vfio/device: support enable/disable specific irq

This patch added 'start' parameter to 'vfio_set_irq' API to specify
start IRQ number to configure to vfio-pci kernel driver.  This patch
also converted previous 'vfio_disable_irq' to 'vfio_disable_irq_all' to
disable all enabled irqs.  'vfio_disable_irq' has been updated to
disable specific irqs from the given 'start' parameter.

To disable (de-assign) one or more IRQs from vfio-pci kernel driver,
irq_set data -1 should be passed to irq_set->data.  uapi <linux/vfio.h>
says that value -1 with DATA_EVENTFD|ACTION_TRIGGER) will de-assign
interrupts if already assigned.

This patch also fixed de-assign behavior by replacing DATA_NONE to
DATA_EVENTFD with data -1 along with adding a new API to disable
specific interrupts with start and count.

Signed-off-by: Minwoo Im <[email protected]>

CHANGELOG.md

@@ -6,6 +6,11 @@
 
 ``nvme_pci_init`` has been deprecated and will generate a warning.
 
+``vfio_set_irq`` has been updated to receive ``start`` parameter to specify
+start irq number to enable.  With this, ``vfio_disable_irq`` has been updated
+to disable specific one or more irqs from ``start`` for ``count`` of irqs.
+``vfio_disable_irq_all`` has been newly added to disable all the enabled irqs.
+
 ## v5.2.0: (unreleased)
 
 ### ``nvme_ctrl``

examples/eventfd.c

@@ -70,7 +70,7 @@ int main(int argc, char **argv)
 	if (efd < 0)
 		err(1, "failed to create eventfd");
 
-	if (vfio_set_irq(&ctrl.pci.dev, efds, 2))
+	if (vfio_set_irq(&ctrl.pci.dev, efds, 0, 2))
 		err(1, "failed to set irqs");
 
 	if (nvme_create_ioqpair(&ctrl, 1, 64, 1, 0x0))

include/vfn/vfio/device.h

@@ -28,24 +28,37 @@ struct vfio_device {
  * vfio_set_irq - Enable IRQs through eventfds
  * @dev: &struct vfio_device
  * @eventfds: array of eventfds
+ * @start: start irq number
  * @count: number of eventfds
  *
  * Enable interrupts for a range of vectors. See linux/vfio.h for documentation
  * on the format of @eventfds.
  *
  * Return: ``0`` on success, ``-1`` on error and sets ``errno``.
  */
-int vfio_set_irq(struct vfio_device *dev, int *eventfds, int count);
+int vfio_set_irq(struct vfio_device *dev, int *eventfds, int start, int count);
 
 /**
- * vfio_disable_irq - Disable all IRQs
+ * vfio_disable_irq - Disable number of count IRQs from given start
+ * @dev: &struct vfio_device
+ * @start: start irq number
+ * @count: number of eventfds
+ *
+ * Disable given number of IRQs from start.
+ *
+ * Return: ``0`` on success, ``-1`` on error and sets ``errno``.
+ */
+int vfio_disable_irq(struct vfio_device *dev, int start, int count);
+
+/**
+ * vfio_disable_irq_all - Disable all IRQs
  * @dev: &struct vfio_device
  *
  * Disable all IRQs.
  *
  * Return: ``0`` on success, ``-1`` on error and sets ``errno``.
  */
-int vfio_disable_irq(struct vfio_device *dev);
+int vfio_disable_irq_all(struct vfio_device *dev);
 
 /**
  * vfio_reset - reset vfio device

src/vfio/device.c

@@ -40,7 +40,7 @@
 #include "ccan/minmax/minmax.h"
 #include "ccan/str/str.h"
 
-int vfio_set_irq(struct vfio_device *dev, int *eventfds, int count)
+int vfio_set_irq(struct vfio_device *dev, int *eventfds, int start, int count)
 {
 	struct vfio_irq_set *irq_set;
 	size_t irq_set_size;
@@ -59,7 +59,7 @@ int vfio_set_irq(struct vfio_device *dev, int *eventfds, int count)
 		.argsz = (uint32_t)irq_set_size,
 		.flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER,
 		.index = dev->irq_info.index,
-		.start = 0,
+		.start = start,
 		.count = count,
 	};
 
@@ -76,18 +76,33 @@ int vfio_set_irq(struct vfio_device *dev, int *eventfds, int count)
 	return 0;
 }
 
-int vfio_disable_irq(struct vfio_device *dev)
+int vfio_disable_irq(struct vfio_device *dev, int start, int count)
 {
-	struct vfio_irq_set irq_set;
+	struct vfio_irq_set *irq_set;
+	size_t irq_set_size;
+	int *data;
 	int ret;
 
-	irq_set = (struct vfio_irq_set) {
-		.argsz = sizeof(irq_set),
-		.flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_TRIGGER,
+	irq_set_size = sizeof(*irq_set) + sizeof(int) * count;
+	irq_set = xmalloc(irq_set_size);
+
+	data = xmalloc(sizeof(int) * count);
+	for (int i = 0; i < count; i++)
+		data[i] = -1;
+
+	*irq_set = (struct vfio_irq_set) {
+		.argsz = (uint32_t)irq_set_size,
+		.flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER,
 		.index = dev->irq_info.index,
+		.start = start,
+		.count = count,
 	};
 
-	ret = ioctl(dev->fd, VFIO_DEVICE_SET_IRQS, &irq_set);
+	memcpy(irq_set->data, data, sizeof(int) * count);
+
+	ret = ioctl(dev->fd, VFIO_DEVICE_SET_IRQS, irq_set);
+	free(data);
+	free(irq_set);
 
 	if (ret) {
 		log_debug("failed to disable device irq\n");
@@ -97,6 +112,11 @@ int vfio_disable_irq(struct vfio_device *dev)
 	return 0;
 }
 
+int vfio_disable_irq_all(struct vfio_device *dev)
+{
+	return vfio_disable_irq(dev, 0, dev->irq_info.count);
+}
+
 int vfio_reset(struct vfio_device *dev)
 {
 	if (!(dev->device_info.flags & VFIO_DEVICE_FLAGS_RESET)) {