + if (cmd_type <= INVALID_CMD || cmd_type >= MAX_CMD) {
    + dev_err_ratelimited(&pdev->dev, "Invalid cmd type=%u\n",
    + cmd_type);
    +
    + return -EINVAL;
    + }
    +
    + if (!cmd_request) {
    + dev_err_ratelimited(&pdev->dev, "Null cmd request\n");
    +
    + return -EINVAL;
    + }
    +
    + if (cmd_request_size > NE_SEND_DATA_SIZE) {
    + dev_err_ratelimited(&pdev->dev,
    + "Invalid req size=%zu for cmd type=%u\n",
    + cmd_request_size, cmd_type);
    +
    + return -EINVAL;
    + }
    +
    + if (!cmd_reply) {
    + dev_err_ratelimited(&pdev->dev, "Null cmd reply\n");
    +
    + return -EINVAL;
    + }
    +
    + if (cmd_reply_size > NE_RECV_DATA_SIZE) {
    + dev_err_ratelimited(&pdev->dev, "Invalid reply size=%zu\n",
    + cmd_reply_size);
    +
    + return -EINVAL;
    + }
    +
    + /*
    + * Use this mutex so that the PCI device handles one command request at
    + * a time.
    + */
    + mutex_lock(&ne_pci_dev->pci_dev_mutex);
    +
    + atomic_set(&ne_pci_dev->cmd_reply_avail, 0);
    +
    + rc = ne_submit_request(pdev, cmd_type, cmd_request, cmd_request_size);
    + if (rc < 0) {
    + dev_err_ratelimited(&pdev->dev,
    + "Error in submit request [rc=%d]\n", rc);
    +
    + goto unlock_mutex;
    + }
    +
    + rc = ne_wait_for_reply(pdev);
    + if (rc < 0) {
    + dev_err_ratelimited(&pdev->dev,
    + "Error in wait for reply [rc=%d]\n", rc);
    +
    + goto unlock_mutex;
    + }
    +
    + rc = ne_retrieve_reply(pdev, cmd_reply, cmd_reply_size);
    + if (rc < 0) {
    + dev_err_ratelimited(&pdev->dev,
    + "Error in retrieve reply [rc=%d]\n", rc);
    +
    + goto unlock_mutex;
    + }
    +
    + atomic_set(&ne_pci_dev->cmd_reply_avail, 0);
    +
    + if (cmd_reply->rc < 0) {
    + dev_err_ratelimited(&pdev->dev,
    + "Error in cmd process logic [rc=%d]\n",
    + cmd_reply->rc);
    +
    + rc = cmd_reply->rc;
    +
    + goto unlock_mutex;
    + }
    +
    + mutex_unlock(&ne_pci_dev->pci_dev_mutex);
    +
    + return 0;
    +
    +unlock_mutex:
    + mutex_unlock(&ne_pci_dev->pci_dev_mutex);
    +
    + return rc;
    +}
    +
    +/**
    + * ne_reply_handler - Interrupt handler for retrieving a reply matching
    + * a request sent to the PCI device for enclave lifetime management.
    + *
    + * @irq: received interrupt for a reply sent by the PCI device.
    + * @args: PCI device private data structure.
    + *
    + * @returns: IRQ_HANDLED on handled interrupt, IRQ_NONE otherwise.
    + */
    +static irqreturn_t ne_reply_handler(int irq, void *args)
    +{
    + struct ne_pci_dev *ne_pci_dev = (struct ne_pci_dev *)args;
    +
    + if (!ne_pci_dev)
    + return IRQ_NONE;
    +
    + atomic_set(&ne_pci_dev->cmd_reply_avail, 1);
    +
    + /* TODO: Update to _interruptible. */
    + wake_up(&ne_pci_dev->cmd_reply_wait_q);
    +
    + return IRQ_HANDLED;
    +}
    +
    /**
    * ne_setup_msix - Setup MSI-X vectors for the PCI device.
    *
    @@ -59,7 +271,25 @@ static int ne_setup_msix(struct pci_dev *pdev)
    return rc;
    }

    + /*
    + * This IRQ gets triggered every time the PCI device responds to a
    + * command request. The reply is then retrieved, reading from the MMIO
    + * space of the PCI device.
    + */
    + rc = request_irq(pci_irq_vector(pdev, NE_VEC_REPLY),
    + ne_reply_handler, 0, "enclave_cmd", ne_pci_dev);
    + if (rc < 0) {
    + dev_err(&pdev->dev, "Error in request irq reply [rc=%d]\n", rc);
    +
    + goto free_irq_vectors;
    + }
    +
    return 0;
    +
    +free_irq_vectors:
    + pci_free_irq_vectors(pdev);
    +
    + return rc;
    }

    /**
    @@ -74,6 +304,8 @@ static void ne_teardown_msix(struct pci_dev *pdev)
    if (!ne_pci_dev)
    return;

    + free_irq(pci_irq_vector(pdev, NE_VEC_REPLY), ne_pci_dev);
    +
    pci_free_irq_vectors(pdev);
    }

    --
    2.20.1 (Apple Git-117)



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