Re: [PATCH v3 5/5] hw/vfio: add ramfb migration support

[Cédric Le Goater]

On 10/3/23 10:56, marcandre.lur...@redhat.com wrote:

From: Marc-André Lureau <marcandre.lur...@redhat.com>

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

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

This change breaks linking on various platforms with :

/usr/bin/ld: libqemu-xtensa-softmmu.fa.p/hw_vfio_display.c.o:(.data.rel+0x50): 
undefined reference to `ramfb_vmstate'

Some stubs updates are missing it seems..

Thanks,

C.

Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
---
  hw/vfio/pci.h     |  3 +++
  hw/core/machine.c |  1 +
  hw/vfio/display.c | 23 +++++++++++++++++++++++
  hw/vfio/pci.c     | 32 ++++++++++++++++++++++++++++++++
  4 files changed, 59 insertions(+)

diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index 2d836093a8..fd06695542 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -173,6 +173,7 @@ 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;
@@ -226,4 +227,6 @@ 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 */
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 47a07d1d9b..f2f8940a85 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -32,6 +32,7 @@

GlobalProperty hw_compat_8_1[] = {

      { "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);

diff --git a/hw/vfio/display.c b/hw/vfio/display.c

index bec864f482..de5bf71dd1 100644
--- a/hw/vfio/display.c
+++ b/hw/vfio/display.c
@@ -542,3 +542,26 @@ void vfio_display_finalize(VFIOPCIDevice *vdev)
      vfio_display_edid_exit(vdev->dpy);
      g_free(vdev->dpy);
  }
+
+static bool migrate_needed(void *opaque)
+{
+    /*
+     * If we are here, it's because vfio_display_needed(), which is only true
+     * when dpy->ramfb_migrate atm.
+     *
+     * If the migration condition is changed, we should check here if
+     * ramfb_migrate is true. (this will need a way to lookup the associated
+     * VFIOPCIDevice somehow, or fields to be moved, ..)
+     */
+    return true;
+}
+
+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),
+    }
+};
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 3b2ca3c24c..4689f2e5c1 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2608,6 +2608,25 @@ static bool vfio_msix_present(void *opaque, int 
version_id)
      return msix_present(pdev);
  }

+static bool vfio_display_needed(void *opaque)

+{
+    VFIOPCIDevice *vdev = opaque;
+
+    /* the only thing that justifies the VFIODisplay sub-section atm */
+    return vdev->ramfb_migrate != ON_OFF_AUTO_OFF;
+}
+
+const VMStateDescription vmstate_vfio_display = {
+    .name = "VFIOPCIDevice/VFIODisplay",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = vfio_display_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,
@@ -2616,6 +2635,10 @@ 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
      }
  };

@@ -3275,6 +3298,14 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)

          if (!vfio_migration_realize(vbasedev, errp)) {
              goto out_deregister;
          }
+        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 migration");
+                goto out_deregister;
+            }
+        }
      }

vfio_register_err_notifier(vdev);

@@ -3484,6 +3515,7 @@ 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(),
  };