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    Subject[PATCH v6 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>
    Reviewed-by: Alexander Graf <graf@amazon.com>
    ---
    Changelog

    v5 -> v6

    * Update documentation to kernel-doc format.

    v4 -> v5

    * Remove sanity checks for situations that shouldn't happen, only if
    buggy system or broken logic at all.

    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:
    https://lore.kernel.org/lkml/202004231644.xTmN4Z1z%25lkp@intel.com/
    ---
    drivers/virt/nitro_enclaves/ne_pci_dev.c | 204 +++++++++++++++++++++++
    1 file changed, 204 insertions(+)

    diff --git a/drivers/virt/nitro_enclaves/ne_pci_dev.c b/drivers/virt/nitro_enclaves/ne_pci_dev.c
    index 31650dcd592e..77ccbc43bce3 100644
    --- a/drivers/virt/nitro_enclaves/ne_pci_dev.c
    +++ b/drivers/virt/nitro_enclaves/ne_pci_dev.c
    @@ -33,6 +33,187 @@ 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.
    + * @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.
    + *
    + * Context: Process context. This function is called with the ne_pci_dev mutex held.
    + * Return:
    + * * 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);
    +
    + 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.
    + * @pdev: PCI device to receive the reply from.
    + * @cmd_reply: Command reply payload.
    + * @cmd_reply_size: Size of the command reply payload.
    + *
    + * Context: Process context. This function is called with the ne_pci_dev mutex held.
    + * Return:
    + * * 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);
    +
    + 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 device command.
    + * @pdev: PCI device for which a reply is waited.
    + *
    + * Context: Process context. This function is called with the ne_pci_dev mutex held.
    + * Return:
    + * * 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;
    +
    + /*
    + * TODO: Update to _interruptible and handle interrupted wait event
    + * e.g. -ERESTARTSYS, incoming signals + update timeout, if needed.
    + */
    + 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 = pci_get_drvdata(pdev);
    + int rc = -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) {
    + rc = cmd_reply->rc;
    +
    + dev_err_ratelimited(&pdev->dev, "Error in cmd process logic [rc=%d]\n", rc);
    +
    + goto unlock_mutex;
    + }
    +
    + rc = 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.
    + *
    + * Context: Interrupt context.
    + * Return:
    + * * IRQ_HANDLED on handled interrupt.
    + */
    +static irqreturn_t ne_reply_handler(int irq, void *args)
    +{
    + struct ne_pci_dev *ne_pci_dev = (struct ne_pci_dev *)args;
    +
    + 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.
    * @pdev: PCI device to setup the MSI-X for.
    @@ -44,6 +225,7 @@ MODULE_DEVICE_TABLE(pci, ne_pci_ids);
    */
    static int ne_setup_msix(struct pci_dev *pdev)
    {
    + struct ne_pci_dev *ne_pci_dev = pci_get_drvdata(pdev);
    int nr_vecs = 0;
    int rc = -EINVAL;

    @@ -63,7 +245,25 @@ 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 +274,10 @@ static int ne_setup_msix(struct pci_dev *pdev)
    */
    static void ne_teardown_msix(struct pci_dev *pdev)
    {
    + struct ne_pci_dev *ne_pci_dev = pci_get_drvdata(pdev);
    +
    + 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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