drivers/misc/sgi-gru/grufault.c - maze/linux - Git at Google

 /*
  * SN Platform GRU Driver
  *
  *              FAULT HANDLER FOR GRU DETECTED TLB MISSES
  *
  * This file contains code that handles TLB misses within the GRU.
  * These misses are reported either via interrupts or user polling of
  * the user CB.
  *
  *  Copyright (c) 2008 Silicon Graphics, Inc.  All Rights Reserved.
  *
  *  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.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  */

 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/spinlock.h>
 #include <linux/mm.h>
 #include <linux/hugetlb.h>
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/uaccess.h>
 #include <asm/pgtable.h>
 #include "gru.h"
 #include "grutables.h"
 #include "grulib.h"
 #include "gru_instructions.h"
 #include <asm/uv/uv_hub.h>

 /*
  * Test if a physical address is a valid GRU GSEG address
  */
 static inline int is_gru_paddr(unsigned long paddr)
 {
 	return paddr >= gru_start_paddr && paddr < gru_end_paddr;
 }

 /*
  * Find the vma of a GRU segment. Caller must hold mmap_sem.
  */
 struct vm_area_struct *gru_find_vma(unsigned long vaddr)
 {
 	struct vm_area_struct *vma;

 	vma = find_vma(current->mm, vaddr);
 	if (vma && vma->vm_start <= vaddr && vma->vm_ops == &gru_vm_ops)
 		return vma;
 	return NULL;
 }

 /*
  * Find and lock the gts that contains the specified user vaddr.
  *
  * Returns:
  * 	- *gts with the mmap_sem locked for read and the GTS locked.
  *	- NULL if vaddr invalid OR is not a valid GSEG vaddr.
  */

 static struct gru_thread_state *gru_find_lock_gts(unsigned long vaddr)
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	struct gru_thread_state *gts = NULL;

 	down_read(&mm->mmap_sem);
 	vma = gru_find_vma(vaddr);
 	if (vma)
 		gts = gru_find_thread_state(vma, TSID(vaddr, vma));
 	if (gts)
 		mutex_lock(&gts->ts_ctxlock);
 	else
 		up_read(&mm->mmap_sem);
 	return gts;
 }

 static struct gru_thread_state *gru_alloc_locked_gts(unsigned long vaddr)
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	struct gru_thread_state *gts = NULL;

 	down_write(&mm->mmap_sem);
 	vma = gru_find_vma(vaddr);
 	if (vma)
 		gts = gru_alloc_thread_state(vma, TSID(vaddr, vma));
 	if (gts) {
 		mutex_lock(&gts->ts_ctxlock);
 		downgrade_write(&mm->mmap_sem);
 	} else {
 		up_write(&mm->mmap_sem);
 	}

 	return gts;
 }

 /*
  * Unlock a GTS that was previously locked with gru_find_lock_gts().
  */
 static void gru_unlock_gts(struct gru_thread_state *gts)
 {
 	mutex_unlock(&gts->ts_ctxlock);
 	up_read(&current->mm->mmap_sem);
 }

 /*
  * Set a CB.istatus to active using a user virtual address. This must be done
  * just prior to a TFH RESTART. The new cb.istatus is an in-cache status ONLY.
  * If the line is evicted, the status may be lost. The in-cache update
  * is necessary to prevent the user from seeing a stale cb.istatus that will
  * change as soon as the TFH restart is complete. Races may cause an
  * occasional failure to clear the cb.istatus, but that is ok.
  *
  * If the cb address is not valid (should not happen, but...), nothing
  * bad will happen.. The get_user()/put_user() will fail but there
  * are no bad side-effects.
  */
 static void gru_cb_set_istatus_active(unsigned long __user *cb)
 {
 	union {
 		struct gru_instruction_bits bits;
 		unsigned long dw;
 	} u;

 	if (cb) {
 		get_user(u.dw, cb);
 		u.bits.istatus = CBS_ACTIVE;
 		put_user(u.dw, cb);
 	}
 }

 /*
  * Convert a interrupt IRQ to a pointer to the GRU GTS that caused the
  * interrupt. Interrupts are always sent to a cpu on the blade that contains the
  * GRU (except for headless blades which are not currently supported). A blade
  * has N grus; a block of N consecutive IRQs is assigned to the GRUs. The IRQ
  * number uniquely identifies the GRU chiplet on the local blade that caused the
  * interrupt. Always called in interrupt context.
  */
 static inline struct gru_state *irq_to_gru(int irq)
 {
 	return &gru_base[uv_numa_blade_id()]->bs_grus[irq - IRQ_GRU];
 }

 /*
  * Read & clear a TFM
  *
  * The GRU has an array of fault maps. A map is private to a cpu
  * Only one cpu will be accessing a cpu's fault map.
  *
  * This function scans the cpu-private fault map & clears all bits that
  * are set. The function returns a bitmap that indicates the bits that
  * were cleared. Note that sense the maps may be updated asynchronously by
  * the GRU, atomic operations must be used to clear bits.
  */
 static void get_clear_fault_map(struct gru_state *gru,
 				struct gru_tlb_fault_map *map)
 {
 	unsigned long i, k;
 	struct gru_tlb_fault_map *tfm;

 	tfm = get_tfm_for_cpu(gru, gru_cpu_fault_map_id());
 	prefetchw(tfm);		/* Helps on hardware, required for emulator */
 	for (i = 0; i < BITS_TO_LONGS(GRU_NUM_CBE); i++) {
 		k = tfm->fault_bits[i];
 		if (k)
 			k = xchg(&tfm->fault_bits[i], 0UL);
 		map->fault_bits[i] = k;
 	}

 	/*
 	 * Not functionally required but helps performance. (Required
 	 * on emulator)
 	 */
 	gru_flush_cache(tfm);
 }

 /*
  * Atomic (interrupt context) & non-atomic (user context) functions to
  * convert a vaddr into a physical address. The size of the page
  * is returned in pageshift.
  * 	returns:
  * 		  0 - successful
  * 		< 0 - error code
  * 		  1 - (atomic only) try again in non-atomic context
  */
 static int non_atomic_pte_lookup(struct vm_area_struct *vma,
 				 unsigned long vaddr, int write,
 				 unsigned long *paddr, int *pageshift)
 {
 	struct page *page;

 	/* ZZZ Need to handle HUGE pages */
 	if (is_vm_hugetlb_page(vma))
 		return -EFAULT;
 	*pageshift = PAGE_SHIFT;
 	if (get_user_pages
 	    (current, current->mm, vaddr, 1, write, 0, &page, NULL) <= 0)
 		return -EFAULT;
 	*paddr = page_to_phys(page);
 	put_page(page);
 	return 0;
 }

 /*
  * atomic_pte_lookup
  *
  * Convert a user virtual address to a physical address
  * Only supports Intel large pages (2MB only) on x86_64.
  *	ZZZ - hugepage support is incomplete
  *
  * NOTE: mmap_sem is already held on entry to this function. This
  * guarantees existence of the page tables.
  */
 static int atomic_pte_lookup(struct vm_area_struct *vma, unsigned long vaddr,
 	int write, unsigned long *paddr, int *pageshift)
 {
 	pgd_t *pgdp;
 	pmd_t *pmdp;
 	pud_t *pudp;
 	pte_t pte;

 	pgdp = pgd_offset(vma->vm_mm, vaddr);
 	if (unlikely(pgd_none(*pgdp)))
 		goto err;

 	pudp = pud_offset(pgdp, vaddr);
 	if (unlikely(pud_none(*pudp)))
 		goto err;

 	pmdp = pmd_offset(pudp, vaddr);
 	if (unlikely(pmd_none(*pmdp)))
 		goto err;
 #ifdef CONFIG_X86_64
 	if (unlikely(pmd_large(*pmdp)))
 		pte = *(pte_t *) pmdp;
 	else
 #endif
 		pte = *pte_offset_kernel(pmdp, vaddr);

 	if (unlikely(!pte_present(pte) ||
 		     (write && (!pte_write(pte) || !pte_dirty(pte)))))
 		return 1;

 	*paddr = pte_pfn(pte) << PAGE_SHIFT;
 	*pageshift = is_vm_hugetlb_page(vma) ? HPAGE_SHIFT : PAGE_SHIFT;
 	return 0;

 err:
 	local_irq_enable();
 	return 1;
 }

 /*
  * Drop a TLB entry into the GRU. The fault is described by info in an TFH.
  *	Input:
  *		cb    Address of user CBR. Null if not running in user context
  * 	Return:
  * 		  0 = dropin, exception, or switch to UPM successful
  * 		  1 = range invalidate active
  * 		< 0 = error code
  *
  */
 static int gru_try_dropin(struct gru_thread_state *gts,
 			  struct gru_tlb_fault_handle *tfh,
 			  unsigned long __user *cb)
 {
 	struct mm_struct *mm = gts->ts_mm;
 	struct vm_area_struct *vma;
 	int pageshift, asid, write, ret;
 	unsigned long paddr, gpa, vaddr;

 	/*
 	 * NOTE: The GRU contains magic hardware that eliminates races between
 	 * TLB invalidates and TLB dropins. If an invalidate occurs
 	 * in the window between reading the TFH and the subsequent TLB dropin,
 	 * the dropin is ignored. This eliminates the need for additional locks.
 	 */

 	/*
 	 * Error if TFH state is IDLE or FMM mode & the user issuing a UPM call.
 	 * Might be a hardware race OR a stupid user. Ignore FMM because FMM
 	 * is a transient state.
 	 */
 	if (tfh->state == TFHSTATE_IDLE)
 		goto failidle;
 	if (tfh->state == TFHSTATE_MISS_FMM && cb)
 		goto failfmm;

 	write = (tfh->cause & TFHCAUSE_TLB_MOD) != 0;
 	vaddr = tfh->missvaddr;
 	asid = tfh->missasid;
 	if (asid == 0)
 		goto failnoasid;

 	rmb();	/* TFH must be cache resident before reading ms_range_active */

 	/*
 	 * TFH is cache resident - at least briefly. Fail the dropin
 	 * if a range invalidate is active.
 	 */
 	if (atomic_read(&gts->ts_gms->ms_range_active))
 		goto failactive;

 	vma = find_vma(mm, vaddr);
 	if (!vma)
 		goto failinval;

 	/*
 	 * Atomic lookup is faster & usually works even if called in non-atomic
 	 * context.
 	 */
 	rmb();	/* Must/check ms_range_active before loading PTEs */
 	ret = atomic_pte_lookup(vma, vaddr, write, &paddr, &pageshift);
 	if (ret) {
 		if (!cb)
 			goto failupm;
 		if (non_atomic_pte_lookup(vma, vaddr, write, &paddr,
 					  &pageshift))
 			goto failinval;
 	}
 	if (is_gru_paddr(paddr))
 		goto failinval;

 	paddr = paddr & ~((1UL << pageshift) - 1);
 	gpa = uv_soc_phys_ram_to_gpa(paddr);
 	gru_cb_set_istatus_active(cb);
 	tfh_write_restart(tfh, gpa, GAA_RAM, vaddr, asid, write,
 			  GRU_PAGESIZE(pageshift));
 	STAT(tlb_dropin);
 	gru_dbg(grudev,
 		"%s: tfh 0x%p, vaddr 0x%lx, asid 0x%x, ps %d, gpa 0x%lx\n",
 		ret ? "non-atomic" : "atomic", tfh, vaddr, asid,
 		pageshift, gpa);
 	return 0;

 failnoasid:
 	/* No asid (delayed unload). */
 	STAT(tlb_dropin_fail_no_asid);
 	gru_dbg(grudev, "FAILED no_asid tfh: 0x%p, vaddr 0x%lx\n", tfh, vaddr);
 	if (!cb)
 		tfh_user_polling_mode(tfh);
 	else
 		gru_flush_cache(tfh);
 	return -EAGAIN;

 failupm:
 	/* Atomic failure switch CBR to UPM */
 	tfh_user_polling_mode(tfh);
 	STAT(tlb_dropin_fail_upm);
 	gru_dbg(grudev, "FAILED upm tfh: 0x%p, vaddr 0x%lx\n", tfh, vaddr);
 	return 1;

 failfmm:
 	/* FMM state on UPM call */
 	STAT(tlb_dropin_fail_fmm);
 	gru_dbg(grudev, "FAILED fmm tfh: 0x%p, state %d\n", tfh, tfh->state);
 	return 0;

 failidle:
 	/* TFH was idle  - no miss pending */
 	gru_flush_cache(tfh);
 	if (cb)
 		gru_flush_cache(cb);
 	STAT(tlb_dropin_fail_idle);
 	gru_dbg(grudev, "FAILED idle tfh: 0x%p, state %d\n", tfh, tfh->state);
 	return 0;

 failinval:
 	/* All errors (atomic & non-atomic) switch CBR to EXCEPTION state */
 	tfh_exception(tfh);
 	STAT(tlb_dropin_fail_invalid);
 	gru_dbg(grudev, "FAILED inval tfh: 0x%p, vaddr 0x%lx\n", tfh, vaddr);
 	return -EFAULT;

 failactive:
 	/* Range invalidate active. Switch to UPM iff atomic */
 	if (!cb)
 		tfh_user_polling_mode(tfh);
 	else
 		gru_flush_cache(tfh);
 	STAT(tlb_dropin_fail_range_active);
 	gru_dbg(grudev, "FAILED range active: tfh 0x%p, vaddr 0x%lx\n",
 		tfh, vaddr);
 	return 1;
 }

 /*
  * Process an external interrupt from the GRU. This interrupt is
  * caused by a TLB miss.
  * Note that this is the interrupt handler that is registered with linux
  * interrupt handlers.
  */
 irqreturn_t gru_intr(int irq, void *dev_id)
 {
 	struct gru_state *gru;
 	struct gru_tlb_fault_map map;
 	struct gru_thread_state *gts;
 	struct gru_tlb_fault_handle *tfh = NULL;
 	int cbrnum, ctxnum;

 	STAT(intr);

 	gru = irq_to_gru(irq);
 	if (!gru) {
 		dev_err(grudev, "GRU: invalid interrupt: cpu %d, irq %d\n",
 			raw_smp_processor_id(), irq);
 		return IRQ_NONE;
 	}
 	get_clear_fault_map(gru, &map);
 	gru_dbg(grudev, "irq %d, gru %x, map 0x%lx\n", irq, gru->gs_gid,
 		map.fault_bits[0]);

 	for_each_cbr_in_tfm(cbrnum, map.fault_bits) {
 		tfh = get_tfh_by_index(gru, cbrnum);
 		prefetchw(tfh);	/* Helps on hdw, required for emulator */

 		/*
 		 * When hardware sets a bit in the faultmap, it implicitly
 		 * locks the GRU context so that it cannot be unloaded.
 		 * The gts cannot change until a TFH start/writestart command
 		 * is issued.
 		 */
 		ctxnum = tfh->ctxnum;
 		gts = gru->gs_gts[ctxnum];

 		/*
 		 * This is running in interrupt context. Trylock the mmap_sem.
 		 * If it fails, retry the fault in user context.
 		 */
 		if (down_read_trylock(&gts->ts_mm->mmap_sem)) {
 			gru_try_dropin(gts, tfh, NULL);
 			up_read(&gts->ts_mm->mmap_sem);
 		} else {
 			tfh_user_polling_mode(tfh);
 		}
 	}
 	return IRQ_HANDLED;
 }


 static int gru_user_dropin(struct gru_thread_state *gts,
 			   struct gru_tlb_fault_handle *tfh,
 			   unsigned long __user *cb)
 {
 	struct gru_mm_struct *gms = gts->ts_gms;
 	int ret;

 	while (1) {
 		wait_event(gms->ms_wait_queue,
 			   atomic_read(&gms->ms_range_active) == 0);
 		prefetchw(tfh);	/* Helps on hdw, required for emulator */
 		ret = gru_try_dropin(gts, tfh, cb);
 		if (ret <= 0)
 			return ret;
 		STAT(call_os_wait_queue);
 	}
 }

 /*
  * This interface is called as a result of a user detecting a "call OS" bit
  * in a user CB. Normally means that a TLB fault has occurred.
  * 	cb - user virtual address of the CB
  */
 int gru_handle_user_call_os(unsigned long cb)
 {
 	struct gru_tlb_fault_handle *tfh;
 	struct gru_thread_state *gts;
 	unsigned long __user *cbp;
 	int ucbnum, cbrnum, ret = -EINVAL;

 	STAT(call_os);
 	gru_dbg(grudev, "address 0x%lx\n", cb);

 	/* sanity check the cb pointer */
 	ucbnum = get_cb_number((void *)cb);
 	if ((cb & (GRU_HANDLE_STRIDE - 1)) || ucbnum >= GRU_NUM_CB)
 		return -EINVAL;
 	cbp = (unsigned long *)cb;

 	gts = gru_find_lock_gts(cb);
 	if (!gts)
 		return -EINVAL;

 	if (ucbnum >= gts->ts_cbr_au_count * GRU_CBR_AU_SIZE) {
 		ret = -EINVAL;
 		goto exit;
 	}

 	/*
 	 * If force_unload is set, the UPM TLB fault is phony. The task
 	 * has migrated to another node and the GSEG must be moved. Just
 	 * unload the context. The task will page fault and assign a new
 	 * context.
 	 */
 	ret = -EAGAIN;
 	cbrnum = thread_cbr_number(gts, ucbnum);
 	if (gts->ts_force_unload) {
 		gru_unload_context(gts, 1);
 	} else if (gts->ts_gru) {
 		tfh = get_tfh_by_index(gts->ts_gru, cbrnum);
 		ret = gru_user_dropin(gts, tfh, cbp);
 	}
 exit:
 	gru_unlock_gts(gts);
 	return ret;
 }

 /*
  * Fetch the exception detail information for a CB that terminated with
  * an exception.
  */
 int gru_get_exception_detail(unsigned long arg)
 {
 	struct control_block_extended_exc_detail excdet;
 	struct gru_control_block_extended *cbe;
 	struct gru_thread_state *gts;
 	int ucbnum, cbrnum, ret;

 	STAT(user_exception);
 	if (copy_from_user(&excdet, (void __user *)arg, sizeof(excdet)))
 		return -EFAULT;

 	gru_dbg(grudev, "address 0x%lx\n", excdet.cb);
 	gts = gru_find_lock_gts(excdet.cb);
 	if (!gts)
 		return -EINVAL;

 	if (gts->ts_gru) {
 		ucbnum = get_cb_number((void *)excdet.cb);
 		cbrnum = thread_cbr_number(gts, ucbnum);
 		cbe = get_cbe_by_index(gts->ts_gru, cbrnum);
 		prefetchw(cbe);		/* Harmless on hardware, required for emulator */
 		excdet.opc = cbe->opccpy;
 		excdet.exopc = cbe->exopccpy;
 		excdet.ecause = cbe->ecause;
 		excdet.exceptdet0 = cbe->idef1upd;
 		excdet.exceptdet1 = cbe->idef3upd;
 		ret = 0;
 	} else {
 		ret = -EAGAIN;
 	}
 	gru_unlock_gts(gts);

 	gru_dbg(grudev, "address 0x%lx, ecause 0x%x\n", excdet.cb,
 		excdet.ecause);
 	if (!ret && copy_to_user((void __user *)arg, &excdet, sizeof(excdet)))
 		ret = -EFAULT;
 	return ret;
 }

 /*
  * User request to unload a context. Content is saved for possible reload.
  */
 int gru_user_unload_context(unsigned long arg)
 {
 	struct gru_thread_state *gts;
 	struct gru_unload_context_req req;

 	STAT(user_unload_context);
 	if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
 		return -EFAULT;

 	gru_dbg(grudev, "gseg 0x%lx\n", req.gseg);

 	gts = gru_find_lock_gts(req.gseg);
 	if (!gts)
 		return -EINVAL;

 	if (gts->ts_gru)
 		gru_unload_context(gts, 1);
 	gru_unlock_gts(gts);

 	return 0;
 }

 /*
  * User request to flush a range of virtual addresses from the GRU TLB
  * (Mainly for testing).
  */
 int gru_user_flush_tlb(unsigned long arg)
 {
 	struct gru_thread_state *gts;
 	struct gru_flush_tlb_req req;

 	STAT(user_flush_tlb);
 	if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
 		return -EFAULT;

 	gru_dbg(grudev, "gseg 0x%lx, vaddr 0x%lx, len 0x%lx\n", req.gseg,
 		req.vaddr, req.len);

 	gts = gru_find_lock_gts(req.gseg);
 	if (!gts)
 		return -EINVAL;

 	gru_flush_tlb_range(gts->ts_gms, req.vaddr, req.vaddr + req.len);
 	gru_unlock_gts(gts);

 	return 0;
 }

 /*
  * Register the current task as the user of the GSEG slice.
  * Needed for TLB fault interrupt targeting.
  */
 int gru_set_task_slice(long address)
 {
 	struct gru_thread_state *gts;

 	STAT(set_task_slice);
 	gru_dbg(grudev, "address 0x%lx\n", address);
 	gts = gru_alloc_locked_gts(address);
 	if (!gts)
 		return -EINVAL;

 	gts->ts_tgid_owner = current->tgid;
 	gru_unlock_gts(gts);

 	return 0;
 }
	/*
	* SN Platform GRU Driver
	*
	* FAULT HANDLER FOR GRU DETECTED TLB MISSES
	*
	* This file contains code that handles TLB misses within the GRU.
	* These misses are reported either via interrupts or user polling of
	* the user CB.
	*
	* Copyright (c) 2008 Silicon Graphics, Inc. All Rights Reserved.
	*
	* 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.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*/

	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/spinlock.h>
	#include <linux/mm.h>
	#include <linux/hugetlb.h>
	#include <linux/device.h>
	#include <linux/io.h>
	#include <linux/uaccess.h>
	#include <asm/pgtable.h>
	#include "gru.h"
	#include "grutables.h"
	#include "grulib.h"
	#include "gru_instructions.h"
	#include <asm/uv/uv_hub.h>

	/*
	* Test if a physical address is a valid GRU GSEG address
	*/
	static inline int is_gru_paddr(unsigned long paddr)
	{
	return paddr >= gru_start_paddr && paddr < gru_end_paddr;
	}

	/*
	* Find the vma of a GRU segment. Caller must hold mmap_sem.
	*/
	struct vm_area_struct *gru_find_vma(unsigned long vaddr)
	{
	struct vm_area_struct *vma;

	vma = find_vma(current->mm, vaddr);
	if (vma && vma->vm_start <= vaddr && vma->vm_ops == &gru_vm_ops)
	return vma;
	return NULL;
	}

	/*
	* Find and lock the gts that contains the specified user vaddr.
	*
	* Returns:
	* - *gts with the mmap_sem locked for read and the GTS locked.
	* - NULL if vaddr invalid OR is not a valid GSEG vaddr.
	*/

	static struct gru_thread_state *gru_find_lock_gts(unsigned long vaddr)
	{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	struct gru_thread_state *gts = NULL;

	down_read(&mm->mmap_sem);
	vma = gru_find_vma(vaddr);
	if (vma)
	gts = gru_find_thread_state(vma, TSID(vaddr, vma));
	if (gts)
	mutex_lock(&gts->ts_ctxlock);
	else
	up_read(&mm->mmap_sem);
	return gts;
	}

	static struct gru_thread_state *gru_alloc_locked_gts(unsigned long vaddr)
	{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	struct gru_thread_state *gts = NULL;

	down_write(&mm->mmap_sem);
	vma = gru_find_vma(vaddr);
	if (vma)
	gts = gru_alloc_thread_state(vma, TSID(vaddr, vma));
	if (gts) {
	mutex_lock(&gts->ts_ctxlock);
	downgrade_write(&mm->mmap_sem);
	} else {
	up_write(&mm->mmap_sem);
	}

	return gts;
	}

	/*
	* Unlock a GTS that was previously locked with gru_find_lock_gts().
	*/
	static void gru_unlock_gts(struct gru_thread_state *gts)
	{
	mutex_unlock(&gts->ts_ctxlock);
	up_read(&current->mm->mmap_sem);
	}

	/*
	* Set a CB.istatus to active using a user virtual address. This must be done
	* just prior to a TFH RESTART. The new cb.istatus is an in-cache status ONLY.
	* If the line is evicted, the status may be lost. The in-cache update
	* is necessary to prevent the user from seeing a stale cb.istatus that will
	* change as soon as the TFH restart is complete. Races may cause an
	* occasional failure to clear the cb.istatus, but that is ok.
	*
	* If the cb address is not valid (should not happen, but...), nothing
	* bad will happen.. The get_user()/put_user() will fail but there
	* are no bad side-effects.
	*/
	static void gru_cb_set_istatus_active(unsigned long __user *cb)
	{
	union {
	struct gru_instruction_bits bits;
	unsigned long dw;
	} u;

	if (cb) {
	get_user(u.dw, cb);
	u.bits.istatus = CBS_ACTIVE;
	put_user(u.dw, cb);
	}
	}

	/*
	* Convert a interrupt IRQ to a pointer to the GRU GTS that caused the
	* interrupt. Interrupts are always sent to a cpu on the blade that contains the
	* GRU (except for headless blades which are not currently supported). A blade
	* has N grus; a block of N consecutive IRQs is assigned to the GRUs. The IRQ
	* number uniquely identifies the GRU chiplet on the local blade that caused the
	* interrupt. Always called in interrupt context.
	*/
	static inline struct gru_state *irq_to_gru(int irq)
	{
	return &gru_base[uv_numa_blade_id()]->bs_grus[irq - IRQ_GRU];
	}

	/*
	* Read & clear a TFM
	*
	* The GRU has an array of fault maps. A map is private to a cpu
	* Only one cpu will be accessing a cpu's fault map.
	*
	* This function scans the cpu-private fault map & clears all bits that
	* are set. The function returns a bitmap that indicates the bits that
	* were cleared. Note that sense the maps may be updated asynchronously by
	* the GRU, atomic operations must be used to clear bits.
	*/
	static void get_clear_fault_map(struct gru_state *gru,
	struct gru_tlb_fault_map *map)
	{
	unsigned long i, k;
	struct gru_tlb_fault_map *tfm;

	tfm = get_tfm_for_cpu(gru, gru_cpu_fault_map_id());
	prefetchw(tfm); /* Helps on hardware, required for emulator */
	for (i = 0; i < BITS_TO_LONGS(GRU_NUM_CBE); i++) {
	k = tfm->fault_bits[i];
	if (k)
	k = xchg(&tfm->fault_bits[i], 0UL);
	map->fault_bits[i] = k;
	}

	/*
	* Not functionally required but helps performance. (Required
	* on emulator)
	*/
	gru_flush_cache(tfm);
	}

	/*
	* Atomic (interrupt context) & non-atomic (user context) functions to
	* convert a vaddr into a physical address. The size of the page
	* is returned in pageshift.
	* returns:
	* 0 - successful
	* < 0 - error code
	* 1 - (atomic only) try again in non-atomic context
	*/
	static int non_atomic_pte_lookup(struct vm_area_struct *vma,
	unsigned long vaddr, int write,
	unsigned long paddr, int pageshift)
	{
	struct page *page;

	/* ZZZ Need to handle HUGE pages */
	if (is_vm_hugetlb_page(vma))
	return -EFAULT;
	*pageshift = PAGE_SHIFT;
	if (get_user_pages
	(current, current->mm, vaddr, 1, write, 0, &page, NULL) <= 0)
	return -EFAULT;
	*paddr = page_to_phys(page);
	put_page(page);
	return 0;
	}

	/*
	* atomic_pte_lookup
	*
	* Convert a user virtual address to a physical address
	* Only supports Intel large pages (2MB only) on x86_64.
	* ZZZ - hugepage support is incomplete
	*
	* NOTE: mmap_sem is already held on entry to this function. This
	* guarantees existence of the page tables.
	*/
	static int atomic_pte_lookup(struct vm_area_struct *vma, unsigned long vaddr,
	int write, unsigned long paddr, int pageshift)
	{
	pgd_t *pgdp;
	pmd_t *pmdp;
	pud_t *pudp;
	pte_t pte;

	pgdp = pgd_offset(vma->vm_mm, vaddr);
	if (unlikely(pgd_none(*pgdp)))
	goto err;

	pudp = pud_offset(pgdp, vaddr);
	if (unlikely(pud_none(*pudp)))
	goto err;

	pmdp = pmd_offset(pudp, vaddr);
	if (unlikely(pmd_none(*pmdp)))
	goto err;
	#ifdef CONFIG_X86_64
	if (unlikely(pmd_large(*pmdp)))
	pte = (pte_t ) pmdp;
	else
	#endif
	pte = *pte_offset_kernel(pmdp, vaddr);

	if (unlikely(!pte_present(pte) \|\|
	(write && (!pte_write(pte) \|\| !pte_dirty(pte)))))
	return 1;

	*paddr = pte_pfn(pte) << PAGE_SHIFT;
	*pageshift = is_vm_hugetlb_page(vma) ? HPAGE_SHIFT : PAGE_SHIFT;
	return 0;

	err:
	local_irq_enable();
	return 1;
	}

	/*
	* Drop a TLB entry into the GRU. The fault is described by info in an TFH.
	* Input:
	* cb Address of user CBR. Null if not running in user context
	* Return:
	* 0 = dropin, exception, or switch to UPM successful
	* 1 = range invalidate active
	* < 0 = error code
	*
	*/
	static int gru_try_dropin(struct gru_thread_state *gts,
	struct gru_tlb_fault_handle *tfh,
	unsigned long __user *cb)
	{
	struct mm_struct *mm = gts->ts_mm;
	struct vm_area_struct *vma;
	int pageshift, asid, write, ret;
	unsigned long paddr, gpa, vaddr;

	/*
	* NOTE: The GRU contains magic hardware that eliminates races between
	* TLB invalidates and TLB dropins. If an invalidate occurs
	* in the window between reading the TFH and the subsequent TLB dropin,
	* the dropin is ignored. This eliminates the need for additional locks.
	*/

	/*
	* Error if TFH state is IDLE or FMM mode & the user issuing a UPM call.
	* Might be a hardware race OR a stupid user. Ignore FMM because FMM
	* is a transient state.
	*/
	if (tfh->state == TFHSTATE_IDLE)
	goto failidle;
	if (tfh->state == TFHSTATE_MISS_FMM && cb)
	goto failfmm;

	write = (tfh->cause & TFHCAUSE_TLB_MOD) != 0;
	vaddr = tfh->missvaddr;
	asid = tfh->missasid;
	if (asid == 0)
	goto failnoasid;

	rmb(); /* TFH must be cache resident before reading ms_range_active */

	/*
	* TFH is cache resident - at least briefly. Fail the dropin
	* if a range invalidate is active.
	*/
	if (atomic_read(&gts->ts_gms->ms_range_active))
	goto failactive;

	vma = find_vma(mm, vaddr);
	if (!vma)
	goto failinval;

	/*
	* Atomic lookup is faster & usually works even if called in non-atomic
	* context.
	*/
	rmb(); /* Must/check ms_range_active before loading PTEs */
	ret = atomic_pte_lookup(vma, vaddr, write, &paddr, &pageshift);
	if (ret) {
	if (!cb)
	goto failupm;
	if (non_atomic_pte_lookup(vma, vaddr, write, &paddr,
	&pageshift))
	goto failinval;
	}
	if (is_gru_paddr(paddr))
	goto failinval;

	paddr = paddr & ~((1UL << pageshift) - 1);
	gpa = uv_soc_phys_ram_to_gpa(paddr);
	gru_cb_set_istatus_active(cb);
	tfh_write_restart(tfh, gpa, GAA_RAM, vaddr, asid, write,
	GRU_PAGESIZE(pageshift));
	STAT(tlb_dropin);
	gru_dbg(grudev,
	"%s: tfh 0x%p, vaddr 0x%lx, asid 0x%x, ps %d, gpa 0x%lx\n",
	ret ? "non-atomic" : "atomic", tfh, vaddr, asid,
	pageshift, gpa);
	return 0;

	failnoasid:
	/* No asid (delayed unload). */
	STAT(tlb_dropin_fail_no_asid);
	gru_dbg(grudev, "FAILED no_asid tfh: 0x%p, vaddr 0x%lx\n", tfh, vaddr);
	if (!cb)
	tfh_user_polling_mode(tfh);
	else
	gru_flush_cache(tfh);
	return -EAGAIN;

	failupm:
	/* Atomic failure switch CBR to UPM */
	tfh_user_polling_mode(tfh);
	STAT(tlb_dropin_fail_upm);
	gru_dbg(grudev, "FAILED upm tfh: 0x%p, vaddr 0x%lx\n", tfh, vaddr);
	return 1;

	failfmm:
	/* FMM state on UPM call */
	STAT(tlb_dropin_fail_fmm);
	gru_dbg(grudev, "FAILED fmm tfh: 0x%p, state %d\n", tfh, tfh->state);
	return 0;

	failidle:
	/* TFH was idle - no miss pending */
	gru_flush_cache(tfh);
	if (cb)
	gru_flush_cache(cb);
	STAT(tlb_dropin_fail_idle);
	gru_dbg(grudev, "FAILED idle tfh: 0x%p, state %d\n", tfh, tfh->state);
	return 0;

	failinval:
	/* All errors (atomic & non-atomic) switch CBR to EXCEPTION state */
	tfh_exception(tfh);
	STAT(tlb_dropin_fail_invalid);
	gru_dbg(grudev, "FAILED inval tfh: 0x%p, vaddr 0x%lx\n", tfh, vaddr);
	return -EFAULT;

	failactive:
	/* Range invalidate active. Switch to UPM iff atomic */
	if (!cb)
	tfh_user_polling_mode(tfh);
	else
	gru_flush_cache(tfh);
	STAT(tlb_dropin_fail_range_active);
	gru_dbg(grudev, "FAILED range active: tfh 0x%p, vaddr 0x%lx\n",
	tfh, vaddr);
	return 1;
	}

	/*
	* Process an external interrupt from the GRU. This interrupt is
	* caused by a TLB miss.
	* Note that this is the interrupt handler that is registered with linux
	* interrupt handlers.
	*/
	irqreturn_t gru_intr(int irq, void *dev_id)
	{
	struct gru_state *gru;
	struct gru_tlb_fault_map map;
	struct gru_thread_state *gts;
	struct gru_tlb_fault_handle *tfh = NULL;
	int cbrnum, ctxnum;

	STAT(intr);

	gru = irq_to_gru(irq);
	if (!gru) {
	dev_err(grudev, "GRU: invalid interrupt: cpu %d, irq %d\n",
	raw_smp_processor_id(), irq);
	return IRQ_NONE;
	}
	get_clear_fault_map(gru, &map);
	gru_dbg(grudev, "irq %d, gru %x, map 0x%lx\n", irq, gru->gs_gid,
	map.fault_bits[0]);

	for_each_cbr_in_tfm(cbrnum, map.fault_bits) {
	tfh = get_tfh_by_index(gru, cbrnum);
	prefetchw(tfh); /* Helps on hdw, required for emulator */

	/*
	* When hardware sets a bit in the faultmap, it implicitly
	* locks the GRU context so that it cannot be unloaded.
	* The gts cannot change until a TFH start/writestart command
	* is issued.
	*/
	ctxnum = tfh->ctxnum;
	gts = gru->gs_gts[ctxnum];

	/*
	* This is running in interrupt context. Trylock the mmap_sem.
	* If it fails, retry the fault in user context.
	*/
	if (down_read_trylock(&gts->ts_mm->mmap_sem)) {
	gru_try_dropin(gts, tfh, NULL);
	up_read(&gts->ts_mm->mmap_sem);
	} else {
	tfh_user_polling_mode(tfh);
	}
	}
	return IRQ_HANDLED;
	}


	static int gru_user_dropin(struct gru_thread_state *gts,
	struct gru_tlb_fault_handle *tfh,
	unsigned long __user *cb)
	{
	struct gru_mm_struct *gms = gts->ts_gms;
	int ret;

	while (1) {
	wait_event(gms->ms_wait_queue,
	atomic_read(&gms->ms_range_active) == 0);
	prefetchw(tfh); /* Helps on hdw, required for emulator */
	ret = gru_try_dropin(gts, tfh, cb);
	if (ret <= 0)
	return ret;
	STAT(call_os_wait_queue);
	}
	}

	/*
	* This interface is called as a result of a user detecting a "call OS" bit
	* in a user CB. Normally means that a TLB fault has occurred.
	* cb - user virtual address of the CB
	*/
	int gru_handle_user_call_os(unsigned long cb)
	{
	struct gru_tlb_fault_handle *tfh;
	struct gru_thread_state *gts;
	unsigned long __user *cbp;
	int ucbnum, cbrnum, ret = -EINVAL;

	STAT(call_os);
	gru_dbg(grudev, "address 0x%lx\n", cb);

	/* sanity check the cb pointer */
	ucbnum = get_cb_number((void *)cb);
	if ((cb & (GRU_HANDLE_STRIDE - 1)) \|\| ucbnum >= GRU_NUM_CB)
	return -EINVAL;
	cbp = (unsigned long *)cb;

	gts = gru_find_lock_gts(cb);
	if (!gts)
	return -EINVAL;

	if (ucbnum >= gts->ts_cbr_au_count * GRU_CBR_AU_SIZE) {
	ret = -EINVAL;
	goto exit;
	}

	/*
	* If force_unload is set, the UPM TLB fault is phony. The task
	* has migrated to another node and the GSEG must be moved. Just
	* unload the context. The task will page fault and assign a new
	* context.
	*/
	ret = -EAGAIN;
	cbrnum = thread_cbr_number(gts, ucbnum);
	if (gts->ts_force_unload) {
	gru_unload_context(gts, 1);
	} else if (gts->ts_gru) {
	tfh = get_tfh_by_index(gts->ts_gru, cbrnum);
	ret = gru_user_dropin(gts, tfh, cbp);
	}
	exit:
	gru_unlock_gts(gts);
	return ret;
	}

	/*
	* Fetch the exception detail information for a CB that terminated with
	* an exception.
	*/
	int gru_get_exception_detail(unsigned long arg)
	{
	struct control_block_extended_exc_detail excdet;
	struct gru_control_block_extended *cbe;
	struct gru_thread_state *gts;
	int ucbnum, cbrnum, ret;

	STAT(user_exception);
	if (copy_from_user(&excdet, (void __user *)arg, sizeof(excdet)))
	return -EFAULT;

	gru_dbg(grudev, "address 0x%lx\n", excdet.cb);
	gts = gru_find_lock_gts(excdet.cb);
	if (!gts)
	return -EINVAL;

	if (gts->ts_gru) {
	ucbnum = get_cb_number((void *)excdet.cb);
	cbrnum = thread_cbr_number(gts, ucbnum);
	cbe = get_cbe_by_index(gts->ts_gru, cbrnum);
	prefetchw(cbe); /* Harmless on hardware, required for emulator */
	excdet.opc = cbe->opccpy;
	excdet.exopc = cbe->exopccpy;
	excdet.ecause = cbe->ecause;
	excdet.exceptdet0 = cbe->idef1upd;
	excdet.exceptdet1 = cbe->idef3upd;
	ret = 0;
	} else {
	ret = -EAGAIN;
	}
	gru_unlock_gts(gts);

	gru_dbg(grudev, "address 0x%lx, ecause 0x%x\n", excdet.cb,
	excdet.ecause);
	if (!ret && copy_to_user((void __user *)arg, &excdet, sizeof(excdet)))
	ret = -EFAULT;
	return ret;
	}

	/*
	* User request to unload a context. Content is saved for possible reload.
	*/
	int gru_user_unload_context(unsigned long arg)
	{
	struct gru_thread_state *gts;
	struct gru_unload_context_req req;

	STAT(user_unload_context);
	if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
	return -EFAULT;

	gru_dbg(grudev, "gseg 0x%lx\n", req.gseg);

	gts = gru_find_lock_gts(req.gseg);
	if (!gts)
	return -EINVAL;

	if (gts->ts_gru)
	gru_unload_context(gts, 1);
	gru_unlock_gts(gts);

	return 0;
	}

	/*
	* User request to flush a range of virtual addresses from the GRU TLB
	* (Mainly for testing).
	*/
	int gru_user_flush_tlb(unsigned long arg)
	{
	struct gru_thread_state *gts;
	struct gru_flush_tlb_req req;

	STAT(user_flush_tlb);
	if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
	return -EFAULT;

	gru_dbg(grudev, "gseg 0x%lx, vaddr 0x%lx, len 0x%lx\n", req.gseg,
	req.vaddr, req.len);

	gts = gru_find_lock_gts(req.gseg);
	if (!gts)
	return -EINVAL;

	gru_flush_tlb_range(gts->ts_gms, req.vaddr, req.vaddr + req.len);
	gru_unlock_gts(gts);

	return 0;
	}

	/*
	* Register the current task as the user of the GSEG slice.
	* Needed for TLB fault interrupt targeting.
	*/
	int gru_set_task_slice(long address)
	{
	struct gru_thread_state *gts;

	STAT(set_task_slice);
	gru_dbg(grudev, "address 0x%lx\n", address);
	gts = gru_alloc_locked_gts(address);
	if (!gts)
	return -EINVAL;

	gts->ts_tgid_owner = current->tgid;
	gru_unlock_gts(gts);

	return 0;
	}