vfio/xe: Add device specific vfio_pci driver variant for Intel graphics

In addition to generic VFIO PCI functionality, the driver implements
VFIO migration uAPI, allowing userspace to enable migration for Intel
Graphics SR-IOV Virtual Functions.
The driver binds to VF device and uses API exposed by Xe driver to
transfer the VF migration data under the control of PF device.

Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Alex Williamson <alex@shazbot.org>
Link: https://patch.msgid.link/20251127093934.1462188-5-michal.winiarski@intel.com
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>

MAINTAINERS

@@ -26964,6 +26964,13 @@ L:	virtualization@lists.linux.dev
 S:	Maintained
 F:	drivers/vfio/pci/virtio
 
+VFIO XE PCI DRIVER
+M:	Michał Winiarski <michal.winiarski@intel.com>
+L:	kvm@vger.kernel.org
+L:	intel-xe@lists.freedesktop.org
+S:	Supported
+F:	drivers/vfio/pci/xe
+
 VGA_SWITCHEROO
 R:	Lukas Wunner <lukas@wunner.de>
 S:	Maintained

drivers/vfio/pci/Kconfig

@@ -67,4 +67,6 @@ source "drivers/vfio/pci/nvgrace-gpu/Kconfig"
 
 source "drivers/vfio/pci/qat/Kconfig"
 
+source "drivers/vfio/pci/xe/Kconfig"
+
 endmenu

drivers/vfio/pci/Makefile

@@ -19,3 +19,5 @@ obj-$(CONFIG_VIRTIO_VFIO_PCI) += virtio/
 obj-$(CONFIG_NVGRACE_GPU_VFIO_PCI) += nvgrace-gpu/
 
 obj-$(CONFIG_QAT_VFIO_PCI) += qat/
+
+obj-$(CONFIG_XE_VFIO_PCI) += xe/

drivers/vfio/pci/xe/Kconfig

@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config XE_VFIO_PCI
+	tristate "VFIO support for Intel Graphics"
+	depends on DRM_XE && PCI_IOV
+	select VFIO_PCI_CORE
+	help
+	  This option enables device specific VFIO driver variant for Intel Graphics.
+	  In addition to generic VFIO PCI functionality, it implements VFIO
+	  migration uAPI allowing userspace to enable migration for
+	  Intel Graphics SR-IOV Virtual Functions supported by the Xe driver.
+
+	  If you don't know what to do here, say N.

drivers/vfio/pci/xe/Makefile

@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_XE_VFIO_PCI) += xe-vfio-pci.o
+xe-vfio-pci-y := main.o