hw/vfio: add ramfb migration support

Add a "VFIODisplay" subsection whenever "x-ramfb-migrate" is turned on.

Turn it off by default on machines <= 8.1 for compatibility reasons.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
[ clg:  - checkpatch fixes
  	- improved warn_report() in vfio_realize() ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/core/machine.c

@@ -35,6 +35,7 @@
 GlobalProperty hw_compat_8_1[] = {
     { TYPE_PCI_BRIDGE, "x-pci-express-writeable-slt-bug", "true" },
     { "ramfb", "x-migrate", "off" },
+    { "vfio-pci-nohotplug", "x-ramfb-migrate", "off" }
 };
 const size_t hw_compat_8_1_len = G_N_ELEMENTS(hw_compat_8_1);
 

hw/vfio/display.c

@@ -544,3 +544,24 @@ void vfio_display_finalize(VFIOPCIDevice *vdev)
     vfio_display_edid_exit(vdev->dpy);
     g_free(vdev->dpy);
 }
+
+static bool migrate_needed(void *opaque)
+{
+    VFIODisplay *dpy = opaque;
+    bool ramfb_exists = dpy->ramfb != NULL;
+
+    /* see vfio_display_migration_needed() */
+    assert(ramfb_exists);
+    return ramfb_exists;
+}
+
+const VMStateDescription vfio_display_vmstate = {
+    .name = "VFIODisplay",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = migrate_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_STRUCT_POINTER(ramfb, VFIODisplay, ramfb_vmstate, RAMFBState),
+        VMSTATE_END_OF_LIST(),
+    }
+};

hw/vfio/pci.c

@@ -2675,6 +2675,33 @@ static bool vfio_msix_present(void *opaque, int version_id)
     return msix_present(pdev);
 }
 
+static bool vfio_display_migration_needed(void *opaque)
+{
+    VFIOPCIDevice *vdev = opaque;
+
+    /*
+     * We need to migrate the VFIODisplay object if ramfb *migration* was
+     * explicitly requested (in which case we enforced both ramfb=on and
+     * display=on), or ramfb migration was left at the default "auto"
+     * setting, and *ramfb* was explicitly requested (in which case we
+     * enforced display=on).
+     */
+    return vdev->ramfb_migrate == ON_OFF_AUTO_ON ||
+        (vdev->ramfb_migrate == ON_OFF_AUTO_AUTO && vdev->enable_ramfb);
+}
+
+const VMStateDescription vmstate_vfio_display = {
+    .name = "VFIOPCIDevice/VFIODisplay",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = vfio_display_migration_needed,
+    .fields = (VMStateField[]){
+        VMSTATE_STRUCT_POINTER(dpy, VFIOPCIDevice, vfio_display_vmstate,
+                               VFIODisplay),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 const VMStateDescription vmstate_vfio_pci_config = {
     .name = "VFIOPCIDevice",
     .version_id = 1,
@@ -2683,6 +2710,10 @@ const VMStateDescription vmstate_vfio_pci_config = {
         VMSTATE_PCI_DEVICE(pdev, VFIOPCIDevice),
         VMSTATE_MSIX_TEST(pdev, VFIOPCIDevice, vfio_msix_present),
         VMSTATE_END_OF_LIST()
+    },
+    .subsections = (const VMStateDescription * []) {
+        &vmstate_vfio_display,
+        NULL
     }
 };
 
@@ -3300,6 +3331,20 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
         }
     }
 
+    if (vdev->ramfb_migrate == ON_OFF_AUTO_ON && !vdev->enable_ramfb) {
+        warn_report("x-ramfb-migrate=on but ramfb=off. "
+                    "Forcing x-ramfb-migrate to off.");
+        vdev->ramfb_migrate = ON_OFF_AUTO_OFF;
+    }
+    if (vbasedev->enable_migration == ON_OFF_AUTO_OFF) {
+        if (vdev->ramfb_migrate == ON_OFF_AUTO_AUTO) {
+            vdev->ramfb_migrate = ON_OFF_AUTO_OFF;
+        } else if (vdev->ramfb_migrate == ON_OFF_AUTO_ON) {
+            error_setg(errp, "x-ramfb-migrate requires enable-migration");
+            goto out_deregister;
+        }
+    }
+
     if (!pdev->failover_pair_id) {
         if (!vfio_migration_realize(vbasedev, errp)) {
             goto out_deregister;
@@ -3511,6 +3556,8 @@ static const TypeInfo vfio_pci_dev_info = {
 
 static Property vfio_pci_dev_nohotplug_properties[] = {
     DEFINE_PROP_BOOL("ramfb", VFIOPCIDevice, enable_ramfb, false),
+    DEFINE_PROP_ON_OFF_AUTO("x-ramfb-migrate", VFIOPCIDevice, ramfb_migrate,
+                            ON_OFF_AUTO_AUTO),
     DEFINE_PROP_END_OF_LIST(),
 };
 

hw/vfio/pci.h

@@ -174,6 +174,7 @@ struct VFIOPCIDevice {
     bool no_kvm_ioeventfd;
     bool no_vfio_ioeventfd;
     bool enable_ramfb;
+    OnOffAuto ramfb_migrate;
     bool defer_kvm_irq_routing;
     bool clear_parent_atomics_on_exit;
     VFIODisplay *dpy;
@@ -227,4 +228,6 @@ void vfio_display_reset(VFIOPCIDevice *vdev);
 int vfio_display_probe(VFIOPCIDevice *vdev, Error **errp);
 void vfio_display_finalize(VFIOPCIDevice *vdev);
 
+extern const VMStateDescription vfio_display_vmstate;
+
 #endif /* HW_VFIO_VFIO_PCI_H */

stubs/ramfb.c

@@ -2,6 +2,8 @@
 #include "qapi/error.h"
 #include "hw/display/ramfb.h"
 
+const VMStateDescription ramfb_vmstate = {};
+
 void ramfb_display_update(QemuConsole *con, RAMFBState *s)
 {
 }