[PATCH 13/16] util/vfio-helpers: Introduce qemu_vfio_pci_msix_init_irqs()

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

qemu_vfio_pci_init_irq() allows us to initialize any type of IRQ,
but only one. Introduce qemu_vfio_pci_msix_init_irqs() which is
specific to MSIX IRQ type, and allow us to use multiple IRQs
(thus passing multiple eventfd notifiers).
All eventfd notifiers are initialized with the special '-1' value
meaning "un-assigned".

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/qemu/vfio-helpers.h |  6 +++-
 util/vfio-helpers.c         | 65 ++++++++++++++++++++++++++++++++++++-
 util/trace-events           |  1 +
 3 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/include/qemu/vfio-helpers.h b/include/qemu/vfio-helpers.h
index 4b97a904e93..492072cba2f 100644
--- a/include/qemu/vfio-helpers.h
+++ b/include/qemu/vfio-helpers.h
@@ -1,11 +1,13 @@
 /*
  * QEMU VFIO helpers
  *
- * Copyright 2016 - 2018 Red Hat, Inc.
+ * Copyright 2016 - 2020 Red Hat, Inc.
  *
  * Authors:
  *   Fam Zheng <famz@redhat.com>
+ *   Philippe Mathieu-Daudé <philmd@redhat.com>
  *
+ * SPDX-License-Identifier: GPL-2.0-or-later
  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  * See the COPYING file in the top-level directory.
  */
@@ -29,5 +31,7 @@ void qemu_vfio_pci_unmap_bar(QEMUVFIOState *s, int index, void *bar,
                              uint64_t offset, uint64_t size);
 int qemu_vfio_pci_init_irq(QEMUVFIOState *s, EventNotifier *e,
                            int irq_type, Error **errp);
+int qemu_vfio_pci_msix_init_irqs(QEMUVFIOState *s,
+                                 unsigned *irq_count, Error **errp);
 
 #endif
diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
index 874d76c2a2a..d88e2c7dc1f 100644
--- a/util/vfio-helpers.c
+++ b/util/vfio-helpers.c
@@ -1,11 +1,13 @@
 /*
  * VFIO utility
  *
- * Copyright 2016 - 2018 Red Hat, Inc.
+ * Copyright 2016 - 2020 Red Hat, Inc.
  *
  * Authors:
  *   Fam Zheng <famz@redhat.com>
+ *   Philippe Mathieu-Daudé <philmd@redhat.com>
  *
+ * SPDX-License-Identifier: GPL-2.0-or-later
  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  * See the COPYING file in the top-level directory.
  */
@@ -230,6 +232,67 @@ int qemu_vfio_pci_init_irq(QEMUVFIOState *s, EventNotifier *e,
     return 0;
 }
 
+/**
+ * Initialize device MSIX IRQs and register event notifiers.
+ * @irq_count: pointer to number of MSIX IRQs to initialize
+ *
+ * If the number of IRQs requested exceeds the available on the device,
+ * store the number of available IRQs in @irq_count and return -EOVERFLOW.
+ */
+int qemu_vfio_pci_msix_init_irqs(QEMUVFIOState *s,
+                                 unsigned *irq_count, Error **errp)
+{
+    int r;
+    size_t irq_set_size;
+    struct vfio_irq_set *irq_set;
+    struct vfio_irq_info irq_info = {
+        .argsz = sizeof(irq_info),
+        .index = VFIO_PCI_MSIX_IRQ_INDEX
+    };
+
+    if (ioctl(s->device, VFIO_DEVICE_GET_IRQ_INFO, &irq_info)) {
+        error_setg_errno(errp, errno, "Failed to get device interrupt info");
+        return -errno;
+    }
+    trace_qemu_vfio_msix_info_irqs(irq_info.count, *irq_count);
+    if (irq_info.count < *irq_count) {
+        error_setg(errp, "Not enough device interrupts available");
+        *irq_count = irq_info.count;
+        return -EOVERFLOW;
+    }
+    if (!(irq_info.flags & VFIO_IRQ_INFO_EVENTFD)) {
+        error_setg(errp, "Device interrupt doesn't support eventfd");
+        return -EINVAL;
+    }
+
+    irq_set_size = sizeof(*irq_set) + *irq_count * sizeof(int32_t);
+    irq_set = g_malloc0(irq_set_size);
+
+    /* Get to a known IRQ state */
+    *irq_set = (struct vfio_irq_set) {
+        .argsz = irq_set_size,
+        .flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER,
+        .index = VFIO_PCI_MSIX_IRQ_INDEX,
+        .start = 0,
+        .count = *irq_count,
+    };
+
+    for (unsigned i = 0; i < *irq_count; i++) {
+        ((int32_t *)&irq_set->data)[i] = -1; /* un-assigned: skip */
+    }
+    r = ioctl(s->device, VFIO_DEVICE_SET_IRQS, irq_set);
+    g_free(irq_set);
+    if (r < 0) {
+        error_setg_errno(errp, errno, "Failed to setup device interrupts");
+        return -errno;
+    } else if (r > 0) {
+        error_setg(errp, "Not enough device interrupts available");
+        *irq_count = r;
+        return -EOVERFLOW;
+    }
+    return 0;
+}
+
 static int qemu_vfio_pci_read_config(QEMUVFIOState *s, void *buf,
                                      int size, int ofs)
 {
diff --git a/util/trace-events b/util/trace-events
index 3c36def9f30..ec93578b125 100644
--- a/util/trace-events
+++ b/util/trace-events
@@ -87,6 +87,7 @@ qemu_vfio_do_mapping(void *s, void *host, uint64_t iova, size_t size) "s %p host
 qemu_vfio_dma_map(void *s, void *host, size_t size, bool temporary, uint64_t *iova) "s %p host %p size 0x%zx temporary %d &iova %p"
 qemu_vfio_dma_mapped(void *s, void *host, uint64_t iova, size_t size) "s %p host %p <-> iova 0x%"PRIx64" size 0x%zx"
 qemu_vfio_dma_unmap(void *s, void *host) "s %p host %p"
+qemu_vfio_msix_info_irqs(uint32_t count, unsigned asked) "msix irqs %"PRIu32" (asked: %u)"
 qemu_vfio_iommu_iova_pgsizes(uint64_t iova_pgsizes) "iommu page size bitmask: 0x%08"PRIx64
 qemu_vfio_pci_read_config(void *buf, int ofs, int size, uint64_t region_ofs, uint64_t region_size) "read cfg ptr %p ofs 0x%x size %d (region ofs 0x%"PRIx64" size %"PRId64")"
 qemu_vfio_pci_write_config(void *buf, int ofs, int size, uint64_t region_ofs, uint64_t region_size) "write cfg ptr %p ofs 0x%x size %d (region ofs 0x%"PRIx64" size %"PRId64")"
-- 
2.26.2