Re: [Intel-gfx] [PATCH v2 1/5] drm/hdcp: optimizing the srm handling

Sean Paul
2020-02-18T15:43:29Z

On Wed, Feb 12, 2020 at 03:59:38PM +0530, Ramalingam C wrote:
> As we are not using the sysfs infrastructure anymore, link to it is
> removed. And global srm data and mutex to protect it are removed,
> with required handling at revocation check function.
>
> v2:
> srm_data is dropped and few more comments are addressed.
> v3:
> ptr passing around is fixed with functional testing.
> v4:
> fix htmldoc [lkp]
>
> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>

I think we could probably improve things even further, but this is a good start.
Thanks for doing this!

Reviewed-by: Sean Paul <sean@poorly.run>

> Suggested-by: Sean Paul <seanpaul@chromium.org>
> ---
> drivers/gpu/drm/drm_hdcp.c | 158 ++++++++++++---------------------
> drivers/gpu/drm/drm_internal.h | 4 -
> drivers/gpu/drm/drm_sysfs.c | 2 -
> include/drm/drm_hdcp.h | 4 +-
> 4 files changed, 61 insertions(+), 107 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_hdcp.c b/drivers/gpu/drm/drm_hdcp.c
> index 9191633a3c43..7f386adcf872 100644
> --- a/drivers/gpu/drm/drm_hdcp.c
> +++ b/drivers/gpu/drm/drm_hdcp.c
> @@ -23,14 +23,6 @@
>
> #include "drm_internal.h"
>
> -static struct hdcp_srm {
> - u32 revoked_ksv_cnt;
> - u8 *revoked_ksv_list;
> -
> - /* Mutex to protect above struct member */
> - struct mutex mutex;
> -} *srm_data;
> -
> static inline void drm_hdcp_print_ksv(const u8 *ksv)
> {
> DRM_DEBUG("\t%#02x, %#02x, %#02x, %#02x, %#02x\n",
> @@ -60,11 +52,11 @@ static u32 drm_hdcp_get_revoked_ksv_count(const u8 *buf, u32 vrls_length)
> return ksv_count;
> }
>
> -static u32 drm_hdcp_get_revoked_ksvs(const u8 *buf, u8 *revoked_ksv_list,
> +static u32 drm_hdcp_get_revoked_ksvs(const u8 *buf, u8 **revoked_ksv_list,
> u32 vrls_length)
> {
> - u32 parsed_bytes = 0, ksv_count = 0;
> u32 vrl_ksv_cnt, vrl_ksv_sz, vrl_idx = 0;
> + u32 parsed_bytes = 0, ksv_count = 0;
>
> do {
> vrl_ksv_cnt = *buf;
> @@ -74,10 +66,10 @@ static u32 drm_hdcp_get_revoked_ksvs(const u8 *buf, u8 *revoked_ksv_list,
>
> DRM_DEBUG("vrl: %d, Revoked KSVs: %d\n", vrl_idx++,
> vrl_ksv_cnt);
> - memcpy(revoked_ksv_list, buf, vrl_ksv_sz);
> + memcpy((*revoked_ksv_list) + (ksv_count * DRM_HDCP_KSV_LEN),
> + buf, vrl_ksv_sz);
>
> ksv_count += vrl_ksv_cnt;
> - revoked_ksv_list += vrl_ksv_sz;
> buf += vrl_ksv_sz;
>
> parsed_bytes += (vrl_ksv_sz + 1);
> @@ -91,7 +83,8 @@ static inline u32 get_vrl_length(const u8 *buf)
> return drm_hdcp_be24_to_cpu(buf);
> }
>
> -static int drm_hdcp_parse_hdcp1_srm(const u8 *buf, size_t count)
> +static int drm_hdcp_parse_hdcp1_srm(const u8 *buf, size_t count,
> + u8 **revoked_ksv_list, u32 *revoked_ksv_cnt)
> {
> struct hdcp_srm_header *header;
> u32 vrl_length, ksv_count;
> @@ -131,29 +124,28 @@ static int drm_hdcp_parse_hdcp1_srm(const u8 *buf, size_t count)
> ksv_count = drm_hdcp_get_revoked_ksv_count(buf, vrl_length);
> if (!ksv_count) {
> DRM_DEBUG("Revoked KSV count is 0\n");
> - return count;
> + return 0;
> }
>
> - kfree(srm_data->revoked_ksv_list);
> - srm_data->revoked_ksv_list = kcalloc(ksv_count, DRM_HDCP_KSV_LEN,
> - GFP_KERNEL);
> - if (!srm_data->revoked_ksv_list) {
> + *revoked_ksv_list = kcalloc(ksv_count, DRM_HDCP_KSV_LEN, GFP_KERNEL);
> + if (!*revoked_ksv_list) {
> DRM_ERROR("Out of Memory\n");
> return -ENOMEM;
> }
>
> - if (drm_hdcp_get_revoked_ksvs(buf, srm_data->revoked_ksv_list,
> + if (drm_hdcp_get_revoked_ksvs(buf, revoked_ksv_list,
> vrl_length) != ksv_count) {
> - srm_data->revoked_ksv_cnt = 0;
> - kfree(srm_data->revoked_ksv_list);
> + *revoked_ksv_cnt = 0;
> + kfree(*revoked_ksv_list);
> return -EINVAL;
> }
>
> - srm_data->revoked_ksv_cnt = ksv_count;
> - return count;
> + *revoked_ksv_cnt = ksv_count;
> + return 0;
> }
>
> -static int drm_hdcp_parse_hdcp2_srm(const u8 *buf, size_t count)
> +static int drm_hdcp_parse_hdcp2_srm(const u8 *buf, size_t count,
> + u8 **revoked_ksv_list, u32 *revoked_ksv_cnt)
> {
> struct hdcp_srm_header *header;
> u32 vrl_length, ksv_count, ksv_sz;
> @@ -195,13 +187,11 @@ static int drm_hdcp_parse_hdcp2_srm(const u8 *buf, size_t count)
> ksv_count = (*buf << 2) | DRM_HDCP_2_KSV_COUNT_2_LSBITS(*(buf + 1));
> if (!ksv_count) {
> DRM_DEBUG("Revoked KSV count is 0\n");
> - return count;
> + return 0;
> }
>
> - kfree(srm_data->revoked_ksv_list);
> - srm_data->revoked_ksv_list = kcalloc(ksv_count, DRM_HDCP_KSV_LEN,
> - GFP_KERNEL);
> - if (!srm_data->revoked_ksv_list) {
> + *revoked_ksv_list = kcalloc(ksv_count, DRM_HDCP_KSV_LEN, GFP_KERNEL);
> + if (!*revoked_ksv_list) {
> DRM_ERROR("Out of Memory\n");
> return -ENOMEM;
> }
> @@ -210,10 +200,10 @@ static int drm_hdcp_parse_hdcp2_srm(const u8 *buf, size_t count)
> buf += DRM_HDCP_2_NO_OF_DEV_PLUS_RESERVED_SZ;
>
> DRM_DEBUG("Revoked KSVs: %d\n", ksv_count);
> - memcpy(srm_data->revoked_ksv_list, buf, ksv_sz);
> + memcpy(*revoked_ksv_list, buf, ksv_sz);
>
> - srm_data->revoked_ksv_cnt = ksv_count;
> - return count;
> + *revoked_ksv_cnt = ksv_count;
> + return 0;
> }
>
> static inline bool is_srm_version_hdcp1(const u8 *buf)
> @@ -226,22 +216,27 @@ static inline bool is_srm_version_hdcp2(const u8 *buf)
> return *buf == (u8)(DRM_HDCP_2_SRM_ID << 4 | DRM_HDCP_2_INDICATOR);
> }
>
> -static void drm_hdcp_srm_update(const u8 *buf, size_t count)
> +static int drm_hdcp_srm_update(const u8 *buf, size_t count,
> + u8 **revoked_ksv_list, u32 *revoked_ksv_cnt)
> {
> if (count < sizeof(struct hdcp_srm_header))
> - return;
> + return -EINVAL;
>
> if (is_srm_version_hdcp1(buf))
> - drm_hdcp_parse_hdcp1_srm(buf, count);
> + return drm_hdcp_parse_hdcp1_srm(buf, count, revoked_ksv_list,
> + revoked_ksv_cnt);
> else if (is_srm_version_hdcp2(buf))
> - drm_hdcp_parse_hdcp2_srm(buf, count);
> + return drm_hdcp_parse_hdcp2_srm(buf, count, revoked_ksv_list,
> + revoked_ksv_cnt);
> + else
> + return -EINVAL;
> }
>
> -static void drm_hdcp_request_srm(struct drm_device *drm_dev)
> +static int drm_hdcp_request_srm(struct drm_device *drm_dev,
> + u8 **revoked_ksv_list, u32 *revoked_ksv_cnt)
> {
> char fw_name[36] = "display_hdcp_srm.bin";
> const struct firmware *fw;
> -
> int ret;
>
> ret = request_firmware_direct(&fw, (const char *)fw_name,
> @@ -250,10 +245,12 @@ static void drm_hdcp_request_srm(struct drm_device *drm_dev)
> goto exit;
>
> if (fw->size && fw->data)
> - drm_hdcp_srm_update(fw->data, fw->size);
> + ret = drm_hdcp_srm_update(fw->data, fw->size, revoked_ksv_list,
> + revoked_ksv_cnt);
>
> exit:
> release_firmware(fw);
> + return ret;
> }
>
> /**
> @@ -279,71 +276,34 @@ static void drm_hdcp_request_srm(struct drm_device *drm_dev)
> * https://www.digital-cp.com/sites/default/files/specifications/HDCP%20on%20HDMI%20Specification%20Rev2_2_Final1.pdf
> *
> * Returns:
> - * TRUE on any of the KSV is revoked, else FALSE.
> + * Count of the revoked KSVs or -ve error number incase of the failure.
> */
> -bool drm_hdcp_check_ksvs_revoked(struct drm_device *drm_dev, u8 *ksvs,
> - u32 ksv_count)
> +int drm_hdcp_check_ksvs_revoked(struct drm_device *drm_dev, u8 *ksvs,
> + u32 ksv_count)
> {
> - u32 rev_ksv_cnt, cnt, i, j;
> - u8 *rev_ksv_list;
> -
> - if (!srm_data)
> - return false;
> -
> - mutex_lock(&srm_data->mutex);
> - drm_hdcp_request_srm(drm_dev);
> -
> - rev_ksv_cnt = srm_data->revoked_ksv_cnt;
> - rev_ksv_list = srm_data->revoked_ksv_list;
> -
> - /* If the Revoked ksv list is empty */
> - if (!rev_ksv_cnt || !rev_ksv_list) {
> - mutex_unlock(&srm_data->mutex);
> - return false;
> - }
> -
> - for (cnt = 0; cnt < ksv_count; cnt++) {
> - rev_ksv_list = srm_data->revoked_ksv_list;
> - for (i = 0; i < rev_ksv_cnt; i++) {
> - for (j = 0; j < DRM_HDCP_KSV_LEN; j++)
> - if (ksvs[j] != rev_ksv_list[j]) {
> - break;
> - } else if (j == (DRM_HDCP_KSV_LEN - 1)) {
> - DRM_DEBUG("Revoked KSV is ");
> - drm_hdcp_print_ksv(ksvs);
> - mutex_unlock(&srm_data->mutex);
> - return true;
> - }
> - /* Move the offset to next KSV in the revoked list */
> - rev_ksv_list += DRM_HDCP_KSV_LEN;
> - }
> -
> - /* Iterate to next ksv_offset */
> - ksvs += DRM_HDCP_KSV_LEN;
> - }
> - mutex_unlock(&srm_data->mutex);
> - return false;
> + u32 revoked_ksv_cnt = 0, i, j;
> + u8 *revoked_ksv_list = NULL;
> + int ret = 0;
> +
> + ret = drm_hdcp_request_srm(drm_dev, &revoked_ksv_list,
> + &revoked_ksv_cnt);
> +
> + /* revoked_ksv_cnt will be zero when above function failed */
> + for (i = 0; i < revoked_ksv_cnt; i++)
> + for (j = 0; j < ksv_count; j++)
> + if (!memcmp(&ksvs[j * DRM_HDCP_KSV_LEN],
> + &revoked_ksv_list[i * DRM_HDCP_KSV_LEN],
> + DRM_HDCP_KSV_LEN)) {
> + DRM_DEBUG("Revoked KSV is ");
> + drm_hdcp_print_ksv(&ksvs[j * DRM_HDCP_KSV_LEN]);
> + ret++;
> + }
> +
> + kfree(revoked_ksv_list);
> + return ret;
> }
> EXPORT_SYMBOL_GPL(drm_hdcp_check_ksvs_revoked);
>
> -int drm_setup_hdcp_srm(struct class *drm_class)
> -{
> - srm_data = kzalloc(sizeof(*srm_data), GFP_KERNEL);
> - if (!srm_data)
> - return -ENOMEM;
> - mutex_init(&srm_data->mutex);
> -
> - return 0;
> -}
> -
> -void drm_teardown_hdcp_srm(struct class *drm_class)
> -{
> - if (srm_data) {
> - kfree(srm_data->revoked_ksv_list);
> - kfree(srm_data);
> - }
> -}
> -
> static struct drm_prop_enum_list drm_cp_enum_list[] = {
> { DRM_MODE_CONTENT_PROTECTION_UNDESIRED, "Undesired" },
> { DRM_MODE_CONTENT_PROTECTION_DESIRED, "Desired" },
> diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
> index aeec2e68d772..5714a78365ac 100644
> --- a/drivers/gpu/drm/drm_internal.h
> +++ b/drivers/gpu/drm/drm_internal.h
> @@ -236,7 +236,3 @@ int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
> void drm_framebuffer_print_info(struct drm_printer *p, unsigned int indent,
> const struct drm_framebuffer *fb);
> int drm_framebuffer_debugfs_init(struct drm_minor *minor);
> -
> -/* drm_hdcp.c */
> -int drm_setup_hdcp_srm(struct class *drm_class);
> -void drm_teardown_hdcp_srm(struct class *drm_class);
> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
> index dd2bc85f43cc..2e83c3d72af9 100644
> --- a/drivers/gpu/drm/drm_sysfs.c
> +++ b/drivers/gpu/drm/drm_sysfs.c
> @@ -85,7 +85,6 @@ int drm_sysfs_init(void)
> }
>
> drm_class->devnode = drm_devnode;
> - drm_setup_hdcp_srm(drm_class);
> return 0;
> }
>
> @@ -98,7 +97,6 @@ void drm_sysfs_destroy(void)
> {
> if (IS_ERR_OR_NULL(drm_class))
> return;
> - drm_teardown_hdcp_srm(drm_class);
> class_remove_file(drm_class, &class_attr_version.attr);
> class_destroy(drm_class);
> drm_class = NULL;
> diff --git a/include/drm/drm_hdcp.h b/include/drm/drm_hdcp.h
> index 06a11202a097..d512089b873f 100644
> --- a/include/drm/drm_hdcp.h
> +++ b/include/drm/drm_hdcp.h
> @@ -288,8 +288,8 @@ struct hdcp_srm_header {
> struct drm_device;
> struct drm_connector;
>
> -bool drm_hdcp_check_ksvs_revoked(struct drm_device *dev,
> - u8 *ksvs, u32 ksv_count);
> +int drm_hdcp_check_ksvs_revoked(struct drm_device *dev,
> + u8 *ksvs, u32 ksv_count);
> int drm_connector_attach_content_protection_property(
> struct drm_connector *connector, bool hdcp_content_type);
> void drm_hdcp_update_content_protection(struct drm_connector *connector,
> --
> 2.20.1
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

--
Sean Paul, Software Engineer, Google / Chromium OS