1 files changed, 362 insertions, 0 deletions
diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
new file mode 100644
index 000000000..acaa44809
--- /dev/null
+++ b/drivers/misc/cxl/context.c
@@ -0,0 +1,362 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2014 IBM Corp.
+ */
+
+#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 filesystem semantics (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);
+
+	/*
+	 * 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, 0,
+		      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;
+
+	bitmap_free(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)
+		mmgrab(ctx->mm);
+}
+
+void cxl_context_mm_count_put(struct cxl_context *ctx)
+{
+	if (ctx->mm)
+		mmdrop(ctx->mm);
+}