Files
linux/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
Michael Kelley 8b35874f56 drm/hyperv: During panic do VMBus unload after frame buffer is flushed
In a VM, Linux panic information (reason for the panic, stack trace,
etc.) may be written to a serial console and/or a virtual frame buffer
for a graphics console. The latter may need to be flushed back to the
host hypervisor for display.

The current Hyper-V DRM driver for the frame buffer does the flushing
*after* the VMBus connection has been unloaded, such that panic messages
are not displayed on the graphics console. A user with a Hyper-V graphics
console is left with just a hung empty screen after a panic. The enhanced
control that DRM provides over the panic display in the graphics console
is similarly non-functional.

Commit 3671f37777 ("drm/hyperv: Add support for drm_panic") added
the Hyper-V DRM driver support to flush the virtual frame buffer. It
provided necessary functionality but did not handle the sequencing
problem with VMBus unload.

Fix the full problem by using VMBus functions to suppress the VMBus
unload that is normally done by the VMBus driver in the panic path. Then
after the frame buffer has been flushed, do the VMBus unload so that a
kdump kernel can start cleanly. As expected, CONFIG_DRM_PANIC must be
selected for these changes to have effect. As a side benefit, the
enhanced features of the DRM panic path are also functional.

Fixes: 3671f37777 ("drm/hyperv: Add support for drm_panic")
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
2026-05-13 22:31:01 +00:00

341 lines
9.3 KiB
C

// 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 hyperv_blit_to_vram_rect(struct drm_framebuffer *fb,
const struct iosys_map *vmap,
struct drm_rect *rect)
{
struct hyperv_drm_device *hv = to_hv(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 hyperv_connector_get_modes(struct drm_connector *connector)
{
struct hyperv_drm_device *hv = to_hv(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 hyperv_connector_helper_funcs = {
.get_modes = hyperv_connector_get_modes,
};
static const struct drm_connector_funcs hyperv_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 hyperv_conn_init(struct hyperv_drm_device *hv)
{
drm_connector_helper_add(&hv->connector, &hyperv_connector_helper_funcs);
return drm_connector_init(&hv->dev, &hv->connector,
&hyperv_connector_funcs,
DRM_MODE_CONNECTOR_VIRTUAL);
}
static int hyperv_check_size(struct hyperv_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 hyperv_formats[] = {
DRM_FORMAT_XRGB8888,
};
static const uint64_t hyperv_modifiers[] = {
DRM_FORMAT_MOD_LINEAR,
DRM_FORMAT_MOD_INVALID
};
static void hyperv_crtc_helper_atomic_enable(struct drm_crtc *crtc,
struct drm_atomic_state *state)
{
struct hyperv_drm_device *hv = to_hv(crtc->dev);
struct drm_plane *plane = &hv->plane;
struct drm_plane_state *plane_state = plane->state;
struct drm_crtc_state *crtc_state = crtc->state;
hyperv_hide_hw_ptr(hv->hdev);
hyperv_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 hyperv_crtc_helper_funcs = {
.atomic_check = drm_crtc_helper_atomic_check,
.atomic_flush = drm_crtc_vblank_atomic_flush,
.atomic_enable = hyperv_crtc_helper_atomic_enable,
.atomic_disable = drm_crtc_vblank_atomic_disable,
};
static const struct drm_crtc_funcs hyperv_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 hyperv_plane_atomic_check(struct drm_plane *plane,
struct drm_atomic_state *state)
{
struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
struct hyperv_drm_device *hv = to_hv(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 hyperv_plane_atomic_update(struct drm_plane *plane,
struct drm_atomic_state *state)
{
struct hyperv_drm_device *hv = to_hv(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;
hyperv_blit_to_vram_rect(new_state->fb, &shadow_plane_state->data[0], &damage);
hyperv_update_dirt(hv->hdev, &damage);
}
}
static int hyperv_plane_get_scanout_buffer(struct drm_plane *plane,
struct drm_scanout_buffer *sb)
{
struct hyperv_drm_device *hv = to_hv(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 hyperv_plane_panic_flush(struct drm_plane *plane)
{
struct hyperv_drm_device *hv = to_hv(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;
hyperv_update_dirt(hv->hdev, &rect);
}
vmbus_initiate_unload(true);
}
static const struct drm_plane_helper_funcs hyperv_plane_helper_funcs = {
DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
.atomic_check = hyperv_plane_atomic_check,
.atomic_update = hyperv_plane_atomic_update,
.get_scanout_buffer = hyperv_plane_get_scanout_buffer,
.panic_flush = hyperv_plane_panic_flush,
};
static const struct drm_plane_funcs hyperv_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 hyperv_drm_simple_encoder_funcs_cleanup = {
.destroy = drm_encoder_cleanup,
};
static inline int hyperv_pipe_init(struct hyperv_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,
&hyperv_plane_funcs,
hyperv_formats, ARRAY_SIZE(hyperv_formats),
hyperv_modifiers,
DRM_PLANE_TYPE_PRIMARY, NULL);
if (ret)
return ret;
drm_plane_helper_add(plane, &hyperv_plane_helper_funcs);
drm_plane_enable_fb_damage_clips(plane);
ret = drm_crtc_init_with_planes(dev, crtc, plane, NULL,
&hyperv_crtc_funcs, NULL);
if (ret)
return ret;
drm_crtc_helper_add(crtc, &hyperv_crtc_helper_funcs);
encoder->possible_crtcs = drm_crtc_mask(crtc);
ret = drm_encoder_init(dev, encoder,
&hyperv_drm_simple_encoder_funcs_cleanup,
DRM_MODE_ENCODER_NONE, NULL);
if (ret)
return ret;
ret = hyperv_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
hyperv_mode_valid(struct drm_device *dev,
const struct drm_display_mode *mode)
{
struct hyperv_drm_device *hv = to_hv(dev);
if (hyperv_check_size(hv, mode->hdisplay, mode->vdisplay, NULL))
return MODE_BAD;
return MODE_OK;
}
static const struct drm_mode_config_funcs hyperv_mode_config_funcs = {
.fb_create = drm_gem_fb_create_with_dirty,
.mode_valid = hyperv_mode_valid,
.atomic_check = drm_atomic_helper_check,
.atomic_commit = drm_atomic_helper_commit,
};
int hyperv_mode_config_init(struct hyperv_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 = &hyperv_mode_config_funcs;
ret = hyperv_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;
}