Messages in this thread | | | Subject | Re: [PATCH v1 05/15] nitro_enclaves: Handle PCI device command requests | From | Liran Alon <> | Date | Sat, 25 Apr 2020 17:52:17 +0300 |
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On 21/04/2020 21:41, Andra Paraschiv wrote: > 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> > --- > .../virt/amazon/nitro_enclaves/ne_pci_dev.c | 264 ++++++++++++++++++ > 1 file changed, 264 insertions(+) > > diff --git a/drivers/virt/amazon/nitro_enclaves/ne_pci_dev.c b/drivers/virt/amazon/nitro_enclaves/ne_pci_dev.c > index 8fbee95ea291..7453d129689a 100644 > --- a/drivers/virt/amazon/nitro_enclaves/ne_pci_dev.c > +++ b/drivers/virt/amazon/nitro_enclaves/ne_pci_dev.c > @@ -40,6 +40,251 @@ 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 = NULL; These local vars are unnecessarily initialized. > + > + BUG_ON(!pdev); > + > + ne_pci_dev = pci_get_drvdata(pdev); > + BUG_ON(!ne_pci_dev); > + BUG_ON(!ne_pci_dev->iomem_base); You should remove these defensive BUG_ON() calls. > + > + if (WARN_ON(cmd_type <= INVALID_CMD || cmd_type >= MAX_CMD)) { > + dev_err_ratelimited(&pdev->dev, "Invalid cmd type=%d\n", > + cmd_type); > + > + return -EINVAL; > + } > + > + if (WARN_ON(!cmd_request)) > + return -EINVAL; > + > + if (WARN_ON(cmd_request_size > NE_SEND_DATA_SIZE)) { > + dev_err_ratelimited(&pdev->dev, > + "Invalid req size=%ld for cmd type=%d\n", > + cmd_request_size, cmd_type); > + > + return -EINVAL; > + } It doesn't make sense to have WARN_ON() print error to dmesg on every evaluation to true, together with using dev_err_ratelimited() which attempts to rate-limit prints.
Anyway, these conditions were already checked by ne_do_request(). Why also check them here?
> + > + 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 = NULL; These local vars are unnecessarily initialized. > + > + BUG_ON(!pdev); > + > + ne_pci_dev = pci_get_drvdata(pdev); > + BUG_ON(!ne_pci_dev); > + BUG_ON(!ne_pci_dev->iomem_base); You should remove these defensive BUG_ON() calls. > + > + if (WARN_ON(!cmd_reply)) > + return -EINVAL; > + > + if (WARN_ON(cmd_reply_size > NE_RECV_DATA_SIZE)) { > + dev_err_ratelimited(&pdev->dev, "Invalid reply size=%ld\n", > + cmd_reply_size); > + > + return -EINVAL; > + } It doesn't make sense to have WARN_ON() print error to dmesg on every evaluation to true, together with using dev_err_ratelimited() which attempts to rate-limit prints.
Anyway, these conditions were already checked by ne_do_request(). Why also check them here?
> + > + 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 = NULL; > + int rc = -EINVAL; These local vars are unnecessarily initialized. > + > + BUG_ON(!pdev); > + > + ne_pci_dev = pci_get_drvdata(pdev); > + BUG_ON(!ne_pci_dev); You should remove these defensive BUG_ON() calls. > + > + /* > + * 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(DEFAULT_TIMEOUT_MSECS)); > + if (!rc) { > + pr_err("Wait event timed out when waiting for PCI cmd reply\n"); > + > + 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) This function is introduced in this patch but it is not used. It will cause compiling the kernel on this commit to raise warnings/errors on unused functions. You should introduce functions on the patch that they are used. > +{ > + struct ne_pci_dev *ne_pci_dev = NULL; > + int rc = -EINVAL; These local vars are unnecessarily initialized. > + > + BUG_ON(!pdev); > + > + ne_pci_dev = pci_get_drvdata(pdev); > + BUG_ON(!ne_pci_dev); > + BUG_ON(!ne_pci_dev->iomem_base); You should remove these defensive BUG_ON() calls. > + > + if (WARN_ON(cmd_type <= INVALID_CMD || cmd_type >= MAX_CMD)) { > + dev_err_ratelimited(&pdev->dev, "Invalid cmd type=%d\n", > + cmd_type); > + > + return -EINVAL; > + } > + > + if (WARN_ON(!cmd_request)) > + return -EINVAL; > + > + if (WARN_ON(cmd_request_size > NE_SEND_DATA_SIZE)) { > + dev_err_ratelimited(&pdev->dev, > + "Invalid req size=%ld for cmd type=%d\n", > + cmd_request_size, cmd_type); > + > + return -EINVAL; > + } > + > + if (WARN_ON(!cmd_reply)) > + return -EINVAL; > + > + if (WARN_ON(cmd_reply_size > NE_RECV_DATA_SIZE)) { > + dev_err_ratelimited(&pdev->dev, "Invalid reply size=%ld\n", > + cmd_reply_size); > + > + return -EINVAL; > + } I would consider specifying all these conditions in function documentation instead of enforcing them at runtime on every function call. > + > + /* > + * 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, > + "Failure in submit cmd request [rc=%d]\n", > + rc); > + > + mutex_unlock(&ne_pci_dev->pci_dev_mutex); > + > + return rc; Consider leaving function with a goto to a label that unlocks mutex and then return. > + } > + > + rc = ne_wait_for_reply(pdev); > + if (rc < 0) { > + dev_err_ratelimited(&pdev->dev, > + "Failure in wait cmd reply [rc=%d]\n", > + rc); > + > + mutex_unlock(&ne_pci_dev->pci_dev_mutex); > + > + return rc; > + } > + > + rc = ne_retrieve_reply(pdev, cmd_reply, cmd_reply_size); > + if (rc < 0) { > + dev_err_ratelimited(&pdev->dev, > + "Failure in retrieve cmd reply [rc=%d]\n", > + rc); > + > + mutex_unlock(&ne_pci_dev->pci_dev_mutex); > + > + return rc; > + } > + > + atomic_set(&ne_pci_dev->cmd_reply_avail, 0); > + > + if (cmd_reply->rc < 0) { > + dev_err_ratelimited(&pdev->dev, > + "Failure in cmd process logic [rc=%d]\n", > + cmd_reply->rc); > + > + mutex_unlock(&ne_pci_dev->pci_dev_mutex); > + > + return cmd_reply->rc; > + } > + > + mutex_unlock(&ne_pci_dev->pci_dev_mutex); > + > + return 0; > +} > + > +/** > + * 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; > + > + 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. > * > @@ -75,8 +320,25 @@ static int ne_setup_msix(struct pci_dev *pdev, struct ne_pci_dev *ne_pci_dev) > goto err_alloc_irq_vecs; > } > > + /* > + * 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_ratelimited(&pdev->dev, > + "Failure in allocating irq reply [rc=%d]\n", > + rc); > + > + goto err_req_irq_reply; > + } > + > return 0; > > +err_req_irq_reply: > + pci_free_irq_vectors(pdev); > err_alloc_irq_vecs: > return rc; > } > @@ -232,6 +494,7 @@ static int ne_probe(struct pci_dev *pdev, const struct pci_device_id *id) > > err_ne_pci_dev_enable: > err_ne_pci_dev_disable: > + free_irq(pci_irq_vector(pdev, NE_VEC_REPLY), ne_pci_dev); > pci_free_irq_vectors(pdev); I suggest to introduce a ne_teardown_msix() utility. That is aimed to cleanup after ne_setup_msix(). > err_setup_msix: > pci_iounmap(pdev, ne_pci_dev->iomem_base); > @@ -255,6 +518,7 @@ static void ne_remove(struct pci_dev *pdev) > > pci_set_drvdata(pdev, NULL); > > + free_irq(pci_irq_vector(pdev, NE_VEC_REPLY), ne_pci_dev); > pci_free_irq_vectors(pdev); > > pci_iounmap(pdev, ne_pci_dev->iomem_base);
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