[PATCH v2 04/18] nitro_enclaves: Init PCI device driver

[Andra Paraschiv]

The Nitro Enclaves PCI device is used by the kernel driver as a means of
communication with the hypervisor on the host where the primary VM and
the enclaves run. It handles requests with regard to enclave lifetime.

Setup the PCI device driver and add support for MSI-X interrupts.

Signed-off-by: Alexandru-Catalin Vasile <lexnv@xxxxxxxxxx>
Signed-off-by: Alexandru Ciobotaru <alcioa@xxxxxxxxxx>
Signed-off-by: Andra Paraschiv <andraprs@xxxxxxxxxx>
---
 drivers/virt/nitro_enclaves/ne_pci_dev.c | 303 +++++++++++++++++++++++
 1 file changed, 303 insertions(+)
 create mode 100644 drivers/virt/nitro_enclaves/ne_pci_dev.c

diff --git a/drivers/virt/nitro_enclaves/ne_pci_dev.c b/drivers/virt/nitro_enclaves/ne_pci_dev.c
new file mode 100644
index 000000000000..8e39e30c882f
--- /dev/null
+++ b/drivers/virt/nitro_enclaves/ne_pci_dev.c
@@ -0,0 +1,303 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Nitro Enclaves (NE) PCI device driver. */
+
+#include <linux/bug.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/nitro_enclaves.h>
+#include <linux/pci.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+#include "ne_misc_dev.h"
+#include "ne_pci_dev.h"
+
+#define DEFAULT_TIMEOUT_MSECS (120000) // 120 sec
+
+#define NE "nitro_enclaves: "
+
+static const struct pci_device_id ne_pci_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMAZON, PCI_DEVICE_ID_NE) },
+	{ 0, }
+};
+
+MODULE_DEVICE_TABLE(pci, ne_pci_ids);
+
+/**
+ * ne_setup_msix - Setup MSI-X vectors for the PCI device.
+ *
+ * @pdev: PCI device to setup the MSI-X for.
+ *
+ * @returns: 0 on success, negative return value on failure.
+ */
+static int ne_setup_msix(struct pci_dev *pdev)
+{
+	struct ne_pci_dev *ne_pci_dev = NULL;
+	int nr_vecs = 0;
+	int rc = -EINVAL;
+
+	if (WARN_ON(!pdev))
+		return -EINVAL;
+
+	ne_pci_dev = pci_get_drvdata(pdev);
+	if (WARN_ON(!ne_pci_dev))
+		return -EINVAL;
+
+	nr_vecs = pci_msix_vec_count(pdev);
+	if (nr_vecs < 0) {
+		rc = nr_vecs;
+
+		dev_err_ratelimited(&pdev->dev,
+				    NE "Error in getting vec count [rc=%d]\n",
+				    rc);
+
+		return rc;
+	}
+
+	rc = pci_alloc_irq_vectors(pdev, nr_vecs, nr_vecs, PCI_IRQ_MSIX);
+	if (rc < 0) {
+		dev_err_ratelimited(&pdev->dev,
+				    NE "Error in alloc MSI-X vecs [rc=%d]\n",
+				    rc);
+
+		return rc;
+	}
+
+	return 0;
+}
+
+/**
+ * ne_teardown_msix - Teardown MSI-X vectors for the PCI device.
+ *
+ * @pdev: PCI device to teardown the MSI-X for.
+ */
+static void ne_teardown_msix(struct pci_dev *pdev)
+{
+	struct ne_pci_dev *ne_pci_dev = NULL;
+
+	if (WARN_ON(!pdev))
+		return;
+
+	ne_pci_dev = pci_get_drvdata(pdev);
+	if (WARN_ON(!ne_pci_dev))
+		return;
+
+	pci_free_irq_vectors(pdev);
+}
+
+/**
+ * ne_pci_dev_enable - Select PCI device version and enable it.
+ *
+ * @pdev: PCI device to select version for and then enable.
+ *
+ * @returns: 0 on success, negative return value on failure.
+ */
+static int ne_pci_dev_enable(struct pci_dev *pdev)
+{
+	u8 dev_enable_reply = 0;
+	u16 dev_version_reply = 0;
+	struct ne_pci_dev *ne_pci_dev = NULL;
+
+	if (WARN_ON(!pdev))
+		return -EINVAL;
+
+	ne_pci_dev = pci_get_drvdata(pdev);
+	if (WARN_ON(!ne_pci_dev) || WARN_ON(!ne_pci_dev->iomem_base))
+		return -EINVAL;
+
+	iowrite16(NE_VERSION_MAX, ne_pci_dev->iomem_base + NE_VERSION);
+
+	dev_version_reply = ioread16(ne_pci_dev->iomem_base + NE_VERSION);
+	if (dev_version_reply != NE_VERSION_MAX) {
+		dev_err_ratelimited(&pdev->dev,
+				    NE "Error in pci dev version cmd\n");
+
+		return -EIO;
+	}
+
+	iowrite8(NE_ENABLE_ON, ne_pci_dev->iomem_base + NE_ENABLE);
+
+	dev_enable_reply = ioread8(ne_pci_dev->iomem_base + NE_ENABLE);
+	if (dev_enable_reply != NE_ENABLE_ON) {
+		dev_err_ratelimited(&pdev->dev,
+				    NE "Error in pci dev enable cmd\n");
+
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/**
+ * ne_pci_dev_disable - Disable PCI device.
+ *
+ * @pdev: PCI device to disable.
+ */
+static void ne_pci_dev_disable(struct pci_dev *pdev)
+{
+	u8 dev_disable_reply = 0;
+	struct ne_pci_dev *ne_pci_dev = NULL;
+	const unsigned int sleep_time = 10; // 10 ms
+	unsigned int sleep_time_count = 0;
+
+	if (WARN_ON(!pdev))
+		return;
+
+	ne_pci_dev = pci_get_drvdata(pdev);
+	if (WARN_ON(!ne_pci_dev) || WARN_ON(!ne_pci_dev->iomem_base))
+		return;
+
+	iowrite8(NE_ENABLE_OFF, ne_pci_dev->iomem_base + NE_ENABLE);
+
+	/*
+	 * Check for NE_ENABLE_OFF in a loop, to handle cases when the device
+	 * state is not immediately set to disabled and going through a
+	 * transitory state of disabling.
+	 */
+	while (sleep_time_count < DEFAULT_TIMEOUT_MSECS) {
+		dev_disable_reply = ioread8(ne_pci_dev->iomem_base + NE_ENABLE);
+		if (dev_disable_reply == NE_ENABLE_OFF)
+			return;
+
+		msleep_interruptible(sleep_time);
+		sleep_time_count += sleep_time;
+	}
+
+	dev_disable_reply = ioread8(ne_pci_dev->iomem_base + NE_ENABLE);
+	if (dev_disable_reply != NE_ENABLE_OFF)
+		dev_err_ratelimited(&pdev->dev,
+				    NE "Error in pci dev disable cmd\n");
+}
+
+static int ne_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+	struct ne_pci_dev *ne_pci_dev = NULL;
+	int rc = -EINVAL;
+
+	ne_pci_dev = kzalloc(sizeof(*ne_pci_dev), GFP_KERNEL);
+	if (!ne_pci_dev)
+		return -ENOMEM;
+
+	rc = pci_enable_device(pdev);
+	if (rc < 0) {
+		dev_err_ratelimited(&pdev->dev,
+				    NE "Error in pci dev enable [rc=%d]\n", rc);
+
+		goto free_ne_pci_dev;
+	}
+
+	rc = pci_request_regions_exclusive(pdev, "ne_pci_dev");
+	if (rc < 0) {
+		dev_err_ratelimited(&pdev->dev,
+				    NE "Error in pci request regions [rc=%d]\n",
+				    rc);
+
+		goto disable_pci_dev;
+	}
+
+	ne_pci_dev->iomem_base = pci_iomap(pdev, PCI_BAR_NE, 0);
+	if (!ne_pci_dev->iomem_base) {
+		rc = -ENOMEM;
+
+		dev_err_ratelimited(&pdev->dev,
+				    NE "Error in pci iomap [rc=%d]\n", rc);
+
+		goto release_pci_regions;
+	}
+
+	pci_set_drvdata(pdev, ne_pci_dev);
+
+	rc = ne_setup_msix(pdev);
+	if (rc < 0) {
+		dev_err_ratelimited(&pdev->dev,
+				    NE "Error in pci dev msix setup [rc=%d]\n",
+				    rc);
+
+		goto iounmap_pci_bar;
+	}
+
+	ne_pci_dev_disable(pdev);
+
+	rc = ne_pci_dev_enable(pdev);
+	if (rc < 0) {
+		dev_err_ratelimited(&pdev->dev,
+				    NE "Error in ne_pci_dev enable [rc=%d]\n",
+				    rc);
+
+		goto teardown_msix;
+	}
+
+	atomic_set(&ne_pci_dev->cmd_reply_avail, 0);
+	init_waitqueue_head(&ne_pci_dev->cmd_reply_wait_q);
+	INIT_LIST_HEAD(&ne_pci_dev->enclaves_list);
+	mutex_init(&ne_pci_dev->enclaves_list_mutex);
+	mutex_init(&ne_pci_dev->pci_dev_mutex);
+
+	return 0;
+
+teardown_msix:
+	ne_teardown_msix(pdev);
+iounmap_pci_bar:
+	pci_set_drvdata(pdev, NULL);
+	pci_iounmap(pdev, ne_pci_dev->iomem_base);
+release_pci_regions:
+	pci_release_regions(pdev);
+disable_pci_dev:
+	pci_disable_device(pdev);
+free_ne_pci_dev:
+	kzfree(ne_pci_dev);
+
+	return rc;
+}
+
+static void ne_pci_remove(struct pci_dev *pdev)
+{
+	struct ne_pci_dev *ne_pci_dev = pci_get_drvdata(pdev);
+
+	if (!ne_pci_dev || !ne_pci_dev->iomem_base)
+		return;
+
+	ne_pci_dev_disable(pdev);
+
+	ne_teardown_msix(pdev);
+
+	pci_set_drvdata(pdev, NULL);
+
+	pci_iounmap(pdev, ne_pci_dev->iomem_base);
+
+	pci_release_regions(pdev);
+
+	pci_disable_device(pdev);
+
+	kzfree(ne_pci_dev);
+}
+
+/*
+ * TODO: Add suspend / resume functions for power management w/ CONFIG_PM, if
+ * needed.
+ */
+struct pci_driver ne_pci_driver = {
+	.name		= "ne_pci_dev",
+	.id_table	= ne_pci_ids,
+	.probe		= ne_pci_probe,
+	.remove		= ne_pci_remove,
+};
-- 
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