[PATCH v11 08/13] vfio/pci: Add framework for custom interrupt indices

[Eric Auger <eric.auger@xxxxxxxxxx>]

Implement IRQ capability chain infrastructure. All interrupt
indexes beyond VFIO_PCI_NUM_IRQS are handled as extended
interrupts. They are registered with a specific type/subtype
and supported flags.

Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
---
 drivers/vfio/pci/vfio_pci.c         | 99 +++++++++++++++++++++++------
 drivers/vfio/pci/vfio_pci_intrs.c   | 62 ++++++++++++++++++
 drivers/vfio/pci/vfio_pci_private.h | 14 ++++
 3 files changed, 157 insertions(+), 18 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 2a6cc1a87323..93e03a4a5f32 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -608,6 +608,14 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
 
 	WARN_ON(iommu_unregister_device_fault_handler(&vdev->pdev->dev));
 
+	for (i = 0; i < vdev->num_ext_irqs; i++)
+		vfio_pci_set_irqs_ioctl(vdev, VFIO_IRQ_SET_DATA_NONE |
+					VFIO_IRQ_SET_ACTION_TRIGGER,
+					VFIO_PCI_NUM_IRQS + i, 0, 0, NULL);
+	vdev->num_ext_irqs = 0;
+	kfree(vdev->ext_irqs);
+	vdev->ext_irqs = NULL;
+
 	/* Device closed, don't need mutex here */
 	list_for_each_entry_safe(ioeventfd, ioeventfd_tmp,
 				 &vdev->ioeventfds_list, next) {
@@ -823,6 +831,9 @@ static int vfio_pci_get_irq_count(struct vfio_pci_device *vdev, int irq_type)
 			return 1;
 	} else if (irq_type == VFIO_PCI_REQ_IRQ_INDEX) {
 		return 1;
+	} else if (irq_type >= VFIO_PCI_NUM_IRQS &&
+		   irq_type < VFIO_PCI_NUM_IRQS + vdev->num_ext_irqs) {
+		return 1;
 	}
 
 	return 0;
@@ -1008,7 +1019,7 @@ static long vfio_pci_ioctl(void *device_data,
 			info.flags |= VFIO_DEVICE_FLAGS_RESET;
 
 		info.num_regions = VFIO_PCI_NUM_REGIONS + vdev->num_regions;
-		info.num_irqs = VFIO_PCI_NUM_IRQS;
+		info.num_irqs = VFIO_PCI_NUM_IRQS + vdev->num_ext_irqs;
 
 		if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV)) {
 			int ret = vfio_pci_info_zdev_add_caps(vdev, &caps);
@@ -1187,36 +1198,87 @@ static long vfio_pci_ioctl(void *device_data,
 
 	} else if (cmd == VFIO_DEVICE_GET_IRQ_INFO) {
 		struct vfio_irq_info info;
+		struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
+		unsigned long capsz;
 
 		minsz = offsetofend(struct vfio_irq_info, count);
 
+		/* For backward compatibility, cannot require this */
+		capsz = offsetofend(struct vfio_irq_info, cap_offset);
+
 		if (copy_from_user(&info, (void __user *)arg, minsz))
 			return -EFAULT;
 
-		if (info.argsz < minsz || info.index >= VFIO_PCI_NUM_IRQS)
+		if (info.argsz < minsz ||
+			info.index >= VFIO_PCI_NUM_IRQS + vdev->num_ext_irqs)
 			return -EINVAL;
 
-		switch (info.index) {
-		case VFIO_PCI_INTX_IRQ_INDEX ... VFIO_PCI_MSIX_IRQ_INDEX:
-		case VFIO_PCI_REQ_IRQ_INDEX:
-			break;
-		case VFIO_PCI_ERR_IRQ_INDEX:
-			if (pci_is_pcie(vdev->pdev))
-				break;
-			fallthrough;
-		default:
-			return -EINVAL;
-		}
+		if (info.argsz >= capsz)
+			minsz = capsz;
 
 		info.flags = VFIO_IRQ_INFO_EVENTFD;
 
-		info.count = vfio_pci_get_irq_count(vdev, info.index);
-
-		if (info.index == VFIO_PCI_INTX_IRQ_INDEX)
+		switch (info.index) {
+		case VFIO_PCI_INTX_IRQ_INDEX:
 			info.flags |= (VFIO_IRQ_INFO_MASKABLE |
 				       VFIO_IRQ_INFO_AUTOMASKED);
-		else
+			break;
+		case VFIO_PCI_MSI_IRQ_INDEX ... VFIO_PCI_MSIX_IRQ_INDEX:
+		case VFIO_PCI_REQ_IRQ_INDEX:
 			info.flags |= VFIO_IRQ_INFO_NORESIZE;
+			break;
+		case VFIO_PCI_ERR_IRQ_INDEX:
+			info.flags |= VFIO_IRQ_INFO_NORESIZE;
+			if (!pci_is_pcie(vdev->pdev))
+				return -EINVAL;
+			break;
+		default:
+		{
+			struct vfio_irq_info_cap_type cap_type = {
+				.header.id = VFIO_IRQ_INFO_CAP_TYPE,
+				.header.version = 1 };
+			int ret, i;
+
+			if (info.index >= VFIO_PCI_NUM_IRQS +
+						vdev->num_ext_irqs)
+				return -EINVAL;
+			info.index = array_index_nospec(info.index,
+							VFIO_PCI_NUM_IRQS +
+							vdev->num_ext_irqs);
+			i = info.index - VFIO_PCI_NUM_IRQS;
+
+			info.flags = vdev->ext_irqs[i].flags;
+			cap_type.type = vdev->ext_irqs[i].type;
+			cap_type.subtype = vdev->ext_irqs[i].subtype;
+
+			ret = vfio_info_add_capability(&caps,
+					&cap_type.header,
+					sizeof(cap_type));
+			if (ret)
+				return ret;
+		}
+		}
+
+		info.count = vfio_pci_get_irq_count(vdev, info.index);
+
+		if (caps.size) {
+			info.flags |= VFIO_IRQ_INFO_FLAG_CAPS;
+			if (info.argsz < sizeof(info) + caps.size) {
+				info.argsz = sizeof(info) + caps.size;
+				info.cap_offset = 0;
+			} else {
+				vfio_info_cap_shift(&caps, sizeof(info));
+				if (copy_to_user((void __user *)arg +
+						  sizeof(info), caps.buf,
+						  caps.size)) {
+					kfree(caps.buf);
+					return -EFAULT;
+				}
+				info.cap_offset = sizeof(info);
+			}
+
+			kfree(caps.buf);
+		}
 
 		return copy_to_user((void __user *)arg, &info, minsz) ?
 			-EFAULT : 0;
@@ -1235,7 +1297,8 @@ static long vfio_pci_ioctl(void *device_data,
 		max = vfio_pci_get_irq_count(vdev, hdr.index);
 
 		ret = vfio_set_irqs_validate_and_prepare(&hdr, max,
-						 VFIO_PCI_NUM_IRQS, &data_size);
+				VFIO_PCI_NUM_IRQS + vdev->num_ext_irqs,
+				&data_size);
 		if (ret)
 			return ret;
 
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index 869dce5f134d..1e785a5f5fb2 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -19,6 +19,7 @@
 #include <linux/vfio.h>
 #include <linux/wait.h>
 #include <linux/slab.h>
+#include <linux/nospec.h>
 
 #include "vfio_pci_private.h"
 
@@ -635,6 +636,24 @@ static int vfio_pci_set_req_trigger(struct vfio_pci_device *vdev,
 					       count, flags, data);
 }
 
+static int vfio_pci_set_ext_irq_trigger(struct vfio_pci_device *vdev,
+					unsigned int index, unsigned int start,
+					unsigned int count, uint32_t flags,
+					void *data)
+{
+	int i;
+
+	if (start != 0 || count > 1)
+		return -EINVAL;
+
+	index = array_index_nospec(index,
+				   VFIO_PCI_NUM_IRQS + vdev->num_ext_irqs);
+	i = index - VFIO_PCI_NUM_IRQS;
+
+	return vfio_pci_set_ctx_trigger_single(&vdev->ext_irqs[i].trigger,
+					       count, flags, data);
+}
+
 int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags,
 			    unsigned index, unsigned start, unsigned count,
 			    void *data)
@@ -684,6 +703,13 @@ int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags,
 			break;
 		}
 		break;
+	default:
+		switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) {
+		case VFIO_IRQ_SET_ACTION_TRIGGER:
+			func = vfio_pci_set_ext_irq_trigger;
+			break;
+		}
+		break;
 	}
 
 	if (!func)
@@ -691,3 +717,39 @@ int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags,
 
 	return func(vdev, index, start, count, flags, data);
 }
+
+int vfio_pci_get_ext_irq_index(struct vfio_pci_device *vdev,
+			       unsigned int type, unsigned int subtype)
+{
+	int i;
+
+	for (i = 0; i <  vdev->num_ext_irqs; i++) {
+		if (vdev->ext_irqs[i].type == type &&
+		    vdev->ext_irqs[i].subtype == subtype) {
+			return i;
+		}
+	}
+	return -EINVAL;
+}
+
+int vfio_pci_register_irq(struct vfio_pci_device *vdev,
+			  unsigned int type, unsigned int subtype,
+			  u32 flags)
+{
+	struct vfio_ext_irq *ext_irqs;
+
+	ext_irqs = krealloc(vdev->ext_irqs,
+			    (vdev->num_ext_irqs + 1) * sizeof(*ext_irqs),
+			    GFP_KERNEL);
+	if (!ext_irqs)
+		return -ENOMEM;
+
+	vdev->ext_irqs = ext_irqs;
+
+	vdev->ext_irqs[vdev->num_ext_irqs].type = type;
+	vdev->ext_irqs[vdev->num_ext_irqs].subtype = subtype;
+	vdev->ext_irqs[vdev->num_ext_irqs].flags = flags;
+	vdev->ext_irqs[vdev->num_ext_irqs].trigger = NULL;
+	vdev->num_ext_irqs++;
+	return 0;
+}
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 1d9b0f648133..e180b5435c8f 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -77,6 +77,13 @@ struct vfio_pci_region {
 	u32				flags;
 };
 
+struct vfio_ext_irq {
+	u32				type;
+	u32				subtype;
+	u32				flags;
+	struct eventfd_ctx		*trigger;
+};
+
 struct vfio_pci_dummy_resource {
 	struct resource		resource;
 	int			index;
@@ -111,6 +118,8 @@ struct vfio_pci_device {
 	struct vfio_pci_irq_ctx	*ctx;
 	int			num_ctx;
 	int			irq_type;
+	struct vfio_ext_irq	*ext_irqs;
+	int			num_ext_irqs;
 	int			num_regions;
 	struct vfio_pci_region	*region;
 	u8			msi_qmax;
@@ -154,6 +163,11 @@ struct vfio_pci_device {
 
 extern void vfio_pci_intx_mask(struct vfio_pci_device *vdev);
 extern void vfio_pci_intx_unmask(struct vfio_pci_device *vdev);
+extern int vfio_pci_register_irq(struct vfio_pci_device *vdev,
+				 unsigned int type, unsigned int subtype,
+				 u32 flags);
+extern int vfio_pci_get_ext_irq_index(struct vfio_pci_device *vdev,
+				      unsigned int type, unsigned int subtype);
 
 extern int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev,
 				   uint32_t flags, unsigned index,
-- 
2.21.3