[PATCH v2 5/9] drm/i915/pxp: Add GSC-CS backend to send GSC fw messages

[Ceraolo Spurio, Daniele]

On 1/11/2023 1:42 PM, Alan Previn wrote:
> Add GSC engine based method for sending PXP firmware packets
> to the GSC firmware for MTL (and future) products. Use the newly
> added helpers to populate the GSC-CS memory header and send the
> message packet to the FW by dispatching the GSC_HECI_CMD_PKT
> instruction on the GSC engine.
>
> Signed-off-by: Alan Previn <alan.previn.teres.alexis at intel.com>
> ---
>   drivers/gpu/drm/i915/pxp/intel_pxp_gsccs.c | 93 ++++++++++++++++++++++
>   1 file changed, 93 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/pxp/intel_pxp_gsccs.c b/drivers/gpu/drm/i915/pxp/intel_pxp_gsccs.c
> index 97ca187e6fde..ff235822743e 100644
> --- a/drivers/gpu/drm/i915/pxp/intel_pxp_gsccs.c
> +++ b/drivers/gpu/drm/i915/pxp/intel_pxp_gsccs.c
> @@ -6,6 +6,7 @@
>   #include "gem/i915_gem_internal.h"
>   
>   #include "gt/intel_context.h"
> +#include "gt/uc/intel_gsc_uc_heci_cmd_submit.h"
>   
>   #include "i915_drv.h"
>   #include "intel_pxp_cmd_interface_43.h"
> @@ -39,6 +40,98 @@ static inline struct gsccs_teelink_priv *pxp_to_gsccs_priv(struct intel_pxp *pxp
>   	return (struct gsccs_teelink_priv *)pxp->gsccs_priv;
>   }
>   
> +static int gsccs_send_message(struct intel_pxp *pxp,

This is unused in this patch, so it would cause a compiler warning 
unless you add  the maybe_unused tag (which needs to be removed when the 
function gets used). It might also be worth squashing this patch with 
the next one to not have an unused function as they're both relatively 
small.

> +			      void *msg_in, size_t msg_in_size,
> +			      void *msg_out, size_t msg_out_size_max,
> +			      size_t *msg_out_len)
> +{
> +	struct intel_gt *gt = pxp->ctrl_gt;
> +	struct drm_i915_private *i915 = gt->i915;
> +	struct gsccs_session_resources *exec = &pxp_to_gsccs_priv(pxp)->arb_exec_res;
> +	struct intel_gsc_mtl_header *header = exec->pkt_vaddr;
> +	struct intel_gsc_heci_non_priv_pkt pkt;
> +	size_t max_msg_size;
> +	u32 reply_size;
> +	int ret;
> +
> +	if (!intel_uc_uses_gsc_uc(&gt->uc))
> +		return -ENODEV;

This also needs a check that the GSC FW is loaded (could also be 
performed at a higher level).

> +
> +	if (!exec->ce)
> +		return -ENODEV;
> +
> +	max_msg_size = PXP43_MAX_HECI_IN_SIZE - sizeof(*header);
> +
> +	if (msg_in_size > max_msg_size || msg_out_size_max > max_msg_size)
> +		return -ENOSPC;
> +
> +	mutex_lock(&exec->cmd_mutex);

This seems to perform the same role as pxp->tee_mutex, which is unused 
when we're in gsccs mode. I'm wondering if there is a way to have only 
one mutex and use it in both scenarios. Not a blocker.

Daniele

> +
> +	if (!exec->pkt_vma || !exec->bb_vma)
> +		return -ENOENT;
> +
> +	memset(header, 0, sizeof(*header));
> +	intel_gsc_uc_heci_cmd_emit_mtl_header(header, GSC_HECI_MEADDRESS_PXP,
> +					      msg_in_size + sizeof(*header),
> +					      exec->host_session_handle);
> +
> +	memcpy(exec->pkt_vaddr + sizeof(*header), msg_in, msg_in_size);
> +
> +	pkt.addr_in = i915_vma_offset(exec->pkt_vma);
> +	pkt.size_in = header->message_size;
> +	pkt.addr_out = pkt.addr_in + PXP43_MAX_HECI_IN_SIZE;
> +	pkt.size_out = msg_out_size_max + sizeof(*header);
> +	pkt.heci_pkt_vma = exec->pkt_vma;
> +	pkt.bb_vma = exec->bb_vma;
> +
> +	ret = intel_gsc_uc_heci_cmd_submit_nonpriv(&pxp->ctrl_gt->uc.gsc,
> +						   exec->ce, &pkt, exec->bb_vaddr, 500);
> +	if (ret) {
> +		drm_err(&i915->drm, "failed to send gsc PXP msg (%d)\n", ret);
> +		goto unlock;
> +	}
> +
> +	/* we keep separate location for reply, so get the response header loc first */
> +	header = exec->pkt_vaddr + PXP43_MAX_HECI_IN_SIZE;
> +
> +	/* Response validity marker, status and busyness */
> +	if (header->validity_marker != GSC_HECI_VALIDITY_MARKER) {
> +		drm_err(&i915->drm, "gsc PXP reply with invalid validity marker\n");
> +		ret = -EINVAL;
> +		goto unlock;
> +	}
> +	if (header->status != 0) {
> +		drm_dbg(&i915->drm, "gsc PXP reply status has error = 0x%08x\n",
> +			header->status);
> +		ret = -EINVAL;
> +		goto unlock;
> +	}
> +	if (header->flags & GSC_HECI_FLAG_MSG_PENDING) {
> +		drm_dbg(&i915->drm, "gsc PXP reply is busy\n");
> +		ret = -EAGAIN;
> +		goto unlock;
> +	}
> +
> +	reply_size = header->message_size - sizeof(*header);
> +	if (reply_size > msg_out_size_max) {
> +		drm_warn(&i915->drm, "caller with insufficient PXP reply size %u (%ld)\n",
> +			 reply_size, msg_out_size_max);
> +		reply_size = msg_out_size_max;
> +	} else if (reply_size != msg_out_size_max) {
> +		drm_dbg(&i915->drm, "caller unexpected PXP reply size %u (%ld)\n",
> +			reply_size, msg_out_size_max);
> +	}
> +
> +	memcpy(msg_out, exec->pkt_vaddr + PXP43_MAX_HECI_IN_SIZE + sizeof(*header),
> +	       reply_size);
> +	if (msg_out_len)
> +		*msg_out_len = reply_size;
> +
> +unlock:
> +	mutex_unlock(&exec->cmd_mutex);
> +	return ret;
> +}
> +
>   int intel_pxp_gsccs_create_session(struct intel_pxp *pxp,
>   				   int arb_session_id)
>   {