arch/tile/mm/homecache.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright 2010 Tilera Corporation. 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, version 2.
  *
  *   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, GOOD TITLE or
  *   NON INFRINGEMENT.  See the GNU General Public License for
  *   more details.
  *
  * This code maintains the "home" for each page in the system.
  */

 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/spinlock.h>
 #include <linux/list.h>
 #include <linux/bootmem.h>
 #include <linux/rmap.h>
 #include <linux/pagemap.h>
 #include <linux/mutex.h>
 #include <linux/interrupt.h>
 #include <linux/sysctl.h>
 #include <linux/pagevec.h>
 #include <linux/ptrace.h>
 #include <linux/timex.h>
 #include <linux/cache.h>
 #include <linux/smp.h>
 #include <linux/module.h>

 #include <asm/page.h>
 #include <asm/sections.h>
 #include <asm/tlbflush.h>
 #include <asm/pgalloc.h>
 #include <asm/homecache.h>

 #include <arch/sim.h>

 #include "migrate.h"


 #if CHIP_HAS_COHERENT_LOCAL_CACHE()

 /*
  * The noallocl2 option suppresses all use of the L2 cache to cache
  * locally from a remote home.  There's no point in using it if we
  * don't have coherent local caching, though.
  */
 static int __write_once noallocl2;
 static int __init set_noallocl2(char *str)
 {
 	noallocl2 = 1;
 	return 0;
 }
 early_param("noallocl2", set_noallocl2);

 #else

 #define noallocl2 0

 #endif

 /* Provide no-op versions of these routines to keep flush_remote() cleaner. */
 #define mark_caches_evicted_start() 0
 #define mark_caches_evicted_finish(mask, timestamp) do {} while (0)


 /*
  * Update the irq_stat for cpus that we are going to interrupt
  * with TLB or cache flushes.  Also handle removing dataplane cpus
  * from the TLB flush set, and setting dataplane_tlb_state instead.
  */
 static void hv_flush_update(const struct cpumask *cache_cpumask,
 			    struct cpumask *tlb_cpumask,
 			    unsigned long tlb_va, unsigned long tlb_length,
 			    HV_Remote_ASID *asids, int asidcount)
 {
 	struct cpumask mask;
 	int i, cpu;

 	cpumask_clear(&mask);
 	if (cache_cpumask)
 		cpumask_or(&mask, &mask, cache_cpumask);
 	if (tlb_cpumask && tlb_length) {
 		cpumask_or(&mask, &mask, tlb_cpumask);
 	}

 	for (i = 0; i < asidcount; ++i)
 		cpumask_set_cpu(asids[i].y * smp_width + asids[i].x, &mask);

 	/*
 	 * Don't bother to update atomically; losing a count
 	 * here is not that critical.
 	 */
 	for_each_cpu(cpu, &mask)
 		++per_cpu(irq_stat, cpu).irq_hv_flush_count;
 }

 /*
  * This wrapper function around hv_flush_remote() does several things:
  *
  *  - Provides a return value error-checking panic path, since
  *    there's never any good reason for hv_flush_remote() to fail.
  *  - Accepts a 32-bit PFN rather than a 64-bit PA, which generally
  *    is the type that Linux wants to pass around anyway.
  *  - Centralizes the mark_caches_evicted() handling.
  *  - Canonicalizes that lengths of zero make cpumasks NULL.
  *  - Handles deferring TLB flushes for dataplane tiles.
  *  - Tracks remote interrupts in the per-cpu irq_cpustat_t.
  *
  * Note that we have to wait until the cache flush completes before
  * updating the per-cpu last_cache_flush word, since otherwise another
  * concurrent flush can race, conclude the flush has already
  * completed, and start to use the page while it's still dirty
  * remotely (running concurrently with the actual evict, presumably).
  */
 void flush_remote(unsigned long cache_pfn, unsigned long cache_control,
 		  const struct cpumask *cache_cpumask_orig,
 		  HV_VirtAddr tlb_va, unsigned long tlb_length,
 		  unsigned long tlb_pgsize,
 		  const struct cpumask *tlb_cpumask_orig,
 		  HV_Remote_ASID *asids, int asidcount)
 {
 	int rc;
 	int timestamp = 0;  /* happy compiler */
 	struct cpumask cache_cpumask_copy, tlb_cpumask_copy;
 	struct cpumask *cache_cpumask, *tlb_cpumask;
 	HV_PhysAddr cache_pa;
 	char cache_buf[NR_CPUS*5], tlb_buf[NR_CPUS*5];

 	mb();   /* provided just to simplify "magic hypervisor" mode */

 	/*
 	 * Canonicalize and copy the cpumasks.
 	 */
 	if (cache_cpumask_orig && cache_control) {
 		cpumask_copy(&cache_cpumask_copy, cache_cpumask_orig);
 		cache_cpumask = &cache_cpumask_copy;
 	} else {
 		cpumask_clear(&cache_cpumask_copy);
 		cache_cpumask = NULL;
 	}
 	if (cache_cpumask == NULL)
 		cache_control = 0;
 	if (tlb_cpumask_orig && tlb_length) {
 		cpumask_copy(&tlb_cpumask_copy, tlb_cpumask_orig);
 		tlb_cpumask = &tlb_cpumask_copy;
 	} else {
 		cpumask_clear(&tlb_cpumask_copy);
 		tlb_cpumask = NULL;
 	}

 	hv_flush_update(cache_cpumask, tlb_cpumask, tlb_va, tlb_length,
 			asids, asidcount);
 	cache_pa = (HV_PhysAddr)cache_pfn << PAGE_SHIFT;
 	if (cache_control & HV_FLUSH_EVICT_L2)
 		timestamp = mark_caches_evicted_start();
 	rc = hv_flush_remote(cache_pa, cache_control,
 			     cpumask_bits(cache_cpumask),
 			     tlb_va, tlb_length, tlb_pgsize,
 			     cpumask_bits(tlb_cpumask),
 			     asids, asidcount);
 	if (cache_control & HV_FLUSH_EVICT_L2)
 		mark_caches_evicted_finish(cache_cpumask, timestamp);
 	if (rc == 0)
 		return;
 	cpumask_scnprintf(cache_buf, sizeof(cache_buf), &cache_cpumask_copy);
 	cpumask_scnprintf(tlb_buf, sizeof(tlb_buf), &tlb_cpumask_copy);

 	pr_err("hv_flush_remote(%#llx, %#lx, %p [%s],"
 	       " %#lx, %#lx, %#lx, %p [%s], %p, %d) = %d\n",
 	       cache_pa, cache_control, cache_cpumask, cache_buf,
 	       (unsigned long)tlb_va, tlb_length, tlb_pgsize,
 	       tlb_cpumask, tlb_buf,
 	       asids, asidcount, rc);
 	panic("Unsafe to continue.");
 }

 void homecache_evict(const struct cpumask *mask)
 {
 	flush_remote(0, HV_FLUSH_EVICT_L2, mask, 0, 0, 0, NULL, NULL, 0);
 }

 /* Return a mask of the cpus whose caches currently own these pages. */
 static void homecache_mask(struct page *page, int pages,
 			   struct cpumask *home_mask)
 {
 	int i;
 	cpumask_clear(home_mask);
 	for (i = 0; i < pages; ++i) {
 		int home = page_home(&page[i]);
 		if (home == PAGE_HOME_IMMUTABLE ||
 		    home == PAGE_HOME_INCOHERENT) {
 			cpumask_copy(home_mask, cpu_possible_mask);
 			return;
 		}
 #if CHIP_HAS_CBOX_HOME_MAP()
 		if (home == PAGE_HOME_HASH) {
 			cpumask_or(home_mask, home_mask, &hash_for_home_map);
 			continue;
 		}
 #endif
 		if (home == PAGE_HOME_UNCACHED)
 			continue;
 		BUG_ON(home < 0 || home >= NR_CPUS);
 		cpumask_set_cpu(home, home_mask);
 	}
 }

 /*
  * Return the passed length, or zero if it's long enough that we
  * believe we should evict the whole L2 cache.
  */
 static unsigned long cache_flush_length(unsigned long length)
 {
 	return (length >= CHIP_L2_CACHE_SIZE()) ? HV_FLUSH_EVICT_L2 : length;
 }

 /* Flush a page out of whatever cache(s) it is in. */
 void homecache_flush_cache(struct page *page, int order)
 {
 	int pages = 1 << order;
 	int length = cache_flush_length(pages * PAGE_SIZE);
 	unsigned long pfn = page_to_pfn(page);
 	struct cpumask home_mask;

 	homecache_mask(page, pages, &home_mask);
 	flush_remote(pfn, length, &home_mask, 0, 0, 0, NULL, NULL, 0);
 	sim_validate_lines_evicted(PFN_PHYS(pfn), pages * PAGE_SIZE);
 }


 /* Report the home corresponding to a given PTE. */
 static int pte_to_home(pte_t pte)
 {
 	if (hv_pte_get_nc(pte))
 		return PAGE_HOME_IMMUTABLE;
 	switch (hv_pte_get_mode(pte)) {
 	case HV_PTE_MODE_CACHE_TILE_L3:
 		return get_remote_cache_cpu(pte);
 	case HV_PTE_MODE_CACHE_NO_L3:
 		return PAGE_HOME_INCOHERENT;
 	case HV_PTE_MODE_UNCACHED:
 		return PAGE_HOME_UNCACHED;
 #if CHIP_HAS_CBOX_HOME_MAP()
 	case HV_PTE_MODE_CACHE_HASH_L3:
 		return PAGE_HOME_HASH;
 #endif
 	}
 	panic("Bad PTE %#llx\n", pte.val);
 }

 /* Update the home of a PTE if necessary (can also be used for a pgprot_t). */
 pte_t pte_set_home(pte_t pte, int home)
 {
 	/* Check for non-linear file mapping "PTEs" and pass them through. */
 	if (pte_file(pte))
 		return pte;

 #if CHIP_HAS_MMIO()
 	/* Check for MMIO mappings and pass them through. */
 	if (hv_pte_get_mode(pte) == HV_PTE_MODE_MMIO)
 		return pte;
 #endif


 	/*
 	 * Only immutable pages get NC mappings.  If we have a
 	 * non-coherent PTE, but the underlying page is not
 	 * immutable, it's likely the result of a forced
 	 * caching setting running up against ptrace setting
 	 * the page to be writable underneath.  In this case,
 	 * just keep the PTE coherent.
 	 */
 	if (hv_pte_get_nc(pte) && home != PAGE_HOME_IMMUTABLE) {
 		pte = hv_pte_clear_nc(pte);
 		pr_err("non-immutable page incoherently referenced: %#llx\n",
 		       pte.val);
 	}

 	switch (home) {

 	case PAGE_HOME_UNCACHED:
 		pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED);
 		break;

 	case PAGE_HOME_INCOHERENT:
 		pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
 		break;

 	case PAGE_HOME_IMMUTABLE:
 		/*
 		 * We could home this page anywhere, since it's immutable,
 		 * but by default just home it to follow "hash_default".
 		 */
 		BUG_ON(hv_pte_get_writable(pte));
 		if (pte_get_forcecache(pte)) {
 			/* Upgrade "force any cpu" to "No L3" for immutable. */
 			if (hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_TILE_L3
 			    && pte_get_anyhome(pte)) {
 				pte = hv_pte_set_mode(pte,
 						      HV_PTE_MODE_CACHE_NO_L3);
 			}
 		} else
 #if CHIP_HAS_CBOX_HOME_MAP()
 		if (hash_default)
 			pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3);
 		else
 #endif
 			pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
 		pte = hv_pte_set_nc(pte);
 		break;

 #if CHIP_HAS_CBOX_HOME_MAP()
 	case PAGE_HOME_HASH:
 		pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3);
 		break;
 #endif

 	default:
 		BUG_ON(home < 0 || home >= NR_CPUS ||
 		       !cpu_is_valid_lotar(home));
 		pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_TILE_L3);
 		pte = set_remote_cache_cpu(pte, home);
 		break;
 	}

 #if CHIP_HAS_NC_AND_NOALLOC_BITS()
 	if (noallocl2)
 		pte = hv_pte_set_no_alloc_l2(pte);

 	/* Simplify "no local and no l3" to "uncached" */
 	if (hv_pte_get_no_alloc_l2(pte) && hv_pte_get_no_alloc_l1(pte) &&
 	    hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_NO_L3) {
 		pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED);
 	}
 #endif

 	/* Checking this case here gives a better panic than from the hv. */
 	BUG_ON(hv_pte_get_mode(pte) == 0);

 	return pte;
 }
 EXPORT_SYMBOL(pte_set_home);

 /*
  * The routines in this section are the "static" versions of the normal
  * dynamic homecaching routines; they just set the home cache
  * of a kernel page once, and require a full-chip cache/TLB flush,
  * so they're not suitable for anything but infrequent use.
  */

 #if CHIP_HAS_CBOX_HOME_MAP()
 static inline int initial_page_home(void) { return PAGE_HOME_HASH; }
 #else
 static inline int initial_page_home(void) { return 0; }
 #endif

 int page_home(struct page *page)
 {
 	if (PageHighMem(page)) {
 		return initial_page_home();
 	} else {
 		unsigned long kva = (unsigned long)page_address(page);
 		return pte_to_home(*virt_to_pte(NULL, kva));
 	}
 }

 void homecache_change_page_home(struct page *page, int order, int home)
 {
 	int i, pages = (1 << order);
 	unsigned long kva;

 	BUG_ON(PageHighMem(page));
 	BUG_ON(page_count(page) > 1);
 	BUG_ON(page_mapcount(page) != 0);
 	kva = (unsigned long) page_address(page);
 	flush_remote(0, HV_FLUSH_EVICT_L2, &cpu_cacheable_map,
 		     kva, pages * PAGE_SIZE, PAGE_SIZE, cpu_online_mask,
 		     NULL, 0);

 	for (i = 0; i < pages; ++i, kva += PAGE_SIZE) {
 		pte_t *ptep = virt_to_pte(NULL, kva);
 		pte_t pteval = *ptep;
 		BUG_ON(!pte_present(pteval) || pte_huge(pteval));
 		*ptep = pte_set_home(pteval, home);
 	}
 }

 struct page *homecache_alloc_pages(gfp_t gfp_mask,
 				   unsigned int order, int home)
 {
 	struct page *page;
 	BUG_ON(gfp_mask & __GFP_HIGHMEM);   /* must be lowmem */
 	page = alloc_pages(gfp_mask, order);
 	if (page)
 		homecache_change_page_home(page, order, home);
 	return page;
 }
 EXPORT_SYMBOL(homecache_alloc_pages);

 struct page *homecache_alloc_pages_node(int nid, gfp_t gfp_mask,
 					unsigned int order, int home)
 {
 	struct page *page;
 	BUG_ON(gfp_mask & __GFP_HIGHMEM);   /* must be lowmem */
 	page = alloc_pages_node(nid, gfp_mask, order);
 	if (page)
 		homecache_change_page_home(page, order, home);
 	return page;
 }

 void homecache_free_pages(unsigned long addr, unsigned int order)
 {
 	struct page *page;

 	if (addr == 0)
 		return;

 	VM_BUG_ON(!virt_addr_valid((void *)addr));
 	page = virt_to_page((void *)addr);
 	if (put_page_testzero(page)) {
 		int pages = (1 << order);
 		homecache_change_page_home(page, order, initial_page_home());
 		while (pages--)
 			__free_page(page++);
 	}
 }
	/*
	* Copyright 2010 Tilera Corporation. 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, version 2.
	*
	* 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, GOOD TITLE or
	* NON INFRINGEMENT. See the GNU General Public License for
	* more details.
	*
	* This code maintains the "home" for each page in the system.
	*/

	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/spinlock.h>
	#include <linux/list.h>
	#include <linux/bootmem.h>
	#include <linux/rmap.h>
	#include <linux/pagemap.h>
	#include <linux/mutex.h>
	#include <linux/interrupt.h>
	#include <linux/sysctl.h>
	#include <linux/pagevec.h>
	#include <linux/ptrace.h>
	#include <linux/timex.h>
	#include <linux/cache.h>
	#include <linux/smp.h>
	#include <linux/module.h>

	#include <asm/page.h>
	#include <asm/sections.h>
	#include <asm/tlbflush.h>
	#include <asm/pgalloc.h>
	#include <asm/homecache.h>

	#include <arch/sim.h>

	#include "migrate.h"


	#if CHIP_HAS_COHERENT_LOCAL_CACHE()

	/*
	* The noallocl2 option suppresses all use of the L2 cache to cache
	* locally from a remote home. There's no point in using it if we
	* don't have coherent local caching, though.
	*/
	static int __write_once noallocl2;
	static int __init set_noallocl2(char *str)
	{
	noallocl2 = 1;
	return 0;
	}
	early_param("noallocl2", set_noallocl2);

	#else

	#define noallocl2 0

	#endif

	/* Provide no-op versions of these routines to keep flush_remote() cleaner. */
	#define mark_caches_evicted_start() 0
	#define mark_caches_evicted_finish(mask, timestamp) do {} while (0)


	/*
	* Update the irq_stat for cpus that we are going to interrupt
	* with TLB or cache flushes. Also handle removing dataplane cpus
	* from the TLB flush set, and setting dataplane_tlb_state instead.
	*/
	static void hv_flush_update(const struct cpumask *cache_cpumask,
	struct cpumask *tlb_cpumask,
	unsigned long tlb_va, unsigned long tlb_length,
	HV_Remote_ASID *asids, int asidcount)
	{
	struct cpumask mask;
	int i, cpu;

	cpumask_clear(&mask);
	if (cache_cpumask)
	cpumask_or(&mask, &mask, cache_cpumask);
	if (tlb_cpumask && tlb_length) {
	cpumask_or(&mask, &mask, tlb_cpumask);
	}

	for (i = 0; i < asidcount; ++i)
	cpumask_set_cpu(asids[i].y * smp_width + asids[i].x, &mask);

	/*
	* Don't bother to update atomically; losing a count
	* here is not that critical.
	*/
	for_each_cpu(cpu, &mask)
	++per_cpu(irq_stat, cpu).irq_hv_flush_count;
	}

	/*
	* This wrapper function around hv_flush_remote() does several things:
	*
	* - Provides a return value error-checking panic path, since
	* there's never any good reason for hv_flush_remote() to fail.
	* - Accepts a 32-bit PFN rather than a 64-bit PA, which generally
	* is the type that Linux wants to pass around anyway.
	* - Centralizes the mark_caches_evicted() handling.
	* - Canonicalizes that lengths of zero make cpumasks NULL.
	* - Handles deferring TLB flushes for dataplane tiles.
	* - Tracks remote interrupts in the per-cpu irq_cpustat_t.
	*
	* Note that we have to wait until the cache flush completes before
	* updating the per-cpu last_cache_flush word, since otherwise another
	* concurrent flush can race, conclude the flush has already
	* completed, and start to use the page while it's still dirty
	* remotely (running concurrently with the actual evict, presumably).
	*/
	void flush_remote(unsigned long cache_pfn, unsigned long cache_control,
	const struct cpumask *cache_cpumask_orig,
	HV_VirtAddr tlb_va, unsigned long tlb_length,
	unsigned long tlb_pgsize,
	const struct cpumask *tlb_cpumask_orig,
	HV_Remote_ASID *asids, int asidcount)
	{
	int rc;
	int timestamp = 0; /* happy compiler */
	struct cpumask cache_cpumask_copy, tlb_cpumask_copy;
	struct cpumask cache_cpumask, tlb_cpumask;
	HV_PhysAddr cache_pa;
	char cache_buf[NR_CPUS5], tlb_buf[NR_CPUS5];

	mb(); /* provided just to simplify "magic hypervisor" mode */

	/*
	* Canonicalize and copy the cpumasks.
	*/
	if (cache_cpumask_orig && cache_control) {
	cpumask_copy(&cache_cpumask_copy, cache_cpumask_orig);
	cache_cpumask = &cache_cpumask_copy;
	} else {
	cpumask_clear(&cache_cpumask_copy);
	cache_cpumask = NULL;
	}
	if (cache_cpumask == NULL)
	cache_control = 0;
	if (tlb_cpumask_orig && tlb_length) {
	cpumask_copy(&tlb_cpumask_copy, tlb_cpumask_orig);
	tlb_cpumask = &tlb_cpumask_copy;
	} else {
	cpumask_clear(&tlb_cpumask_copy);
	tlb_cpumask = NULL;
	}

	hv_flush_update(cache_cpumask, tlb_cpumask, tlb_va, tlb_length,
	asids, asidcount);
	cache_pa = (HV_PhysAddr)cache_pfn << PAGE_SHIFT;
	if (cache_control & HV_FLUSH_EVICT_L2)
	timestamp = mark_caches_evicted_start();
	rc = hv_flush_remote(cache_pa, cache_control,
	cpumask_bits(cache_cpumask),
	tlb_va, tlb_length, tlb_pgsize,
	cpumask_bits(tlb_cpumask),
	asids, asidcount);
	if (cache_control & HV_FLUSH_EVICT_L2)
	mark_caches_evicted_finish(cache_cpumask, timestamp);
	if (rc == 0)
	return;
	cpumask_scnprintf(cache_buf, sizeof(cache_buf), &cache_cpumask_copy);
	cpumask_scnprintf(tlb_buf, sizeof(tlb_buf), &tlb_cpumask_copy);

	pr_err("hv_flush_remote(%#llx, %#lx, %p [%s],"
	" %#lx, %#lx, %#lx, %p [%s], %p, %d) = %d\n",
	cache_pa, cache_control, cache_cpumask, cache_buf,
	(unsigned long)tlb_va, tlb_length, tlb_pgsize,
	tlb_cpumask, tlb_buf,
	asids, asidcount, rc);
	panic("Unsafe to continue.");
	}

	void homecache_evict(const struct cpumask *mask)
	{
	flush_remote(0, HV_FLUSH_EVICT_L2, mask, 0, 0, 0, NULL, NULL, 0);
	}

	/* Return a mask of the cpus whose caches currently own these pages. */
	static void homecache_mask(struct page *page, int pages,
	struct cpumask *home_mask)
	{
	int i;
	cpumask_clear(home_mask);
	for (i = 0; i < pages; ++i) {
	int home = page_home(&page[i]);
	if (home == PAGE_HOME_IMMUTABLE \|\|
	home == PAGE_HOME_INCOHERENT) {
	cpumask_copy(home_mask, cpu_possible_mask);
	return;
	}
	#if CHIP_HAS_CBOX_HOME_MAP()
	if (home == PAGE_HOME_HASH) {
	cpumask_or(home_mask, home_mask, &hash_for_home_map);
	continue;
	}
	#endif
	if (home == PAGE_HOME_UNCACHED)
	continue;
	BUG_ON(home < 0 \|\| home >= NR_CPUS);
	cpumask_set_cpu(home, home_mask);
	}
	}

	/*
	* Return the passed length, or zero if it's long enough that we
	* believe we should evict the whole L2 cache.
	*/
	static unsigned long cache_flush_length(unsigned long length)
	{
	return (length >= CHIP_L2_CACHE_SIZE()) ? HV_FLUSH_EVICT_L2 : length;
	}

	/* Flush a page out of whatever cache(s) it is in. */
	void homecache_flush_cache(struct page *page, int order)
	{
	int pages = 1 << order;
	int length = cache_flush_length(pages * PAGE_SIZE);
	unsigned long pfn = page_to_pfn(page);
	struct cpumask home_mask;

	homecache_mask(page, pages, &home_mask);
	flush_remote(pfn, length, &home_mask, 0, 0, 0, NULL, NULL, 0);
	sim_validate_lines_evicted(PFN_PHYS(pfn), pages * PAGE_SIZE);
	}


	/* Report the home corresponding to a given PTE. */
	static int pte_to_home(pte_t pte)
	{
	if (hv_pte_get_nc(pte))
	return PAGE_HOME_IMMUTABLE;
	switch (hv_pte_get_mode(pte)) {
	case HV_PTE_MODE_CACHE_TILE_L3:
	return get_remote_cache_cpu(pte);
	case HV_PTE_MODE_CACHE_NO_L3:
	return PAGE_HOME_INCOHERENT;
	case HV_PTE_MODE_UNCACHED:
	return PAGE_HOME_UNCACHED;
	#if CHIP_HAS_CBOX_HOME_MAP()
	case HV_PTE_MODE_CACHE_HASH_L3:
	return PAGE_HOME_HASH;
	#endif
	}
	panic("Bad PTE %#llx\n", pte.val);
	}

	/* Update the home of a PTE if necessary (can also be used for a pgprot_t). */
	pte_t pte_set_home(pte_t pte, int home)
	{
	/* Check for non-linear file mapping "PTEs" and pass them through. */
	if (pte_file(pte))
	return pte;

	#if CHIP_HAS_MMIO()
	/* Check for MMIO mappings and pass them through. */
	if (hv_pte_get_mode(pte) == HV_PTE_MODE_MMIO)
	return pte;
	#endif


	/*
	* Only immutable pages get NC mappings. If we have a
	* non-coherent PTE, but the underlying page is not
	* immutable, it's likely the result of a forced
	* caching setting running up against ptrace setting
	* the page to be writable underneath. In this case,
	* just keep the PTE coherent.
	*/
	if (hv_pte_get_nc(pte) && home != PAGE_HOME_IMMUTABLE) {
	pte = hv_pte_clear_nc(pte);
	pr_err("non-immutable page incoherently referenced: %#llx\n",
	pte.val);
	}

	switch (home) {

	case PAGE_HOME_UNCACHED:
	pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED);
	break;

	case PAGE_HOME_INCOHERENT:
	pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
	break;

	case PAGE_HOME_IMMUTABLE:
	/*
	* We could home this page anywhere, since it's immutable,
	* but by default just home it to follow "hash_default".
	*/
	BUG_ON(hv_pte_get_writable(pte));
	if (pte_get_forcecache(pte)) {
	/* Upgrade "force any cpu" to "No L3" for immutable. */
	if (hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_TILE_L3
	&& pte_get_anyhome(pte)) {
	pte = hv_pte_set_mode(pte,
	HV_PTE_MODE_CACHE_NO_L3);
	}
	} else
	#if CHIP_HAS_CBOX_HOME_MAP()
	if (hash_default)
	pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3);
	else
	#endif
	pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
	pte = hv_pte_set_nc(pte);
	break;

	#if CHIP_HAS_CBOX_HOME_MAP()
	case PAGE_HOME_HASH:
	pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3);
	break;
	#endif

	default:
	BUG_ON(home < 0 \|\| home >= NR_CPUS \|\|
	!cpu_is_valid_lotar(home));
	pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_TILE_L3);
	pte = set_remote_cache_cpu(pte, home);
	break;
	}

	#if CHIP_HAS_NC_AND_NOALLOC_BITS()
	if (noallocl2)
	pte = hv_pte_set_no_alloc_l2(pte);

	/* Simplify "no local and no l3" to "uncached" */
	if (hv_pte_get_no_alloc_l2(pte) && hv_pte_get_no_alloc_l1(pte) &&
	hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_NO_L3) {
	pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED);
	}
	#endif

	/* Checking this case here gives a better panic than from the hv. */
	BUG_ON(hv_pte_get_mode(pte) == 0);

	return pte;
	}
	EXPORT_SYMBOL(pte_set_home);

	/*
	* The routines in this section are the "static" versions of the normal
	* dynamic homecaching routines; they just set the home cache
	* of a kernel page once, and require a full-chip cache/TLB flush,
	* so they're not suitable for anything but infrequent use.
	*/

	#if CHIP_HAS_CBOX_HOME_MAP()
	static inline int initial_page_home(void) { return PAGE_HOME_HASH; }
	#else
	static inline int initial_page_home(void) { return 0; }
	#endif

	int page_home(struct page *page)
	{
	if (PageHighMem(page)) {
	return initial_page_home();
	} else {
	unsigned long kva = (unsigned long)page_address(page);
	return pte_to_home(*virt_to_pte(NULL, kva));
	}
	}

	void homecache_change_page_home(struct page *page, int order, int home)
	{
	int i, pages = (1 << order);
	unsigned long kva;

	BUG_ON(PageHighMem(page));
	BUG_ON(page_count(page) > 1);
	BUG_ON(page_mapcount(page) != 0);
	kva = (unsigned long) page_address(page);
	flush_remote(0, HV_FLUSH_EVICT_L2, &cpu_cacheable_map,
	kva, pages * PAGE_SIZE, PAGE_SIZE, cpu_online_mask,
	NULL, 0);

	for (i = 0; i < pages; ++i, kva += PAGE_SIZE) {
	pte_t *ptep = virt_to_pte(NULL, kva);
	pte_t pteval = *ptep;
	BUG_ON(!pte_present(pteval) \|\| pte_huge(pteval));
	*ptep = pte_set_home(pteval, home);
	}
	}

	struct page *homecache_alloc_pages(gfp_t gfp_mask,
	unsigned int order, int home)
	{
	struct page *page;
	BUG_ON(gfp_mask & __GFP_HIGHMEM); /* must be lowmem */
	page = alloc_pages(gfp_mask, order);
	if (page)
	homecache_change_page_home(page, order, home);
	return page;
	}
	EXPORT_SYMBOL(homecache_alloc_pages);

	struct page *homecache_alloc_pages_node(int nid, gfp_t gfp_mask,
	unsigned int order, int home)
	{
	struct page *page;
	BUG_ON(gfp_mask & __GFP_HIGHMEM); /* must be lowmem */
	page = alloc_pages_node(nid, gfp_mask, order);
	if (page)
	homecache_change_page_home(page, order, home);
	return page;
	}

	void homecache_free_pages(unsigned long addr, unsigned int order)
	{
	struct page *page;

	if (addr == 0)
	return;

	VM_BUG_ON(!virt_addr_valid((void *)addr));
	page = virt_to_page((void *)addr);
	if (put_page_testzero(page)) {
	int pages = (1 << order);
	homecache_change_page_home(page, order, initial_page_home());
	while (pages--)
	__free_page(page++);
	}
	}