[dpdk-dev] [RFC PATCH v3 1/3] vfio: revert change that does intr eventfd setup at probe

[Nithin Dabilpuram <ndabilpuram@marvell.com>]

This reverts commit 89aac60e0be9ed95a87b16e3595f102f9faaffb4.
"vfio: fix interrupts race condition"

The above mentioned commit moves the interrupt's eventfd setup
to probe time but only enables one interrupt for all types of
interrupt handles i.e VFIO_MSI, VFIO_LEGACY, VFIO_MSIX, UIO.
It works fine with default case but breaks below cases specifically
for MSIX based interrupt handles.

* Applications like l3fwd-power that request rxq interrupts
  while ethdev setup.
* Drivers that need > 1 MSIx interrupts to be configured for
  functionality to work.

VFIO PCI for MSIx expects all the possible vectors to be setup up
when using VFIO_IRQ_SET_ACTION_TRIGGER so that they can be
allocated from kernel pci subsystem. Only way to increase the number
of vectors later is first free all by using VFIO_IRQ_SET_DATA_NONE
with action trigger and then enable new vector count.

Above commit changes the behavior of rte_intr_[enable|disable] to
only mask and unmask unlike earlier behavior and thereby
breaking above two scenarios.

Fixes: 89aac60e0be9 ("vfio: fix interrupts race condition")
Cc: david.marchand@redhat.com

Signed-off-by: Nithin Dabilpuram <ndabilpuram@marvell.com>
---
 drivers/bus/pci/linux/pci_vfio.c          |  78 ++++++------
 lib/librte_eal/linux/eal/eal_interrupts.c | 201 +++++++++++++++++++++++-------
 2 files changed, 191 insertions(+), 88 deletions(-)

diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
index ee31239..1ceb1c0 100644
--- a/drivers/bus/pci/linux/pci_vfio.c
+++ b/drivers/bus/pci/linux/pci_vfio.c
@@ -187,11 +187,8 @@ pci_vfio_set_bus_master(int dev_fd, bool op)
 static int
 pci_vfio_setup_interrupts(struct rte_pci_device *dev, int vfio_dev_fd)
 {
-	char irq_set_buf[sizeof(struct vfio_irq_set) + sizeof(int)];
-	struct vfio_irq_set *irq_set;
-	enum rte_intr_mode intr_mode;
 	int i, ret, intr_idx;
-	int fd;
+	enum rte_intr_mode intr_mode;
 
 	/* default to invalid index */
 	intr_idx = VFIO_PCI_NUM_IRQS;
@@ -223,6 +220,7 @@ pci_vfio_setup_interrupts(struct rte_pci_device *dev, int vfio_dev_fd)
 	/* start from MSI-X interrupt type */
 	for (i = VFIO_PCI_MSIX_IRQ_INDEX; i >= 0; i--) {
 		struct vfio_irq_info irq = { .argsz = sizeof(irq) };
+		int fd = -1;
 
 		/* skip interrupt modes we don't want */
 		if (intr_mode != RTE_INTR_MODE_NONE &&
@@ -238,51 +236,51 @@ pci_vfio_setup_interrupts(struct rte_pci_device *dev, int vfio_dev_fd)
 			return -1;
 		}
 
-		/* found a usable interrupt mode */
-		if ((irq.flags & VFIO_IRQ_INFO_EVENTFD) != 0)
-			break;
-
 		/* if this vector cannot be used with eventfd, fail if we explicitly
 		 * specified interrupt type, otherwise continue */
-		if (intr_mode != RTE_INTR_MODE_NONE) {
-			RTE_LOG(ERR, EAL, "  interrupt vector does not support eventfd!\n");
+		if ((irq.flags & VFIO_IRQ_INFO_EVENTFD) == 0) {
+			if (intr_mode != RTE_INTR_MODE_NONE) {
+				RTE_LOG(ERR, EAL,
+						"  interrupt vector does not support eventfd!\n");
+				return -1;
+			} else
+				continue;
+		}
+
+		/* set up an eventfd for interrupts */
+		fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
+		if (fd < 0) {
+			RTE_LOG(ERR, EAL, "  cannot set up eventfd, "
+					"error %i (%s)\n", errno, strerror(errno));
 			return -1;
 		}
-	}
 
-	if (i < 0)
-		return -1;
+		dev->intr_handle.fd = fd;
+		dev->intr_handle.vfio_dev_fd = vfio_dev_fd;
 
-	fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
-	if (fd < 0) {
-		RTE_LOG(ERR, EAL, "  cannot set up eventfd, error %i (%s)\n",
-			errno, strerror(errno));
-		return -1;
-	}
+		switch (i) {
+		case VFIO_PCI_MSIX_IRQ_INDEX:
+			intr_mode = RTE_INTR_MODE_MSIX;
+			dev->intr_handle.type = RTE_INTR_HANDLE_VFIO_MSIX;
+			break;
+		case VFIO_PCI_MSI_IRQ_INDEX:
+			intr_mode = RTE_INTR_MODE_MSI;
+			dev->intr_handle.type = RTE_INTR_HANDLE_VFIO_MSI;
+			break;
+		case VFIO_PCI_INTX_IRQ_INDEX:
+			intr_mode = RTE_INTR_MODE_LEGACY;
+			dev->intr_handle.type = RTE_INTR_HANDLE_VFIO_LEGACY;
+			break;
+		default:
+			RTE_LOG(ERR, EAL, "  unknown interrupt type!\n");
+			return -1;
+		}
 
-	irq_set = (struct vfio_irq_set *)irq_set_buf;
-	irq_set->argsz = sizeof(irq_set_buf);
-	irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD|VFIO_IRQ_SET_ACTION_TRIGGER;
-	irq_set->index = i;
-	irq_set->start = 0;
-	irq_set->count = 1;
-	memcpy(&irq_set->data, &fd, sizeof(int));
-	if (ioctl(vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set) < 0) {
-		RTE_LOG(ERR, EAL, "  error configuring interrupt\n");
-		close(fd);
-		return -1;
+		return 0;
 	}
 
-	dev->intr_handle.fd = fd;
-	dev->intr_handle.vfio_dev_fd = vfio_dev_fd;
-	if (i == VFIO_PCI_MSIX_IRQ_INDEX)
-		dev->intr_handle.type = RTE_INTR_HANDLE_VFIO_MSIX;
-	else if (i == VFIO_PCI_MSI_IRQ_INDEX)
-		dev->intr_handle.type = RTE_INTR_HANDLE_VFIO_MSI;
-	else if (i == VFIO_PCI_INTX_IRQ_INDEX)
-		dev->intr_handle.type = RTE_INTR_HANDLE_VFIO_LEGACY;
-
-	return 0;
+	/* if we're here, we haven't found a suitable interrupt vector */
+	return -1;
 }
 
 #ifdef HAVE_VFIO_DEV_REQ_INTERFACE
diff --git a/lib/librte_eal/linux/eal/eal_interrupts.c b/lib/librte_eal/linux/eal/eal_interrupts.c
index 27976b3..79ad5e8 100644
--- a/lib/librte_eal/linux/eal/eal_interrupts.c
+++ b/lib/librte_eal/linux/eal/eal_interrupts.c
@@ -109,19 +109,42 @@ static pthread_t intr_thread;
 
 /* enable legacy (INTx) interrupts */
 static int
-vfio_enable_intx(const struct rte_intr_handle *intr_handle)
-{
-	struct vfio_irq_set irq_set;
-	int ret;
-
-	/* unmask INTx */
-	irq_set.argsz = sizeof(irq_set);
-	irq_set.flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_UNMASK;
-	irq_set.index = VFIO_PCI_INTX_IRQ_INDEX;
-	irq_set.start = 0;
-	irq_set.count = 1;
-
-	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, &irq_set);
+vfio_enable_intx(const struct rte_intr_handle *intr_handle) {
+	struct vfio_irq_set *irq_set;
+	char irq_set_buf[IRQ_SET_BUF_LEN];
+	int len, ret;
+	int *fd_ptr;
+
+	len = sizeof(irq_set_buf);
+
+	/* enable INTx */
+	irq_set = (struct vfio_irq_set *) irq_set_buf;
+	irq_set->argsz = len;
+	irq_set->count = 1;
+	irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER;
+	irq_set->index = VFIO_PCI_INTX_IRQ_INDEX;
+	irq_set->start = 0;
+	fd_ptr = (int *) &irq_set->data;
+	*fd_ptr = intr_handle->fd;
+
+	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
+
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Error enabling INTx interrupts for fd %d\n",
+						intr_handle->fd);
+		return -1;
+	}
+
+	/* unmask INTx after enabling */
+	memset(irq_set, 0, len);
+	len = sizeof(struct vfio_irq_set);
+	irq_set->argsz = len;
+	irq_set->count = 1;
+	irq_set->flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_UNMASK;
+	irq_set->index = VFIO_PCI_INTX_IRQ_INDEX;
+	irq_set->start = 0;
+
+	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
 
 	if (ret) {
 		RTE_LOG(ERR, EAL, "Error unmasking INTx interrupts for fd %d\n",
@@ -133,51 +156,128 @@ vfio_enable_intx(const struct rte_intr_handle *intr_handle)
 
 /* disable legacy (INTx) interrupts */
 static int
-vfio_disable_intx(const struct rte_intr_handle *intr_handle)
-{
-	struct vfio_irq_set irq_set;
-	int ret;
+vfio_disable_intx(const struct rte_intr_handle *intr_handle) {
+	struct vfio_irq_set *irq_set;
+	char irq_set_buf[IRQ_SET_BUF_LEN];
+	int len, ret;
 
-	/* mask interrupts */
-	irq_set.argsz = sizeof(irq_set);
-	irq_set.flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_MASK;
-	irq_set.index = VFIO_PCI_INTX_IRQ_INDEX;
-	irq_set.start = 0;
-	irq_set.count = 1;
+	len = sizeof(struct vfio_irq_set);
 
-	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, &irq_set);
+	/* mask interrupts before disabling */
+	irq_set = (struct vfio_irq_set *) irq_set_buf;
+	irq_set->argsz = len;
+	irq_set->count = 1;
+	irq_set->flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_MASK;
+	irq_set->index = VFIO_PCI_INTX_IRQ_INDEX;
+	irq_set->start = 0;
+
+	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
 
 	if (ret) {
 		RTE_LOG(ERR, EAL, "Error masking INTx interrupts for fd %d\n",
 						intr_handle->fd);
 		return -1;
 	}
+
+	/* disable INTx*/
+	memset(irq_set, 0, len);
+	irq_set->argsz = len;
+	irq_set->count = 0;
+	irq_set->flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_TRIGGER;
+	irq_set->index = VFIO_PCI_INTX_IRQ_INDEX;
+	irq_set->start = 0;
+
+	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
+
+	if (ret) {
+		RTE_LOG(ERR, EAL,
+			"Error disabling INTx interrupts for fd %d\n", intr_handle->fd);
+		return -1;
+	}
 	return 0;
 }
 
+/* enable MSI interrupts */
+static int
+vfio_enable_msi(const struct rte_intr_handle *intr_handle) {
+	int len, ret;
+	char irq_set_buf[IRQ_SET_BUF_LEN];
+	struct vfio_irq_set *irq_set;
+	int *fd_ptr;
+
+	len = sizeof(irq_set_buf);
+
+	irq_set = (struct vfio_irq_set *) irq_set_buf;
+	irq_set->argsz = len;
+	irq_set->count = 1;
+	irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER;
+	irq_set->index = VFIO_PCI_MSI_IRQ_INDEX;
+	irq_set->start = 0;
+	fd_ptr = (int *) &irq_set->data;
+	*fd_ptr = intr_handle->fd;
+
+	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
+
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Error enabling MSI interrupts for fd %d\n",
+						intr_handle->fd);
+		return -1;
+	}
+	return 0;
+}
+
+/* disable MSI interrupts */
+static int
+vfio_disable_msi(const struct rte_intr_handle *intr_handle) {
+	struct vfio_irq_set *irq_set;
+	char irq_set_buf[IRQ_SET_BUF_LEN];
+	int len, ret;
+
+	len = sizeof(struct vfio_irq_set);
+
+	irq_set = (struct vfio_irq_set *) irq_set_buf;
+	irq_set->argsz = len;
+	irq_set->count = 0;
+	irq_set->flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_TRIGGER;
+	irq_set->index = VFIO_PCI_MSI_IRQ_INDEX;
+	irq_set->start = 0;
+
+	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
+
+	if (ret)
+		RTE_LOG(ERR, EAL,
+			"Error disabling MSI interrupts for fd %d\n", intr_handle->fd);
+
+	return ret;
+}
+
 /* enable MSI-X interrupts */
 static int
-vfio_enable_msix(const struct rte_intr_handle *intr_handle)
-{
+vfio_enable_msix(const struct rte_intr_handle *intr_handle) {
+	int len, ret;
 	char irq_set_buf[MSIX_IRQ_SET_BUF_LEN];
 	struct vfio_irq_set *irq_set;
-	int len, ret;
-
-	if (intr_handle->nb_efd == 0)
-		return 0;
+	int *fd_ptr;
 
 	len = sizeof(irq_set_buf);
 
 	irq_set = (struct vfio_irq_set *) irq_set_buf;
 	irq_set->argsz = len;
+	/* 0 < irq_set->count < RTE_MAX_RXTX_INTR_VEC_ID + 1 */
+	irq_set->count = intr_handle->max_intr ?
+		(intr_handle->max_intr > RTE_MAX_RXTX_INTR_VEC_ID + 1 ?
+		RTE_MAX_RXTX_INTR_VEC_ID + 1 : intr_handle->max_intr) : 1;
 	irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER;
 	irq_set->index = VFIO_PCI_MSIX_IRQ_INDEX;
-	irq_set->start = RTE_INTR_VEC_RXTX_OFFSET;
-	irq_set->count = intr_handle->nb_efd;
-	memcpy(&irq_set->data, intr_handle->efds,
-	       sizeof(*intr_handle->efds) * intr_handle->nb_efd);
+	irq_set->start = 0;
+	fd_ptr = (int *) &irq_set->data;
+	/* INTR vector offset 0 reserve for non-efds mapping */
+	fd_ptr[RTE_INTR_VEC_ZERO_OFFSET] = intr_handle->fd;
+	memcpy(&fd_ptr[RTE_INTR_VEC_RXTX_OFFSET], intr_handle->efds,
+		sizeof(*intr_handle->efds) * intr_handle->nb_efd);
 
 	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
+
 	if (ret) {
 		RTE_LOG(ERR, EAL, "Error enabling MSI-X interrupts for fd %d\n",
 						intr_handle->fd);
@@ -189,21 +289,22 @@ vfio_enable_msix(const struct rte_intr_handle *intr_handle)
 
 /* disable MSI-X interrupts */
 static int
-vfio_disable_msix(const struct rte_intr_handle *intr_handle)
-{
-	struct vfio_irq_set irq_set;
-	int ret;
+vfio_disable_msix(const struct rte_intr_handle *intr_handle) {
+	struct vfio_irq_set *irq_set;
+	char irq_set_buf[MSIX_IRQ_SET_BUF_LEN];
+	int len, ret;
 
-	if (intr_handle->nb_efd == 0)
-		return 0;
+	len = sizeof(struct vfio_irq_set);
 
-	irq_set.argsz = sizeof(irq_set);
-	irq_set.flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_TRIGGER;
-	irq_set.index = VFIO_PCI_MSIX_IRQ_INDEX;
-	irq_set.start = RTE_INTR_VEC_RXTX_OFFSET;
-	irq_set.count = intr_handle->nb_efd;
+	irq_set = (struct vfio_irq_set *) irq_set_buf;
+	irq_set->argsz = len;
+	irq_set->count = 0;
+	irq_set->flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_TRIGGER;
+	irq_set->index = VFIO_PCI_MSIX_IRQ_INDEX;
+	irq_set->start = 0;
+
+	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, irq_set);
 
-	ret = ioctl(intr_handle->vfio_dev_fd, VFIO_DEVICE_SET_IRQS, &irq_set);
 	if (ret)
 		RTE_LOG(ERR, EAL,
 			"Error disabling MSI-X interrupts for fd %d\n", intr_handle->fd);
@@ -564,7 +665,9 @@ rte_intr_enable(const struct rte_intr_handle *intr_handle)
 			return -1;
 		break;
 	case RTE_INTR_HANDLE_VFIO_MSI:
-		return 0;
+		if (vfio_enable_msi(intr_handle))
+			return -1;
+		break;
 	case RTE_INTR_HANDLE_VFIO_LEGACY:
 		if (vfio_enable_intx(intr_handle))
 			return -1;
@@ -618,7 +721,9 @@ rte_intr_disable(const struct rte_intr_handle *intr_handle)
 			return -1;
 		break;
 	case RTE_INTR_HANDLE_VFIO_MSI:
-		return 0;
+		if (vfio_disable_msi(intr_handle))
+			return -1;
+		break;
 	case RTE_INTR_HANDLE_VFIO_LEGACY:
 		if (vfio_disable_intx(intr_handle))
 			return -1;
-- 
2.8.4