1 files changed, 628 insertions, 0 deletions
diff --git a/arch/um/drivers/virtio_pcidev.c b/arch/um/drivers/virtio_pcidev.c
new file mode 100644
index 000000000000..3c4c4c928fdd
--- /dev/null
+++ b/arch/um/drivers/virtio_pcidev.c
@@ -0,0 +1,628 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Intel Corporation
+ * Author: Johannes Berg <johannes@sipsolutions.net>
+ */
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/logic_iomem.h>
+#include <linux/of_platform.h>
+#include <linux/irqdomain.h>
+#include <linux/virtio_pcidev.h>
+#include <linux/virtio-uml.h>
+#include <linux/delay.h>
+#include <linux/msi.h>
+#include <linux/unaligned.h>
+#include <irq_kern.h>
+
+#include "virt-pci.h"
+
+#define to_virtio_pcidev(_pdev) \
+	container_of(_pdev, struct virtio_pcidev_device, pdev)
+
+/* for MSI-X we have a 32-bit payload */
+#define MAX_IRQ_MSG_SIZE (sizeof(struct virtio_pcidev_msg) + sizeof(u32))
+#define NUM_IRQ_MSGS	10
+
+struct virtio_pcidev_message_buffer {
+	struct virtio_pcidev_msg hdr;
+	u8 data[8];
+};
+
+struct virtio_pcidev_device {
+	struct um_pci_device pdev;
+	struct virtio_device *vdev;
+
+	struct virtqueue *cmd_vq, *irq_vq;
+
+#define VIRTIO_PCIDEV_WRITE_BUFS	20
+	struct virtio_pcidev_message_buffer bufs[VIRTIO_PCIDEV_WRITE_BUFS + 1];
+	void *extra_ptrs[VIRTIO_PCIDEV_WRITE_BUFS + 1];
+	DECLARE_BITMAP(used_bufs, VIRTIO_PCIDEV_WRITE_BUFS);
+
+#define UM_PCI_STAT_WAITING	0
+	unsigned long status;
+
+	bool platform;
+};
+
+static unsigned int virtio_pcidev_max_delay_us = 40000;
+module_param_named(max_delay_us, virtio_pcidev_max_delay_us, uint, 0644);
+
+static int virtio_pcidev_get_buf(struct virtio_pcidev_device *dev, bool *posted)
+{
+	int i;
+
+	for (i = 0; i < VIRTIO_PCIDEV_WRITE_BUFS; i++) {
+		if (!test_and_set_bit(i, dev->used_bufs))
+			return i;
+	}
+
+	*posted = false;
+	return VIRTIO_PCIDEV_WRITE_BUFS;
+}
+
+static void virtio_pcidev_free_buf(struct virtio_pcidev_device *dev, void *buf)
+{
+	int i;
+
+	if (buf == &dev->bufs[VIRTIO_PCIDEV_WRITE_BUFS]) {
+		kfree(dev->extra_ptrs[VIRTIO_PCIDEV_WRITE_BUFS]);
+		dev->extra_ptrs[VIRTIO_PCIDEV_WRITE_BUFS] = NULL;
+		return;
+	}
+
+	for (i = 0; i < VIRTIO_PCIDEV_WRITE_BUFS; i++) {
+		if (buf == &dev->bufs[i]) {
+			kfree(dev->extra_ptrs[i]);
+			dev->extra_ptrs[i] = NULL;
+			WARN_ON(!test_and_clear_bit(i, dev->used_bufs));
+			return;
+		}
+	}
+
+	WARN_ON(1);
+}
+
+static int virtio_pcidev_send_cmd(struct virtio_pcidev_device *dev,
+				  struct virtio_pcidev_msg *cmd,
+				  unsigned int cmd_size,
+				  const void *extra, unsigned int extra_size,
+				  void *out, unsigned int out_size)
+{
+	struct scatterlist out_sg, extra_sg, in_sg;
+	struct scatterlist *sgs_list[] = {
+		[0] = &out_sg,
+		[1] = extra ? &extra_sg : &in_sg,
+		[2] = extra ? &in_sg : NULL,
+	};
+	struct virtio_pcidev_message_buffer *buf;
+	int delay_count = 0;
+	bool bounce_out;
+	int ret, len;
+	int buf_idx;
+	bool posted;
+
+	if (WARN_ON(cmd_size < sizeof(*cmd) || cmd_size > sizeof(*buf)))
+		return -EINVAL;
+
+	switch (cmd->op) {
+	case VIRTIO_PCIDEV_OP_CFG_WRITE:
+	case VIRTIO_PCIDEV_OP_MMIO_WRITE:
+	case VIRTIO_PCIDEV_OP_MMIO_MEMSET:
+		/* in PCI, writes are posted, so don't wait */
+		posted = !out;
+		WARN_ON(!posted);
+		break;
+	default:
+		posted = false;
+		break;
+	}
+
+	bounce_out = !posted && cmd_size <= sizeof(*cmd) &&
+		     out && out_size <= sizeof(buf->data);
+
+	buf_idx = virtio_pcidev_get_buf(dev, &posted);
+	buf = &dev->bufs[buf_idx];
+	memcpy(buf, cmd, cmd_size);
+
+	if (posted && extra && extra_size > sizeof(buf) - cmd_size) {
+		dev->extra_ptrs[buf_idx] = kmemdup(extra, extra_size,
+						   GFP_ATOMIC);
+
+		if (!dev->extra_ptrs[buf_idx]) {
+			virtio_pcidev_free_buf(dev, buf);
+			return -ENOMEM;
+		}
+		extra = dev->extra_ptrs[buf_idx];
+	} else if (extra && extra_size <= sizeof(buf) - cmd_size) {
+		memcpy((u8 *)buf + cmd_size, extra, extra_size);
+		cmd_size += extra_size;
+		extra_size = 0;
+		extra = NULL;
+		cmd = (void *)buf;
+	} else {
+		cmd = (void *)buf;
+	}
+
+	sg_init_one(&out_sg, cmd, cmd_size);
+	if (extra)
+		sg_init_one(&extra_sg, extra, extra_size);
+	/* allow stack for small buffers */
+	if (bounce_out)
+		sg_init_one(&in_sg, buf->data, out_size);
+	else if (out)
+		sg_init_one(&in_sg, out, out_size);
+
+	/* add to internal virtio queue */
+	ret = virtqueue_add_sgs(dev->cmd_vq, sgs_list,
+				extra ? 2 : 1,
+				out ? 1 : 0,
+				cmd, GFP_ATOMIC);
+	if (ret) {
+		virtio_pcidev_free_buf(dev, buf);
+		return ret;
+	}
+
+	if (posted) {
+		virtqueue_kick(dev->cmd_vq);
+		return 0;
+	}
+
+	/* kick and poll for getting a response on the queue */
+	set_bit(UM_PCI_STAT_WAITING, &dev->status);
+	virtqueue_kick(dev->cmd_vq);
+	ret = 0;
+
+	while (1) {
+		void *completed = virtqueue_get_buf(dev->cmd_vq, &len);
+
+		if (completed == buf)
+			break;
+
+		if (completed)
+			virtio_pcidev_free_buf(dev, completed);
+
+		if (WARN_ONCE(virtqueue_is_broken(dev->cmd_vq) ||
+			      ++delay_count > virtio_pcidev_max_delay_us,
+			      "um virt-pci delay: %d", delay_count)) {
+			ret = -EIO;
+			break;
+		}
+		udelay(1);
+	}
+	clear_bit(UM_PCI_STAT_WAITING, &dev->status);
+
+	if (bounce_out)
+		memcpy(out, buf->data, out_size);
+
+	virtio_pcidev_free_buf(dev, buf);
+
+	return ret;
+}
+
+static unsigned long virtio_pcidev_cfgspace_read(struct um_pci_device *pdev,
+						 unsigned int offset, int size)
+{
+	struct virtio_pcidev_device *dev = to_virtio_pcidev(pdev);
+	struct virtio_pcidev_msg hdr = {
+		.op = VIRTIO_PCIDEV_OP_CFG_READ,
+		.size = size,
+		.addr = offset,
+	};
+	/* max 8, we might not use it all */
+	u8 data[8];
+
+	memset(data, 0xff, sizeof(data));
+
+	/* size has been checked in um_pci_cfgspace_read() */
+	if (virtio_pcidev_send_cmd(dev, &hdr, sizeof(hdr), NULL, 0, data, size))
+		return ULONG_MAX;
+
+	switch (size) {
+	case 1:
+		return data[0];
+	case 2:
+		return le16_to_cpup((void *)data);
+	case 4:
+		return le32_to_cpup((void *)data);
+#ifdef CONFIG_64BIT
+	case 8:
+		return le64_to_cpup((void *)data);
+#endif
+	default:
+		return ULONG_MAX;
+	}
+}
+
+static void virtio_pcidev_cfgspace_write(struct um_pci_device *pdev,
+					 unsigned int offset, int size,
+					 unsigned long val)
+{
+	struct virtio_pcidev_device *dev = to_virtio_pcidev(pdev);
+	struct {
+		struct virtio_pcidev_msg hdr;
+		/* maximum size - we may only use parts of it */
+		u8 data[8];
+	} msg = {
+		.hdr = {
+			.op = VIRTIO_PCIDEV_OP_CFG_WRITE,
+			.size = size,
+			.addr = offset,
+		},
+	};
+
+	/* size has been checked in um_pci_cfgspace_write() */
+	switch (size) {
+	case 1:
+		msg.data[0] = (u8)val;
+		break;
+	case 2:
+		put_unaligned_le16(val, (void *)msg.data);
+		break;
+	case 4:
+		put_unaligned_le32(val, (void *)msg.data);
+		break;
+#ifdef CONFIG_64BIT
+	case 8:
+		put_unaligned_le64(val, (void *)msg.data);
+		break;
+#endif
+	}
+
+	WARN_ON(virtio_pcidev_send_cmd(dev, &msg.hdr, sizeof(msg), NULL, 0, NULL, 0));
+}
+
+static void virtio_pcidev_bar_copy_from(struct um_pci_device *pdev,
+					int bar, void *buffer,
+					unsigned int offset, int size)
+{
+	struct virtio_pcidev_device *dev = to_virtio_pcidev(pdev);
+	struct virtio_pcidev_msg hdr = {
+		.op = VIRTIO_PCIDEV_OP_MMIO_READ,
+		.bar = bar,
+		.size = size,
+		.addr = offset,
+	};
+
+	memset(buffer, 0xff, size);
+
+	virtio_pcidev_send_cmd(dev, &hdr, sizeof(hdr), NULL, 0, buffer, size);
+}
+
+static unsigned long virtio_pcidev_bar_read(struct um_pci_device *pdev, int bar,
+					    unsigned int offset, int size)
+{
+	/* 8 is maximum size - we may only use parts of it */
+	u8 data[8];
+
+	/* size has been checked in um_pci_bar_read() */
+	virtio_pcidev_bar_copy_from(pdev, bar, data, offset, size);
+
+	switch (size) {
+	case 1:
+		return data[0];
+	case 2:
+		return le16_to_cpup((void *)data);
+	case 4:
+		return le32_to_cpup((void *)data);
+#ifdef CONFIG_64BIT
+	case 8:
+		return le64_to_cpup((void *)data);
+#endif
+	default:
+		return ULONG_MAX;
+	}
+}
+
+static void virtio_pcidev_bar_copy_to(struct um_pci_device *pdev,
+				      int bar, unsigned int offset,
+				      const void *buffer, int size)
+{
+	struct virtio_pcidev_device *dev = to_virtio_pcidev(pdev);
+	struct virtio_pcidev_msg hdr = {
+		.op = VIRTIO_PCIDEV_OP_MMIO_WRITE,
+		.bar = bar,
+		.size = size,
+		.addr = offset,
+	};
+
+	virtio_pcidev_send_cmd(dev, &hdr, sizeof(hdr), buffer, size, NULL, 0);
+}
+
+static void virtio_pcidev_bar_write(struct um_pci_device *pdev, int bar,
+				    unsigned int offset, int size,
+				    unsigned long val)
+{
+	/* maximum size - we may only use parts of it */
+	u8 data[8];
+
+	/* size has been checked in um_pci_bar_write() */
+	switch (size) {
+	case 1:
+		data[0] = (u8)val;
+		break;
+	case 2:
+		put_unaligned_le16(val, (void *)data);
+		break;
+	case 4:
+		put_unaligned_le32(val, (void *)data);
+		break;
+#ifdef CONFIG_64BIT
+	case 8:
+		put_unaligned_le64(val, (void *)data);
+		break;
+#endif
+	}
+
+	virtio_pcidev_bar_copy_to(pdev, bar, offset, data, size);
+}
+
+static void virtio_pcidev_bar_set(struct um_pci_device *pdev, int bar,
+				  unsigned int offset, u8 value, int size)
+{
+	struct virtio_pcidev_device *dev = to_virtio_pcidev(pdev);
+	struct {
+		struct virtio_pcidev_msg hdr;
+		u8 data;
+	} msg = {
+		.hdr = {
+			.op = VIRTIO_PCIDEV_OP_CFG_WRITE,
+			.bar = bar,
+			.size = size,
+			.addr = offset,
+		},
+		.data = value,
+	};
+
+	virtio_pcidev_send_cmd(dev, &msg.hdr, sizeof(msg), NULL, 0, NULL, 0);
+}
+
+static const struct um_pci_ops virtio_pcidev_um_pci_ops = {
+	.cfgspace_read	= virtio_pcidev_cfgspace_read,
+	.cfgspace_write	= virtio_pcidev_cfgspace_write,
+	.bar_read	= virtio_pcidev_bar_read,
+	.bar_write	= virtio_pcidev_bar_write,
+	.bar_copy_from	= virtio_pcidev_bar_copy_from,
+	.bar_copy_to	= virtio_pcidev_bar_copy_to,
+	.bar_set	= virtio_pcidev_bar_set,
+};
+
+static void virtio_pcidev_irq_vq_addbuf(struct virtqueue *vq, void *buf, bool kick)
+{
+	struct scatterlist sg[1];
+
+	sg_init_one(sg, buf, MAX_IRQ_MSG_SIZE);
+	if (virtqueue_add_inbuf(vq, sg, 1, buf, GFP_ATOMIC))
+		kfree(buf);
+	else if (kick)
+		virtqueue_kick(vq);
+}
+
+static void virtio_pcidev_handle_irq_message(struct virtqueue *vq,
+					     struct virtio_pcidev_msg *msg)
+{
+	struct virtio_device *vdev = vq->vdev;
+	struct virtio_pcidev_device *dev = vdev->priv;
+
+	if (!dev->pdev.irq)
+		return;
+
+	/* we should properly chain interrupts, but on ARCH=um we don't care */
+
+	switch (msg->op) {
+	case VIRTIO_PCIDEV_OP_INT:
+		generic_handle_irq(dev->pdev.irq);
+		break;
+	case VIRTIO_PCIDEV_OP_MSI:
+		/* our MSI message is just the interrupt number */
+		if (msg->size == sizeof(u32))
+			generic_handle_irq(le32_to_cpup((void *)msg->data));
+		else
+			generic_handle_irq(le16_to_cpup((void *)msg->data));
+		break;
+	case VIRTIO_PCIDEV_OP_PME:
+		/* nothing to do - we already woke up due to the message */
+		break;
+	default:
+		dev_err(&vdev->dev, "unexpected virt-pci message %d\n", msg->op);
+		break;
+	}
+}
+
+static void virtio_pcidev_cmd_vq_cb(struct virtqueue *vq)
+{
+	struct virtio_device *vdev = vq->vdev;
+	struct virtio_pcidev_device *dev = vdev->priv;
+	void *cmd;
+	int len;
+
+	if (test_bit(UM_PCI_STAT_WAITING, &dev->status))
+		return;
+
+	while ((cmd = virtqueue_get_buf(vq, &len)))
+		virtio_pcidev_free_buf(dev, cmd);
+}
+
+static void virtio_pcidev_irq_vq_cb(struct virtqueue *vq)
+{
+	struct virtio_pcidev_msg *msg;
+	int len;
+
+	while ((msg = virtqueue_get_buf(vq, &len))) {
+		if (len >= sizeof(*msg))
+			virtio_pcidev_handle_irq_message(vq, msg);
+
+		/* recycle the message buffer */
+		virtio_pcidev_irq_vq_addbuf(vq, msg, true);
+	}
+}
+
+static int virtio_pcidev_init_vqs(struct virtio_pcidev_device *dev)
+{
+	struct virtqueue_info vqs_info[] = {
+		{ "cmd", virtio_pcidev_cmd_vq_cb },
+		{ "irq", virtio_pcidev_irq_vq_cb },
+	};
+	struct virtqueue *vqs[2];
+	int err, i;
+
+	err = virtio_find_vqs(dev->vdev, 2, vqs, vqs_info, NULL);
+	if (err)
+		return err;
+
+	dev->cmd_vq = vqs[0];
+	dev->irq_vq = vqs[1];
+
+	virtio_device_ready(dev->vdev);
+
+	for (i = 0; i < NUM_IRQ_MSGS; i++) {
+		void *msg = kzalloc(MAX_IRQ_MSG_SIZE, GFP_KERNEL);
+
+		if (msg)
+			virtio_pcidev_irq_vq_addbuf(dev->irq_vq, msg, false);
+	}
+
+	virtqueue_kick(dev->irq_vq);
+
+	return 0;
+}
+
+static void __virtio_pcidev_virtio_platform_remove(struct virtio_device *vdev,
+						   struct virtio_pcidev_device *dev)
+{
+	um_pci_platform_device_unregister(&dev->pdev);
+
+	virtio_reset_device(vdev);
+	vdev->config->del_vqs(vdev);
+
+	kfree(dev);
+}
+
+static int virtio_pcidev_virtio_platform_probe(struct virtio_device *vdev,
+					       struct virtio_pcidev_device *dev)
+{
+	int err;
+
+	dev->platform = true;
+
+	err = virtio_pcidev_init_vqs(dev);
+	if (err)
+		goto err_free;
+
+	err = um_pci_platform_device_register(&dev->pdev);
+	if (err)
+		goto err_reset;
+
+	err = of_platform_default_populate(vdev->dev.of_node, NULL, &vdev->dev);
+	if (err)
+		goto err_unregister;
+
+	return 0;
+
+err_unregister:
+	um_pci_platform_device_unregister(&dev->pdev);
+err_reset:
+	virtio_reset_device(vdev);
+	vdev->config->del_vqs(vdev);
+err_free:
+	kfree(dev);
+	return err;
+}
+
+static int virtio_pcidev_virtio_probe(struct virtio_device *vdev)
+{
+	struct virtio_pcidev_device *dev;
+	int err;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	dev->vdev = vdev;
+	vdev->priv = dev;
+
+	dev->pdev.ops = &virtio_pcidev_um_pci_ops;
+
+	if (of_device_is_compatible(vdev->dev.of_node, "simple-bus"))
+		return virtio_pcidev_virtio_platform_probe(vdev, dev);
+
+	err = virtio_pcidev_init_vqs(dev);
+	if (err)
+		goto err_free;
+
+	err = um_pci_device_register(&dev->pdev);
+	if (err)
+		goto err_reset;
+
+	device_set_wakeup_enable(&vdev->dev, true);
+
+	/*
+	 * In order to do suspend-resume properly, don't allow VQs
+	 * to be suspended.
+	 */
+	virtio_uml_set_no_vq_suspend(vdev, true);
+
+	return 0;
+
+err_reset:
+	virtio_reset_device(vdev);
+	vdev->config->del_vqs(vdev);
+err_free:
+	kfree(dev);
+	return err;
+}
+
+static void virtio_pcidev_virtio_remove(struct virtio_device *vdev)
+{
+	struct virtio_pcidev_device *dev = vdev->priv;
+
+	if (dev->platform) {
+		of_platform_depopulate(&vdev->dev);
+		__virtio_pcidev_virtio_platform_remove(vdev, dev);
+		return;
+	}
+
+	device_set_wakeup_enable(&vdev->dev, false);
+
+	um_pci_device_unregister(&dev->pdev);
+
+	/* Stop all virtqueues */
+	virtio_reset_device(vdev);
+	dev->cmd_vq = NULL;
+	dev->irq_vq = NULL;
+	vdev->config->del_vqs(vdev);
+
+	kfree(dev);
+}
+
+static struct virtio_device_id id_table[] = {
+	{ CONFIG_UML_PCI_OVER_VIRTIO_DEVICE_ID, VIRTIO_DEV_ANY_ID },
+	{ 0 },
+};
+MODULE_DEVICE_TABLE(virtio, id_table);
+
+static struct virtio_driver virtio_pcidev_virtio_driver = {
+	.driver.name = "virtio-pci",
+	.id_table = id_table,
+	.probe = virtio_pcidev_virtio_probe,
+	.remove = virtio_pcidev_virtio_remove,
+};
+
+static int __init virtio_pcidev_init(void)
+{
+	if (WARN(CONFIG_UML_PCI_OVER_VIRTIO_DEVICE_ID < 0,
+		 "No virtio device ID configured for PCI - no PCI support\n"))
+		return 0;
+
+	return register_virtio_driver(&virtio_pcidev_virtio_driver);
+}
+late_initcall(virtio_pcidev_init);
+
+static void __exit virtio_pcidev_exit(void)
+{
+	unregister_virtio_driver(&virtio_pcidev_virtio_driver);
+}
+module_exit(virtio_pcidev_exit);