vfio-platform: Deprecate all forms of vfio-platform devices

As an outcome of KVM forum 2024 "vfio-platform: live and let die?"
talk, let's deprecate vfio-platform devices.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250305124225.952791-1-eric.auger@redhat.com
[ clg: Fixed spelling in vfio-amd-xgbe section ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>

docs/about/deprecated.rst

@@ -434,6 +434,31 @@ Stream ``reconnect`` (since 9.2)
 The ``reconnect`` option only allows specifiying second granularity timeouts,
 which is not enough for all types of use cases, use ``reconnect-ms`` instead.
 
+VFIO device options
+'''''''''''''''''''
+
+``-device vfio-calxeda-xgmac`` (since 10.0)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+The vfio-calxeda-xgmac device allows to assign a host Calxeda Highbank
+10Gb XGMAC Ethernet controller device ("calxeda,hb-xgmac" compatibility
+string) to a guest. Calxeda HW has been ewasted now and there is no point
+keeping that device.
+
+``-device vfio-amd-xgbe`` (since 10.0)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+The vfio-amd-xgbe device allows to assign a host AMD 10GbE controller
+to a guest ("amd,xgbe-seattle-v1a" compatibility string). AMD "Seattle"
+is not supported anymore and there is no point keeping that device.
+
+``-device vfio-platform`` (since 10.0)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+The vfio-platform device allows to assign a host platform device
+to a guest in a generic manner. Integrating a new device into
+the vfio-platform infrastructure requires some adaptation at
+both kernel and qemu level. No such attempt has been done for years
+and the conclusion is that vfio-platform has not got any traction.
+PCIe passthrough shall be the mainline solution.
+
 CPU device properties
 '''''''''''''''''''''
 

hw/vfio/amd-xgbe.c

@@ -15,12 +15,14 @@
 #include "hw/vfio/vfio-amd-xgbe.h"
 #include "migration/vmstate.h"
 #include "qemu/module.h"
+#include "qemu/error-report.h"
 
 static void amd_xgbe_realize(DeviceState *dev, Error **errp)
 {
     VFIOPlatformDevice *vdev = VFIO_PLATFORM_DEVICE(dev);
     VFIOAmdXgbeDeviceClass *k = VFIO_AMD_XGBE_DEVICE_GET_CLASS(dev);
 
+    warn_report("-device vfio-amd-xgbe is deprecated");
     vdev->compat = g_strdup("amd,xgbe-seattle-v1a");
     vdev->num_compat = 1;
 

hw/vfio/calxeda-xgmac.c

@@ -15,12 +15,14 @@
 #include "hw/vfio/vfio-calxeda-xgmac.h"
 #include "migration/vmstate.h"
 #include "qemu/module.h"
+#include "qemu/error-report.h"
 
 static void calxeda_xgmac_realize(DeviceState *dev, Error **errp)
 {
     VFIOPlatformDevice *vdev = VFIO_PLATFORM_DEVICE(dev);
     VFIOCalxedaXgmacDeviceClass *k = VFIO_CALXEDA_XGMAC_DEVICE_GET_CLASS(dev);
 
+    warn_report("-device vfio-calxeda-xgmac is deprecated");
     vdev->compat = g_strdup("calxeda,hb-xgmac");
     vdev->num_compat = 1;
 

hw/vfio/platform.c

@@ -575,6 +575,7 @@ static void vfio_platform_realize(DeviceState *dev, Error **errp)
     VFIODevice *vbasedev = &vdev->vbasedev;
     int i;
 
+    warn_report("-device vfio-platform is deprecated");
     qemu_mutex_init(&vdev->intp_mutex);
 
     trace_vfio_platform_realize(vbasedev->sysfsdev ?