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.au...@redhat.com>

---

v11 -> v12:
- check !vdev->num_ext_irqs in vfio_pci_set_ext_irq_trigger()
  [Shameer, Qubingbing]
---
 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 a528b72b57d2..e6b94bad77da 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -610,6 +610,14 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
        ret = iommu_unregister_device_fault_handler(&vdev->pdev->dev);
        WARN_ON(ret == -EBUSY);
 
+       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) {
@@ -825,6 +833,9 @@ 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;
@@ -1010,7 +1021,7 @@ 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);
@@ -1189,36 +1200,87 @@ 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;
@@ -1237,7 +1299,8 @@ 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..d67995fe872f 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 || !vdev->num_ext_irqs)
+               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,
-- 
2.26.2

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