[PATCH V1 12/26] vfio-pci: preserve MSI

[Steve Sistare <steven.sistare@oracle.com>]

Save the MSI message area as part of vfio-pci vmstate, and preserve the
interrupt and notifier eventfd's.  migrate_incoming loads the MSI data,
then the vfio-pci post_load handler finds the eventfds in CPR state,
rebuilds vector data structures, and attaches the interrupts to the new
KVM instance.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 hw/vfio/pci.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 116 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index fa77c36..df6e298 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -56,11 +56,37 @@ static void vfio_disable_interrupts(VFIOPCIDevice *vdev);
 static void vfio_mmap_set_enabled(VFIOPCIDevice *vdev, bool enabled);
 static void vfio_msi_disable_common(VFIOPCIDevice *vdev);
 
+#define EVENT_FD_NAME(vdev, name)   \
+    g_strdup_printf("%s_%s", (vdev)->vbasedev.name, (name))
+
+static void save_event_fd(VFIOPCIDevice *vdev, const char *name, int nr,
+                          EventNotifier *ev)
+{
+    int fd = event_notifier_get_fd(ev);
+
+    if (fd >= 0) {
+        g_autofree char *fdname = EVENT_FD_NAME(vdev, name);
+        cpr_resave_fd(fdname, nr, fd);
+    }
+}
+
+static int load_event_fd(VFIOPCIDevice *vdev, const char *name, int nr)
+{
+    g_autofree char *fdname = EVENT_FD_NAME(vdev, name);
+    return cpr_find_fd(fdname, nr);
+}
+
+static void delete_event_fd(VFIOPCIDevice *vdev, const char *name, int nr)
+{
+    g_autofree char *fdname = EVENT_FD_NAME(vdev, name);
+    cpr_delete_fd(fdname, nr);
+}
+
 /* Create new or reuse existing eventfd */
 static int vfio_notifier_init(VFIOPCIDevice *vdev, EventNotifier *e,
                               const char *name, int nr)
 {
-    int fd = -1;   /* placeholder until a subsequent patch */
+    int fd = load_event_fd(vdev, name, nr);
     int ret = 0;
 
     if (fd >= 0) {
@@ -71,6 +97,8 @@ static int vfio_notifier_init(VFIOPCIDevice *vdev, EventNotifier *e,
             Error *err = NULL;
             error_setg_errno(&err, -ret, "vfio_notifier_init %s failed", name);
             error_report_err(err);
+        } else {
+            save_event_fd(vdev, name, nr, e);
         }
     }
     return ret;
@@ -79,6 +107,7 @@ static int vfio_notifier_init(VFIOPCIDevice *vdev, EventNotifier *e,
 static void vfio_notifier_cleanup(VFIOPCIDevice *vdev, EventNotifier *e,
                                   const char *name, int nr)
 {
+    delete_event_fd(vdev, name, nr);
     event_notifier_cleanup(e);
 }
 
@@ -561,6 +590,15 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev, unsigned int nr,
     int ret;
     bool resizing = !!(vdev->nr_vectors < nr + 1);
 
+    /*
+     * Ignore the callback from msix_set_vector_notifiers during resume.
+     * The necessary subset of these actions is called from vfio_claim_vectors
+     * during post load.
+     */
+    if (vdev->vbasedev.reused) {
+        return 0;
+    }
+
     trace_vfio_msix_vector_do_use(vdev->vbasedev.name, nr);
 
     vector = &vdev->msi_vectors[nr];
@@ -2896,6 +2934,11 @@ static void vfio_register_err_notifier(VFIOPCIDevice *vdev)
     fd = event_notifier_get_fd(&vdev->err_notifier);
     qemu_set_fd_handler(fd, vfio_err_notifier_handler, NULL, vdev);
 
+    /* Do not alter irq_signaling during vfio_realize for cpr */
+    if (vdev->vbasedev.reused) {
+        return;
+    }
+
     if (!vfio_set_irq_signaling(&vdev->vbasedev, VFIO_PCI_ERR_IRQ_INDEX, 0,
                                 VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) {
         error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
@@ -2960,6 +3003,12 @@ static void vfio_register_req_notifier(VFIOPCIDevice *vdev)
     fd = event_notifier_get_fd(&vdev->req_notifier);
     qemu_set_fd_handler(fd, vfio_req_notifier_handler, NULL, vdev);
 
+    /* Do not alter irq_signaling during vfio_realize for cpr */
+    if (vdev->vbasedev.reused) {
+        vdev->req_enabled = true;
+        return;
+    }
+
     if (!vfio_set_irq_signaling(&vdev->vbasedev, VFIO_PCI_REQ_IRQ_INDEX, 0,
                                 VFIO_IRQ_SET_ACTION_TRIGGER, fd, &err)) {
         error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
@@ -3454,6 +3503,46 @@ static void vfio_pci_set_fd(Object *obj, const char *str, Error **errp)
 }
 #endif
 
+static void vfio_claim_vectors(VFIOPCIDevice *vdev, int nr_vectors, bool msix)
+{
+    int i, fd;
+    bool pending = false;
+    PCIDevice *pdev = &vdev->pdev;
+
+    vdev->nr_vectors = nr_vectors;
+    vdev->msi_vectors = g_new0(VFIOMSIVector, nr_vectors);
+    vdev->interrupt = msix ? VFIO_INT_MSIX : VFIO_INT_MSI;
+
+    vfio_prepare_kvm_msi_virq_batch(vdev);
+
+    for (i = 0; i < nr_vectors; i++) {
+        VFIOMSIVector *vector = &vdev->msi_vectors[i];
+
+        fd = load_event_fd(vdev, "interrupt", i);
+        if (fd >= 0) {
+            vfio_vector_init(vdev, i);
+            qemu_set_fd_handler(fd, vfio_msi_interrupt, NULL, vector);
+        }
+
+        if (load_event_fd(vdev, "kvm_interrupt", i) >= 0) {
+            vfio_add_kvm_msi_virq(vdev, vector, i, msix);
+        } else {
+            vdev->msi_vectors[i].virq = -1;
+        }
+
+        if (msix && msix_is_pending(pdev, i) && msix_is_masked(pdev, i)) {
+            set_bit(i, vdev->msix->pending);
+            pending = true;
+        }
+    }
+
+    vfio_commit_kvm_msi_virq_batch(vdev);
+
+    if (msix) {
+        memory_region_set_enabled(&pdev->msix_pba_mmio, pending);
+    }
+}
+
 /*
  * The kernel may change non-emulated config bits.  Exclude them from the
  * changed-bits check in get_pci_config_device.
@@ -3472,13 +3561,39 @@ static int vfio_pci_pre_load(void *opaque)
     return 0;
 }
 
+static int vfio_pci_post_load(void *opaque, int version_id)
+{
+    VFIOPCIDevice *vdev = opaque;
+    PCIDevice *pdev = &vdev->pdev;
+    int nr_vectors;
+
+    if (msix_enabled(pdev)) {
+        msix_set_vector_notifiers(pdev, vfio_msix_vector_use,
+                                   vfio_msix_vector_release, NULL);
+        nr_vectors = vdev->msix->entries;
+        vfio_claim_vectors(vdev, nr_vectors, true);
+
+    } else if (msi_enabled(pdev)) {
+        nr_vectors = msi_nr_vectors_allocated(pdev);
+        vfio_claim_vectors(vdev, nr_vectors, false);
+
+    } else if (vfio_pci_read_config(pdev, PCI_INTERRUPT_PIN, 1)) {
+        g_assert_not_reached();      /* completed in a subsequent patch */
+    }
+
+    return 0;
+}
+
 static const VMStateDescription vfio_pci_vmstate = {
     .name = "vfio-pci",
     .version_id = 0,
     .minimum_version_id = 0,
     .pre_load = vfio_pci_pre_load,
+    .post_load = vfio_pci_post_load,
     .needed = cpr_needed_for_reuse,
     .fields = (VMStateField[]) {
+        VMSTATE_PCI_DEVICE(pdev, VFIOPCIDevice),
+        VMSTATE_MSIX_TEST(pdev, VFIOPCIDevice, vfio_msix_present),
         VMSTATE_END_OF_LIST()
     }
 };
-- 
1.8.3.1