Re: [PATCH 4/5] drm/xe/hdcp: Enable HDCP for XE

[Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>]

On 2/9/2024 2:14 AM, Suraj Kandpal wrote:
> Enable HDCP for Xe by defining functions which take care of
> interaction of HDCP as a client with the GSC CS interface.
>
> --v2
> -add kfree at appropriate place [Daniele]
> -remove useless define [Daniele]
> -move host session logic to xe_gsc_submit.c [Daniele]
> -call xe_gsc_check_and_update_pending directly in an if condition
> [Daniele]
> -use xe_device instead of drm_i915_private [Daniele]
>
> --v3
> -use xe prefix for newly exposed function [Daniele]
> -remove client specific defines from intel_gsc_mtl_header [Daniele]
> -add missing kfree() [Daniele]
> -have NULL check for hdcp_message in finish function [Daniele]
> -dont have too many variable declarations in the same line [Daniele]
>
> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> ---
>   drivers/gpu/drm/xe/display/xe_hdcp_gsc.c | 180 ++++++++++++++++++++++-
>   drivers/gpu/drm/xe/xe_gsc_submit.c       |  15 ++
>   drivers/gpu/drm/xe/xe_gsc_submit.h       |   1 +
>   3 files changed, 193 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/display/xe_hdcp_gsc.c b/drivers/gpu/drm/xe/display/xe_hdcp_gsc.c
> index 425db3532ce5..aa8c13916bb6 100644
> --- a/drivers/gpu/drm/xe/display/xe_hdcp_gsc.c
> +++ b/drivers/gpu/drm/xe/display/xe_hdcp_gsc.c
> @@ -4,12 +4,27 @@
>    */
>   
>   #include <drm/drm_print.h>
> +#include <linux/delay.h>
>   
> +#include "abi/gsc_command_header_abi.h"
>   #include "intel_hdcp_gsc.h"
>   #include "xe_device_types.h"
>   #include "xe_gt.h"
>   #include "xe_gsc_proxy.h"
>   #include "xe_pm.h"
> +#include "xe_bo.h"
> +#include "xe_map.h"
> +#include "xe_gsc_submit.h"
> +
> +#define HECI_MEADDRESS_HDCP 18
> +
> +struct intel_hdcp_gsc_message {
> +	struct xe_bo *hdcp_bo;
> +	u64 hdcp_cmd_in;
> +	u64 hdcp_cmd_out;
> +};
> +
> +#define HDCP_GSC_HEADER_SIZE sizeof(struct intel_gsc_mtl_header)
>   
>   bool intel_hdcp_gsc_cs_required(struct xe_device *xe)
>   {
> @@ -40,19 +55,178 @@ bool intel_hdcp_gsc_check_status(struct xe_device *xe)
>   	return ret;
>   }
>   
> +/*This function helps allocate memory for the command that we will send to gsc cs */
> +static int intel_hdcp_gsc_initialize_message(struct xe_device *xe,
> +					     struct intel_hdcp_gsc_message *hdcp_message)
> +{
> +	struct xe_bo *bo = NULL;
> +	u64 cmd_in, cmd_out;
> +	int ret = 0;
> +
> +	/* allocate object of two page for HDCP command memory and store it */
> +	xe_device_mem_access_get(xe);
> +	bo = xe_bo_create_pin_map(xe, xe_device_get_root_tile(xe), NULL, PAGE_SIZE * 2,
> +				  ttm_bo_type_kernel,
> +				  XE_BO_CREATE_SYSTEM_BIT |
> +				  XE_BO_CREATE_GGTT_BIT);
> +
> +	if (IS_ERR(bo)) {
> +		drm_err(&xe->drm, "Failed to allocate bo for HDCP streaming command!\n");
> +		ret = PTR_ERR(bo);
> +		goto out;
> +	}
> +
> +	cmd_in = xe_bo_ggtt_addr(bo);
> +	cmd_out = cmd_in + PAGE_SIZE;
> +	xe_map_memset(xe, &bo->vmap, 0, 0, bo->size);
> +
> +	hdcp_message->hdcp_bo = bo;
> +	hdcp_message->hdcp_cmd_in = cmd_in;
> +	hdcp_message->hdcp_cmd_out = cmd_out;
> +out:
> +	xe_device_mem_access_put(xe);
> +	return ret;
> +}
> +
> +static int intel_hdcp_gsc_hdcp2_init(struct xe_device *xe)
> +{
> +	struct intel_hdcp_gsc_message *hdcp_message;
> +	int ret;
> +
> +	hdcp_message = kzalloc(sizeof(*hdcp_message), GFP_KERNEL);
> +
> +	if (!hdcp_message)
> +		return -ENOMEM;
> +
> +	/*
> +	 * NOTE: No need to lock the comp mutex here as it is already
> +	 * going to be taken before this function called
> +	 */
> +	ret = intel_hdcp_gsc_initialize_message(xe, hdcp_message);
> +	xe->display.hdcp.hdcp_message = hdcp_message;
> +
> +	if (ret) {
> +		drm_err(&xe->drm, "Could not initialize hdcp_message\n");
> +		kfree(hdcp_message);

Here you're leaving xe->display.hdcp.hdcp_message pointing to a memory 
location that we no longer own. is that safe for the _fini function?

LGTM apart from this (assuming it is going to be squashed with the next 
patch for merge).

Daniele

> +	}
> +
> +	return ret;
> +}
> +
>   int intel_hdcp_gsc_init(struct xe_device *xe)
>   {
> -	drm_dbg_kms(&xe->drm, "HDCP support not yet implemented\n");
> -	return -ENODEV;
> +	struct i915_hdcp_arbiter *data;
> +	int ret;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	mutex_lock(&xe->display.hdcp.hdcp_mutex);
> +	xe->display.hdcp.arbiter = data;
> +	xe->display.hdcp.arbiter->hdcp_dev = xe->drm.dev;
> +	xe->display.hdcp.arbiter->ops = &gsc_hdcp_ops;
> +	ret = intel_hdcp_gsc_hdcp2_init(xe);
> +	if (ret)
> +		kfree(data);
> +
> +	mutex_unlock(&xe->display.hdcp.hdcp_mutex);
> +
> +	return ret;
>   }
>   
>   void intel_hdcp_gsc_fini(struct xe_device *xe)
>   {
> +	struct intel_hdcp_gsc_message *hdcp_message =
> +					xe->display.hdcp.hdcp_message;
> +
> +	if (!hdcp_message)
> +		return;
> +
> +	xe_bo_unpin_map_no_vm(hdcp_message->hdcp_bo);
> +	kfree(hdcp_message);
> +}
> +
> +static int xe_gsc_send_sync(struct xe_device *xe,
> +			    struct intel_hdcp_gsc_message *hdcp_message,
> +			    u32 msg_size_in, u32 msg_size_out,
> +			    u32 addr_out_off)
> +{
> +	struct xe_gt *gt = hdcp_message->hdcp_bo->tile->media_gt;
> +	struct iosys_map *map = &hdcp_message->hdcp_bo->vmap;
> +	struct xe_gsc *gsc = &gt->uc.gsc;
> +	int ret;
> +
> +	ret = xe_gsc_pkt_submit_kernel(gsc, hdcp_message->hdcp_cmd_in, msg_size_in,
> +				       hdcp_message->hdcp_cmd_out, msg_size_out);
> +	if (ret) {
> +		drm_err(&xe->drm, "failed to send gsc HDCP msg (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	if (xe_gsc_check_and_update_pending(xe, map, 0, map, addr_out_off))
> +		return -EAGAIN;
> +
> +	ret = xe_gsc_read_out_header(xe, map, addr_out_off,
> +				     sizeof(struct hdcp_cmd_header), NULL);
> +
> +	return ret;
>   }
>   
>   ssize_t intel_hdcp_gsc_msg_send(struct xe_device *xe, u8 *msg_in,
>   				size_t msg_in_len, u8 *msg_out,
>   				size_t msg_out_len)
>   {
> -	return -ENODEV;
> +	const size_t max_msg_size = PAGE_SIZE - HDCP_GSC_HEADER_SIZE;
> +	struct intel_hdcp_gsc_message *hdcp_message;
> +	u64 host_session_id;
> +	u32 msg_size_in, msg_size_out;
> +	u32 addr_out_off, addr_in_wr_off = 0;
> +	int ret, tries = 0;
> +
> +	if (msg_in_len > max_msg_size || msg_out_len > max_msg_size) {
> +		ret = -ENOSPC;
> +		goto out;
> +	}
> +
> +	msg_size_in = msg_in_len + HDCP_GSC_HEADER_SIZE;
> +	msg_size_out = msg_out_len + HDCP_GSC_HEADER_SIZE;
> +	hdcp_message = xe->display.hdcp.hdcp_message;
> +	addr_out_off = PAGE_SIZE;
> +
> +	host_session_id = xe_gsc_create_host_session_id();
> +	xe_device_mem_access_get(xe);
> +	addr_in_wr_off = xe_gsc_emit_header(xe, &hdcp_message->hdcp_bo->vmap,
> +					    addr_in_wr_off, HECI_MEADDRESS_HDCP,
> +					    host_session_id, msg_in_len);
> +	xe_map_memcpy_to(xe, &hdcp_message->hdcp_bo->vmap, addr_in_wr_off,
> +			 msg_in, msg_in_len);
> +	/*
> +	 * Keep sending request in case the pending bit is set no need to add
> +	 * message handle as we are using same address hence loc. of header is
> +	 * same and it will contain the message handle. we will send the message
> +	 * 20 times each message 50 ms apart
> +	 */
> +	do {
> +		ret = xe_gsc_send_sync(xe, hdcp_message, msg_size_in, msg_size_out,
> +				       addr_out_off);
> +
> +		/* Only try again if gsc says so */
> +		if (ret != -EAGAIN)
> +			break;
> +
> +		msleep(50);
> +
> +	} while (++tries < 20);
> +
> +	if (ret)
> +		goto out;
> +
> +	xe_map_memcpy_from(xe, msg_out, &hdcp_message->hdcp_bo->vmap,
> +			   addr_out_off + HDCP_GSC_HEADER_SIZE,
> +			   msg_out_len);
> +
> +out:
> +	xe_device_mem_access_put(xe);
> +	return ret;
>   }
> diff --git a/drivers/gpu/drm/xe/xe_gsc_submit.c b/drivers/gpu/drm/xe/xe_gsc_submit.c
> index 348994b271be..9a18f5667db3 100644
> --- a/drivers/gpu/drm/xe/xe_gsc_submit.c
> +++ b/drivers/gpu/drm/xe/xe_gsc_submit.c
> @@ -40,6 +40,21 @@ gsc_to_gt(struct xe_gsc *gsc)
>   	return container_of(gsc, struct xe_gt, uc.gsc);
>   }
>   
> +/**
> + * xe_gsc_get_host_session_id - Creates a random 64 bit host_session id with
> + * bits 56-63 masked.
> + *
> + * Returns: random host_session_id which can be used to send messages to gsc cs
> + */
> +u64 xe_gsc_create_host_session_id(void)
> +{
> +	u64 host_session_id;
> +
> +	get_random_bytes(&host_session_id, sizeof(u64));
> +	host_session_id &= ~HOST_SESSION_CLIENT_MASK;
> +	return host_session_id;
> +}
> +
>   /**
>    * xe_gsc_emit_header - write the MTL GSC header in memory
>    * @xe: the Xe device
> diff --git a/drivers/gpu/drm/xe/xe_gsc_submit.h b/drivers/gpu/drm/xe/xe_gsc_submit.h
> index 1939855031a6..1416b5745a4c 100644
> --- a/drivers/gpu/drm/xe/xe_gsc_submit.h
> +++ b/drivers/gpu/drm/xe/xe_gsc_submit.h
> @@ -28,4 +28,5 @@ int xe_gsc_read_out_header(struct xe_device *xe,
>   int xe_gsc_pkt_submit_kernel(struct xe_gsc *gsc, u64 addr_in, u32 size_in,
>   			     u64 addr_out, u32 size_out);
>   
> +u64 xe_gsc_create_host_session_id(void);
>   #endif