alistair23-linux/drivers/misc/habanalabs/context.c

// SPDX-License-Identifier: GPL-2.0

/*
 * Copyright 2016-2019 HabanaLabs, Ltd.
 * All Rights Reserved.
 */

#include "habanalabs.h"

#include <linux/slab.h>

static void hl_ctx_fini(struct hl_ctx *ctx)
{
	struct hl_device *hdev = ctx->hdev;
	int i;

	/*
	 * If we arrived here, there are no jobs waiting for this context
	 * on its queues so we can safely remove it.
	 * This is because for each CS, we increment the ref count and for
	 * every CS that was finished we decrement it and we won't arrive
	 * to this function unless the ref count is 0
	 */

	for (i = 0 ; i < HL_MAX_PENDING_CS ; i++)
		dma_fence_put(ctx->cs_pending[i]);

	if (ctx->asid != HL_KERNEL_ASID_ID) {
		/*
		 * The engines are stopped as there is no executing CS, but the
		 * Coresight might be still working by accessing addresses
		 * related to the stopped engines. Hence stop it explicitly.
		 */
		hdev->asic_funcs->halt_coresight(hdev);
		hl_vm_ctx_fini(ctx);
		hl_asid_free(hdev, ctx->asid);
	}
}

void hl_ctx_do_release(struct kref *ref)
{
	struct hl_ctx *ctx;

	ctx = container_of(ref, struct hl_ctx, refcount);

	hl_ctx_fini(ctx);

	if (ctx->hpriv)
		hl_hpriv_put(ctx->hpriv);

	kfree(ctx);
}

int hl_ctx_create(struct hl_device *hdev, struct hl_fpriv *hpriv)
{
	struct hl_ctx_mgr *mgr = &hpriv->ctx_mgr;
	struct hl_ctx *ctx;
	int rc;

	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
	if (!ctx) {
		rc = -ENOMEM;
		goto out_err;
	}

	rc = hl_ctx_init(hdev, ctx, false);
	if (rc)
		goto free_ctx;

	hl_hpriv_get(hpriv);
	ctx->hpriv = hpriv;

	/* TODO: remove for multiple contexts */
	hpriv->ctx = ctx;
	hdev->user_ctx = ctx;

	mutex_lock(&mgr->ctx_lock);
	rc = idr_alloc(&mgr->ctx_handles, ctx, 1, 0, GFP_KERNEL);
	mutex_unlock(&mgr->ctx_lock);

	if (rc < 0) {
		dev_err(hdev->dev, "Failed to allocate IDR for a new CTX\n");
		hl_ctx_free(hdev, ctx);
		goto out_err;
	}

	return 0;

free_ctx:
	kfree(ctx);
out_err:
	return rc;
}

void hl_ctx_free(struct hl_device *hdev, struct hl_ctx *ctx)
{
	if (kref_put(&ctx->refcount, hl_ctx_do_release) == 1)
		return;

	dev_warn(hdev->dev,
		"Context %d closed or terminated but its CS are executing\n",
		ctx->asid);
}

int hl_ctx_init(struct hl_device *hdev, struct hl_ctx *ctx, bool is_kernel_ctx)
{
	int rc = 0;

	ctx->hdev = hdev;

	kref_init(&ctx->refcount);

	ctx->cs_sequence = 1;
	spin_lock_init(&ctx->cs_lock);
	atomic_set(&ctx->thread_ctx_switch_token, 1);
	ctx->thread_ctx_switch_wait_token = 0;

	if (is_kernel_ctx) {
		ctx->asid = HL_KERNEL_ASID_ID; /* KMD gets ASID 0 */
	} else {
		ctx->asid = hl_asid_alloc(hdev);
		if (!ctx->asid) {
			dev_err(hdev->dev, "No free ASID, failed to create context\n");
			return -ENOMEM;
		}

		rc = hl_vm_ctx_init(ctx);
		if (rc) {
			dev_err(hdev->dev, "Failed to init mem ctx module\n");
			rc = -ENOMEM;
			goto mem_ctx_err;
		}
	}

	return 0;

mem_ctx_err:
	if (ctx->asid != HL_KERNEL_ASID_ID)
		hl_asid_free(hdev, ctx->asid);

	return rc;
}

void hl_ctx_get(struct hl_device *hdev, struct hl_ctx *ctx)
{
	kref_get(&ctx->refcount);
}

int hl_ctx_put(struct hl_ctx *ctx)
{
	return kref_put(&ctx->refcount, hl_ctx_do_release);
}

struct dma_fence *hl_ctx_get_fence(struct hl_ctx *ctx, u64 seq)
{
	struct hl_device *hdev = ctx->hdev;
	struct dma_fence *fence;

	spin_lock(&ctx->cs_lock);

	if (seq >= ctx->cs_sequence) {
		dev_notice(hdev->dev,
			"Can't wait on seq %llu because current CS is at seq %llu\n",
			seq, ctx->cs_sequence);
		spin_unlock(&ctx->cs_lock);
		return ERR_PTR(-EINVAL);
	}


	if (seq + HL_MAX_PENDING_CS < ctx->cs_sequence) {
		dev_dbg(hdev->dev,
			"Can't wait on seq %llu because current CS is at seq %llu (Fence is gone)\n",
			seq, ctx->cs_sequence);
		spin_unlock(&ctx->cs_lock);
		return NULL;
	}

	fence = dma_fence_get(
			ctx->cs_pending[seq & (HL_MAX_PENDING_CS - 1)]);
	spin_unlock(&ctx->cs_lock);

	return fence;
}

/*
 * hl_ctx_mgr_init - initialize the context manager
 *
 * @mgr: pointer to context manager structure
 *
 * This manager is an object inside the hpriv object of the user process.
 * The function is called when a user process opens the FD.
 */
void hl_ctx_mgr_init(struct hl_ctx_mgr *mgr)
{
	mutex_init(&mgr->ctx_lock);
	idr_init(&mgr->ctx_handles);
}

/*
 * hl_ctx_mgr_fini - finalize the context manager
 *
 * @hdev: pointer to device structure
 * @mgr: pointer to context manager structure
 *
 * This function goes over all the contexts in the manager and frees them.
 * It is called when a process closes the FD.
 */
void hl_ctx_mgr_fini(struct hl_device *hdev, struct hl_ctx_mgr *mgr)
{
	struct hl_ctx *ctx;
	struct idr *idp;
	u32 id;

	idp = &mgr->ctx_handles;

	idr_for_each_entry(idp, ctx, id)
		hl_ctx_free(hdev, ctx);

	idr_destroy(&mgr->ctx_handles);
	mutex_destroy(&mgr->ctx_lock);
}