Merge tag 'io_uring-7.3-20261002' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linuxgrafted

Pull io_uring fixes from Jens Axboe:

 - Fix a task_work add use-after-free with SQPOLL.

   The sqpoll thread could pop and complete the last request while
   io_req_normal_work_add() was still looking at them after the mpscq
   push.

   Use the same approach as DEFER_TASKRUN to protect from that, holding
   an RCU read lock across the add, and have exit wait for an RCU grace
   period for SQPOLL rings as well.

 - CQE32 ring fixes: correct the free entry check for 32b CQEs, zero the
   big_cqe for aux CQEs, and only post the dummy skip CQE on CQE_MIXED
   rings

 - Mark the source filter table as COW when cloning bpf filters, so
   registering another filter on the source doesn't modify the shared
   table in place

 - Initialize the task context before running the BPF loop

 - Requeue zcrx multishot receives stopped by a local resource

 - End a TX_TIMESTAMP multishot cmd when the CQ is full (lollipopkit)

* tag 'io_uring-7.3-20261002' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
  io_uring: fix task_work add use-after-free with SQPOLL
  io_uring/cmd_net: end TX_TIMESTAMP multishot when the CQ is full
  io_uring/zcrx: requeue multishot receives stopped by a local resource
  io_uring: initialize task context before running the BPF loop
  io_uring: zero big_cqe for aux CQEs on CQE32 rings
  io_uring: fix free entry check for 32b CQEs on CQE32 rings
  io_uring: only post the dummy skip CQE on CQE_MIXED rings
  io_uring/bpf_filter: mark source as COW when cloning filters

6 files changed, 1293 insertions, 0 deletions

diff --git a/drivers/gpu/drm/hyperv/Kconfig b/drivers/gpu/drm/hyperv/Kconfig
new file mode 100644
index 000000000..86234f6a7
--- /dev/null
+++ b/drivers/gpu/drm/hyperv/Kconfig
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config DRM_HYPERV
+	tristate "DRM Support for Hyper-V synthetic video device"
+	depends on DRM && PCI && HYPERV_VMBUS
+	select DRM_CLIENT_SELECTION
+	select DRM_KMS_HELPER
+	select DRM_GEM_SHMEM_HELPER
+	help
+	 This is a KMS driver for Hyper-V synthetic video device. Choose this
+	 option if you would like to enable drm driver for Hyper-V virtual
+	 machine. Unselect Hyper-V framebuffer driver (CONFIG_FB_HYPERV) so
+	 that DRM driver is used by default.
+
+	 If M is selected the module will be called hyperv_drm.
diff --git a/drivers/gpu/drm/hyperv/Makefile b/drivers/gpu/drm/hyperv/Makefile
new file mode 100644
index 000000000..265f12f2c
--- /dev/null
+++ b/drivers/gpu/drm/hyperv/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+hyperv_drm-y := \
+	hyperv_drm_drv.o \
+	hyperv_drm_modeset.o \
+	hyperv_drm_proto.o
+
+obj-$(CONFIG_DRM_HYPERV) += hyperv_drm.o
diff --git a/drivers/gpu/drm/hyperv/hyperv_drm.h b/drivers/gpu/drm/hyperv/hyperv_drm.h
new file mode 100644
index 000000000..78136ec2c
--- /dev/null
+++ b/drivers/gpu/drm/hyperv/hyperv_drm.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2021 Microsoft
+ */
+
+#ifndef _HYPERV_DRM_H_
+#define _HYPERV_DRM_H_
+
+#define VMBUS_MAX_PACKET_SIZE 0x4000
+
+struct hv_drm_device {
+	/* drm */
+	struct drm_device dev;
+	struct drm_plane plane;
+	struct drm_crtc crtc;
+	struct drm_encoder encoder;
+	struct drm_connector connector;
+
+	/* mode */
+	u32 screen_width_max;
+	u32 screen_height_max;
+	u32 preferred_width;
+	u32 preferred_height;
+	u32 screen_depth;
+
+	/* hw */
+	struct resource *mem;
+	void __iomem *vram;
+	unsigned long fb_base;
+	unsigned long fb_size;
+	struct completion wait;
+	u32 synthvid_version;
+	u32 mmio_megabytes;
+	bool dirt_needed;
+
+	u8 init_buf[VMBUS_MAX_PACKET_SIZE];
+	u8 recv_buf[VMBUS_MAX_PACKET_SIZE];
+
+	struct hv_device *hdev;
+};
+
+#define to_hv_drm(_dev) container_of(_dev, struct hv_drm_device, dev)
+
+/* hyperv_drm_modeset */
+int hv_drm_mode_config_init(struct hv_drm_device *hv);
+
+/* hyperv_drm_proto */
+int hv_drm_update_vram_location(struct hv_device *hdev, phys_addr_t vram_pp);
+int hv_drm_update_situation(struct hv_device *hdev, u8 active, u32 bpp,
+			    u32 w, u32 h, u32 pitch);
+int hv_drm_hide_hw_ptr(struct hv_device *hdev);
+int hv_drm_update_dirt(struct hv_device *hdev, struct drm_rect *rect);
+int hv_drm_connect_vsp(struct hv_device *hdev);
+
+#endif
diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
new file mode 100644
index 000000000..0efd0593d
--- /dev/null
+++ b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
@@ -0,0 +1,272 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2021 Microsoft
+ */
+
+#include <linux/aperture.h>
+#include <linux/efi.h>
+#include <linux/hyperv.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+
+#include <drm/clients/drm_client_setup.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fbdev_shmem.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_print.h>
+#include <drm/drm_simple_kms_helper.h>
+
+#include "hyperv_drm.h"
+
+#define DRIVER_NAME "hyperv_drm"
+#define DRIVER_DESC "DRM driver for Hyper-V synthetic video device"
+#define DRIVER_MAJOR 1
+#define DRIVER_MINOR 0
+
+DEFINE_DRM_GEM_FOPS(hv_drm_fops);
+
+static struct drm_driver hv_drm_driver = {
+	.driver_features = DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC,
+
+	.name		 = DRIVER_NAME,
+	.desc		 = DRIVER_DESC,
+	.major		 = DRIVER_MAJOR,
+	.minor		 = DRIVER_MINOR,
+
+	.fops		 = &hv_drm_fops,
+	DRM_GEM_SHMEM_DRIVER_OPS,
+	DRM_FBDEV_SHMEM_DRIVER_OPS,
+};
+
+static int hv_drm_pci_probe(struct pci_dev *pdev,
+			    const struct pci_device_id *ent)
+{
+	return 0;
+}
+
+static void hv_drm_pci_remove(struct pci_dev *pdev)
+{
+}
+
+static const struct pci_device_id hv_drm_pci_tbl[] = {
+	{
+		PCI_VDEVICE_SUB(MICROSOFT, PCI_DEVICE_ID_HYPERV_VIDEO,
+				0, 0),
+	},
+	{ /* end of list */ }
+};
+MODULE_DEVICE_TABLE(pci, hv_drm_pci_tbl);
+
+/*
+ * PCI stub to support gen1 VM.
+ */
+static struct pci_driver hv_drm_pci_driver = {
+	.name =		KBUILD_MODNAME,
+	.id_table =	hv_drm_pci_tbl,
+	.probe =	hv_drm_pci_probe,
+	.remove =	hv_drm_pci_remove,
+};
+
+static int hv_drm_setup_vram(struct hv_drm_device *hv,
+			     struct hv_device *hdev)
+{
+	struct drm_device *dev = &hv->dev;
+	int ret;
+
+	hv->fb_size = (unsigned long)hv->mmio_megabytes * 1024 * 1024;
+
+	ret = vmbus_allocate_mmio(&hv->mem, hdev, 0, -1, hv->fb_size, 0x100000,
+				  true);
+	if (ret) {
+		drm_err(dev, "Failed to allocate mmio\n");
+		return -ENOMEM;
+	}
+
+	/*
+	 * Map the VRAM cacheable for performance. This is also required for VM
+	 * connect to display properly for ARM64 Linux VM, as the host also maps
+	 * the VRAM cacheable.
+	 */
+	hv->vram = ioremap_cache(hv->mem->start, hv->fb_size);
+	if (!hv->vram) {
+		drm_err(dev, "Failed to map vram\n");
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	hv->fb_base = hv->mem->start;
+	return 0;
+
+error:
+	vmbus_free_mmio(hv->mem->start, hv->fb_size);
+	return ret;
+}
+
+static int hv_drm_vmbus_probe(struct hv_device *hdev,
+			      const struct hv_vmbus_device_id *dev_id)
+{
+	struct hv_drm_device *hv;
+	struct drm_device *dev;
+	int ret;
+
+	hv = devm_drm_dev_alloc(&hdev->device, &hv_drm_driver,
+				struct hv_drm_device, dev);
+	if (IS_ERR(hv))
+		return PTR_ERR(hv);
+
+	dev = &hv->dev;
+	init_completion(&hv->wait);
+	hv_set_drvdata(hdev, hv);
+	hv->hdev = hdev;
+
+	ret = hv_drm_connect_vsp(hdev);
+	if (ret) {
+		drm_err(dev, "Failed to connect to vmbus.\n");
+		goto err_hv_set_drv_data;
+	}
+
+	aperture_remove_all_conflicting_devices(hv_drm_driver.name);
+
+	ret = hv_drm_setup_vram(hv, hdev);
+	if (ret)
+		goto err_vmbus_close;
+
+	/*
+	 * Should be done only once during init and resume. Failing to update
+	 * vram location is not fatal. Device will update dirty area till
+	 * preferred resolution only.
+	 */
+	ret = hv_drm_update_vram_location(hdev, hv->fb_base);
+	if (ret)
+		drm_warn(dev, "Failed to update vram location.\n");
+
+	ret = hv_drm_mode_config_init(hv);
+	if (ret)
+		goto err_free_mmio;
+
+	ret = drm_dev_register(dev, 0);
+	if (ret) {
+		drm_err(dev, "Failed to register drm driver.\n");
+		goto err_free_mmio;
+	}
+
+	/* If DRM panic path is stubbed out VMBus code must do the unload */
+	if (IS_ENABLED(CONFIG_DRM_PANIC))
+		vmbus_set_skip_unload(true);
+
+	drm_client_setup(dev, NULL);
+
+	return 0;
+
+err_free_mmio:
+	iounmap(hv->vram);
+	vmbus_free_mmio(hv->mem->start, hv->fb_size);
+err_vmbus_close:
+	vmbus_close(hdev->channel);
+err_hv_set_drv_data:
+	hv_set_drvdata(hdev, NULL);
+	return ret;
+}
+
+static void hv_drm_vmbus_remove(struct hv_device *hdev)
+{
+	struct drm_device *dev = hv_get_drvdata(hdev);
+	struct hv_drm_device *hv = to_hv_drm(dev);
+
+	vmbus_set_skip_unload(false);
+	drm_dev_unplug(dev);
+	drm_atomic_helper_shutdown(dev);
+	vmbus_close(hdev->channel);
+	hv_set_drvdata(hdev, NULL);
+
+	iounmap(hv->vram);
+	vmbus_free_mmio(hv->mem->start, hv->fb_size);
+}
+
+static void hv_drm_vmbus_shutdown(struct hv_device *hdev)
+{
+	drm_atomic_helper_shutdown(hv_get_drvdata(hdev));
+}
+
+static int hv_drm_vmbus_suspend(struct hv_device *hdev)
+{
+	struct drm_device *dev = hv_get_drvdata(hdev);
+	int ret;
+
+	ret = drm_mode_config_helper_suspend(dev);
+	if (ret)
+		return ret;
+
+	vmbus_close(hdev->channel);
+
+	return 0;
+}
+
+static int hv_drm_vmbus_resume(struct hv_device *hdev)
+{
+	struct drm_device *dev = hv_get_drvdata(hdev);
+	struct hv_drm_device *hv = to_hv_drm(dev);
+	int ret;
+
+	ret = hv_drm_connect_vsp(hdev);
+	if (ret)
+		return ret;
+
+	ret = hv_drm_update_vram_location(hdev, hv->fb_base);
+	if (ret)
+		return ret;
+
+	return drm_mode_config_helper_resume(dev);
+}
+
+static const struct hv_vmbus_device_id hv_drm_vmbus_tbl[] = {
+	/* Synthetic Video Device GUID */
+	{HV_SYNTHVID_GUID},
+	{}
+};
+MODULE_DEVICE_TABLE(vmbus, hv_drm_vmbus_tbl);
+
+static struct hv_driver hv_drm_hv_driver = {
+	.name = KBUILD_MODNAME,
+	.id_table = hv_drm_vmbus_tbl,
+	.probe = hv_drm_vmbus_probe,
+	.remove = hv_drm_vmbus_remove,
+	.shutdown = hv_drm_vmbus_shutdown,
+	.suspend = hv_drm_vmbus_suspend,
+	.resume = hv_drm_vmbus_resume,
+	.driver = {
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+};
+
+static int __init hv_drm_init(void)
+{
+	int ret;
+
+	if (drm_firmware_drivers_only())
+		return -ENODEV;
+
+	ret = pci_register_driver(&hv_drm_pci_driver);
+	if (ret != 0)
+		return ret;
+
+	ret = vmbus_driver_register(&hv_drm_hv_driver);
+	if (ret)
+		pci_unregister_driver(&hv_drm_pci_driver);
+
+	return ret;
+}
+
+static void __exit hv_drm_exit(void)
+{
+	vmbus_driver_unregister(&hv_drm_hv_driver);
+	pci_unregister_driver(&hv_drm_pci_driver);
+}
+
+module_init(hv_drm_init);
+module_exit(hv_drm_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Deepak Rawat <drawat.floss@gmail.com>");
+MODULE_DESCRIPTION("DRM driver for Hyper-V synthetic video device");
diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
new file mode 100644
index 000000000..1855749c1
--- /dev/null
+++ b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
@@ -0,0 +1,340 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2021 Microsoft
+ */
+
+#include <linux/hyperv.h>
+
+#include <drm/drm_atomic.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_edid.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem_atomic_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_panic.h>
+#include <drm/drm_plane.h>
+#include <drm/drm_print.h>
+#include <drm/drm_vblank.h>
+#include <drm/drm_vblank_helper.h>
+
+#include "hyperv_drm.h"
+
+static int hv_drm_blit_to_vram_rect(struct drm_framebuffer *fb,
+				    const struct iosys_map *vmap,
+				    struct drm_rect *rect)
+{
+	struct hv_drm_device *hv = to_hv_drm(fb->dev);
+	struct iosys_map dst = IOSYS_MAP_INIT_VADDR_IOMEM(hv->vram);
+	int idx;
+
+	if (!drm_dev_enter(&hv->dev, &idx))
+		return -ENODEV;
+
+	iosys_map_incr(&dst, drm_fb_clip_offset(fb->pitches[0], fb->format, rect));
+	drm_fb_memcpy(&dst, fb->pitches, vmap, fb, rect);
+
+	drm_dev_exit(idx);
+
+	return 0;
+}
+
+static int hv_drm_connector_get_modes(struct drm_connector *connector)
+{
+	struct hv_drm_device *hv = to_hv_drm(connector->dev);
+	int count;
+
+	count = drm_add_modes_noedid(connector,
+				     connector->dev->mode_config.max_width,
+				     connector->dev->mode_config.max_height);
+	drm_set_preferred_mode(connector, hv->preferred_width,
+			       hv->preferred_height);
+
+	return count;
+}
+
+static const struct drm_connector_helper_funcs hv_drm_connector_helper_funcs = {
+	.get_modes = hv_drm_connector_get_modes,
+};
+
+static const struct drm_connector_funcs hv_drm_connector_funcs = {
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = drm_connector_cleanup,
+	.reset = drm_atomic_helper_connector_reset,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static inline int hv_drm_conn_init(struct hv_drm_device *hv)
+{
+	drm_connector_helper_add(&hv->connector, &hv_drm_connector_helper_funcs);
+	return drm_connector_init(&hv->dev, &hv->connector,
+				  &hv_drm_connector_funcs,
+				  DRM_MODE_CONNECTOR_VIRTUAL);
+}
+
+static int hv_drm_check_size(struct hv_drm_device *hv, int w, int h,
+			     struct drm_framebuffer *fb)
+{
+	u32 pitch = w * (hv->screen_depth / 8);
+
+	if (fb)
+		pitch = fb->pitches[0];
+
+	if (pitch * h > hv->fb_size)
+		return -EINVAL;
+
+	return 0;
+}
+
+static const uint32_t hv_drm_formats[] = {
+	DRM_FORMAT_XRGB8888,
+};
+
+static const uint64_t hv_drm_modifiers[] = {
+	DRM_FORMAT_MOD_LINEAR,
+	DRM_FORMAT_MOD_INVALID
+};
+
+static void hv_drm_crtc_helper_atomic_enable(struct drm_crtc *crtc,
+					     struct drm_atomic_commit *state)
+{
+	struct hv_drm_device *hv = to_hv_drm(crtc->dev);
+	struct drm_plane *plane = &hv->plane;
+	struct drm_plane_state *plane_state = plane->state;
+	struct drm_crtc_state *crtc_state = crtc->state;
+
+	hv_drm_hide_hw_ptr(hv->hdev);
+	hv_drm_update_situation(hv->hdev, 1,  hv->screen_depth,
+				crtc_state->mode.hdisplay,
+				crtc_state->mode.vdisplay,
+				plane_state->fb->pitches[0]);
+
+	drm_crtc_vblank_on(crtc);
+}
+
+static const struct drm_crtc_helper_funcs hv_drm_crtc_helper_funcs = {
+	.atomic_check = drm_crtc_helper_atomic_check,
+	.atomic_flush = drm_crtc_vblank_atomic_flush,
+	.atomic_enable = hv_drm_crtc_helper_atomic_enable,
+	.atomic_disable = drm_crtc_vblank_atomic_disable,
+};
+
+static const struct drm_crtc_funcs hv_drm_crtc_funcs = {
+	.reset = drm_atomic_helper_crtc_reset,
+	.destroy = drm_crtc_cleanup,
+	.set_config = drm_atomic_helper_set_config,
+	.page_flip = drm_atomic_helper_page_flip,
+	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
+	DRM_CRTC_VBLANK_TIMER_FUNCS,
+};
+
+static int hv_drm_plane_atomic_check(struct drm_plane *plane,
+				     struct drm_atomic_commit *state)
+{
+	struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
+	struct hv_drm_device *hv = to_hv_drm(plane->dev);
+	struct drm_framebuffer *fb = plane_state->fb;
+	struct drm_crtc *crtc = plane_state->crtc;
+	struct drm_crtc_state *crtc_state = NULL;
+	int ret;
+
+	if (crtc)
+		crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
+
+	ret = drm_atomic_helper_check_plane_state(plane_state, crtc_state,
+						  DRM_PLANE_NO_SCALING,
+						  DRM_PLANE_NO_SCALING,
+						  false, false);
+	if (ret)
+		return ret;
+
+	if (!plane_state->visible)
+		return 0;
+
+	if (fb->pitches[0] * fb->height > hv->fb_size) {
+		drm_err(&hv->dev, "fb size requested by %s for %dX%d (pitch %d) greater than %ld\n",
+			current->comm, fb->width, fb->height, fb->pitches[0], hv->fb_size);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void hv_drm_plane_atomic_update(struct drm_plane *plane,
+				       struct drm_atomic_commit *state)
+{
+	struct hv_drm_device *hv = to_hv_drm(plane->dev);
+	struct drm_plane_state *old_state = drm_atomic_get_old_plane_state(state, plane);
+	struct drm_plane_state *new_state = drm_atomic_get_new_plane_state(state, plane);
+	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(new_state);
+	struct drm_rect damage;
+	struct drm_rect dst_clip;
+	struct drm_atomic_helper_damage_iter iter;
+
+	drm_atomic_helper_damage_iter_init(&iter, old_state, new_state);
+	drm_atomic_for_each_plane_damage(&iter, &damage) {
+		dst_clip = new_state->dst;
+
+		if (!drm_rect_intersect(&dst_clip, &damage))
+			continue;
+
+		hv_drm_blit_to_vram_rect(new_state->fb, &shadow_plane_state->data[0], &damage);
+		hv_drm_update_dirt(hv->hdev, &damage);
+	}
+}
+
+static int hv_drm_plane_get_scanout_buffer(struct drm_plane *plane,
+					   struct drm_scanout_buffer *sb)
+{
+	struct hv_drm_device *hv = to_hv_drm(plane->dev);
+	struct iosys_map map = IOSYS_MAP_INIT_VADDR_IOMEM(hv->vram);
+
+	if (plane->state && plane->state->fb) {
+		sb->format = plane->state->fb->format;
+		sb->width = plane->state->fb->width;
+		sb->height = plane->state->fb->height;
+		sb->pitch[0] = plane->state->fb->pitches[0];
+		sb->map[0] = map;
+		return 0;
+	}
+	return -ENODEV;
+}
+
+static void hv_drm_plane_panic_flush(struct drm_plane *plane)
+{
+	struct hv_drm_device *hv = to_hv_drm(plane->dev);
+	struct drm_rect rect;
+
+	if (plane->state && plane->state->fb) {
+		rect.x1 = 0;
+		rect.y1 = 0;
+		rect.x2 = plane->state->fb->width;
+		rect.y2 = plane->state->fb->height;
+
+		hv_drm_update_dirt(hv->hdev, &rect);
+	}
+
+	vmbus_initiate_unload(true);
+}
+
+static const struct drm_plane_helper_funcs hv_drm_plane_helper_funcs = {
+	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
+	.atomic_check = hv_drm_plane_atomic_check,
+	.atomic_update = hv_drm_plane_atomic_update,
+	.get_scanout_buffer = hv_drm_plane_get_scanout_buffer,
+	.panic_flush = hv_drm_plane_panic_flush,
+};
+
+static const struct drm_plane_funcs hv_drm_plane_funcs = {
+	.update_plane		= drm_atomic_helper_update_plane,
+	.disable_plane		= drm_atomic_helper_disable_plane,
+	.destroy		= drm_plane_cleanup,
+	DRM_GEM_SHADOW_PLANE_FUNCS,
+};
+
+static const struct drm_encoder_funcs hv_drm_simple_encoder_funcs_cleanup = {
+	.destroy = drm_encoder_cleanup,
+};
+
+static inline int hv_drm_pipe_init(struct hv_drm_device *hv)
+{
+	struct drm_device *dev = &hv->dev;
+	struct drm_encoder *encoder = &hv->encoder;
+	struct drm_plane *plane = &hv->plane;
+	struct drm_crtc *crtc = &hv->crtc;
+	struct drm_connector *connector = &hv->connector;
+	int ret;
+
+	ret = drm_universal_plane_init(dev, plane, 0,
+				       &hv_drm_plane_funcs,
+				       hv_drm_formats, ARRAY_SIZE(hv_drm_formats),
+				       hv_drm_modifiers,
+				       DRM_PLANE_TYPE_PRIMARY, NULL);
+	if (ret)
+		return ret;
+	drm_plane_helper_add(plane, &hv_drm_plane_helper_funcs);
+	drm_plane_enable_fb_damage_clips(plane);
+
+	ret = drm_crtc_init_with_planes(dev, crtc, plane, NULL,
+					&hv_drm_crtc_funcs, NULL);
+	if (ret)
+		return ret;
+	drm_crtc_helper_add(crtc, &hv_drm_crtc_helper_funcs);
+
+	encoder->possible_crtcs = drm_crtc_mask(crtc);
+	ret = drm_encoder_init(dev, encoder,
+			       &hv_drm_simple_encoder_funcs_cleanup,
+			       DRM_MODE_ENCODER_NONE, NULL);
+	if (ret)
+		return ret;
+
+	ret = hv_drm_conn_init(hv);
+	if (ret) {
+		drm_err(dev, "Failed to initialized connector.\n");
+		return ret;
+	}
+
+	return drm_connector_attach_encoder(connector, encoder);
+}
+
+static enum drm_mode_status
+hv_drm_mode_valid(struct drm_device *dev,
+		  const struct drm_display_mode *mode)
+{
+	struct hv_drm_device *hv = to_hv_drm(dev);
+
+	if (hv_drm_check_size(hv, mode->hdisplay, mode->vdisplay, NULL))
+		return MODE_BAD;
+
+	return MODE_OK;
+}
+
+static const struct drm_mode_config_funcs hv_drm_mode_config_funcs = {
+	.fb_create = drm_gem_fb_create_with_dirty,
+	.mode_valid = hv_drm_mode_valid,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+int hv_drm_mode_config_init(struct hv_drm_device *hv)
+{
+	struct drm_device *dev = &hv->dev;
+	int ret;
+
+	ret = drmm_mode_config_init(dev);
+	if (ret) {
+		drm_err(dev, "Failed to initialized mode setting.\n");
+		return ret;
+	}
+
+	dev->mode_config.min_width = 0;
+	dev->mode_config.min_height = 0;
+	dev->mode_config.max_width = hv->screen_width_max;
+	dev->mode_config.max_height = hv->screen_height_max;
+
+	dev->mode_config.preferred_depth = hv->screen_depth;
+	dev->mode_config.prefer_shadow = 0;
+
+	dev->mode_config.funcs = &hv_drm_mode_config_funcs;
+
+	ret = hv_drm_pipe_init(hv);
+	if (ret) {
+		drm_err(dev, "Failed to initialized pipe.\n");
+		return ret;
+	}
+
+	ret = drm_vblank_init(dev, 1);
+	if (ret)
+		return ret;
+
+	drm_mode_config_reset(dev);
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_proto.c b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c
new file mode 100644
index 000000000..f0ef627b4
--- /dev/null
+++ b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c
@@ -0,0 +1,604 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2021 Microsoft
+ */
+
+#include <linux/hyperv.h>
+
+#include <drm/drm_print.h>
+#include <drm/drm_simple_kms_helper.h>
+
+#include "hyperv_drm.h"
+
+#define VMBUS_RING_BUFSIZE VMBUS_RING_SIZE(256 * 1024)
+#define VMBUS_VSP_TIMEOUT (10 * HZ)
+
+#define SYNTHVID_VERSION(major, minor) ((minor) << 16 | (major))
+#define SYNTHVID_VER_GET_MAJOR(ver) (ver & 0x0000ffff)
+#define SYNTHVID_VER_GET_MINOR(ver) ((ver & 0xffff0000) >> 16)
+
+/* Support for VERSION_WIN7 is removed. #define is retained for reference. */
+#define SYNTHVID_VERSION_WIN7 SYNTHVID_VERSION(3, 0)
+#define SYNTHVID_VERSION_WIN8 SYNTHVID_VERSION(3, 2)
+#define SYNTHVID_VERSION_WIN10 SYNTHVID_VERSION(3, 5)
+
+#define SYNTHVID_DEPTH_WIN8 32
+#define SYNTHVID_WIDTH_WIN8 1600
+#define SYNTHVID_HEIGHT_WIN8 1200
+#define SYNTHVID_FB_SIZE_WIN8 (8 * 1024 * 1024)
+
+enum pipe_msg_type {
+	PIPE_MSG_INVALID,
+	PIPE_MSG_DATA,
+	PIPE_MSG_MAX
+};
+
+enum synthvid_msg_type {
+	SYNTHVID_ERROR			= 0,
+	SYNTHVID_VERSION_REQUEST	= 1,
+	SYNTHVID_VERSION_RESPONSE	= 2,
+	SYNTHVID_VRAM_LOCATION		= 3,
+	SYNTHVID_VRAM_LOCATION_ACK	= 4,
+	SYNTHVID_SITUATION_UPDATE	= 5,
+	SYNTHVID_SITUATION_UPDATE_ACK	= 6,
+	SYNTHVID_POINTER_POSITION	= 7,
+	SYNTHVID_POINTER_SHAPE		= 8,
+	SYNTHVID_FEATURE_CHANGE		= 9,
+	SYNTHVID_DIRT			= 10,
+	SYNTHVID_RESOLUTION_REQUEST	= 13,
+	SYNTHVID_RESOLUTION_RESPONSE	= 14,
+
+	SYNTHVID_MAX			= 15
+};
+
+struct pipe_msg_hdr {
+	u32 type;
+	u32 size; /* size of message after this field */
+} __packed;
+
+struct hvd_screen_info {
+	u16 width;
+	u16 height;
+} __packed;
+
+struct synthvid_msg_hdr {
+	u32 type;
+	u32 size;  /* size of this header + payload after this field */
+} __packed;
+
+struct synthvid_version_req {
+	u32 version;
+} __packed;
+
+struct synthvid_version_resp {
+	u32 version;
+	u8 is_accepted;
+	u8 max_video_outputs;
+} __packed;
+
+struct synthvid_vram_location {
+	u64 user_ctx;
+	u8 is_vram_gpa_specified;
+	u64 vram_gpa;
+} __packed;
+
+struct synthvid_vram_location_ack {
+	u64 user_ctx;
+} __packed;
+
+struct video_output_situation {
+	u8 active;
+	u32 vram_offset;
+	u8 depth_bits;
+	u32 width_pixels;
+	u32 height_pixels;
+	u32 pitch_bytes;
+} __packed;
+
+struct synthvid_situation_update {
+	u64 user_ctx;
+	u8 video_output_count;
+	struct video_output_situation video_output[1];
+} __packed;
+
+struct synthvid_situation_update_ack {
+	u64 user_ctx;
+} __packed;
+
+struct synthvid_pointer_position {
+	u8 is_visible;
+	u8 video_output;
+	s32 image_x;
+	s32 image_y;
+} __packed;
+
+#define SYNTHVID_CURSOR_MAX_X 96
+#define SYNTHVID_CURSOR_MAX_Y 96
+#define SYNTHVID_CURSOR_ARGB_PIXEL_SIZE 4
+#define SYNTHVID_CURSOR_MAX_SIZE (SYNTHVID_CURSOR_MAX_X * \
+	SYNTHVID_CURSOR_MAX_Y * SYNTHVID_CURSOR_ARGB_PIXEL_SIZE)
+#define SYNTHVID_CURSOR_COMPLETE (-1)
+
+struct synthvid_pointer_shape {
+	u8 part_idx;
+	u8 is_argb;
+	u32 width; /* SYNTHVID_CURSOR_MAX_X at most */
+	u32 height; /* SYNTHVID_CURSOR_MAX_Y at most */
+	u32 hot_x; /* hotspot relative to upper-left of pointer image */
+	u32 hot_y;
+	u8 data[4];
+} __packed;
+
+struct synthvid_feature_change {
+	u8 is_dirt_needed;
+	u8 is_ptr_pos_needed;
+	u8 is_ptr_shape_needed;
+	u8 is_situ_needed;
+} __packed;
+
+struct rect {
+	s32 x1, y1; /* top left corner */
+	s32 x2, y2; /* bottom right corner, exclusive */
+} __packed;
+
+struct synthvid_dirt {
+	u8 video_output;
+	u8 dirt_count;
+	struct rect rect[1];
+} __packed;
+
+#define SYNTHVID_EDID_BLOCK_SIZE	128
+#define	SYNTHVID_MAX_RESOLUTION_COUNT	64
+
+struct synthvid_supported_resolution_req {
+	u8 maximum_resolution_count;
+} __packed;
+
+struct synthvid_supported_resolution_resp {
+	u8 edid_block[SYNTHVID_EDID_BLOCK_SIZE];
+	u8 resolution_count;
+	u8 default_resolution_index;
+	u8 is_standard;
+	struct hvd_screen_info supported_resolution[SYNTHVID_MAX_RESOLUTION_COUNT];
+} __packed;
+
+struct synthvid_msg {
+	struct pipe_msg_hdr pipe_hdr;
+	struct synthvid_msg_hdr vid_hdr;
+	union {
+		struct synthvid_version_req ver_req;
+		struct synthvid_version_resp ver_resp;
+		struct synthvid_vram_location vram;
+		struct synthvid_vram_location_ack vram_ack;
+		struct synthvid_situation_update situ;
+		struct synthvid_situation_update_ack situ_ack;
+		struct synthvid_pointer_position ptr_pos;
+		struct synthvid_pointer_shape ptr_shape;
+		struct synthvid_feature_change feature_chg;
+		struct synthvid_dirt dirt;
+		struct synthvid_supported_resolution_req resolution_req;
+		struct synthvid_supported_resolution_resp resolution_resp;
+	};
+} __packed;
+
+static inline bool hv_drm_version_ge(u32 ver1, u32 ver2)
+{
+	if (SYNTHVID_VER_GET_MAJOR(ver1) > SYNTHVID_VER_GET_MAJOR(ver2) ||
+	    (SYNTHVID_VER_GET_MAJOR(ver1) == SYNTHVID_VER_GET_MAJOR(ver2) &&
+	     SYNTHVID_VER_GET_MINOR(ver1) >= SYNTHVID_VER_GET_MINOR(ver2)))
+		return true;
+
+	return false;
+}
+
+static inline int hv_drm_sendpacket(struct hv_device *hdev, struct synthvid_msg *msg)
+{
+	static atomic64_t request_id = ATOMIC64_INIT(0);
+	struct hv_drm_device *hv = hv_get_drvdata(hdev);
+	int ret;
+
+	msg->pipe_hdr.type = PIPE_MSG_DATA;
+	msg->pipe_hdr.size = msg->vid_hdr.size;
+
+	ret = vmbus_sendpacket(hdev->channel, msg,
+			       msg->vid_hdr.size + sizeof(struct pipe_msg_hdr),
+			       atomic64_inc_return(&request_id),
+			       VM_PKT_DATA_INBAND, 0);
+
+	if (ret)
+		drm_err_ratelimited(&hv->dev, "Unable to send packet via vmbus; error %d\n", ret);
+
+	return ret;
+}
+
+static int hv_drm_negotiate_version(struct hv_device *hdev, u32 ver)
+{
+	struct hv_drm_device *hv = hv_get_drvdata(hdev);
+	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
+	struct drm_device *dev = &hv->dev;
+	unsigned long t;
+
+	memset(msg, 0, sizeof(struct synthvid_msg));
+	msg->vid_hdr.type = SYNTHVID_VERSION_REQUEST;
+	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_version_req);
+	msg->ver_req.version = ver;
+	hv_drm_sendpacket(hdev, msg);
+
+	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
+	if (!t) {
+		drm_err(dev, "Time out on waiting version response\n");
+		return -ETIMEDOUT;
+	}
+
+	if (!msg->ver_resp.is_accepted) {
+		drm_err(dev, "Version request not accepted\n");
+		return -ENODEV;
+	}
+
+	hv->synthvid_version = ver;
+	drm_info(dev, "Synthvid Version major %d, minor %d\n",
+		 SYNTHVID_VER_GET_MAJOR(ver), SYNTHVID_VER_GET_MINOR(ver));
+
+	return 0;
+}
+
+int hv_drm_update_vram_location(struct hv_device *hdev, phys_addr_t vram_pp)
+{
+	struct hv_drm_device *hv = hv_get_drvdata(hdev);
+	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
+	struct drm_device *dev = &hv->dev;
+	unsigned long t;
+
+	memset(msg, 0, sizeof(struct synthvid_msg));
+	msg->vid_hdr.type = SYNTHVID_VRAM_LOCATION;
+	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_vram_location);
+	msg->vram.user_ctx = vram_pp;
+	msg->vram.vram_gpa = vram_pp;
+	msg->vram.is_vram_gpa_specified = 1;
+	hv_drm_sendpacket(hdev, msg);
+
+	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
+	if (!t) {
+		drm_err(dev, "Time out on waiting vram location ack\n");
+		return -ETIMEDOUT;
+	}
+	if (msg->vram_ack.user_ctx != vram_pp) {
+		drm_err(dev, "Unable to set VRAM location\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+int hv_drm_update_situation(struct hv_device *hdev, u8 active, u32 bpp,
+			    u32 w, u32 h, u32 pitch)
+{
+	struct synthvid_msg msg;
+
+	memset(&msg, 0, sizeof(struct synthvid_msg));
+
+	msg.vid_hdr.type = SYNTHVID_SITUATION_UPDATE;
+	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_situation_update);
+	msg.situ.user_ctx = 0;
+	msg.situ.video_output_count = 1;
+	msg.situ.video_output[0].active = active;
+	/* vram_offset should always be 0 */
+	msg.situ.video_output[0].vram_offset = 0;
+	msg.situ.video_output[0].depth_bits = bpp;
+	msg.situ.video_output[0].width_pixels = w;
+	msg.situ.video_output[0].height_pixels = h;
+	msg.situ.video_output[0].pitch_bytes = pitch;
+
+	hv_drm_sendpacket(hdev, &msg);
+
+	return 0;
+}
+
+/*
+ * Hyper-V supports a hardware cursor feature. It's not used by Linux VM,
+ * but the Hyper-V host still draws a point as an extra mouse pointer,
+ * which is unwanted, especially when Xorg is running.
+ *
+ * Hide the unwanted pointer, by setting msg.ptr_pos.is_visible = 1 and setting
+ * the msg.ptr_shape.data. Note: setting msg.ptr_pos.is_visible to 0 doesn't
+ * work in tests.
+ *
+ * The hv_drm_hide_hw_ptr() is also called in the handler of the
+ * SYNTHVID_FEATURE_CHANGE event, otherwise the host still draws an extra
+ * unwanted mouse pointer after the VM Connection window is closed and reopened.
+ */
+int hv_drm_hide_hw_ptr(struct hv_device *hdev)
+{
+	struct synthvid_msg msg;
+
+	memset(&msg, 0, sizeof(struct synthvid_msg));
+	msg.vid_hdr.type = SYNTHVID_POINTER_POSITION;
+	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_pointer_position);
+	msg.ptr_pos.is_visible = 1;
+	msg.ptr_pos.video_output = 0;
+	msg.ptr_pos.image_x = 0;
+	msg.ptr_pos.image_y = 0;
+	hv_drm_sendpacket(hdev, &msg);
+
+	memset(&msg, 0, sizeof(struct synthvid_msg));
+	msg.vid_hdr.type = SYNTHVID_POINTER_SHAPE;
+	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_pointer_shape);
+	msg.ptr_shape.part_idx = SYNTHVID_CURSOR_COMPLETE;
+	msg.ptr_shape.is_argb = 1;
+	msg.ptr_shape.width = 1;
+	msg.ptr_shape.height = 1;
+	msg.ptr_shape.hot_x = 0;
+	msg.ptr_shape.hot_y = 0;
+	msg.ptr_shape.data[0] = 0;
+	msg.ptr_shape.data[1] = 1;
+	msg.ptr_shape.data[2] = 1;
+	msg.ptr_shape.data[3] = 1;
+	hv_drm_sendpacket(hdev, &msg);
+
+	return 0;
+}
+
+int hv_drm_update_dirt(struct hv_device *hdev, struct drm_rect *rect)
+{
+	struct hv_drm_device *hv = hv_get_drvdata(hdev);
+	struct synthvid_msg msg;
+
+	if (!hv->dirt_needed)
+		return 0;
+
+	memset(&msg, 0, sizeof(struct synthvid_msg));
+
+	msg.vid_hdr.type = SYNTHVID_DIRT;
+	msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_dirt);
+	msg.dirt.video_output = 0;
+	msg.dirt.dirt_count = 1;
+	msg.dirt.rect[0].x1 = rect->x1;
+	msg.dirt.rect[0].y1 = rect->y1;
+	msg.dirt.rect[0].x2 = rect->x2;
+	msg.dirt.rect[0].y2 = rect->y2;
+
+	hv_drm_sendpacket(hdev, &msg);
+
+	return 0;
+}
+
+static int hv_drm_get_supported_resolution(struct hv_device *hdev)
+{
+	struct hv_drm_device *hv = hv_get_drvdata(hdev);
+	struct synthvid_msg *msg = (struct synthvid_msg *)hv->init_buf;
+	struct drm_device *dev = &hv->dev;
+	unsigned long t;
+	u8 index;
+	int i;
+
+	memset(msg, 0, sizeof(struct synthvid_msg));
+	msg->vid_hdr.type = SYNTHVID_RESOLUTION_REQUEST;
+	msg->vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
+		sizeof(struct synthvid_supported_resolution_req);
+	msg->resolution_req.maximum_resolution_count =
+		SYNTHVID_MAX_RESOLUTION_COUNT;
+	hv_drm_sendpacket(hdev, msg);
+
+	t = wait_for_completion_timeout(&hv->wait, VMBUS_VSP_TIMEOUT);
+	if (!t) {
+		drm_err(dev, "Time out on waiting resolution response\n");
+		return -ETIMEDOUT;
+	}
+
+	if (msg->resolution_resp.resolution_count == 0 ||
+	    msg->resolution_resp.resolution_count >
+	    SYNTHVID_MAX_RESOLUTION_COUNT) {
+		drm_err(dev, "Invalid resolution count: %d\n",
+			msg->resolution_resp.resolution_count);
+		return -ENODEV;
+	}
+
+	index = msg->resolution_resp.default_resolution_index;
+	if (index >= msg->resolution_resp.resolution_count) {
+		drm_err(dev, "Invalid resolution index: %d\n", index);
+		return -ENODEV;
+	}
+
+	for (i = 0; i < msg->resolution_resp.resolution_count; i++) {
+		hv->screen_width_max = max_t(u32, hv->screen_width_max,
+			msg->resolution_resp.supported_resolution[i].width);
+		hv->screen_height_max = max_t(u32, hv->screen_height_max,
+			msg->resolution_resp.supported_resolution[i].height);
+	}
+
+	hv->preferred_width =
+		msg->resolution_resp.supported_resolution[index].width;
+	hv->preferred_height =
+		msg->resolution_resp.supported_resolution[index].height;
+
+	return 0;
+}
+
+static void hv_drm_receive_sub(struct hv_device *hdev, u32 bytes_recvd)
+{
+	struct hv_drm_device *hv = hv_get_drvdata(hdev);
+	struct synthvid_msg *msg;
+	size_t hdr_size;
+	size_t need;
+
+	if (!hv)
+		return;
+
+	hdr_size = sizeof(struct pipe_msg_hdr) +
+		   sizeof(struct synthvid_msg_hdr);
+	if (bytes_recvd < hdr_size) {
+		drm_err_ratelimited(&hv->dev,
+				    "synthvid packet too small for header: %u\n",
+				    bytes_recvd);
+		return;
+	}
+
+	msg = (struct synthvid_msg *)hv->recv_buf;
+	need = hdr_size;
+
+	switch (msg->vid_hdr.type) {
+	case SYNTHVID_VERSION_RESPONSE:
+		need += sizeof(struct synthvid_version_resp);
+		break;
+	case SYNTHVID_RESOLUTION_RESPONSE:
+		/*
+		 * The resolution response is variable length: the host
+		 * fills resolution_count entries, not the full
+		 * SYNTHVID_MAX_RESOLUTION_COUNT array. Require the fixed
+		 * prefix first so resolution_count can be read, then
+		 * demand exactly the count-sized array.
+		 */
+		need += offsetof(struct synthvid_supported_resolution_resp,
+				 supported_resolution);
+		if (bytes_recvd < need)
+			break;
+		if (msg->resolution_resp.resolution_count >
+		    SYNTHVID_MAX_RESOLUTION_COUNT) {
+			drm_err_ratelimited(&hv->dev,
+					    "synthvid resolution count too large: %u\n",
+					    msg->resolution_resp.resolution_count);
+			return;
+		}
+		need += msg->resolution_resp.resolution_count *
+			sizeof(struct hvd_screen_info);
+		break;
+	case SYNTHVID_VRAM_LOCATION_ACK:
+		need += sizeof(struct synthvid_vram_location_ack);
+		break;
+	case SYNTHVID_FEATURE_CHANGE:
+		/*
+		 * Not a completion-driving message: validate its own payload
+		 * and consume it here rather than falling through to the
+		 * memcpy/complete shared by the wait-event responses.
+		 */
+		if (bytes_recvd < need +
+		    sizeof(struct synthvid_feature_change)) {
+			drm_err_ratelimited(&hv->dev,
+					    "synthvid feature change packet too small: %u\n",
+					    bytes_recvd);
+			return;
+		}
+		hv->dirt_needed = msg->feature_chg.is_dirt_needed;
+		if (hv->dirt_needed)
+			hv_drm_hide_hw_ptr(hv->hdev);
+		return;
+	default:
+		return;
+	}
+
+	/*
+	 * Shared completion path for the wait-event responses
+	 * (VERSION_RESPONSE, RESOLUTION_RESPONSE, VRAM_LOCATION_ACK):
+	 * require the type-specific payload before handing the buffer to
+	 * the waiter.
+	 */
+	if (bytes_recvd < need) {
+		drm_err_ratelimited(&hv->dev,
+				    "synthvid packet too small for type %u: %u < %zu\n",
+				    msg->vid_hdr.type, bytes_recvd, need);
+		return;
+	}
+	memcpy(hv->init_buf, msg, bytes_recvd);
+	complete(&hv->wait);
+}
+
+static void hv_drm_receive(void *ctx)
+{
+	struct hv_device *hdev = ctx;
+	struct hv_drm_device *hv = hv_get_drvdata(hdev);
+	struct synthvid_msg *recv_buf;
+	u32 bytes_recvd;
+	u64 req_id;
+	int ret;
+
+	if (!hv)
+		return;
+
+	recv_buf = (struct synthvid_msg *)hv->recv_buf;
+
+	do {
+		ret = vmbus_recvpacket(hdev->channel, recv_buf,
+				       VMBUS_MAX_PACKET_SIZE,
+				       &bytes_recvd, &req_id);
+		if (ret) {
+			/*
+			 * A nonzero return (e.g. -ENOBUFS for an oversized
+			 * packet) is itself a malformed message: bytes_recvd
+			 * then reports the required length rather than a copied
+			 * payload, so it must not be forwarded to the
+			 * sub-handler. Channel recovery is not attempted.
+			 */
+			drm_err_ratelimited(&hv->dev,
+					    "vmbus_recvpacket failed: %d (need %u)\n",
+					    ret, bytes_recvd);
+		} else if (bytes_recvd > 0 &&
+			   recv_buf->pipe_hdr.type == PIPE_MSG_DATA) {
+			hv_drm_receive_sub(hdev, bytes_recvd);
+		}
+	} while (bytes_recvd > 0 && ret == 0);
+}
+
+int hv_drm_connect_vsp(struct hv_device *hdev)
+{
+	struct hv_drm_device *hv = hv_get_drvdata(hdev);
+	struct drm_device *dev = &hv->dev;
+	int ret;
+
+	ret = vmbus_open(hdev->channel, VMBUS_RING_BUFSIZE, VMBUS_RING_BUFSIZE,
+			 NULL, 0, hv_drm_receive, hdev);
+	if (ret) {
+		drm_err(dev, "Unable to open vmbus channel\n");
+		return ret;
+	}
+
+	/* Negotiate the protocol version with host */
+	switch (vmbus_proto_version) {
+	case VERSION_WIN10:
+	case VERSION_WIN10_V5:
+		ret = hv_drm_negotiate_version(hdev, SYNTHVID_VERSION_WIN10);
+		if (!ret)
+			break;
+		fallthrough;
+	case VERSION_WIN8:
+	case VERSION_WIN8_1:
+		ret = hv_drm_negotiate_version(hdev, SYNTHVID_VERSION_WIN8);
+		break;
+	default:
+		ret = hv_drm_negotiate_version(hdev, SYNTHVID_VERSION_WIN10);
+		break;
+	}
+
+	if (ret) {
+		drm_err(dev, "Synthetic video device version not accepted %d\n", ret);
+		goto error;
+	}
+
+	hv->screen_depth = SYNTHVID_DEPTH_WIN8;
+
+	if (hv_drm_version_ge(hv->synthvid_version, SYNTHVID_VERSION_WIN10)) {
+		ret = hv_drm_get_supported_resolution(hdev);
+		if (ret)
+			drm_err(dev, "Failed to get supported resolution from host, use default\n");
+	}
+
+	if (!hv->screen_width_max) {
+		hv->screen_width_max = SYNTHVID_WIDTH_WIN8;
+		hv->screen_height_max = SYNTHVID_HEIGHT_WIN8;
+		hv->preferred_width = SYNTHVID_WIDTH_WIN8;
+		hv->preferred_height = SYNTHVID_HEIGHT_WIN8;
+	}
+
+	hv->mmio_megabytes = hdev->channel->offermsg.offer.mmio_megabytes;
+
+	return 0;
+
+error:
+	vmbus_close(hdev->channel);
+	return ret;
+}