[PATCH V3 23/42] vfio-pci: preserve INTx

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

Preserve vfio INTx state across cpr-transfer.  Preserve VFIOINTx fields as
follows:
  pin : Recover this from the vfio config in kernel space
  interrupt : Preserve its eventfd descriptor across exec.
  unmask : Ditto
  route.irq : This could perhaps be recovered in vfio_pci_post_load by
    calling pci_device_route_intx_to_irq(pin), whose implementation reads
    config space for a bridge device such as ich9.  However, there is no
    guarantee that the bridge vmstate is read before vfio vmstate.  Rather
    than fiddling with MigrationPriority for vmstate handlers, explicitly
    save route.irq in vfio vmstate.
  pending : save in vfio vmstate.
  mmap_timeout, mmap_timer : Re-initialize
  bool kvm_accel : Re-initialize

In vfio_realize, defer calling vfio_intx_enable until the vmstate
is available, in vfio_pci_post_load.  Modify vfio_intx_enable and
vfio_intx_kvm_enable to skip vfio initialization, but still perform
kvm initialization.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 hw/vfio/cpr.c | 27 ++++++++++++++++++++++++++-
 hw/vfio/pci.c | 29 ++++++++++++++++++++++++++---
 2 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/hw/vfio/cpr.c b/hw/vfio/cpr.c
index be132fa..6081a89 100644
--- a/hw/vfio/cpr.c
+++ b/hw/vfio/cpr.c
@@ -140,12 +140,36 @@ static int vfio_cpr_pci_post_load(void *opaque, int version_id)
         vfio_cpr_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 */
+        Error *err = NULL;
+        if (!vfio_intx_enable(vdev, &err)) {
+            error_report_err(err);
+            return -1;
+        }
     }
 
     return 0;
 }
 
+static const VMStateDescription vfio_intx_vmstate = {
+    .name = "vfio-cpr-intx",
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .fields = (VMStateField[]) {
+        VMSTATE_BOOL(pending, VFIOINTx),
+        VMSTATE_UINT32(route.mode, VFIOINTx),
+        VMSTATE_INT32(route.irq, VFIOINTx),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+#define VMSTATE_VFIO_INTX(_field, _state) {                         \
+    .name       = (stringify(_field)),                              \
+    .size       = sizeof(VFIOINTx),                                 \
+    .vmsd       = &vfio_intx_vmstate,                               \
+    .flags      = VMS_STRUCT,                                       \
+    .offset     = vmstate_offset_value(_state, _field, VFIOINTx),   \
+}
+
 const VMStateDescription vfio_cpr_pci_vmstate = {
     .name = "vfio-cpr-pci",
     .version_id = 0,
@@ -156,6 +180,7 @@ const VMStateDescription vfio_cpr_pci_vmstate = {
     .fields = (VMStateField[]) {
         VMSTATE_PCI_DEVICE(pdev, VFIOPCIDevice),
         VMSTATE_MSIX_TEST(pdev, VFIOPCIDevice, vfio_msix_present),
+        VMSTATE_VFIO_INTX(intx, VFIOPCIDevice),
         VMSTATE_END_OF_LIST()
     }
 };
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index bfa72bc..84282c0 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -160,12 +160,17 @@ static bool vfio_intx_enable_kvm(VFIOPCIDevice *vdev, Error **errp)
         return true;
     }
 
+    if (vdev->vbasedev.cpr.reused) {
+        goto skip_state;
+    }
+
     /* Get to a known interrupt state */
     qemu_set_fd_handler(irq_fd, NULL, NULL, vdev);
     vfio_device_irq_mask(&vdev->vbasedev, VFIO_PCI_INTX_IRQ_INDEX);
     vdev->intx.pending = false;
     pci_irq_deassert(&vdev->pdev);
 
+skip_state:
     /* Get an eventfd for resample/unmask */
     if (!vfio_notifier_init(vdev, &vdev->intx.unmask, "intx-unmask", 0, errp)) {
         goto fail;
@@ -179,6 +184,10 @@ static bool vfio_intx_enable_kvm(VFIOPCIDevice *vdev, Error **errp)
         goto fail_irqfd;
     }
 
+    if (vdev->vbasedev.cpr.reused) {
+        goto skip_irq;
+    }
+
     if (!vfio_device_irq_set_signaling(&vdev->vbasedev, VFIO_PCI_INTX_IRQ_INDEX, 0,
                                        VFIO_IRQ_SET_ACTION_UNMASK,
                                        event_notifier_get_fd(&vdev->intx.unmask),
@@ -189,6 +198,7 @@ static bool vfio_intx_enable_kvm(VFIOPCIDevice *vdev, Error **errp)
     /* Let'em rip */
     vfio_device_irq_unmask(&vdev->vbasedev, VFIO_PCI_INTX_IRQ_INDEX);
 
+skip_irq:
     vdev->intx.kvm_accel = true;
 
     trace_vfio_intx_enable_kvm(vdev->vbasedev.name);
@@ -304,7 +314,13 @@ bool vfio_intx_enable(VFIOPCIDevice *vdev, Error **errp)
         return true;
     }
 
-    vfio_disable_interrupts(vdev);
+    /*
+     * Do not alter interrupt state during vfio_realize and cpr load.  The
+     * reused flag is cleared thereafter.
+     */
+    if (!vdev->vbasedev.cpr.reused) {
+        vfio_disable_interrupts(vdev);
+    }
 
     vdev->intx.pin = pin - 1; /* Pin A (1) -> irq[0] */
     pci_config_set_interrupt_pin(vdev->pdev.config, pin);
@@ -327,7 +343,8 @@ bool vfio_intx_enable(VFIOPCIDevice *vdev, Error **errp)
     fd = event_notifier_get_fd(&vdev->intx.interrupt);
     qemu_set_fd_handler(fd, vfio_intx_interrupt, NULL, vdev);
 
-    if (!vfio_device_irq_set_signaling(&vdev->vbasedev, VFIO_PCI_INTX_IRQ_INDEX, 0,
+    if (!vdev->vbasedev.cpr.reused &&
+        !vfio_device_irq_set_signaling(&vdev->vbasedev, VFIO_PCI_INTX_IRQ_INDEX, 0,
                                 VFIO_IRQ_SET_ACTION_TRIGGER, fd, errp)) {
         qemu_set_fd_handler(fd, NULL, NULL, vdev);
         vfio_notifier_cleanup(vdev, &vdev->intx.interrupt, "intx-interrupt", 0);
@@ -3182,7 +3199,13 @@ static bool vfio_interrupt_setup(VFIOPCIDevice *vdev, Error **errp)
                                              vfio_intx_routing_notifier);
         vdev->irqchip_change_notifier.notify = vfio_irqchip_change;
         kvm_irqchip_add_change_notifier(&vdev->irqchip_change_notifier);
-        if (!vfio_intx_enable(vdev, errp)) {
+
+        /*
+         * During CPR, do not call vfio_intx_enable at this time.  Instead,
+         * call it from vfio_pci_post_load after the intx routing data has
+         * been loaded from vmstate.
+         */
+        if (!vdev->vbasedev.cpr.reused && !vfio_intx_enable(vdev, errp)) {
             timer_free(vdev->intx.mmap_timer);
             pci_device_set_intx_routing_notifier(&vdev->pdev, NULL);
             kvm_irqchip_remove_change_notifier(&vdev->irqchip_change_notifier);
-- 
1.8.3.1