Re: [PATCH 2/3] drm/xe/hdcp: Enable HDCP for XE

From: Jani Nikula <jani.nikula@linux.intel.com>
To: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>,
	Suraj Kandpal <suraj.kandpal@intel.com>,
	intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org
Cc: chaitanya.kumar.borah@intel.com, ankit.k.nautiyal@intel.com
Subject: Re: [PATCH 2/3] drm/xe/hdcp: Enable HDCP for XE
Date: Wed, 07 Feb 2024 11:40:32 +0200	[thread overview]
Message-ID: <87fry4d33j.fsf@intel.com> (raw)
In-Reply-To: <c30a93fa-8372-43cc-8151-e660c30d4e36@intel.com>

On Mon, 05 Feb 2024, Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com> wrote:
> On 2/2/2024 12:37 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.
>>
>> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
>> ---
>>   drivers/gpu/drm/xe/display/xe_hdcp_gsc.c | 188 ++++++++++++++++++++++-
>>   1 file changed, 184 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/xe/display/xe_hdcp_gsc.c b/drivers/gpu/drm/xe/display/xe_hdcp_gsc.c
>> index 0f11a39333e2..eca941d7b281 100644
>> --- a/drivers/gpu/drm/xe/display/xe_hdcp_gsc.c
>> +++ b/drivers/gpu/drm/xe/display/xe_hdcp_gsc.c
>> @@ -3,8 +3,24 @@
>>    * Copyright 2023, Intel Corporation.
>>    */
>>   
>> +#include "abi/gsc_command_header_abi.h"
>
> My original idea was for the users to not include this header and rely 
> on the size provided by the emit functions. I see you use the check the 
> input size, which I didn't do on the proxy side because the buffer is 
> sized to be big enough for all possible commands. Overall not a blocker, 
> just consider the option.
>
>>   #include "i915_drv.h"
>
> Do you actually need i915_drv.h? You shouldn't be using any structure 
> from i915 here. If you just need it for the pointers to struct 
> drm_i915_private, just add a forward declaration for the structure.

Xe side it really must be struct xe_device, not drm_i915_private.

See xe Makefile.

BR,
Jani.

>
>>   #include "intel_hdcp_gsc.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 HOST_SESSION_CLIENT_MASK GENMASK_ULL(63, 56)
>> +#define HDCP_GSC_MESSAGE_SIZE sizeof(struct intel_hdcp_gsc_message)
>
> this define is unused. Also, intel_hdcp_gsc_message is not the actual 
> message, but just contains a pointer to the object that holds the message.
>
>> +#define HDCP_GSC_HEADER_SIZE sizeof(struct intel_gsc_mtl_header)
>>   
>>   bool intel_hdcp_gsc_cs_required(struct drm_i915_private *i915)
>>   {
>> @@ -13,22 +29,186 @@ bool intel_hdcp_gsc_cs_required(struct drm_i915_private *i915)
>>   
>>   bool intel_hdcp_gsc_check_status(struct drm_i915_private *i915)
>>   {
>> -	return false;
>> +	return true;
>
> Shouldn't you actually do a check in here?
>
>> +}
>> +
>> +/*This function helps allocate memory for the command that we will send to gsc cs */
>> +static int intel_hdcp_gsc_initialize_message(struct drm_i915_private *i915,
>
> Having a drm_i915_private here that is actually an xe_device is really 
> weird. I understand that the aim is to re-use most of the display code 
> from i915, but if you need to different back-ends maybe just have the 
> function accept a void pointer and then internally cast it to 
> drm_i915_private or xe_device based on the driver, or use struct 
> intel_display and cast it back to i915 or Xe with a container_of. I'll 
> leave the final comment on this to someone that has more understanding 
> than me of what's going on on the display side of things.
>
>> +					     struct intel_hdcp_gsc_message *hdcp_message)
>> +{
>> +	struct xe_bo *bo = NULL;
>> +	u64 cmd_in, cmd_out;
>> +	int err, ret = 0;
>> +
>> +	/* allocate object of two page for HDCP command memory and store it */
>> +
>> +	xe_device_mem_access_get(i915);
>> +	bo = xe_bo_create_pin_map(i915, xe_device_get_root_tile(i915), NULL, PAGE_SIZE * 2,
>> +				  ttm_bo_type_kernel,
>> +				  XE_BO_CREATE_SYSTEM_BIT |
>> +				  XE_BO_CREATE_GGTT_BIT);
>> +
>> +	if (IS_ERR(bo)) {
>> +		drm_err(&i915->drm, "Failed to allocate bo for HDCP streaming command!\n");
>> +		ret = err;
>> +		goto out;
>> +	}
>> +
>> +	cmd_in = xe_bo_ggtt_addr(bo);
>> +
>> +	if (iosys_map_is_null(&bo->vmap)) {
>
> this can't happen, if the bo fails to map then xe_bo_create_pin_map will 
> return an error.
>
>> +		drm_err(&i915->drm, "Failed to map gsc message page!\n");
>> +		ret = PTR_ERR(&bo->vmap);
>> +		goto out;
>> +	}
>> +
>> +	cmd_out = cmd_in + PAGE_SIZE;
>> +
>> +	xe_map_memset(i915, &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(i915);
>> +	return ret;
>> +}
>> +
>> +static int intel_hdcp_gsc_hdcp2_init(struct drm_i915_private *i915)
>> +{
>> +	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
>> +	 */
>> +	i915->display.hdcp.hdcp_message = hdcp_message;
>> +	ret = intel_hdcp_gsc_initialize_message(i915, hdcp_message);
>> +
>> +	if (ret)
>> +		drm_err(&i915->drm, "Could not initialize hdcp_message\n");
>
> Don't you need a kfree in this error path? alternatively you can use 
> drmm_kzalloc so that it is always automatically freed.
>
>> +
>> +	return ret;
>>   }
>>   
>>   int intel_hdcp_gsc_init(struct drm_i915_private *i915)
>>   {
>> -	drm_info(&i915->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(&i915->display.hdcp.hdcp_mutex);
>> +	i915->display.hdcp.arbiter = data;
>> +	i915->display.hdcp.arbiter->hdcp_dev = i915->drm.dev;
>> +	i915->display.hdcp.arbiter->ops = &gsc_hdcp_ops;
>
> Does this patch compile on its own? As far as I can see gsc_hdcp_ops is 
> added in the next patch.
>
>> +	ret = intel_hdcp_gsc_hdcp2_init(i915);
>> +	mutex_unlock(&i915->display.hdcp.hdcp_mutex);
>> +
>> +	return ret;
>
> Here as well missing the kfree on error
>
>>   }
>>   
>>   void intel_hdcp_gsc_fini(struct drm_i915_private *i915)
>>   {
>> +	struct intel_hdcp_gsc_message *hdcp_message =
>> +					i915->display.hdcp.hdcp_message;
>> +
>> +	xe_bo_unpin_map_no_vm(hdcp_message->hdcp_bo);
>> +	kfree(hdcp_message);
>> +
>>   }
>>   
>> +static int xe_gsc_send_sync(struct drm_i915_private *i915,
>> +			    struct intel_hdcp_gsc_message *hdcp_message,
>> +			    u32 msg_size_in, u32 msg_size_out,
>> +			    u32 addr_in_off, u32 addr_out_off,
>
> Those 2 variables are unused.
>
>> +			    size_t msg_out_len)
>> +{
>> +	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(&i915->drm, "failed to send gsc HDCP msg (%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = xe_gsc_check_and_update_pending(i915, map, 0, map, addr_out_off);
>
> This returns a bool, so you can call it directly inside the if statement 
> instead of casting the return to int.
>
>> +
>> +	if (ret)
>> +		return -EAGAIN;
>> +
>> +	ret = xe_gsc_read_out_header(i915, map, addr_out_off,
>> +				     sizeof(struct hdcp_cmd_header), NULL);
>
> Note that here you're only checking that the message is at least as big 
> as struct hdcp_cmd_header, but if there was an error and the only thing 
> in the message was the header it'll still pass. This links with a 
> comment below.
>
>> +
>> +	return ret;
>> +}
>>   ssize_t intel_hdcp_gsc_msg_send(struct drm_i915_private *i915, 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, addr_in_off = 0, addr_out_off;
>> +	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 = i915->display.hdcp.hdcp_message;
>> +	addr_out_off = PAGE_SIZE;
>> +
>> +	get_random_bytes(&host_session_id, sizeof(u64));
>> +	host_session_id = host_session_id & ~HOST_SESSION_CLIENT_MASK;
>
> Can you move this host session code to a dedicated function in 
> xe_gsc_submit.c? that way we can re-use it for PXP.  You can also drop 
> the re-definition of HOST_SESSION_CLIENT_MASK because that's already in 
> that file.
>
>> +	xe_device_mem_access_get(i915);
>> +	addr_in_off = xe_gsc_emit_header(i915, &hdcp_message->hdcp_bo->vmap,
>
> Note that this function does not return the input offset, but the next 
> writable location (that's why I called it wr_offset in other code)
>
>> +					 addr_in_off,
>> +					 HECI_MEADDRESS_HDCP, host_session_id,
>> +					 msg_in_len);
>> +
>> +	xe_map_memcpy_to(i915, &hdcp_message->hdcp_bo->vmap, addr_in_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(i915, hdcp_message, msg_size_in, msg_size_out,
>> +				       addr_in_off, addr_out_off, msg_out_len);
>> +
>> +		/* Only try again if gsc says so */
>> +		if (ret != -EAGAIN)
>> +			break;
>> +
>> +		msleep(50);
>> +
>> +	} while (++tries < 20);
>> +
>> +	if (ret)
>> +		goto out;
>> +
>> +	xe_map_memcpy_from(i915, msg_out, &hdcp_message->hdcp_bo->vmap,
>> +			   addr_out_off + HDCP_GSC_HEADER_SIZE,
>> +			   msg_out_len);
>
> here you are copying msg_out_len, but you haven't checked if the GSC has 
> actually written that much, you only checked that you had struct 
> hdcp_cmd_header.
>
> Daniele
>
>> +
>> +out:
>> +	xe_device_mem_access_put(i915);
>> +	return ret;
>>   }
>

-- 
Jani Nikula, Intel