Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 977 insertions, 0 deletions

diff --git a/drivers/misc/sgi-gru/grumain.c b/drivers/misc/sgi-gru/grumain.c
new file mode 100644
index 000000000..e2325e3d0
--- /dev/null
+++ b/drivers/misc/sgi-gru/grumain.c
@@ -0,0 +1,977 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * SN Platform GRU Driver
+ *
+ *            DRIVER TABLE MANAGER + GRU CONTEXT LOAD/UNLOAD
+ *
+ *  Copyright (c) 2008 Silicon Graphics, Inc.  All Rights Reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/spinlock.h>
+#include <linux/sched.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/err.h>
+#include <linux/prefetch.h>
+#include <asm/uv/uv_hub.h>
+#include "gru.h"
+#include "grutables.h"
+#include "gruhandles.h"
+
+unsigned long gru_options __read_mostly;
+
+static struct device_driver gru_driver = {
+	.name = "gru"
+};
+
+static struct device gru_device = {
+	.init_name = "",
+	.driver = &gru_driver,
+};
+
+struct device *grudev = &gru_device;
+
+/*
+ * Select a gru fault map to be used by the current cpu. Note that
+ * multiple cpus may be using the same map.
+ *	ZZZ should be inline but did not work on emulator
+ */
+int gru_cpu_fault_map_id(void)
+{
+#ifdef CONFIG_IA64
+	return uv_blade_processor_id() % GRU_NUM_TFM;
+#else
+	int cpu = smp_processor_id();
+	int id, core;
+
+	core = uv_cpu_core_number(cpu);
+	id = core + UV_MAX_INT_CORES * uv_cpu_socket_number(cpu);
+	return id;
+#endif
+}
+
+/*--------- ASID Management -------------------------------------------
+ *
+ *  Initially, assign asids sequentially from MIN_ASID .. MAX_ASID.
+ *  Once MAX is reached, flush the TLB & start over. However,
+ *  some asids may still be in use. There won't be many (percentage wise) still
+ *  in use. Search active contexts & determine the value of the first
+ *  asid in use ("x"s below). Set "limit" to this value.
+ *  This defines a block of assignable asids.
+ *
+ *  When "limit" is reached, search forward from limit+1 and determine the
+ *  next block of assignable asids.
+ *
+ *  Repeat until MAX_ASID is reached, then start over again.
+ *
+ *  Each time MAX_ASID is reached, increment the asid generation. Since
+ *  the search for in-use asids only checks contexts with GRUs currently
+ *  assigned, asids in some contexts will be missed. Prior to loading
+ *  a context, the asid generation of the GTS asid is rechecked. If it
+ *  doesn't match the current generation, a new asid will be assigned.
+ *
+ *   	0---------------x------------x---------------------x----|
+ *	  ^-next	^-limit	   				^-MAX_ASID
+ *
+ * All asid manipulation & context loading/unloading is protected by the
+ * gs_lock.
+ */
+
+/* Hit the asid limit. Start over */
+static int gru_wrap_asid(struct gru_state *gru)
+{
+	gru_dbg(grudev, "gid %d\n", gru->gs_gid);
+	STAT(asid_wrap);
+	gru->gs_asid_gen++;
+	return MIN_ASID;
+}
+
+/* Find the next chunk of unused asids */
+static int gru_reset_asid_limit(struct gru_state *gru, int asid)
+{
+	int i, gid, inuse_asid, limit;
+
+	gru_dbg(grudev, "gid %d, asid 0x%x\n", gru->gs_gid, asid);
+	STAT(asid_next);
+	limit = MAX_ASID;
+	if (asid >= limit)
+		asid = gru_wrap_asid(gru);
+	gru_flush_all_tlb(gru);
+	gid = gru->gs_gid;
+again:
+	for (i = 0; i < GRU_NUM_CCH; i++) {
+		if (!gru->gs_gts[i] || is_kernel_context(gru->gs_gts[i]))
+			continue;
+		inuse_asid = gru->gs_gts[i]->ts_gms->ms_asids[gid].mt_asid;
+		gru_dbg(grudev, "gid %d, gts %p, gms %p, inuse 0x%x, cxt %d\n",
+			gru->gs_gid, gru->gs_gts[i], gru->gs_gts[i]->ts_gms,
+			inuse_asid, i);
+		if (inuse_asid == asid) {
+			asid += ASID_INC;
+			if (asid >= limit) {
+				/*
+				 * empty range: reset the range limit and
+				 * start over
+				 */
+				limit = MAX_ASID;
+				if (asid >= MAX_ASID)
+					asid = gru_wrap_asid(gru);
+				goto again;
+			}
+		}
+
+		if ((inuse_asid > asid) && (inuse_asid < limit))
+			limit = inuse_asid;
+	}
+	gru->gs_asid_limit = limit;
+	gru->gs_asid = asid;
+	gru_dbg(grudev, "gid %d, new asid 0x%x, new_limit 0x%x\n", gru->gs_gid,
+					asid, limit);
+	return asid;
+}
+
+/* Assign a new ASID to a thread context.  */
+static int gru_assign_asid(struct gru_state *gru)
+{
+	int asid;
+
+	gru->gs_asid += ASID_INC;
+	asid = gru->gs_asid;
+	if (asid >= gru->gs_asid_limit)
+		asid = gru_reset_asid_limit(gru, asid);
+
+	gru_dbg(grudev, "gid %d, asid 0x%x\n", gru->gs_gid, asid);
+	return asid;
+}
+
+/*
+ * Clear n bits in a word. Return a word indicating the bits that were cleared.
+ * Optionally, build an array of chars that contain the bit numbers allocated.
+ */
+static unsigned long reserve_resources(unsigned long *p, int n, int mmax,
+				       char *idx)
+{
+	unsigned long bits = 0;
+	int i;
+
+	while (n--) {
+		i = find_first_bit(p, mmax);
+		if (i == mmax)
+			BUG();
+		__clear_bit(i, p);
+		__set_bit(i, &bits);
+		if (idx)
+			*idx++ = i;
+	}
+	return bits;
+}
+
+unsigned long gru_reserve_cb_resources(struct gru_state *gru, int cbr_au_count,
+				       char *cbmap)
+{
+	return reserve_resources(&gru->gs_cbr_map, cbr_au_count, GRU_CBR_AU,
+				 cbmap);
+}
+
+unsigned long gru_reserve_ds_resources(struct gru_state *gru, int dsr_au_count,
+				       char *dsmap)
+{
+	return reserve_resources(&gru->gs_dsr_map, dsr_au_count, GRU_DSR_AU,
+				 dsmap);
+}
+
+static void reserve_gru_resources(struct gru_state *gru,
+				  struct gru_thread_state *gts)
+{
+	gru->gs_active_contexts++;
+	gts->ts_cbr_map =
+	    gru_reserve_cb_resources(gru, gts->ts_cbr_au_count,
+				     gts->ts_cbr_idx);
+	gts->ts_dsr_map =
+	    gru_reserve_ds_resources(gru, gts->ts_dsr_au_count, NULL);
+}
+
+static void free_gru_resources(struct gru_state *gru,
+			       struct gru_thread_state *gts)
+{
+	gru->gs_active_contexts--;
+	gru->gs_cbr_map |= gts->ts_cbr_map;
+	gru->gs_dsr_map |= gts->ts_dsr_map;
+}
+
+/*
+ * Check if a GRU has sufficient free resources to satisfy an allocation
+ * request. Note: GRU locks may or may not be held when this is called. If
+ * not held, recheck after acquiring the appropriate locks.
+ *
+ * Returns 1 if sufficient resources, 0 if not
+ */
+static int check_gru_resources(struct gru_state *gru, int cbr_au_count,
+			       int dsr_au_count, int max_active_contexts)
+{
+	return hweight64(gru->gs_cbr_map) >= cbr_au_count
+		&& hweight64(gru->gs_dsr_map) >= dsr_au_count
+		&& gru->gs_active_contexts < max_active_contexts;
+}
+
+/*
+ * TLB manangment requires tracking all GRU chiplets that have loaded a GSEG
+ * context.
+ */
+static int gru_load_mm_tracker(struct gru_state *gru,
+					struct gru_thread_state *gts)
+{
+	struct gru_mm_struct *gms = gts->ts_gms;
+	struct gru_mm_tracker *asids = &gms->ms_asids[gru->gs_gid];
+	unsigned short ctxbitmap = (1 << gts->ts_ctxnum);
+	int asid;
+
+	spin_lock(&gms->ms_asid_lock);
+	asid = asids->mt_asid;
+
+	spin_lock(&gru->gs_asid_lock);
+	if (asid == 0 || (asids->mt_ctxbitmap == 0 && asids->mt_asid_gen !=
+			  gru->gs_asid_gen)) {
+		asid = gru_assign_asid(gru);
+		asids->mt_asid = asid;
+		asids->mt_asid_gen = gru->gs_asid_gen;
+		STAT(asid_new);
+	} else {
+		STAT(asid_reuse);
+	}
+	spin_unlock(&gru->gs_asid_lock);
+
+	BUG_ON(asids->mt_ctxbitmap & ctxbitmap);
+	asids->mt_ctxbitmap |= ctxbitmap;
+	if (!test_bit(gru->gs_gid, gms->ms_asidmap))
+		__set_bit(gru->gs_gid, gms->ms_asidmap);
+	spin_unlock(&gms->ms_asid_lock);
+
+	gru_dbg(grudev,
+		"gid %d, gts %p, gms %p, ctxnum %d, asid 0x%x, asidmap 0x%lx\n",
+		gru->gs_gid, gts, gms, gts->ts_ctxnum, asid,
+		gms->ms_asidmap[0]);
+	return asid;
+}
+
+static void gru_unload_mm_tracker(struct gru_state *gru,
+					struct gru_thread_state *gts)
+{
+	struct gru_mm_struct *gms = gts->ts_gms;
+	struct gru_mm_tracker *asids;
+	unsigned short ctxbitmap;
+
+	asids = &gms->ms_asids[gru->gs_gid];
+	ctxbitmap = (1 << gts->ts_ctxnum);
+	spin_lock(&gms->ms_asid_lock);
+	spin_lock(&gru->gs_asid_lock);
+	BUG_ON((asids->mt_ctxbitmap & ctxbitmap) != ctxbitmap);
+	asids->mt_ctxbitmap ^= ctxbitmap;
+	gru_dbg(grudev, "gid %d, gts %p, gms %p, ctxnum %d, asidmap 0x%lx\n",
+		gru->gs_gid, gts, gms, gts->ts_ctxnum, gms->ms_asidmap[0]);
+	spin_unlock(&gru->gs_asid_lock);
+	spin_unlock(&gms->ms_asid_lock);
+}
+
+/*
+ * Decrement the reference count on a GTS structure. Free the structure
+ * if the reference count goes to zero.
+ */
+void gts_drop(struct gru_thread_state *gts)
+{
+	if (gts && atomic_dec_return(&gts->ts_refcnt) == 0) {
+		if (gts->ts_gms)
+			gru_drop_mmu_notifier(gts->ts_gms);
+		kfree(gts);
+		STAT(gts_free);
+	}
+}
+
+/*
+ * Locate the GTS structure for the current thread.
+ */
+static struct gru_thread_state *gru_find_current_gts_nolock(struct gru_vma_data
+			    *vdata, int tsid)
+{
+	struct gru_thread_state *gts;
+
+	list_for_each_entry(gts, &vdata->vd_head, ts_next)
+	    if (gts->ts_tsid == tsid)
+		return gts;
+	return NULL;
+}
+
+/*
+ * Allocate a thread state structure.
+ */
+struct gru_thread_state *gru_alloc_gts(struct vm_area_struct *vma,
+		int cbr_au_count, int dsr_au_count,
+		unsigned char tlb_preload_count, int options, int tsid)
+{
+	struct gru_thread_state *gts;
+	struct gru_mm_struct *gms;
+	int bytes;
+
+	bytes = DSR_BYTES(dsr_au_count) + CBR_BYTES(cbr_au_count);
+	bytes += sizeof(struct gru_thread_state);
+	gts = kmalloc(bytes, GFP_KERNEL);
+	if (!gts)
+		return ERR_PTR(-ENOMEM);
+
+	STAT(gts_alloc);
+	memset(gts, 0, sizeof(struct gru_thread_state)); /* zero out header */
+	atomic_set(&gts->ts_refcnt, 1);
+	mutex_init(&gts->ts_ctxlock);
+	gts->ts_cbr_au_count = cbr_au_count;
+	gts->ts_dsr_au_count = dsr_au_count;
+	gts->ts_tlb_preload_count = tlb_preload_count;
+	gts->ts_user_options = options;
+	gts->ts_user_blade_id = -1;
+	gts->ts_user_chiplet_id = -1;
+	gts->ts_tsid = tsid;
+	gts->ts_ctxnum = NULLCTX;
+	gts->ts_tlb_int_select = -1;
+	gts->ts_cch_req_slice = -1;
+	gts->ts_sizeavail = GRU_SIZEAVAIL(PAGE_SHIFT);
+	if (vma) {
+		gts->ts_mm = current->mm;
+		gts->ts_vma = vma;
+		gms = gru_register_mmu_notifier();
+		if (IS_ERR(gms))
+			goto err;
+		gts->ts_gms = gms;
+	}
+
+	gru_dbg(grudev, "alloc gts %p\n", gts);
+	return gts;
+
+err:
+	gts_drop(gts);
+	return ERR_CAST(gms);
+}
+
+/*
+ * Allocate a vma private data structure.
+ */
+struct gru_vma_data *gru_alloc_vma_data(struct vm_area_struct *vma, int tsid)
+{
+	struct gru_vma_data *vdata = NULL;
+
+	vdata = kmalloc(sizeof(*vdata), GFP_KERNEL);
+	if (!vdata)
+		return NULL;
+
+	STAT(vdata_alloc);
+	INIT_LIST_HEAD(&vdata->vd_head);
+	spin_lock_init(&vdata->vd_lock);
+	gru_dbg(grudev, "alloc vdata %p\n", vdata);
+	return vdata;
+}
+
+/*
+ * Find the thread state structure for the current thread.
+ */
+struct gru_thread_state *gru_find_thread_state(struct vm_area_struct *vma,
+					int tsid)
+{
+	struct gru_vma_data *vdata = vma->vm_private_data;
+	struct gru_thread_state *gts;
+
+	spin_lock(&vdata->vd_lock);
+	gts = gru_find_current_gts_nolock(vdata, tsid);
+	spin_unlock(&vdata->vd_lock);
+	gru_dbg(grudev, "vma %p, gts %p\n", vma, gts);
+	return gts;
+}
+
+/*
+ * Allocate a new thread state for a GSEG. Note that races may allow
+ * another thread to race to create a gts.
+ */
+struct gru_thread_state *gru_alloc_thread_state(struct vm_area_struct *vma,
+					int tsid)
+{
+	struct gru_vma_data *vdata = vma->vm_private_data;
+	struct gru_thread_state *gts, *ngts;
+
+	gts = gru_alloc_gts(vma, vdata->vd_cbr_au_count,
+			    vdata->vd_dsr_au_count,
+			    vdata->vd_tlb_preload_count,
+			    vdata->vd_user_options, tsid);
+	if (IS_ERR(gts))
+		return gts;
+
+	spin_lock(&vdata->vd_lock);
+	ngts = gru_find_current_gts_nolock(vdata, tsid);
+	if (ngts) {
+		gts_drop(gts);
+		gts = ngts;
+		STAT(gts_double_allocate);
+	} else {
+		list_add(&gts->ts_next, &vdata->vd_head);
+	}
+	spin_unlock(&vdata->vd_lock);
+	gru_dbg(grudev, "vma %p, gts %p\n", vma, gts);
+	return gts;
+}
+
+/*
+ * Free the GRU context assigned to the thread state.
+ */
+static void gru_free_gru_context(struct gru_thread_state *gts)
+{
+	struct gru_state *gru;
+
+	gru = gts->ts_gru;
+	gru_dbg(grudev, "gts %p, gid %d\n", gts, gru->gs_gid);
+
+	spin_lock(&gru->gs_lock);
+	gru->gs_gts[gts->ts_ctxnum] = NULL;
+	free_gru_resources(gru, gts);
+	BUG_ON(test_bit(gts->ts_ctxnum, &gru->gs_context_map) == 0);
+	__clear_bit(gts->ts_ctxnum, &gru->gs_context_map);
+	gts->ts_ctxnum = NULLCTX;
+	gts->ts_gru = NULL;
+	gts->ts_blade = -1;
+	spin_unlock(&gru->gs_lock);
+
+	gts_drop(gts);
+	STAT(free_context);
+}
+
+/*
+ * Prefetching cachelines help hardware performance.
+ * (Strictly a performance enhancement. Not functionally required).
+ */
+static void prefetch_data(void *p, int num, int stride)
+{
+	while (num-- > 0) {
+		prefetchw(p);
+		p += stride;
+	}
+}
+
+static inline long gru_copy_handle(void *d, void *s)
+{
+	memcpy(d, s, GRU_HANDLE_BYTES);
+	return GRU_HANDLE_BYTES;
+}
+
+static void gru_prefetch_context(void *gseg, void *cb, void *cbe,
+				unsigned long cbrmap, unsigned long length)
+{
+	int i, scr;
+
+	prefetch_data(gseg + GRU_DS_BASE, length / GRU_CACHE_LINE_BYTES,
+		      GRU_CACHE_LINE_BYTES);
+
+	for_each_cbr_in_allocation_map(i, &cbrmap, scr) {
+		prefetch_data(cb, 1, GRU_CACHE_LINE_BYTES);
+		prefetch_data(cbe + i * GRU_HANDLE_STRIDE, 1,
+			      GRU_CACHE_LINE_BYTES);
+		cb += GRU_HANDLE_STRIDE;
+	}
+}
+
+static void gru_load_context_data(void *save, void *grubase, int ctxnum,
+				  unsigned long cbrmap, unsigned long dsrmap,
+				  int data_valid)
+{
+	void *gseg, *cb, *cbe;
+	unsigned long length;
+	int i, scr;
+
+	gseg = grubase + ctxnum * GRU_GSEG_STRIDE;
+	cb = gseg + GRU_CB_BASE;
+	cbe = grubase + GRU_CBE_BASE;
+	length = hweight64(dsrmap) * GRU_DSR_AU_BYTES;
+	gru_prefetch_context(gseg, cb, cbe, cbrmap, length);
+
+	for_each_cbr_in_allocation_map(i, &cbrmap, scr) {
+		if (data_valid) {
+			save += gru_copy_handle(cb, save);
+			save += gru_copy_handle(cbe + i * GRU_HANDLE_STRIDE,
+						save);
+		} else {
+			memset(cb, 0, GRU_CACHE_LINE_BYTES);
+			memset(cbe + i * GRU_HANDLE_STRIDE, 0,
+						GRU_CACHE_LINE_BYTES);
+		}
+		/* Flush CBE to hide race in context restart */
+		mb();
+		gru_flush_cache(cbe + i * GRU_HANDLE_STRIDE);
+		cb += GRU_HANDLE_STRIDE;
+	}
+
+	if (data_valid)
+		memcpy(gseg + GRU_DS_BASE, save, length);
+	else
+		memset(gseg + GRU_DS_BASE, 0, length);
+}
+
+static void gru_unload_context_data(void *save, void *grubase, int ctxnum,
+				    unsigned long cbrmap, unsigned long dsrmap)
+{
+	void *gseg, *cb, *cbe;
+	unsigned long length;
+	int i, scr;
+
+	gseg = grubase + ctxnum * GRU_GSEG_STRIDE;
+	cb = gseg + GRU_CB_BASE;
+	cbe = grubase + GRU_CBE_BASE;
+	length = hweight64(dsrmap) * GRU_DSR_AU_BYTES;
+
+	/* CBEs may not be coherent. Flush them from cache */
+	for_each_cbr_in_allocation_map(i, &cbrmap, scr)
+		gru_flush_cache(cbe + i * GRU_HANDLE_STRIDE);
+	mb();		/* Let the CL flush complete */
+
+	gru_prefetch_context(gseg, cb, cbe, cbrmap, length);
+
+	for_each_cbr_in_allocation_map(i, &cbrmap, scr) {
+		save += gru_copy_handle(save, cb);
+		save += gru_copy_handle(save, cbe + i * GRU_HANDLE_STRIDE);
+		cb += GRU_HANDLE_STRIDE;
+	}
+	memcpy(save, gseg + GRU_DS_BASE, length);
+}
+
+void gru_unload_context(struct gru_thread_state *gts, int savestate)
+{
+	struct gru_state *gru = gts->ts_gru;
+	struct gru_context_configuration_handle *cch;
+	int ctxnum = gts->ts_ctxnum;
+
+	if (!is_kernel_context(gts))
+		zap_vma_ptes(gts->ts_vma, UGRUADDR(gts), GRU_GSEG_PAGESIZE);
+	cch = get_cch(gru->gs_gru_base_vaddr, ctxnum);
+
+	gru_dbg(grudev, "gts %p, cbrmap 0x%lx, dsrmap 0x%lx\n",
+		gts, gts->ts_cbr_map, gts->ts_dsr_map);
+	lock_cch_handle(cch);
+	if (cch_interrupt_sync(cch))
+		BUG();
+
+	if (!is_kernel_context(gts))
+		gru_unload_mm_tracker(gru, gts);
+	if (savestate) {
+		gru_unload_context_data(gts->ts_gdata, gru->gs_gru_base_vaddr,
+					ctxnum, gts->ts_cbr_map,
+					gts->ts_dsr_map);
+		gts->ts_data_valid = 1;
+	}
+
+	if (cch_deallocate(cch))
+		BUG();
+	unlock_cch_handle(cch);
+
+	gru_free_gru_context(gts);
+}
+
+/*
+ * Load a GRU context by copying it from the thread data structure in memory
+ * to the GRU.
+ */
+void gru_load_context(struct gru_thread_state *gts)
+{
+	struct gru_state *gru = gts->ts_gru;
+	struct gru_context_configuration_handle *cch;
+	int i, err, asid, ctxnum = gts->ts_ctxnum;
+
+	cch = get_cch(gru->gs_gru_base_vaddr, ctxnum);
+	lock_cch_handle(cch);
+	cch->tfm_fault_bit_enable =
+	    (gts->ts_user_options == GRU_OPT_MISS_FMM_POLL
+	     || gts->ts_user_options == GRU_OPT_MISS_FMM_INTR);
+	cch->tlb_int_enable = (gts->ts_user_options == GRU_OPT_MISS_FMM_INTR);
+	if (cch->tlb_int_enable) {
+		gts->ts_tlb_int_select = gru_cpu_fault_map_id();
+		cch->tlb_int_select = gts->ts_tlb_int_select;
+	}
+	if (gts->ts_cch_req_slice >= 0) {
+		cch->req_slice_set_enable = 1;
+		cch->req_slice = gts->ts_cch_req_slice;
+	} else {
+		cch->req_slice_set_enable =0;
+	}
+	cch->tfm_done_bit_enable = 0;
+	cch->dsr_allocation_map = gts->ts_dsr_map;
+	cch->cbr_allocation_map = gts->ts_cbr_map;
+
+	if (is_kernel_context(gts)) {
+		cch->unmap_enable = 1;
+		cch->tfm_done_bit_enable = 1;
+		cch->cb_int_enable = 1;
+		cch->tlb_int_select = 0;	/* For now, ints go to cpu 0 */
+	} else {
+		cch->unmap_enable = 0;
+		cch->tfm_done_bit_enable = 0;
+		cch->cb_int_enable = 0;
+		asid = gru_load_mm_tracker(gru, gts);
+		for (i = 0; i < 8; i++) {
+			cch->asid[i] = asid + i;
+			cch->sizeavail[i] = gts->ts_sizeavail;
+		}
+	}
+
+	err = cch_allocate(cch);
+	if (err) {
+		gru_dbg(grudev,
+			"err %d: cch %p, gts %p, cbr 0x%lx, dsr 0x%lx\n",
+			err, cch, gts, gts->ts_cbr_map, gts->ts_dsr_map);
+		BUG();
+	}
+
+	gru_load_context_data(gts->ts_gdata, gru->gs_gru_base_vaddr, ctxnum,
+			gts->ts_cbr_map, gts->ts_dsr_map, gts->ts_data_valid);
+
+	if (cch_start(cch))
+		BUG();
+	unlock_cch_handle(cch);
+
+	gru_dbg(grudev, "gid %d, gts %p, cbrmap 0x%lx, dsrmap 0x%lx, tie %d, tis %d\n",
+		gts->ts_gru->gs_gid, gts, gts->ts_cbr_map, gts->ts_dsr_map,
+		(gts->ts_user_options == GRU_OPT_MISS_FMM_INTR), gts->ts_tlb_int_select);
+}
+
+/*
+ * Update fields in an active CCH:
+ * 	- retarget interrupts on local blade
+ * 	- update sizeavail mask
+ */
+int gru_update_cch(struct gru_thread_state *gts)
+{
+	struct gru_context_configuration_handle *cch;
+	struct gru_state *gru = gts->ts_gru;
+	int i, ctxnum = gts->ts_ctxnum, ret = 0;
+
+	cch = get_cch(gru->gs_gru_base_vaddr, ctxnum);
+
+	lock_cch_handle(cch);
+	if (cch->state == CCHSTATE_ACTIVE) {
+		if (gru->gs_gts[gts->ts_ctxnum] != gts)
+			goto exit;
+		if (cch_interrupt(cch))
+			BUG();
+		for (i = 0; i < 8; i++)
+			cch->sizeavail[i] = gts->ts_sizeavail;
+		gts->ts_tlb_int_select = gru_cpu_fault_map_id();
+		cch->tlb_int_select = gru_cpu_fault_map_id();
+		cch->tfm_fault_bit_enable =
+		  (gts->ts_user_options == GRU_OPT_MISS_FMM_POLL
+		    || gts->ts_user_options == GRU_OPT_MISS_FMM_INTR);
+		if (cch_start(cch))
+			BUG();
+		ret = 1;
+	}
+exit:
+	unlock_cch_handle(cch);
+	return ret;
+}
+
+/*
+ * Update CCH tlb interrupt select. Required when all the following is true:
+ * 	- task's GRU context is loaded into a GRU
+ * 	- task is using interrupt notification for TLB faults
+ * 	- task has migrated to a different cpu on the same blade where
+ * 	  it was previously running.
+ */
+static int gru_retarget_intr(struct gru_thread_state *gts)
+{
+	if (gts->ts_tlb_int_select < 0
+	    || gts->ts_tlb_int_select == gru_cpu_fault_map_id())
+		return 0;
+
+	gru_dbg(grudev, "retarget from %d to %d\n", gts->ts_tlb_int_select,
+		gru_cpu_fault_map_id());
+	return gru_update_cch(gts);
+}
+
+/*
+ * Check if a GRU context is allowed to use a specific chiplet. By default
+ * a context is assigned to any blade-local chiplet. However, users can
+ * override this.
+ * 	Returns 1 if assignment allowed, 0 otherwise
+ */
+static int gru_check_chiplet_assignment(struct gru_state *gru,
+					struct gru_thread_state *gts)
+{
+	int blade_id;
+	int chiplet_id;
+
+	blade_id = gts->ts_user_blade_id;
+	if (blade_id < 0)
+		blade_id = uv_numa_blade_id();
+
+	chiplet_id = gts->ts_user_chiplet_id;
+	return gru->gs_blade_id == blade_id &&
+		(chiplet_id < 0 || chiplet_id == gru->gs_chiplet_id);
+}
+
+/*
+ * Unload the gru context if it is not assigned to the correct blade or
+ * chiplet. Misassignment can occur if the process migrates to a different
+ * blade or if the user changes the selected blade/chiplet.
+ */
+int gru_check_context_placement(struct gru_thread_state *gts)
+{
+	struct gru_state *gru;
+	int ret = 0;
+
+	/*
+	 * If the current task is the context owner, verify that the
+	 * context is correctly placed. This test is skipped for non-owner
+	 * references. Pthread apps use non-owner references to the CBRs.
+	 */
+	gru = gts->ts_gru;
+	/*
+	 * If gru or gts->ts_tgid_owner isn't initialized properly, return
+	 * success to indicate that the caller does not need to unload the
+	 * gru context.The caller is responsible for their inspection and
+	 * reinitialization if needed.
+	 */
+	if (!gru || gts->ts_tgid_owner != current->tgid)
+		return ret;
+
+	if (!gru_check_chiplet_assignment(gru, gts)) {
+		STAT(check_context_unload);
+		ret = -EINVAL;
+	} else if (gru_retarget_intr(gts)) {
+		STAT(check_context_retarget_intr);
+	}
+
+	return ret;
+}
+
+
+/*
+ * Insufficient GRU resources available on the local blade. Steal a context from
+ * a process. This is a hack until a _real_ resource scheduler is written....
+ */
+#define next_ctxnum(n)	((n) <  GRU_NUM_CCH - 2 ? (n) + 1 : 0)
+#define next_gru(b, g)	(((g) < &(b)->bs_grus[GRU_CHIPLETS_PER_BLADE - 1]) ?  \
+				 ((g)+1) : &(b)->bs_grus[0])
+
+static int is_gts_stealable(struct gru_thread_state *gts,
+		struct gru_blade_state *bs)
+{
+	if (is_kernel_context(gts))
+		return down_write_trylock(&bs->bs_kgts_sema);
+	else
+		return mutex_trylock(&gts->ts_ctxlock);
+}
+
+static void gts_stolen(struct gru_thread_state *gts,
+		struct gru_blade_state *bs)
+{
+	if (is_kernel_context(gts)) {
+		up_write(&bs->bs_kgts_sema);
+		STAT(steal_kernel_context);
+	} else {
+		mutex_unlock(&gts->ts_ctxlock);
+		STAT(steal_user_context);
+	}
+}
+
+void gru_steal_context(struct gru_thread_state *gts)
+{
+	struct gru_blade_state *blade;
+	struct gru_state *gru, *gru0;
+	struct gru_thread_state *ngts = NULL;
+	int ctxnum, ctxnum0, flag = 0, cbr, dsr;
+	int blade_id;
+
+	blade_id = gts->ts_user_blade_id;
+	if (blade_id < 0)
+		blade_id = uv_numa_blade_id();
+	cbr = gts->ts_cbr_au_count;
+	dsr = gts->ts_dsr_au_count;
+
+	blade = gru_base[blade_id];
+	spin_lock(&blade->bs_lock);
+
+	ctxnum = next_ctxnum(blade->bs_lru_ctxnum);
+	gru = blade->bs_lru_gru;
+	if (ctxnum == 0)
+		gru = next_gru(blade, gru);
+	blade->bs_lru_gru = gru;
+	blade->bs_lru_ctxnum = ctxnum;
+	ctxnum0 = ctxnum;
+	gru0 = gru;
+	while (1) {
+		if (gru_check_chiplet_assignment(gru, gts)) {
+			if (check_gru_resources(gru, cbr, dsr, GRU_NUM_CCH))
+				break;
+			spin_lock(&gru->gs_lock);
+			for (; ctxnum < GRU_NUM_CCH; ctxnum++) {
+				if (flag && gru == gru0 && ctxnum == ctxnum0)
+					break;
+				ngts = gru->gs_gts[ctxnum];
+				/*
+			 	* We are grabbing locks out of order, so trylock is
+			 	* needed. GTSs are usually not locked, so the odds of
+			 	* success are high. If trylock fails, try to steal a
+			 	* different GSEG.
+			 	*/
+				if (ngts && is_gts_stealable(ngts, blade))
+					break;
+				ngts = NULL;
+			}
+			spin_unlock(&gru->gs_lock);
+			if (ngts || (flag && gru == gru0 && ctxnum == ctxnum0))
+				break;
+		}
+		if (flag && gru == gru0)
+			break;
+		flag = 1;
+		ctxnum = 0;
+		gru = next_gru(blade, gru);
+	}
+	spin_unlock(&blade->bs_lock);
+
+	if (ngts) {
+		gts->ustats.context_stolen++;
+		ngts->ts_steal_jiffies = jiffies;
+		gru_unload_context(ngts, is_kernel_context(ngts) ? 0 : 1);
+		gts_stolen(ngts, blade);
+	} else {
+		STAT(steal_context_failed);
+	}
+	gru_dbg(grudev,
+		"stole gid %d, ctxnum %d from gts %p. Need cb %d, ds %d;"
+		" avail cb %ld, ds %ld\n",
+		gru->gs_gid, ctxnum, ngts, cbr, dsr, hweight64(gru->gs_cbr_map),
+		hweight64(gru->gs_dsr_map));
+}
+
+/*
+ * Assign a gru context.
+ */
+static int gru_assign_context_number(struct gru_state *gru)
+{
+	int ctxnum;
+
+	ctxnum = find_first_zero_bit(&gru->gs_context_map, GRU_NUM_CCH);
+	__set_bit(ctxnum, &gru->gs_context_map);
+	return ctxnum;
+}
+
+/*
+ * Scan the GRUs on the local blade & assign a GRU context.
+ */
+struct gru_state *gru_assign_gru_context(struct gru_thread_state *gts)
+{
+	struct gru_state *gru, *grux;
+	int i, max_active_contexts;
+	int blade_id = gts->ts_user_blade_id;
+
+	if (blade_id < 0)
+		blade_id = uv_numa_blade_id();
+again:
+	gru = NULL;
+	max_active_contexts = GRU_NUM_CCH;
+	for_each_gru_on_blade(grux, blade_id, i) {
+		if (!gru_check_chiplet_assignment(grux, gts))
+			continue;
+		if (check_gru_resources(grux, gts->ts_cbr_au_count,
+					gts->ts_dsr_au_count,
+					max_active_contexts)) {
+			gru = grux;
+			max_active_contexts = grux->gs_active_contexts;
+			if (max_active_contexts == 0)
+				break;
+		}
+	}
+
+	if (gru) {
+		spin_lock(&gru->gs_lock);
+		if (!check_gru_resources(gru, gts->ts_cbr_au_count,
+					 gts->ts_dsr_au_count, GRU_NUM_CCH)) {
+			spin_unlock(&gru->gs_lock);
+			goto again;
+		}
+		reserve_gru_resources(gru, gts);
+		gts->ts_gru = gru;
+		gts->ts_blade = gru->gs_blade_id;
+		gts->ts_ctxnum = gru_assign_context_number(gru);
+		atomic_inc(&gts->ts_refcnt);
+		gru->gs_gts[gts->ts_ctxnum] = gts;
+		spin_unlock(&gru->gs_lock);
+
+		STAT(assign_context);
+		gru_dbg(grudev,
+			"gseg %p, gts %p, gid %d, ctx %d, cbr %d, dsr %d\n",
+			gseg_virtual_address(gts->ts_gru, gts->ts_ctxnum), gts,
+			gts->ts_gru->gs_gid, gts->ts_ctxnum,
+			gts->ts_cbr_au_count, gts->ts_dsr_au_count);
+	} else {
+		gru_dbg(grudev, "failed to allocate a GTS %s\n", "");
+		STAT(assign_context_failed);
+	}
+
+	return gru;
+}
+
+/*
+ * gru_nopage
+ *
+ * Map the user's GRU segment
+ *
+ * 	Note: gru segments alway mmaped on GRU_GSEG_PAGESIZE boundaries.
+ */
+vm_fault_t gru_fault(struct vm_fault *vmf)
+{
+	struct vm_area_struct *vma = vmf->vma;
+	struct gru_thread_state *gts;
+	unsigned long paddr, vaddr;
+	unsigned long expires;
+
+	vaddr = vmf->address;
+	gru_dbg(grudev, "vma %p, vaddr 0x%lx (0x%lx)\n",
+		vma, vaddr, GSEG_BASE(vaddr));
+	STAT(nopfn);
+
+	/* The following check ensures vaddr is a valid address in the VMA */
+	gts = gru_find_thread_state(vma, TSID(vaddr, vma));
+	if (!gts)
+		return VM_FAULT_SIGBUS;
+
+again:
+	mutex_lock(&gts->ts_ctxlock);
+	preempt_disable();
+
+	if (gru_check_context_placement(gts)) {
+		preempt_enable();
+		mutex_unlock(&gts->ts_ctxlock);
+		gru_unload_context(gts, 1);
+		return VM_FAULT_NOPAGE;
+	}
+
+	if (!gts->ts_gru) {
+		STAT(load_user_context);
+		if (!gru_assign_gru_context(gts)) {
+			preempt_enable();
+			mutex_unlock(&gts->ts_ctxlock);
+			set_current_state(TASK_INTERRUPTIBLE);
+			schedule_timeout(GRU_ASSIGN_DELAY);  /* true hack ZZZ */
+			expires = gts->ts_steal_jiffies + GRU_STEAL_DELAY;
+			if (time_before(expires, jiffies))
+				gru_steal_context(gts);
+			goto again;
+		}
+		gru_load_context(gts);
+		paddr = gseg_physical_address(gts->ts_gru, gts->ts_ctxnum);
+		remap_pfn_range(vma, vaddr & ~(GRU_GSEG_PAGESIZE - 1),
+				paddr >> PAGE_SHIFT, GRU_GSEG_PAGESIZE,
+				vma->vm_page_prot);
+	}
+
+	preempt_enable();
+	mutex_unlock(&gts->ts_ctxlock);
+
+	return VM_FAULT_NOPAGE;
+}
+