1 files changed, 674 insertions, 0 deletions

diff --git a/src/VBox/Additions/linux/drm/vbox_main.c b/src/VBox/Additions/linux/drm/vbox_main.c
new file mode 100644
index 00000000..af2d7f43
--- /dev/null
+++ b/src/VBox/Additions/linux/drm/vbox_main.c
@@ -0,0 +1,674 @@
+/* $Id: vbox_main.c $ */
+/** @file
+ * VirtualBox Additions Linux kernel video driver
+ */
+
+/*
+ * Copyright (C) 2013-2020 Oracle Corporation
+ * This file is based on ast_main.c
+ * Copyright 2012 Red Hat Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+ * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+ * USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * Authors: Dave Airlie <airlied@redhat.com>,
+ *          Michael Thayer <michael.thayer@oracle.com,
+ *          Hans de Goede <hdegoede@redhat.com>
+ */
+#include "vbox_drv.h"
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_crtc_helper.h>
+
+#include <VBoxVideoGuest.h>
+#include <VBoxVideoVBE.h>
+
+#include "hgsmi_channels.h"
+
+static void vbox_user_framebuffer_destroy(struct drm_framebuffer *fb)
+{
+	struct vbox_framebuffer *vbox_fb = to_vbox_framebuffer(fb);
+
+	if (vbox_fb->obj)
+#if RTLNX_VER_MIN(5,9,0) || RTLNX_RHEL_MIN(8,4)
+		drm_gem_object_put(vbox_fb->obj);
+#else
+		drm_gem_object_put_unlocked(vbox_fb->obj);
+#endif
+
+	drm_framebuffer_cleanup(fb);
+	kfree(fb);
+}
+
+void vbox_enable_accel(struct vbox_private *vbox)
+{
+	unsigned int i;
+	struct VBVABUFFER *vbva;
+
+	if (!vbox->vbva_info || !vbox->vbva_buffers) {
+		/* Should never happen... */
+		DRM_ERROR("vboxvideo: failed to set up VBVA.\n");
+		return;
+	}
+
+	for (i = 0; i < vbox->num_crtcs; ++i) {
+		if (vbox->vbva_info[i].pVBVA)
+			continue;
+
+		vbva = (void __force *)vbox->vbva_buffers +
+			i * VBVA_MIN_BUFFER_SIZE;
+		if (!VBoxVBVAEnable(&vbox->vbva_info[i],
+				 vbox->guest_pool, vbva, i)) {
+			/* very old host or driver error. */
+			DRM_ERROR("vboxvideo: vbva_enable failed\n");
+			return;
+		}
+	}
+}
+
+void vbox_disable_accel(struct vbox_private *vbox)
+{
+	unsigned int i;
+
+	for (i = 0; i < vbox->num_crtcs; ++i)
+		VBoxVBVADisable(&vbox->vbva_info[i], vbox->guest_pool, i);
+}
+
+void vbox_report_caps(struct vbox_private *vbox)
+{
+	u32 caps = VBVACAPS_DISABLE_CURSOR_INTEGRATION |
+		   VBVACAPS_IRQ | VBVACAPS_USE_VBVA_ONLY;
+
+	if (vbox->initial_mode_queried)
+		caps |= VBVACAPS_VIDEO_MODE_HINTS;
+
+	VBoxHGSMISendCapsInfo(vbox->guest_pool, caps);
+}
+
+/**
+ * Send information about dirty rectangles to VBVA.  If necessary we enable
+ * VBVA first, as this is normally disabled after a change of master in case
+ * the new master does not send dirty rectangle information (is this even
+ * allowed?)
+ */
+void vbox_framebuffer_dirty_rectangles(struct drm_framebuffer *fb,
+				       struct drm_clip_rect *rects,
+				       unsigned int num_rects)
+{
+	struct vbox_private *vbox = fb->dev->dev_private;
+	struct drm_crtc *crtc;
+	unsigned int i;
+
+	/* The user can send rectangles, we do not need the timer. */
+	vbox->need_refresh_timer = false;
+	mutex_lock(&vbox->hw_mutex);
+	list_for_each_entry(crtc, &fb->dev->mode_config.crtc_list, head) {
+		if (CRTC_FB(crtc) != fb)
+			continue;
+
+		for (i = 0; i < num_rects; ++i) {
+			VBVACMDHDR cmd_hdr;
+			unsigned int crtc_id = to_vbox_crtc(crtc)->crtc_id;
+
+			if ((rects[i].x1 > crtc->x + crtc->hwmode.hdisplay) ||
+			    (rects[i].y1 > crtc->y + crtc->hwmode.vdisplay) ||
+			    (rects[i].x2 < crtc->x) ||
+			    (rects[i].y2 < crtc->y))
+				continue;
+
+			cmd_hdr.x = (s16)rects[i].x1;
+			cmd_hdr.y = (s16)rects[i].y1;
+			cmd_hdr.w = (u16)rects[i].x2 - rects[i].x1;
+			cmd_hdr.h = (u16)rects[i].y2 - rects[i].y1;
+
+			if (!VBoxVBVABufferBeginUpdate(&vbox->vbva_info[crtc_id],
+						      vbox->guest_pool))
+				continue;
+
+			VBoxVBVAWrite(&vbox->vbva_info[crtc_id], vbox->guest_pool,
+				   &cmd_hdr, sizeof(cmd_hdr));
+			VBoxVBVABufferEndUpdate(&vbox->vbva_info[crtc_id]);
+		}
+	}
+	mutex_unlock(&vbox->hw_mutex);
+}
+
+static int vbox_user_framebuffer_dirty(struct drm_framebuffer *fb,
+				       struct drm_file *file_priv,
+				       unsigned int flags, unsigned int color,
+				       struct drm_clip_rect *rects,
+				       unsigned int num_rects)
+{
+	vbox_framebuffer_dirty_rectangles(fb, rects, num_rects);
+
+	return 0;
+}
+
+static const struct drm_framebuffer_funcs vbox_fb_funcs = {
+	.destroy = vbox_user_framebuffer_destroy,
+	.dirty = vbox_user_framebuffer_dirty,
+};
+
+int vbox_framebuffer_init(struct drm_device *dev,
+			  struct vbox_framebuffer *vbox_fb,
+#if RTLNX_VER_MIN(4,5,0) || RTLNX_RHEL_MAJ_PREREQ(7,3)
+			  const struct DRM_MODE_FB_CMD *mode_cmd,
+#else
+			  struct DRM_MODE_FB_CMD *mode_cmd,
+#endif
+			  struct drm_gem_object *obj)
+{
+	int ret;
+
+#if RTLNX_VER_MIN(4,11,0) || RTLNX_RHEL_MAJ_PREREQ(7,5)
+	drm_helper_mode_fill_fb_struct(dev, &vbox_fb->base, mode_cmd);
+#else
+	drm_helper_mode_fill_fb_struct(&vbox_fb->base, mode_cmd);
+#endif
+	vbox_fb->obj = obj;
+	ret = drm_framebuffer_init(dev, &vbox_fb->base, &vbox_fb_funcs);
+	if (ret) {
+		DRM_ERROR("framebuffer init failed %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static struct drm_framebuffer *vbox_user_framebuffer_create(
+		struct drm_device *dev,
+		struct drm_file *filp,
+#if RTLNX_VER_MIN(4,5,0) || RTLNX_RHEL_MAJ_PREREQ(7,3)
+		const struct drm_mode_fb_cmd2 *mode_cmd)
+#else
+		struct drm_mode_fb_cmd2 *mode_cmd)
+#endif
+{
+	struct drm_gem_object *obj;
+	struct vbox_framebuffer *vbox_fb;
+	int ret = -ENOMEM;
+
+#if RTLNX_VER_MIN(4,7,0) || RTLNX_RHEL_MAJ_PREREQ(7,4)
+	obj = drm_gem_object_lookup(filp, mode_cmd->handles[0]);
+#else
+	obj = drm_gem_object_lookup(dev, filp, mode_cmd->handles[0]);
+#endif
+	if (!obj)
+		return ERR_PTR(-ENOENT);
+
+	vbox_fb = kzalloc(sizeof(*vbox_fb), GFP_KERNEL);
+	if (!vbox_fb)
+		goto err_unref_obj;
+
+	ret = vbox_framebuffer_init(dev, vbox_fb, mode_cmd, obj);
+	if (ret)
+		goto err_free_vbox_fb;
+
+	return &vbox_fb->base;
+
+err_free_vbox_fb:
+	kfree(vbox_fb);
+err_unref_obj:
+#if RTLNX_VER_MIN(5,9,0) || RTLNX_RHEL_MIN(8,4)
+	drm_gem_object_put(obj);
+#else
+	drm_gem_object_put_unlocked(obj);
+#endif
+	return ERR_PTR(ret);
+}
+
+static const struct drm_mode_config_funcs vbox_mode_funcs = {
+	.fb_create = vbox_user_framebuffer_create,
+};
+
+#if RTLNX_VER_MAX(4,0,0) && !RTLNX_RHEL_MAJ_PREREQ(7,3)
+# define pci_iomap_range(dev, bar, offset, maxlen) \
+	ioremap(pci_resource_start(dev, bar) + (offset), maxlen)
+#endif
+
+/**
+ * Tell the host about the views.  This design originally targeted the
+ * Windows XP driver architecture and assumed that each screen would
+ * have a dedicated frame buffer with the command buffer following it,
+ * the whole being a "view".  The host works out which screen a command
+ * buffer belongs to by checking whether it is in the first view, then
+ * whether it is in the second and so on.  The first match wins.  We
+ * cheat around this by making the first view be the managed memory
+ * plus the first command buffer, the second the same plus the second
+ * buffer and so on.
+ */
+static int vbox_set_views(struct vbox_private *vbox)
+{
+	VBVAINFOVIEW *p;
+	int i;
+
+	p = VBoxHGSMIBufferAlloc(vbox->guest_pool, sizeof(*p),
+			       HGSMI_CH_VBVA, VBVA_INFO_VIEW);
+	if (!p)
+		return -ENOMEM;
+
+	for (i = 0; i < vbox->num_crtcs; ++i) {
+		p->u32ViewIndex = i;
+		p->u32ViewOffset = 0;
+		p->u32ViewSize = vbox->available_vram_size +
+			i * VBVA_MIN_BUFFER_SIZE;
+		p->u32MaxScreenSize = vbox->available_vram_size;
+
+		VBoxHGSMIBufferSubmit(vbox->guest_pool, p);
+	}
+
+	VBoxHGSMIBufferFree(vbox->guest_pool, p);
+
+	return 0;
+}
+
+static int vbox_accel_init(struct vbox_private *vbox)
+{
+	unsigned int i, ret;
+
+	vbox->vbva_info = devm_kcalloc(vbox->dev->dev, vbox->num_crtcs,
+				       sizeof(*vbox->vbva_info), GFP_KERNEL);
+	if (!vbox->vbva_info)
+		return -ENOMEM;
+
+	/* Take a command buffer for each screen from the end of usable VRAM. */
+	vbox->available_vram_size -= vbox->num_crtcs * VBVA_MIN_BUFFER_SIZE;
+
+	vbox->vbva_buffers = pci_iomap_range(vbox->dev->pdev, 0,
+					     vbox->available_vram_size,
+					     vbox->num_crtcs *
+					     VBVA_MIN_BUFFER_SIZE);
+	if (!vbox->vbva_buffers)
+		return -ENOMEM;
+
+	for (i = 0; i < vbox->num_crtcs; ++i)
+		VBoxVBVASetupBufferContext(&vbox->vbva_info[i],
+					  vbox->available_vram_size +
+					  i * VBVA_MIN_BUFFER_SIZE,
+					  VBVA_MIN_BUFFER_SIZE);
+
+	vbox_enable_accel(vbox);
+	ret = vbox_set_views(vbox);
+	if (ret)
+		goto err_pci_iounmap;
+
+	return 0;
+
+err_pci_iounmap:
+	pci_iounmap(vbox->dev->pdev, vbox->vbva_buffers);
+	return ret;
+}
+
+static void vbox_accel_fini(struct vbox_private *vbox)
+{
+	vbox_disable_accel(vbox);
+	pci_iounmap(vbox->dev->pdev, vbox->vbva_buffers);
+}
+
+/** Do we support the 4.3 plus mode hint reporting interface? */
+static bool have_hgsmi_mode_hints(struct vbox_private *vbox)
+{
+	u32 have_hints, have_cursor;
+	int ret;
+
+	ret = VBoxQueryConfHGSMI(vbox->guest_pool,
+			       VBOX_VBVA_CONF32_MODE_HINT_REPORTING,
+			       &have_hints);
+	if (ret)
+		return false;
+
+	ret = VBoxQueryConfHGSMI(vbox->guest_pool,
+			       VBOX_VBVA_CONF32_GUEST_CURSOR_REPORTING,
+			       &have_cursor);
+	if (ret)
+		return false;
+
+	return have_hints == VINF_SUCCESS && have_cursor == VINF_SUCCESS;
+}
+
+/**
+ * Our refresh timer call-back.  Only used for guests without dirty rectangle
+ * support.
+ */
+static void vbox_refresh_timer(struct work_struct *work)
+{
+	struct vbox_private *vbox = container_of(work, struct vbox_private,
+												 refresh_work.work);
+	bool have_unblanked = false;
+	struct drm_crtc *crtci;
+
+	if (!vbox->need_refresh_timer)
+		return;
+	list_for_each_entry(crtci, &vbox->dev->mode_config.crtc_list, head) {
+		struct vbox_crtc *vbox_crtc = to_vbox_crtc(crtci);
+		if (crtci->enabled && !vbox_crtc->blanked)
+			have_unblanked = true;
+	}
+	if (!have_unblanked)
+		return;
+	/* This forces a full refresh. */
+	vbox_enable_accel(vbox);
+	/* Schedule the next timer iteration. */
+	schedule_delayed_work(&vbox->refresh_work, VBOX_REFRESH_PERIOD);
+}
+
+static bool vbox_check_supported(u16 id)
+{
+	u16 dispi_id;
+
+	vbox_write_ioport(VBE_DISPI_INDEX_ID, id);
+	dispi_id = inw(VBE_DISPI_IOPORT_DATA);
+
+	return dispi_id == id;
+}
+
+/**
+ * Set up our heaps and data exchange buffers in VRAM before handing the rest
+ * to the memory manager.
+ */
+static int vbox_hw_init(struct vbox_private *vbox)
+{
+	int ret = -ENOMEM;
+
+	vbox->full_vram_size = inl(VBE_DISPI_IOPORT_DATA);
+	vbox->any_pitch = vbox_check_supported(VBE_DISPI_ID_ANYX);
+
+	DRM_INFO("VRAM %08x\n", vbox->full_vram_size);
+
+	/* Map guest-heap at end of vram */
+	vbox->guest_heap =
+	    pci_iomap_range(vbox->dev->pdev, 0, GUEST_HEAP_OFFSET(vbox),
+			    GUEST_HEAP_SIZE);
+	if (!vbox->guest_heap)
+		return -ENOMEM;
+
+	/* Create guest-heap mem-pool use 2^4 = 16 byte chunks */
+	vbox->guest_pool = gen_pool_create(4, -1);
+	if (!vbox->guest_pool)
+		goto err_unmap_guest_heap;
+
+	ret = gen_pool_add_virt(vbox->guest_pool,
+				(unsigned long)vbox->guest_heap,
+				GUEST_HEAP_OFFSET(vbox),
+				GUEST_HEAP_USABLE_SIZE, -1);
+	if (ret)
+		goto err_destroy_guest_pool;
+
+	/* Reduce available VRAM size to reflect the guest heap. */
+	vbox->available_vram_size = GUEST_HEAP_OFFSET(vbox);
+	/* Linux drm represents monitors as a 32-bit array. */
+	VBoxQueryConfHGSMI(vbox->guest_pool, VBOX_VBVA_CONF32_MONITOR_COUNT,
+			 &vbox->num_crtcs);
+	vbox->num_crtcs = clamp_t(u32, vbox->num_crtcs, 1, VBOX_MAX_SCREENS);
+
+	if (!have_hgsmi_mode_hints(vbox)) {
+		ret = -ENOTSUPP;
+		goto err_destroy_guest_pool;
+	}
+
+	vbox->last_mode_hints = devm_kcalloc(vbox->dev->dev, vbox->num_crtcs,
+					     sizeof(VBVAMODEHINT),
+					     GFP_KERNEL);
+	if (!vbox->last_mode_hints) {
+		ret = -ENOMEM;
+		goto err_destroy_guest_pool;
+	}
+
+	ret = vbox_accel_init(vbox);
+	if (ret)
+		goto err_destroy_guest_pool;
+
+	/* Set up the refresh timer for users which do not send dirty rectangles. */
+	INIT_DELAYED_WORK(&vbox->refresh_work, vbox_refresh_timer);
+
+	return 0;
+
+err_destroy_guest_pool:
+	gen_pool_destroy(vbox->guest_pool);
+err_unmap_guest_heap:
+	pci_iounmap(vbox->dev->pdev, vbox->guest_heap);
+	return ret;
+}
+
+static void vbox_hw_fini(struct vbox_private *vbox)
+{
+	vbox->need_refresh_timer = false;
+	cancel_delayed_work(&vbox->refresh_work);
+	vbox_accel_fini(vbox);
+	gen_pool_destroy(vbox->guest_pool);
+	pci_iounmap(vbox->dev->pdev, vbox->guest_heap);
+}
+
+#if RTLNX_VER_MIN(4,19,0) || RTLNX_RHEL_MIN(8,3)
+int vbox_driver_load(struct drm_device *dev)
+#else
+int vbox_driver_load(struct drm_device *dev, unsigned long flags)
+#endif
+{
+	struct vbox_private *vbox;
+	int ret = 0;
+
+	if (!vbox_check_supported(VBE_DISPI_ID_HGSMI))
+		return -ENODEV;
+
+	vbox = devm_kzalloc(dev->dev, sizeof(*vbox), GFP_KERNEL);
+	if (!vbox)
+		return -ENOMEM;
+
+	dev->dev_private = vbox;
+	vbox->dev = dev;
+
+	mutex_init(&vbox->hw_mutex);
+
+	ret = vbox_hw_init(vbox);
+	if (ret)
+		return ret;
+
+	ret = vbox_mm_init(vbox);
+	if (ret)
+		goto err_hw_fini;
+
+	drm_mode_config_init(dev);
+
+	dev->mode_config.funcs = (void *)&vbox_mode_funcs;
+	dev->mode_config.min_width = 64;
+	dev->mode_config.min_height = 64;
+	dev->mode_config.preferred_depth = 24;
+	dev->mode_config.max_width = VBE_DISPI_MAX_XRES;
+	dev->mode_config.max_height = VBE_DISPI_MAX_YRES;
+
+	ret = vbox_mode_init(dev);
+	if (ret)
+		goto err_drm_mode_cleanup;
+
+	ret = vbox_irq_init(vbox);
+	if (ret)
+		goto err_mode_fini;
+
+	ret = vbox_fbdev_init(dev);
+	if (ret)
+		goto err_irq_fini;
+
+	return 0;
+
+err_irq_fini:
+	vbox_irq_fini(vbox);
+err_mode_fini:
+	vbox_mode_fini(dev);
+err_drm_mode_cleanup:
+	drm_mode_config_cleanup(dev);
+	vbox_mm_fini(vbox);
+err_hw_fini:
+	vbox_hw_fini(vbox);
+	return ret;
+}
+
+#if RTLNX_VER_MIN(4,11,0) || RTLNX_RHEL_MAJ_PREREQ(7,5)
+void vbox_driver_unload(struct drm_device *dev)
+#else
+int vbox_driver_unload(struct drm_device *dev)
+#endif
+{
+	struct vbox_private *vbox = dev->dev_private;
+
+	vbox_fbdev_fini(dev);
+	vbox_irq_fini(vbox);
+	vbox_mode_fini(dev);
+	drm_mode_config_cleanup(dev);
+	vbox_mm_fini(vbox);
+	vbox_hw_fini(vbox);
+#if RTLNX_VER_MAX(4,11,0) && !RTLNX_RHEL_MAJ_PREREQ(7,5)
+	return 0;
+#endif
+}
+
+/**
+ * @note this is described in the DRM framework documentation.  AST does not
+ * have it, but we get an oops on driver unload if it is not present.
+ */
+void vbox_driver_lastclose(struct drm_device *dev)
+{
+	struct vbox_private *vbox = dev->dev_private;
+
+#if RTLNX_VER_MIN(3,16,0) || RTLNX_RHEL_MAJ_PREREQ(7,1)
+	if (vbox->fbdev)
+		drm_fb_helper_restore_fbdev_mode_unlocked(&vbox->fbdev->helper);
+#else
+	drm_modeset_lock_all(dev);
+	if (vbox->fbdev)
+		drm_fb_helper_restore_fbdev_mode(&vbox->fbdev->helper);
+	drm_modeset_unlock_all(dev);
+#endif
+}
+
+int vbox_gem_create(struct drm_device *dev,
+		    u32 size, bool iskernel, struct drm_gem_object **obj)
+{
+	struct vbox_bo *vboxbo;
+	int ret;
+
+	*obj = NULL;
+
+	size = roundup(size, PAGE_SIZE);
+	if (size == 0)
+		return -EINVAL;
+
+	ret = vbox_bo_create(dev, size, 0, 0, &vboxbo);
+	if (ret) {
+		if (ret != -ERESTARTSYS)
+			DRM_ERROR("failed to allocate GEM object\n");
+		return ret;
+	}
+
+	*obj = &vboxbo->gem;
+
+	return 0;
+}
+
+int vbox_dumb_create(struct drm_file *file,
+		     struct drm_device *dev, struct drm_mode_create_dumb *args)
+{
+	int ret;
+	struct drm_gem_object *gobj;
+	u32 handle;
+
+	args->pitch = args->width * ((args->bpp + 7) / 8);
+	args->size = args->pitch * args->height;
+
+	ret = vbox_gem_create(dev, args->size, false, &gobj);
+	if (ret)
+		return ret;
+
+	ret = drm_gem_handle_create(file, gobj, &handle);
+#if RTLNX_VER_MIN(5,9,0) || RTLNX_RHEL_MIN(8,4)
+	drm_gem_object_put(gobj);
+#else
+	drm_gem_object_put_unlocked(gobj);
+#endif
+	if (ret)
+		return ret;
+
+	args->handle = handle;
+
+	return 0;
+}
+
+#if RTLNX_VER_MAX(3,12,0) && !RTLNX_RHEL_MAJ_PREREQ(7,3)
+int vbox_dumb_destroy(struct drm_file *file,
+		      struct drm_device *dev, u32 handle)
+{
+	return drm_gem_handle_delete(file, handle);
+}
+#endif
+
+#if RTLNX_VER_MAX(4,19,0) && !RTLNX_RHEL_MAJ_PREREQ(7,7) && !RTLNX_RHEL_MAJ_PREREQ(8,1) && !RTLNX_SUSE_MAJ_PREREQ(15,1) && !RTLNX_SUSE_MAJ_PREREQ(12,5)
+static void ttm_bo_put(struct ttm_buffer_object *bo)
+{
+	ttm_bo_unref(&bo);
+}
+#endif
+
+void vbox_gem_free_object(struct drm_gem_object *obj)
+{
+	struct vbox_bo *vbox_bo = gem_to_vbox_bo(obj);
+
+	ttm_bo_put(&vbox_bo->bo);
+}
+
+static inline u64 vbox_bo_mmap_offset(struct vbox_bo *bo)
+{
+#if RTLNX_VER_MIN(5,4,0) || RTLNX_RHEL_MIN(8,3)
+        return drm_vma_node_offset_addr(&bo->bo.base.vma_node);
+#elif RTLNX_VER_MAX(3,12,0) && !RTLNX_RHEL_MAJ_PREREQ(7,0)
+	return bo->bo.addr_space_offset;
+#else
+	return drm_vma_node_offset_addr(&bo->bo.vma_node);
+#endif /* >= 5.4.0 */
+}
+
+int
+vbox_dumb_mmap_offset(struct drm_file *file,
+		      struct drm_device *dev,
+		      u32 handle, u64 *offset)
+{
+	struct drm_gem_object *obj;
+	int ret;
+	struct vbox_bo *bo;
+
+	mutex_lock(&dev->struct_mutex);
+#if RTLNX_VER_MIN(4,7,0) || RTLNX_RHEL_MAJ_PREREQ(7,4)
+	obj = drm_gem_object_lookup(file, handle);
+#else
+	obj = drm_gem_object_lookup(dev, file, handle);
+#endif
+	if (!obj) {
+		ret = -ENOENT;
+		goto out_unlock;
+	}
+
+	bo = gem_to_vbox_bo(obj);
+	*offset = vbox_bo_mmap_offset(bo);
+
+	drm_gem_object_put(obj);
+	ret = 0;
+
+out_unlock:
+	mutex_unlock(&dev->struct_mutex);
+	return ret;
+}