extend uio driver to supports msix

This patch extends UIO PCI generic driver to
 support MSI-X interrupt.

Tracked-On:projectacrn/acrn-hypervisor#5407

Signed-off-by: Yonghua Huang <yonghua.huang@intel.com>
Signed-off-by: Yuan Liu <yuan1.liu@intel.com>

drivers/uio/uio.c

@@ -562,6 +562,22 @@ static __poll_t uio_poll(struct file *filep, poll_table *wait)
 	return 0;
 }
 
+#ifdef CONFIG_PCI_MSI
+static long uio_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
+{
+	struct uio_listener *listener = filep->private_data;
+	struct uio_device *idev = listener->dev;
+
+	if (!idev->info)
+		return -EIO;
+
+	if (!idev->info->ioctl)
+		return -ENOTTY;
+
+	return idev->info->ioctl(idev->info, cmd, arg);
+}
+#endif
+
 static ssize_t uio_read(struct file *filep, char __user *buf,
 			size_t count, loff_t *ppos)
 {
@@ -823,6 +839,9 @@ static const struct file_operations uio_fops = {
 	.write		= uio_write,
 	.mmap		= uio_mmap,
 	.poll		= uio_poll,
+#ifdef CONFIG_PCI_MSI
+	.unlocked_ioctl	= uio_ioctl,
+#endif
 	.fasync		= uio_fasync,
 	.llseek		= noop_llseek,
 };

drivers/uio/uio_pci_generic.c

@@ -23,16 +23,129 @@
 #include <linux/pci.h>
 #include <linux/slab.h>
 #include <linux/uio_driver.h>
+#ifdef CONFIG_PCI_MSI
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/eventfd.h>
+#endif
 
 #define DRIVER_VERSION	"0.01.0"
 #define DRIVER_AUTHOR	"Michael S. Tsirkin <mst@redhat.com>"
 #define DRIVER_DESC	"Generic UIO driver for PCI 2.3 devices"
 
+#ifdef CONFIG_PCI_MSI
+struct uio_msix_info {
+	struct msix_entry *entries;
+	struct eventfd_ctx **evts;
+	int nvecs;
+};
+#endif
+
 struct uio_pci_generic_dev {
 	struct uio_info info;
 	struct pci_dev *pdev;
+#ifdef CONFIG_PCI_MSI
+	struct uio_msix_info msix_info;
+#endif
 };
 
+#ifdef CONFIG_PCI_MSI
+static irqreturn_t uio_msix_handler(int irq, void *arg)
+{
+	struct eventfd_ctx *evt = arg;
+
+	eventfd_signal(evt, 1);
+	return IRQ_HANDLED;
+}
+
+static int map_msix_eventfd(struct uio_pci_generic_dev *gdev,
+		int fd, int vector)
+{
+	int irq, err;
+	struct eventfd_ctx *evt;
+
+	/* Passing -1 is used to disable interrupt */
+	if (fd < 0) {
+		pci_disable_msi(gdev->pdev);
+		return 0;
+	}
+
+	if (vector >= gdev->msix_info.nvecs)
+		return -EINVAL;
+
+	irq = gdev->msix_info.entries[vector].vector;
+	evt = gdev->msix_info.evts[vector];
+	if (evt) {
+		free_irq(irq, evt);
+		eventfd_ctx_put(evt);
+		gdev->msix_info.evts[vector] = NULL;
+	}
+
+	evt = eventfd_ctx_fdget(fd);
+	if (!evt)
+		return -EINVAL;
+
+	err = request_irq(irq, uio_msix_handler, 0, "UIO IRQ", evt);
+	if (err) {
+		eventfd_ctx_put(evt);
+		return err;
+	}
+
+	gdev->msix_info.evts[vector] = evt;
+	return 0;
+}
+
+static int uio_msi_ioctl(struct uio_info *info, unsigned int cmd,
+		unsigned long arg)
+{
+	struct uio_pci_generic_dev *gdev;
+	struct uio_msix_data data;
+	int err = -EOPNOTSUPP;
+
+	gdev = container_of(info, struct uio_pci_generic_dev, info);
+
+	switch (cmd) {
+	case UIO_MSIX_DATA: {
+		if (copy_from_user(&data, (void __user *)arg, sizeof(data)))
+			return -EFAULT;
+
+		err = map_msix_eventfd(gdev, data.fd, data.vector);
+		break;
+	}
+	default:
+		pr_warn("Not support ioctl cmd: 0x%x\n", cmd);
+		break;
+	}
+
+	return err;
+}
+
+static int pci_generic_init_msix(struct uio_pci_generic_dev *gdev)
+{
+	unsigned char *buffer;
+	int i, nvecs;
+
+	nvecs = pci_msix_vec_count(gdev->pdev);
+	if (!nvecs)
+		return -EINVAL;
+
+	buffer = devm_kzalloc(&gdev->pdev->dev, nvecs * (sizeof(struct msix_entry) +
+			sizeof(struct eventfd_ctx *)), GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+
+	gdev->msix_info.entries = (struct msix_entry *)buffer;
+	gdev->msix_info.evts = (struct eventfd_ctx **)
+		((unsigned char *)buffer + nvecs * sizeof(struct msix_entry));
+	gdev->msix_info.nvecs = nvecs;
+
+	for (i = 0; i < nvecs; ++i)
+		gdev->msix_info.entries[i].entry = i;
+
+	return  pci_enable_msix_exact(gdev->pdev, gdev->msix_info.entries, nvecs);
+}
+#endif
+
 static inline struct uio_pci_generic_dev *
 to_uio_pci_generic_dev(struct uio_info *info)
 {
@@ -93,14 +206,23 @@ static int probe(struct pci_dev *pdev,
 	gdev->info.name = "uio_pci_generic";
 	gdev->info.version = DRIVER_VERSION;
 	gdev->info.release = release;
+#ifdef CONFIG_PCI_MSI
+	gdev->info.ioctl = uio_msi_ioctl;
+#endif
 	gdev->pdev = pdev;
 	if (pdev->irq && (pdev->irq != IRQ_NOTCONNECTED)) {
 		gdev->info.irq = pdev->irq;
 		gdev->info.irq_flags = IRQF_SHARED;
 		gdev->info.handler = irqhandler;
 	} else {
+#ifdef CONFIG_PCI_MSI
+		err = pci_generic_init_msix(gdev);
+		if (!err)
+			dev_notice(&pdev->dev, "MSIX is enabled for UIO device.\n");
+#else
 		dev_warn(&pdev->dev, "No IRQ assigned to device: "
 			 "no support for interrupts?\n");
+#endif
 	}
 
 	uiomem = &gdev->info.mem[0];
@@ -133,13 +255,46 @@ static int probe(struct pci_dev *pdev,
 		++uiomem;
 	}
 
-	return devm_uio_register_device(&pdev->dev, &gdev->info);
+	err = devm_uio_register_device(&pdev->dev, &gdev->info);
+	if (err)
+		return err;
+
+#ifdef CONFIG_PCI_MSI
+	pci_set_drvdata(pdev, gdev);
+#endif
+
+	return 0;
 }
 
+#ifdef CONFIG_PCI_MSI
+static void remove(struct pci_dev *pdev)
+{
+	int i, irq;
+	struct eventfd_ctx *evt;
+	struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);
+
+	if (gdev->msix_info.entries != NULL) {
+		for (i = 0; i < gdev->msix_info.nvecs; i++) {
+			irq = gdev->msix_info.entries[i].vector;
+			evt = gdev->msix_info.evts[i];
+			if (evt) {
+				free_irq(irq, evt);
+				eventfd_ctx_put(evt);
+				gdev->msix_info.evts[i] = NULL;
+			}
+		}
+		pci_disable_msix(pdev);
+	}
+}
+#endif
+
 static struct pci_driver uio_pci_driver = {
 	.name = "uio_pci_generic",
 	.id_table = NULL, /* only dynamic id's */
 	.probe = probe,
+#ifdef CONFIG_PCI_MSI
+	.remove = remove,
+#endif
 };
 
 module_pci_driver(uio_pci_driver);

include/linux/uio_driver.h

@@ -46,6 +46,15 @@ struct uio_mem {
 
 #define MAX_UIO_MAPS	5
 
+#ifdef CONFIG_PCI_MSI
+struct uio_msix_data {
+	int fd;
+	int vector;
+};
+#define UIO_MSIX_DATA	_IOW('u', 100, struct uio_msix_data)
+#endif
+
+
 struct uio_portio;
 
 /**
@@ -109,6 +118,10 @@ struct uio_info {
 	int (*open)(struct uio_info *info, struct inode *inode);
 	int (*release)(struct uio_info *info, struct inode *inode);
 	int (*irqcontrol)(struct uio_info *info, s32 irq_on);
+#ifdef CONFIG_PCI_MSI
+	int (*ioctl)(struct uio_info *info, unsigned int cmd,
+			unsigned long arg);
+#endif
 };
 
 extern int __must_check