Re: [PATCH v2 5/6] drm/vkms: Support enabling ConfigFS devices

From: Marius Vlad
Date: Tue Aug 15 2023 - 10:03:14 EST


Hi,

See below some minor comments:

On Fri, Jun 23, 2023 at 06:23:47PM -0400, Jim Shargo wrote:
> VKMS now supports creating and using virtual devices!
>
> In addition to the enabling logic, this commit also prevents users from
> adding new objects once a card is registered.
>
> Signed-off-by: Jim Shargo <jshargo@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/vkms/vkms_configfs.c | 37 +++--
> drivers/gpu/drm/vkms/vkms_crtc.c | 4 +-
> drivers/gpu/drm/vkms/vkms_drv.c | 3 +-
> drivers/gpu/drm/vkms/vkms_drv.h | 2 +-
> drivers/gpu/drm/vkms/vkms_output.c | 201 +++++++++++++++++++++++----
> 5 files changed, 202 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
> index 544024735d19..f5eed6d23dcd 100644
> --- a/drivers/gpu/drm/vkms/vkms_configfs.c
> +++ b/drivers/gpu/drm/vkms/vkms_configfs.c
> @@ -504,29 +504,40 @@ static ssize_t device_enabled_store(struct config_item *item, const char *buf,
> {
> struct vkms_configfs *configfs = item_to_configfs(item);
> struct vkms_device *device;
> - int value, ret;
> + int enabled, ret;
>
> - ret = kstrtoint(buf, 0, &value);
> + ret = kstrtoint(buf, 0, &enabled);
> if (ret)
> return ret;
>
> - if (value != 1)
> - return -EINVAL;
> -
> - mutex_lock(&configfs->lock);
> -
> - if (configfs->vkms_device) {
> + if (enabled == 0) {
> + mutex_lock(&configfs->lock);
> + if (configfs->vkms_device) {
> + vkms_remove_device(configfs->vkms_device);
> + configfs->vkms_device = NULL;
> + }
> mutex_unlock(&configfs->lock);
> +
> return len;
> }
>
> - device = vkms_add_device(configfs);
> - mutex_unlock(&configfs->lock);
> + if (enabled == 1) {
> + mutex_lock(&configfs->lock);
> + if (!configfs->vkms_device) {
> + device = vkms_add_device(configfs);
> + if (IS_ERR(device)) {
> + mutex_unlock(&configfs->lock);
> + return -PTR_ERR(device);
> + }
> +
> + configfs->vkms_device = device;
> + }
> + mutex_unlock(&configfs->lock);
>
> - if (IS_ERR(device))
> - return -PTR_ERR(device);
> + return len;
> + }
>
> - return len;
> + return -EINVAL;
> }
>
> CONFIGFS_ATTR(device_, enabled);
> diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
> index d91e49c53adc..5ebb5264f6ef 100644
> --- a/drivers/gpu/drm/vkms/vkms_crtc.c
> +++ b/drivers/gpu/drm/vkms/vkms_crtc.c
> @@ -278,7 +278,7 @@ static const struct drm_crtc_helper_funcs vkms_crtc_helper_funcs = {
>
> struct vkms_crtc *vkms_crtc_init(struct vkms_device *vkmsdev,
> struct drm_plane *primary,
> - struct drm_plane *cursor)
> + struct drm_plane *cursor, const char *name)
> {
> struct drm_device *dev = &vkmsdev->drm;
> struct vkms_crtc *vkms_crtc;
> @@ -290,7 +290,7 @@ struct vkms_crtc *vkms_crtc_init(struct vkms_device *vkmsdev,
> vkms_crtc = &vkmsdev->output.crtcs[vkmsdev->output.num_crtcs++];
>
> ret = drmm_crtc_init_with_planes(dev, &vkms_crtc->base, primary, cursor,
> - &vkms_crtc_funcs, NULL);
> + &vkms_crtc_funcs, name);
> if (ret) {
> DRM_ERROR("Failed to init CRTC\n");
> goto out_error;
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
> index 1b5b7143792f..314a04659c5f 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.c
> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> @@ -210,7 +210,7 @@ static int vkms_platform_probe(struct platform_device *pdev)
> ret = drm_dev_register(&vkms_device->drm, 0);
> if (ret) {
> DRM_ERROR("Unable to register device with id %d\n", pdev->id);
> - return ret;
> + goto out_release_group;
> }
>
> drm_fbdev_generic_setup(&vkms_device->drm, 0);
> @@ -256,6 +256,7 @@ struct vkms_device *vkms_add_device(struct vkms_configfs *configfs)
> dev, &vkms_platform_driver.driver))) {
> pdev = to_platform_device(dev);
> max_id = max(max_id, pdev->id);
> + put_device(dev);
> }
>
> pdev = platform_device_register_data(NULL, DRIVER_NAME, max_id + 1,
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index 3634eeeb4548..3d592d085f49 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -239,7 +239,7 @@ void vkms_remove_device(struct vkms_device *vkms_device);
> /* CRTC */
> struct vkms_crtc *vkms_crtc_init(struct vkms_device *vkmsdev,
> struct drm_plane *primary,
> - struct drm_plane *cursor);
> + struct drm_plane *cursor, const char *name);
>
> int vkms_output_init(struct vkms_device *vkmsdev);
> int vkms_output_init_default(struct vkms_device *vkmsdev);
> diff --git a/drivers/gpu/drm/vkms/vkms_output.c b/drivers/gpu/drm/vkms/vkms_output.c
> index c9e6c653de19..806ff01954ad 100644
> --- a/drivers/gpu/drm/vkms/vkms_output.c
> +++ b/drivers/gpu/drm/vkms/vkms_output.c
> @@ -2,8 +2,10 @@
>
> #include <drm/drm_atomic_helper.h>
> #include <drm/drm_connector.h>
> +#include <drm/drm_crtc.h>
> #include <drm/drm_edid.h>
> #include <drm/drm_encoder.h>
> +#include <drm/drm_plane.h>
> #include <drm/drm_probe_helper.h>
> #include <drm/drm_simple_kms_helper.h>
>
> @@ -82,7 +84,6 @@ static struct drm_encoder *vkms_encoder_init(struct vkms_device *vkms_device)
>
> int vkms_output_init_default(struct vkms_device *vkmsdev)
> {
> - struct vkms_output *output = &vkmsdev->output;
> struct drm_device *dev = &vkmsdev->drm;
> struct drm_connector *connector;
> struct drm_encoder *encoder;
> @@ -101,8 +102,7 @@ int vkms_output_init_default(struct vkms_device *vkmsdev)
> struct vkms_plane *overlay = vkms_plane_init(
> vkmsdev, DRM_PLANE_TYPE_OVERLAY);
> if (IS_ERR(overlay)) {
> - ret = PTR_ERR(overlay);
> - goto err_planes;
> + return PTR_ERR(overlay);
> }
> }
> }
> @@ -110,17 +110,16 @@ int vkms_output_init_default(struct vkms_device *vkmsdev)
> if (vkmsdev->config.cursor) {
> cursor = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_CURSOR);
> if (IS_ERR(cursor)) {
> - ret = PTR_ERR(cursor);
> - goto err_planes;
> + return PTR_ERR(cursor);
> }
> }
>
> vkms_crtc = vkms_crtc_init(vkmsdev, &primary->base,
> - cursor ? &cursor->base : NULL);
> + cursor ? &cursor->base : NULL,
> + "crtc-default");
> if (IS_ERR(vkms_crtc)) {
> DRM_ERROR("Failed to init crtc\n");
> - ret = PTR_ERR(vkms_crtc);
> - goto err_planes;
> + return PTR_ERR(vkms_crtc);
> }
>
> for (int i = 0; i < vkmsdev->output.num_planes; i++) {
> @@ -131,22 +130,20 @@ int vkms_output_init_default(struct vkms_device *vkmsdev)
> connector = vkms_connector_init(vkmsdev);
> if (IS_ERR(connector)) {
> DRM_ERROR("Failed to init connector\n");
> - ret = PTR_ERR(connector);
> - goto err_connector;
> + return PTR_ERR(connector);
> }
>
> encoder = vkms_encoder_init(vkmsdev);
> if (IS_ERR(encoder)) {
> DRM_ERROR("Failed to init encoder\n");
> - ret = PTR_ERR(encoder);
> - goto err_encoder;
> + return PTR_ERR(encoder);
> }
> encoder->possible_crtcs |= drm_crtc_mask(&vkms_crtc->base);
>
> ret = drm_connector_attach_encoder(connector, encoder);
> if (ret) {
> DRM_ERROR("Failed to attach connector to encoder\n");
> - goto err_attach;
> + return ret;
> }
>
> if (vkmsdev->config.writeback) {
> @@ -158,27 +155,175 @@ int vkms_output_init_default(struct vkms_device *vkmsdev)
> drm_mode_config_reset(dev);
>
> return 0;
> +}
>
> -err_attach:
> - drm_encoder_cleanup(encoder);
> +static bool is_object_linked(struct vkms_config_links *links, unsigned long idx)
> +{
> + return links->linked_object_bitmap & (1 << idx);
> +}
>
> -err_encoder:
> - drm_connector_cleanup(connector);
> +int vkms_output_init(struct vkms_device *vkmsdev)
> +{
> + struct drm_device *dev = &vkmsdev->drm;
> + struct vkms_configfs *configfs = vkmsdev->configfs;
> + struct vkms_output *output = &vkmsdev->output;
> + struct plane_map {
> + struct vkms_config_plane *config_plane;
> + struct vkms_plane *plane;
> + } plane_map[VKMS_MAX_PLANES] = { 0 };
> + struct encoder_map {
> + struct vkms_config_encoder *config_encoder;
> + struct drm_encoder *encoder;
> + } encoder_map[VKMS_MAX_OUTPUT_OBJECTS] = { 0 };
> + struct config_item *item;
> + int map_idx = 0;
> +
> + list_for_each_entry(item, &configfs->planes_group.cg_children,
> + ci_entry) {
> + struct vkms_config_plane *config_plane =
> + item_to_config_plane(item);
> + struct vkms_plane *plane =
> + vkms_plane_init(vkmsdev, config_plane->type);
> +
> + if (IS_ERR(plane)) {
> + DRM_ERROR("Unable to init plane from config: %s",
> + item->ci_name);
> + return PTR_ERR(plane);
> + }
>
> -err_connector:
> - drm_crtc_cleanup(&vkms_crtc->base);
> + plane_map[map_idx].config_plane = config_plane;
> + plane_map[map_idx].plane = plane;
> + map_idx += 1;
> + }
>
> -err_planes:
> - for (int i = 0; i < output->num_planes; i++) {
> - drm_plane_cleanup(&output->planes[i].base);
> + map_idx = 0;
> + list_for_each_entry(item, &configfs->encoders_group.cg_children,
> + ci_entry) {
> + struct vkms_config_encoder *config_encoder =
> + item_to_config_encoder(item);
> + struct drm_encoder *encoder = vkms_encoder_init(vkmsdev);
> +
> + if (IS_ERR(encoder)) {
> + DRM_ERROR("Failed to init config encoder: %s",
> + item->ci_name);
> + return PTR_ERR(encoder);
> + }
> + encoder_map[map_idx].config_encoder = config_encoder;
A two connector configuration without an encoder would have the
potential of blowing up if we don't create a second_encoder.
> + encoder_map[map_idx].encoder = encoder;
> + map_idx += 1;
> }
>
> - memset(output, 0, sizeof(*output));
> + list_for_each_entry(item, &configfs->connectors_group.cg_children,
> + ci_entry) {
> + struct vkms_config_connector *config_connector =
> + item_to_config_connector(item);
> + struct drm_connector *connector = vkms_connector_init(vkmsdev);
>
> - return ret;
> -}
> + if (IS_ERR(connector)) {
> + DRM_ERROR("Failed to init connector from config: %s",
> + item->ci_name);
> + return PTR_ERR(connector);
> + }
>
> -int vkms_output_init(struct vkms_device *vkmsdev)
> -{
> - return -ENOTSUPP;
> + for (int j = 0; j < output->num_connectors; j++) {
> + struct encoder_map *encoder = &encoder_map[j];
> +
> + if (is_object_linked(
> + &config_connector->possible_encoders,
> + encoder->config_encoder
> + ->encoder_config_idx)) {
Here encoder->config_encoder for two connectors but a single encoder
will give back a empty encoder.
> + drm_connector_attach_encoder(connector,
> + encoder->encoder);
> + }
> + }
> + }
> +
> + list_for_each_entry(item, &configfs->crtcs_group.cg_children,
> + ci_entry) {
> + struct vkms_config_crtc *config_crtc =
> + item_to_config_crtc(item);
> + struct vkms_crtc *vkms_crtc;
> + struct drm_plane *primary = NULL, *cursor = NULL;
> +
> + for (int j = 0; j < output->num_planes; j++) {
> + struct plane_map *plane_entry = &plane_map[j];
> + struct drm_plane *plane = &plane_entry->plane->base;
> +
> + if (!is_object_linked(
> + &plane_entry->config_plane->possible_crtcs,
> + config_crtc->crtc_config_idx)) {
> + continue;
> + }
> +
> + if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
> + if (primary) {
> + DRM_WARN(
> + "Too many primary planes found for crtc %s.",
> + item->ci_name);
> + return EINVAL;
> + }
> + primary = plane;
> + } else if (plane->type == DRM_PLANE_TYPE_CURSOR) {
> + if (cursor) {
> + DRM_WARN(
> + "Too many cursor planes found for crtc %s.",
> + item->ci_name);
> + return EINVAL;
> + }
> + cursor = plane;
> + }
> + }
> +
> + if (!primary) {
> + DRM_WARN("No primary plane configured for crtc %s",
> + item->ci_name);
> + return EINVAL;
> + }
> +
> + vkms_crtc =
> + vkms_crtc_init(vkmsdev, primary, cursor, item->ci_name);
> + if (IS_ERR(vkms_crtc)) {
> + DRM_WARN("Unable to init crtc from config: %s",
> + item->ci_name);
> + return PTR_ERR(vkms_crtc);
> + }
> +
> + for (int j = 0; j < output->num_planes; j++) {
> + struct plane_map *plane_entry = &plane_map[j];
> +
> + if (!plane_entry->plane)
> + break;
> +
> + if (is_object_linked(
> + &plane_entry->config_plane->possible_crtcs,
> + config_crtc->crtc_config_idx)) {
> + plane_entry->plane->base.possible_crtcs |=
> + drm_crtc_mask(&vkms_crtc->base);
> + }
> + }
> +
> + for (int j = 0; j < output->num_encoders; j++) {
> + struct encoder_map *encoder_entry = &encoder_map[j];
> +
> + if (is_object_linked(&encoder_entry->config_encoder
> + ->possible_crtcs,
> + config_crtc->crtc_config_idx)) {
> + encoder_entry->encoder->possible_crtcs |=
> + drm_crtc_mask(&vkms_crtc->base);
> + }
> + }
> +
> + if (vkmsdev->config.writeback) {
> + int ret = vkms_enable_writeback_connector(vkmsdev,
> + vkms_crtc);
> + if (ret)
> + DRM_WARN(
> + "Failed to init writeback connector for config crtc: %s. Error code %d",
> + item->ci_name, ret);
> + }
> + }
I think we might be needing here a test for missing symlinks - invalid
configurations, like unused crtcs, encoders, connectors. I
suppose anything that's not matched with is_object_linked(),
such we avoid invalid configuration found by drm_mode_config_validate()
and inform users about missing them.

An example here would be to create a second encoder, connector, crtc and
not symlink them to their possible_encoders,possible_crtcs mask. An
i-g-t test for this very thing would be needed to stress different kind
of combinations.

> +
> + drm_mode_config_reset(dev);
> +
> + return 0;
> }
> --
> 2.41.0.162.gfafddb0af9-goog
>

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