drivers/misc/cxl/context.c - third_party/linux - Git at Google

 /*
  * Copyright 2014 IBM Corp.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
  * 2 of the License, or (at your option) any later version.
  */

 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/bitmap.h>
 #include <linux/sched.h>
 #include <linux/pid.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/debugfs.h>
 #include <linux/slab.h>
 #include <linux/idr.h>
 #include <linux/sched/mm.h>
 #include <linux/mmu_context.h>
 #include <asm/cputable.h>
 #include <asm/current.h>
 #include <asm/copro.h>

 #include "cxl.h"

 /*
  * Allocates space for a CXL context.
  */
 struct cxl_context *cxl_context_alloc(void)
 {
 	return kzalloc(sizeof(struct cxl_context), GFP_KERNEL);
 }

 /*
  * Initialises a CXL context.
  */
 int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master)
 {
 	int i;

 	ctx->afu = afu;
 	ctx->master = master;
 	ctx->pid = NULL; /* Set in start work ioctl */
 	mutex_init(&ctx->mapping_lock);
 	ctx->mapping = NULL;
 	ctx->tidr = 0;
 	ctx->assign_tidr = false;

 	if (cxl_is_power8()) {
 		spin_lock_init(&ctx->sste_lock);

 		/*
 		 * Allocate the segment table before we put it in the IDR so that we
 		 * can always access it when dereferenced from IDR. For the same
 		 * reason, the segment table is only destroyed after the context is
 		 * removed from the IDR.  Access to this in the IOCTL is protected by
 		 * Linux filesytem symantics (can't IOCTL until open is complete).
 		 */
 		i = cxl_alloc_sst(ctx);
 		if (i)
 			return i;
 	}

 	INIT_WORK(&ctx->fault_work, cxl_handle_fault);

 	init_waitqueue_head(&ctx->wq);
 	spin_lock_init(&ctx->lock);

 	ctx->irq_bitmap = NULL;
 	ctx->pending_irq = false;
 	ctx->pending_fault = false;
 	ctx->pending_afu_err = false;

 	INIT_LIST_HEAD(&ctx->irq_names);
 	INIT_LIST_HEAD(&ctx->extra_irq_contexts);

 	/*
 	 * When we have to destroy all contexts in cxl_context_detach_all() we
 	 * end up with afu_release_irqs() called from inside a
 	 * idr_for_each_entry(). Hence we need to make sure that anything
 	 * dereferenced from this IDR is ok before we allocate the IDR here.
 	 * This clears out the IRQ ranges to ensure this.
 	 */
 	for (i = 0; i < CXL_IRQ_RANGES; i++)
 		ctx->irqs.range[i] = 0;

 	mutex_init(&ctx->status_mutex);

 	ctx->status = OPENED;

 	/*
 	 * Allocating IDR! We better make sure everything's setup that
 	 * dereferences from it.
 	 */
 	mutex_lock(&afu->contexts_lock);
 	idr_preload(GFP_KERNEL);
 	i = idr_alloc(&ctx->afu->contexts_idr, ctx, ctx->afu->adapter->min_pe,
 		      ctx->afu->num_procs, GFP_NOWAIT);
 	idr_preload_end();
 	mutex_unlock(&afu->contexts_lock);
 	if (i < 0)
 		return i;

 	ctx->pe = i;
 	if (cpu_has_feature(CPU_FTR_HVMODE)) {
 		ctx->elem = &ctx->afu->native->spa[i];
 		ctx->external_pe = ctx->pe;
 	} else {
 		ctx->external_pe = -1; /* assigned when attaching */
 	}
 	ctx->pe_inserted = false;

 	/*
 	 * take a ref on the afu so that it stays alive at-least till
 	 * this context is reclaimed inside reclaim_ctx.
 	 */
 	cxl_afu_get(afu);
 	return 0;
 }

 void cxl_context_set_mapping(struct cxl_context *ctx,
 			struct address_space *mapping)
 {
 	mutex_lock(&ctx->mapping_lock);
 	ctx->mapping = mapping;
 	mutex_unlock(&ctx->mapping_lock);
 }

 static vm_fault_t cxl_mmap_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct cxl_context *ctx = vma->vm_file->private_data;
 	u64 area, offset;
 	vm_fault_t ret;

 	offset = vmf->pgoff << PAGE_SHIFT;

 	pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
 			__func__, ctx->pe, vmf->address, offset);

 	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 		area = ctx->afu->psn_phys;
 		if (offset >= ctx->afu->adapter->ps_size)
 			return VM_FAULT_SIGBUS;
 	} else {
 		area = ctx->psn_phys;
 		if (offset >= ctx->psn_size)
 			return VM_FAULT_SIGBUS;
 	}

 	mutex_lock(&ctx->status_mutex);

 	if (ctx->status != STARTED) {
 		mutex_unlock(&ctx->status_mutex);
 		pr_devel("%s: Context not started, failing problem state access\n", __func__);
 		if (ctx->mmio_err_ff) {
 			if (!ctx->ff_page) {
 				ctx->ff_page = alloc_page(GFP_USER);
 				if (!ctx->ff_page)
 					return VM_FAULT_OOM;
 				memset(page_address(ctx->ff_page), 0xff, PAGE_SIZE);
 			}
 			get_page(ctx->ff_page);
 			vmf->page = ctx->ff_page;
 			vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
 			return 0;
 		}
 		return VM_FAULT_SIGBUS;
 	}

 	ret = vmf_insert_pfn(vma, vmf->address, (area + offset) >> PAGE_SHIFT);

 	mutex_unlock(&ctx->status_mutex);

 	return ret;
 }

 static const struct vm_operations_struct cxl_mmap_vmops = {
 	.fault = cxl_mmap_fault,
 };

 /*
  * Map a per-context mmio space into the given vma.
  */
 int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
 {
 	u64 start = vma->vm_pgoff << PAGE_SHIFT;
 	u64 len = vma->vm_end - vma->vm_start;

 	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
 		if (start + len > ctx->afu->adapter->ps_size)
 			return -EINVAL;

 		if (cxl_is_power9()) {
 			/*
 			 * Make sure there is a valid problem state
 			 * area space for this AFU.
 			 */
 			if (ctx->master && !ctx->afu->psa) {
 				pr_devel("AFU doesn't support mmio space\n");
 				return -EINVAL;
 			}

 			/* Can't mmap until the AFU is enabled */
 			if (!ctx->afu->enabled)
 				return -EBUSY;
 		}
 	} else {
 		if (start + len > ctx->psn_size)
 			return -EINVAL;

 		/* Make sure there is a valid per process space for this AFU */
 		if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
 			pr_devel("AFU doesn't support mmio space\n");
 			return -EINVAL;
 		}

 		/* Can't mmap until the AFU is enabled */
 		if (!ctx->afu->enabled)
 			return -EBUSY;
 	}

 	pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
 		 ctx->psn_phys, ctx->pe , ctx->master);

 	vma->vm_flags |= VM_IO | VM_PFNMAP;
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 	vma->vm_ops = &cxl_mmap_vmops;
 	return 0;
 }

 /*
  * Detach a context from the hardware. This disables interrupts and doesn't
  * return until all outstanding interrupts for this context have completed. The
  * hardware should no longer access *ctx after this has returned.
  */
 int __detach_context(struct cxl_context *ctx)
 {
 	enum cxl_context_status status;

 	mutex_lock(&ctx->status_mutex);
 	status = ctx->status;
 	ctx->status = CLOSED;
 	mutex_unlock(&ctx->status_mutex);
 	if (status != STARTED)
 		return -EBUSY;

 	/* Only warn if we detached while the link was OK.
 	 * If detach fails when hw is down, we don't care.
 	 */
 	WARN_ON(cxl_ops->detach_process(ctx) &&
 		cxl_ops->link_ok(ctx->afu->adapter, ctx->afu));
 	flush_work(&ctx->fault_work); /* Only needed for dedicated process */

 	/*
 	 * Wait until no further interrupts are presented by the PSL
 	 * for this context.
 	 */
 	if (cxl_ops->irq_wait)
 		cxl_ops->irq_wait(ctx);

 	/* release the reference to the group leader and mm handling pid */
 	put_pid(ctx->pid);

 	cxl_ctx_put();

 	/* Decrease the attached context count on the adapter */
 	cxl_adapter_context_put(ctx->afu->adapter);

 	/* Decrease the mm count on the context */
 	cxl_context_mm_count_put(ctx);
 	if (ctx->mm)
 		mm_context_remove_copro(ctx->mm);
 	ctx->mm = NULL;

 	return 0;
 }

 /*
  * Detach the given context from the AFU. This doesn't actually
  * free the context but it should stop the context running in hardware
  * (ie. prevent this context from generating any further interrupts
  * so that it can be freed).
  */
 void cxl_context_detach(struct cxl_context *ctx)
 {
 	int rc;

 	rc = __detach_context(ctx);
 	if (rc)
 		return;

 	afu_release_irqs(ctx, ctx);
 	wake_up_all(&ctx->wq);
 }

 /*
  * Detach all contexts on the given AFU.
  */
 void cxl_context_detach_all(struct cxl_afu *afu)
 {
 	struct cxl_context *ctx;
 	int tmp;

 	mutex_lock(&afu->contexts_lock);
 	idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
 		/*
 		 * Anything done in here needs to be setup before the IDR is
 		 * created and torn down after the IDR removed
 		 */
 		cxl_context_detach(ctx);

 		/*
 		 * We are force detaching - remove any active PSA mappings so
 		 * userspace cannot interfere with the card if it comes back.
 		 * Easiest way to exercise this is to unbind and rebind the
 		 * driver via sysfs while it is in use.
 		 */
 		mutex_lock(&ctx->mapping_lock);
 		if (ctx->mapping)
 			unmap_mapping_range(ctx->mapping, 0, 0, 1);
 		mutex_unlock(&ctx->mapping_lock);
 	}
 	mutex_unlock(&afu->contexts_lock);
 }

 static void reclaim_ctx(struct rcu_head *rcu)
 {
 	struct cxl_context *ctx = container_of(rcu, struct cxl_context, rcu);

 	if (cxl_is_power8())
 		free_page((u64)ctx->sstp);
 	if (ctx->ff_page)
 		__free_page(ctx->ff_page);
 	ctx->sstp = NULL;

 	kfree(ctx->irq_bitmap);

 	/* Drop ref to the afu device taken during cxl_context_init */
 	cxl_afu_put(ctx->afu);

 	kfree(ctx);
 }

 void cxl_context_free(struct cxl_context *ctx)
 {
 	if (ctx->kernelapi && ctx->mapping)
 		cxl_release_mapping(ctx);
 	mutex_lock(&ctx->afu->contexts_lock);
 	idr_remove(&ctx->afu->contexts_idr, ctx->pe);
 	mutex_unlock(&ctx->afu->contexts_lock);
 	call_rcu(&ctx->rcu, reclaim_ctx);
 }

 void cxl_context_mm_count_get(struct cxl_context *ctx)
 {
 	if (ctx->mm)
 		atomic_inc(&ctx->mm->mm_count);
 }

 void cxl_context_mm_count_put(struct cxl_context *ctx)
 {
 	if (ctx->mm)
 		mmdrop(ctx->mm);
 }
	/*
	* Copyright 2014 IBM Corp.
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*/

	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/bitmap.h>
	#include <linux/sched.h>
	#include <linux/pid.h>
	#include <linux/fs.h>
	#include <linux/mm.h>
	#include <linux/debugfs.h>
	#include <linux/slab.h>
	#include <linux/idr.h>
	#include <linux/sched/mm.h>
	#include <linux/mmu_context.h>
	#include <asm/cputable.h>
	#include <asm/current.h>
	#include <asm/copro.h>

	#include "cxl.h"

	/*
	* Allocates space for a CXL context.
	*/
	struct cxl_context *cxl_context_alloc(void)
	{
	return kzalloc(sizeof(struct cxl_context), GFP_KERNEL);
	}

	/*
	* Initialises a CXL context.
	*/
	int cxl_context_init(struct cxl_context ctx, struct cxl_afu afu, bool master)
	{
	int i;

	ctx->afu = afu;
	ctx->master = master;
	ctx->pid = NULL; /* Set in start work ioctl */
	mutex_init(&ctx->mapping_lock);
	ctx->mapping = NULL;
	ctx->tidr = 0;
	ctx->assign_tidr = false;

	if (cxl_is_power8()) {
	spin_lock_init(&ctx->sste_lock);

	/*
	* Allocate the segment table before we put it in the IDR so that we
	* can always access it when dereferenced from IDR. For the same
	* reason, the segment table is only destroyed after the context is
	* removed from the IDR. Access to this in the IOCTL is protected by
	* Linux filesytem symantics (can't IOCTL until open is complete).
	*/
	i = cxl_alloc_sst(ctx);
	if (i)
	return i;
	}

	INIT_WORK(&ctx->fault_work, cxl_handle_fault);

	init_waitqueue_head(&ctx->wq);
	spin_lock_init(&ctx->lock);

	ctx->irq_bitmap = NULL;
	ctx->pending_irq = false;
	ctx->pending_fault = false;
	ctx->pending_afu_err = false;

	INIT_LIST_HEAD(&ctx->irq_names);
	INIT_LIST_HEAD(&ctx->extra_irq_contexts);

	/*
	* When we have to destroy all contexts in cxl_context_detach_all() we
	* end up with afu_release_irqs() called from inside a
	* idr_for_each_entry(). Hence we need to make sure that anything
	* dereferenced from this IDR is ok before we allocate the IDR here.
	* This clears out the IRQ ranges to ensure this.
	*/
	for (i = 0; i < CXL_IRQ_RANGES; i++)
	ctx->irqs.range[i] = 0;

	mutex_init(&ctx->status_mutex);

	ctx->status = OPENED;

	/*
	* Allocating IDR! We better make sure everything's setup that
	* dereferences from it.
	*/
	mutex_lock(&afu->contexts_lock);
	idr_preload(GFP_KERNEL);
	i = idr_alloc(&ctx->afu->contexts_idr, ctx, ctx->afu->adapter->min_pe,
	ctx->afu->num_procs, GFP_NOWAIT);
	idr_preload_end();
	mutex_unlock(&afu->contexts_lock);
	if (i < 0)
	return i;

	ctx->pe = i;
	if (cpu_has_feature(CPU_FTR_HVMODE)) {
	ctx->elem = &ctx->afu->native->spa[i];
	ctx->external_pe = ctx->pe;
	} else {
	ctx->external_pe = -1; /* assigned when attaching */
	}
	ctx->pe_inserted = false;

	/*
	* take a ref on the afu so that it stays alive at-least till
	* this context is reclaimed inside reclaim_ctx.
	*/
	cxl_afu_get(afu);
	return 0;
	}

	void cxl_context_set_mapping(struct cxl_context *ctx,
	struct address_space *mapping)
	{
	mutex_lock(&ctx->mapping_lock);
	ctx->mapping = mapping;
	mutex_unlock(&ctx->mapping_lock);
	}

	static vm_fault_t cxl_mmap_fault(struct vm_fault *vmf)
	{
	struct vm_area_struct *vma = vmf->vma;
	struct cxl_context *ctx = vma->vm_file->private_data;
	u64 area, offset;
	vm_fault_t ret;

	offset = vmf->pgoff << PAGE_SHIFT;

	pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
	__func__, ctx->pe, vmf->address, offset);

	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
	area = ctx->afu->psn_phys;
	if (offset >= ctx->afu->adapter->ps_size)
	return VM_FAULT_SIGBUS;
	} else {
	area = ctx->psn_phys;
	if (offset >= ctx->psn_size)
	return VM_FAULT_SIGBUS;
	}

	mutex_lock(&ctx->status_mutex);

	if (ctx->status != STARTED) {
	mutex_unlock(&ctx->status_mutex);
	pr_devel("%s: Context not started, failing problem state access\n", __func__);
	if (ctx->mmio_err_ff) {
	if (!ctx->ff_page) {
	ctx->ff_page = alloc_page(GFP_USER);
	if (!ctx->ff_page)
	return VM_FAULT_OOM;
	memset(page_address(ctx->ff_page), 0xff, PAGE_SIZE);
	}
	get_page(ctx->ff_page);
	vmf->page = ctx->ff_page;
	vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
	return 0;
	}
	return VM_FAULT_SIGBUS;
	}

	ret = vmf_insert_pfn(vma, vmf->address, (area + offset) >> PAGE_SHIFT);

	mutex_unlock(&ctx->status_mutex);

	return ret;
	}

	static const struct vm_operations_struct cxl_mmap_vmops = {
	.fault = cxl_mmap_fault,
	};

	/*
	* Map a per-context mmio space into the given vma.
	*/
	int cxl_context_iomap(struct cxl_context ctx, struct vm_area_struct vma)
	{
	u64 start = vma->vm_pgoff << PAGE_SHIFT;
	u64 len = vma->vm_end - vma->vm_start;

	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
	if (start + len > ctx->afu->adapter->ps_size)
	return -EINVAL;

	if (cxl_is_power9()) {
	/*
	* Make sure there is a valid problem state
	* area space for this AFU.
	*/
	if (ctx->master && !ctx->afu->psa) {
	pr_devel("AFU doesn't support mmio space\n");
	return -EINVAL;
	}

	/* Can't mmap until the AFU is enabled */
	if (!ctx->afu->enabled)
	return -EBUSY;
	}
	} else {
	if (start + len > ctx->psn_size)
	return -EINVAL;

	/* Make sure there is a valid per process space for this AFU */
	if ((ctx->master && !ctx->afu->psa) \|\| (!ctx->afu->pp_psa)) {
	pr_devel("AFU doesn't support mmio space\n");
	return -EINVAL;
	}

	/* Can't mmap until the AFU is enabled */
	if (!ctx->afu->enabled)
	return -EBUSY;
	}

	pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
	ctx->psn_phys, ctx->pe , ctx->master);

	vma->vm_flags \|= VM_IO \| VM_PFNMAP;
	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	vma->vm_ops = &cxl_mmap_vmops;
	return 0;
	}

	/*
	* Detach a context from the hardware. This disables interrupts and doesn't
	* return until all outstanding interrupts for this context have completed. The
	* hardware should no longer access *ctx after this has returned.
	*/
	int __detach_context(struct cxl_context *ctx)
	{
	enum cxl_context_status status;

	mutex_lock(&ctx->status_mutex);
	status = ctx->status;
	ctx->status = CLOSED;
	mutex_unlock(&ctx->status_mutex);
	if (status != STARTED)
	return -EBUSY;

	/* Only warn if we detached while the link was OK.
	* If detach fails when hw is down, we don't care.
	*/
	WARN_ON(cxl_ops->detach_process(ctx) &&
	cxl_ops->link_ok(ctx->afu->adapter, ctx->afu));
	flush_work(&ctx->fault_work); /* Only needed for dedicated process */

	/*
	* Wait until no further interrupts are presented by the PSL
	* for this context.
	*/
	if (cxl_ops->irq_wait)
	cxl_ops->irq_wait(ctx);

	/* release the reference to the group leader and mm handling pid */
	put_pid(ctx->pid);

	cxl_ctx_put();

	/* Decrease the attached context count on the adapter */
	cxl_adapter_context_put(ctx->afu->adapter);

	/* Decrease the mm count on the context */
	cxl_context_mm_count_put(ctx);
	if (ctx->mm)
	mm_context_remove_copro(ctx->mm);
	ctx->mm = NULL;

	return 0;
	}

	/*
	* Detach the given context from the AFU. This doesn't actually
	* free the context but it should stop the context running in hardware
	* (ie. prevent this context from generating any further interrupts
	* so that it can be freed).
	*/
	void cxl_context_detach(struct cxl_context *ctx)
	{
	int rc;

	rc = __detach_context(ctx);
	if (rc)
	return;

	afu_release_irqs(ctx, ctx);
	wake_up_all(&ctx->wq);
	}

	/*
	* Detach all contexts on the given AFU.
	*/
	void cxl_context_detach_all(struct cxl_afu *afu)
	{
	struct cxl_context *ctx;
	int tmp;

	mutex_lock(&afu->contexts_lock);
	idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
	/*
	* Anything done in here needs to be setup before the IDR is
	* created and torn down after the IDR removed
	*/
	cxl_context_detach(ctx);

	/*
	* We are force detaching - remove any active PSA mappings so
	* userspace cannot interfere with the card if it comes back.
	* Easiest way to exercise this is to unbind and rebind the
	* driver via sysfs while it is in use.
	*/
	mutex_lock(&ctx->mapping_lock);
	if (ctx->mapping)
	unmap_mapping_range(ctx->mapping, 0, 0, 1);
	mutex_unlock(&ctx->mapping_lock);
	}
	mutex_unlock(&afu->contexts_lock);
	}

	static void reclaim_ctx(struct rcu_head *rcu)
	{
	struct cxl_context *ctx = container_of(rcu, struct cxl_context, rcu);

	if (cxl_is_power8())
	free_page((u64)ctx->sstp);
	if (ctx->ff_page)
	__free_page(ctx->ff_page);
	ctx->sstp = NULL;

	kfree(ctx->irq_bitmap);

	/* Drop ref to the afu device taken during cxl_context_init */
	cxl_afu_put(ctx->afu);

	kfree(ctx);
	}

	void cxl_context_free(struct cxl_context *ctx)
	{
	if (ctx->kernelapi && ctx->mapping)
	cxl_release_mapping(ctx);
	mutex_lock(&ctx->afu->contexts_lock);
	idr_remove(&ctx->afu->contexts_idr, ctx->pe);
	mutex_unlock(&ctx->afu->contexts_lock);
	call_rcu(&ctx->rcu, reclaim_ctx);
	}

	void cxl_context_mm_count_get(struct cxl_context *ctx)
	{
	if (ctx->mm)
	atomic_inc(&ctx->mm->mm_count);
	}

	void cxl_context_mm_count_put(struct cxl_context *ctx)
	{
	if (ctx->mm)
	mmdrop(ctx->mm);
	}