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

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

On 2/13/2024 9:33 PM, Kandpal, Suraj wrote:
>>> 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?
>>
> Would it be better to not have a kfree here if initialization fails it gets taken care of
> In finish function anyways that would be safer I presume.

We normally try to clean up immediately when things go wrong, also 
because if this failure causes the driver load to abort the _fini 
function might not get called (but not sure if this is the case here).
In this case this can be easily fixed by simply changing it to:

ret = intel_hdcp_gsc_initialize_message(xe, hdcp_message);
if (ret) {
	drm_err(&xe->drm, "Could not initialize hdcp_message\n");
	kfree(hdcp_message);
	return ret;
}

xe->display.hdcp.hdcp_message = hdcp_message;
return 0;


Which guarantees that xe->display.hdcp.hdcp_message is only set when the 
allocation exists with minimal changes to the code.

Daniele

>
>> LGTM apart from this (assuming it is going to be squashed with the next
>> patch for merge).
> Yes this will be squashed with the next patch when I send the new revision
>
> Regards,
> Suraj Kandpal
>> 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