Re: [PATCH v4 3/3] hw/vfio: add ramfb migration support

[Cédric Le Goater]

On 10/5/23 13:30, 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.

Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
---
  hw/vfio/pci.h     |  3 +++
  hw/core/machine.c |  1 +
  hw/vfio/display.c | 20 ++++++++++++++++++++
  hw/vfio/pci.c     | 44 ++++++++++++++++++++++++++++++++++++++++++++
  stubs/ramfb.c     |  2 ++
  5 files changed, 70 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 e4361e3d48..f2c59a293c 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -33,6 +33,7 @@

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..0bdb807642 100644
--- a/hw/vfio/display.c
+++ b/hw/vfio/display.c
@@ -542,3 +542,23 @@ 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),

This vfio_display_vmstate lacks :

 VMSTATE_END_OF_LIST()

Thanks,

C.

+    }
+};
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 3b2ca3c24c..d2ede2f1a2 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2608,6 +2608,32 @@ 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,
@@ -2616,6 +2642,10 @@ 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
      }
  };

@@ -3271,6 +3301,19 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)

          }
      }

+ if (vdev->ramfb_migrate == ON_OFF_AUTO_ON && !vdev->enable_ramfb) {

+        error_setg(errp, "x-ramfb-migrate requires ramfb=on");
+        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 enable-migration");
+            goto out_deregister;
+        }
+    }
+
      if (!pdev->failover_pair_id) {
          if (!vfio_migration_realize(vbasedev, errp)) {
              goto out_deregister;
@@ -3484,6 +3527,7 @@ 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(),
  };

diff --git a/stubs/ramfb.c b/stubs/ramfb.c

index 48143f3354..cf64733b10 100644
--- a/stubs/ramfb.c
+++ b/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)
  {
  }