Revision 89c38422e072bb453e3045b8f1b962a344c3edea authored by John Garry on 08 November 2018, 10:17:03 UTC, committed by Rob Herring on 08 November 2018, 18:44:34 UTC
Currently the NUMA distance map parsing does not validate the distance table for the distance-matrix rules 1-2 in [1]. However the arch NUMA code may enforce some of these rules, but not all. Such is the case for the arm64 port, which does not enforce the rule that the distance between separates nodes cannot equal LOCAL_DISTANCE. The patch adds the following rules validation: - distance of node to self equals LOCAL_DISTANCE - distance of separate nodes > LOCAL_DISTANCE This change avoids a yet-unresolved crash reported in [2]. A note on dealing with symmetrical distances between nodes: Validating symmetrical distances between nodes is difficult. If it were mandated in the bindings that every distance must be recorded in the table, then it would be easy. However, it isn't. In addition to this, it is also possible to record [b, a] distance only (and not [a, b]). So, when processing the table for [b, a], we cannot assert that current distance of [a, b] != [b, a] as invalid, as [a, b] distance may not be present in the table and current distance would be default at REMOTE_DISTANCE. As such, we maintain the policy that we overwrite distance [a, b] = [b, a] for b > a. This policy is different to kernel ACPI SLIT validation, which allows non-symmetrical distances (ACPI spec SLIT rules allow it). However, the distance debug message is dropped as it may be misleading (for a distance which is later overwritten). Some final notes on semantics: - It is implied that it is the responsibility of the arch NUMA code to reset the NUMA distance map for an error in distance map parsing. - It is the responsibility of the FW NUMA topology parsing (whether OF or ACPI) to enforce NUMA distance rules, and not arch NUMA code. [1] Documents/devicetree/bindings/numa.txt [2] https://www.spinics.net/lists/arm-kernel/msg683304.html Cc: stable@vger.kernel.org # 4.7 Signed-off-by: John Garry <john.garry@huawei.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Rob Herring <robh@kernel.org>
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memremap.c
/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright(c) 2015 Intel Corporation. All rights reserved. */
#include <linux/radix-tree.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/pfn_t.h>
#include <linux/io.h>
#include <linux/kasan.h>
#include <linux/mm.h>
#include <linux/memory_hotplug.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/wait_bit.h>
static DEFINE_MUTEX(pgmap_lock);
static RADIX_TREE(pgmap_radix, GFP_KERNEL);
#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
#define SECTION_SIZE (1UL << PA_SECTION_SHIFT)
static unsigned long order_at(struct resource *res, unsigned long pgoff)
{
unsigned long phys_pgoff = PHYS_PFN(res->start) + pgoff;
unsigned long nr_pages, mask;
nr_pages = PHYS_PFN(resource_size(res));
if (nr_pages == pgoff)
return ULONG_MAX;
/*
* What is the largest aligned power-of-2 range available from
* this resource pgoff to the end of the resource range,
* considering the alignment of the current pgoff?
*/
mask = phys_pgoff | rounddown_pow_of_two(nr_pages - pgoff);
if (!mask)
return ULONG_MAX;
return find_first_bit(&mask, BITS_PER_LONG);
}
#define foreach_order_pgoff(res, order, pgoff) \
for (pgoff = 0, order = order_at((res), pgoff); order < ULONG_MAX; \
pgoff += 1UL << order, order = order_at((res), pgoff))
#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
unsigned long addr,
swp_entry_t entry,
unsigned int flags,
pmd_t *pmdp)
{
struct page *page = device_private_entry_to_page(entry);
/*
* The page_fault() callback must migrate page back to system memory
* so that CPU can access it. This might fail for various reasons
* (device issue, device was unsafely unplugged, ...). When such
* error conditions happen, the callback must return VM_FAULT_SIGBUS.
*
* Note that because memory cgroup charges are accounted to the device
* memory, this should never fail because of memory restrictions (but
* allocation of regular system page might still fail because we are
* out of memory).
*
* There is a more in-depth description of what that callback can and
* cannot do, in include/linux/memremap.h
*/
return page->pgmap->page_fault(vma, addr, page, flags, pmdp);
}
EXPORT_SYMBOL(device_private_entry_fault);
#endif /* CONFIG_DEVICE_PRIVATE */
static void pgmap_radix_release(struct resource *res, unsigned long end_pgoff)
{
unsigned long pgoff, order;
mutex_lock(&pgmap_lock);
foreach_order_pgoff(res, order, pgoff) {
if (pgoff >= end_pgoff)
break;
radix_tree_delete(&pgmap_radix, PHYS_PFN(res->start) + pgoff);
}
mutex_unlock(&pgmap_lock);
synchronize_rcu();
}
static unsigned long pfn_first(struct dev_pagemap *pgmap)
{
const struct resource *res = &pgmap->res;
struct vmem_altmap *altmap = &pgmap->altmap;
unsigned long pfn;
pfn = res->start >> PAGE_SHIFT;
if (pgmap->altmap_valid)
pfn += vmem_altmap_offset(altmap);
return pfn;
}
static unsigned long pfn_end(struct dev_pagemap *pgmap)
{
const struct resource *res = &pgmap->res;
return (res->start + resource_size(res)) >> PAGE_SHIFT;
}
static unsigned long pfn_next(unsigned long pfn)
{
if (pfn % 1024 == 0)
cond_resched();
return pfn + 1;
}
#define for_each_device_pfn(pfn, map) \
for (pfn = pfn_first(map); pfn < pfn_end(map); pfn = pfn_next(pfn))
static void devm_memremap_pages_release(void *data)
{
struct dev_pagemap *pgmap = data;
struct device *dev = pgmap->dev;
struct resource *res = &pgmap->res;
resource_size_t align_start, align_size;
unsigned long pfn;
for_each_device_pfn(pfn, pgmap)
put_page(pfn_to_page(pfn));
if (percpu_ref_tryget_live(pgmap->ref)) {
dev_WARN(dev, "%s: page mapping is still live!\n", __func__);
percpu_ref_put(pgmap->ref);
}
/* pages are dead and unused, undo the arch mapping */
align_start = res->start & ~(SECTION_SIZE - 1);
align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
- align_start;
mem_hotplug_begin();
arch_remove_memory(align_start, align_size, pgmap->altmap_valid ?
&pgmap->altmap : NULL);
kasan_remove_zero_shadow(__va(align_start), align_size);
mem_hotplug_done();
untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
pgmap_radix_release(res, -1);
dev_WARN_ONCE(dev, pgmap->altmap.alloc,
"%s: failed to free all reserved pages\n", __func__);
}
/**
* devm_memremap_pages - remap and provide memmap backing for the given resource
* @dev: hosting device for @res
* @pgmap: pointer to a struct dev_pgmap
*
* Notes:
* 1/ At a minimum the res, ref and type members of @pgmap must be initialized
* by the caller before passing it to this function
*
* 2/ The altmap field may optionally be initialized, in which case altmap_valid
* must be set to true
*
* 3/ pgmap.ref must be 'live' on entry and 'dead' before devm_memunmap_pages()
* time (or devm release event). The expected order of events is that ref has
* been through percpu_ref_kill() before devm_memremap_pages_release(). The
* wait for the completion of all references being dropped and
* percpu_ref_exit() must occur after devm_memremap_pages_release().
*
* 4/ res is expected to be a host memory range that could feasibly be
* treated as a "System RAM" range, i.e. not a device mmio range, but
* this is not enforced.
*/
void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
{
resource_size_t align_start, align_size, align_end;
struct vmem_altmap *altmap = pgmap->altmap_valid ?
&pgmap->altmap : NULL;
struct resource *res = &pgmap->res;
unsigned long pfn, pgoff, order;
pgprot_t pgprot = PAGE_KERNEL;
int error, nid, is_ram;
struct dev_pagemap *conflict_pgmap;
align_start = res->start & ~(SECTION_SIZE - 1);
align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
- align_start;
align_end = align_start + align_size - 1;
conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_start), NULL);
if (conflict_pgmap) {
dev_WARN(dev, "Conflicting mapping in same section\n");
put_dev_pagemap(conflict_pgmap);
return ERR_PTR(-ENOMEM);
}
conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL);
if (conflict_pgmap) {
dev_WARN(dev, "Conflicting mapping in same section\n");
put_dev_pagemap(conflict_pgmap);
return ERR_PTR(-ENOMEM);
}
is_ram = region_intersects(align_start, align_size,
IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
if (is_ram == REGION_MIXED) {
WARN_ONCE(1, "%s attempted on mixed region %pr\n",
__func__, res);
return ERR_PTR(-ENXIO);
}
if (is_ram == REGION_INTERSECTS)
return __va(res->start);
if (!pgmap->ref)
return ERR_PTR(-EINVAL);
pgmap->dev = dev;
mutex_lock(&pgmap_lock);
error = 0;
foreach_order_pgoff(res, order, pgoff) {
error = __radix_tree_insert(&pgmap_radix,
PHYS_PFN(res->start) + pgoff, order, pgmap);
if (error) {
dev_err(dev, "%s: failed: %d\n", __func__, error);
break;
}
}
mutex_unlock(&pgmap_lock);
if (error)
goto err_radix;
nid = dev_to_node(dev);
if (nid < 0)
nid = numa_mem_id();
error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(align_start), 0,
align_size);
if (error)
goto err_pfn_remap;
mem_hotplug_begin();
error = kasan_add_zero_shadow(__va(align_start), align_size);
if (error) {
mem_hotplug_done();
goto err_kasan;
}
error = arch_add_memory(nid, align_start, align_size, altmap, false);
if (!error)
move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
align_start >> PAGE_SHIFT,
align_size >> PAGE_SHIFT, altmap);
mem_hotplug_done();
if (error)
goto err_add_memory;
for_each_device_pfn(pfn, pgmap) {
struct page *page = pfn_to_page(pfn);
/*
* ZONE_DEVICE pages union ->lru with a ->pgmap back
* pointer. It is a bug if a ZONE_DEVICE page is ever
* freed or placed on a driver-private list. Seed the
* storage with LIST_POISON* values.
*/
list_del(&page->lru);
page->pgmap = pgmap;
percpu_ref_get(pgmap->ref);
}
devm_add_action(dev, devm_memremap_pages_release, pgmap);
return __va(res->start);
err_add_memory:
kasan_remove_zero_shadow(__va(align_start), align_size);
err_kasan:
untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
err_pfn_remap:
err_radix:
pgmap_radix_release(res, pgoff);
return ERR_PTR(error);
}
EXPORT_SYMBOL(devm_memremap_pages);
unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
{
/* number of pfns from base where pfn_to_page() is valid */
return altmap->reserve + altmap->free;
}
void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
{
altmap->alloc -= nr_pfns;
}
/**
* get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
* @pfn: page frame number to lookup page_map
* @pgmap: optional known pgmap that already has a reference
*
* If @pgmap is non-NULL and covers @pfn it will be returned as-is. If @pgmap
* is non-NULL but does not cover @pfn the reference to it will be released.
*/
struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
struct dev_pagemap *pgmap)
{
resource_size_t phys = PFN_PHYS(pfn);
/*
* In the cached case we're already holding a live reference.
*/
if (pgmap) {
if (phys >= pgmap->res.start && phys <= pgmap->res.end)
return pgmap;
put_dev_pagemap(pgmap);
}
/* fall back to slow path lookup */
rcu_read_lock();
pgmap = radix_tree_lookup(&pgmap_radix, PHYS_PFN(phys));
if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
pgmap = NULL;
rcu_read_unlock();
return pgmap;
}
EXPORT_SYMBOL_GPL(get_dev_pagemap);
#ifdef CONFIG_DEV_PAGEMAP_OPS
DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
EXPORT_SYMBOL(devmap_managed_key);
static atomic_t devmap_enable;
/*
* Toggle the static key for ->page_free() callbacks when dev_pagemap
* pages go idle.
*/
void dev_pagemap_get_ops(void)
{
if (atomic_inc_return(&devmap_enable) == 1)
static_branch_enable(&devmap_managed_key);
}
EXPORT_SYMBOL_GPL(dev_pagemap_get_ops);
void dev_pagemap_put_ops(void)
{
if (atomic_dec_and_test(&devmap_enable))
static_branch_disable(&devmap_managed_key);
}
EXPORT_SYMBOL_GPL(dev_pagemap_put_ops);
void __put_devmap_managed_page(struct page *page)
{
int count = page_ref_dec_return(page);
/*
* If refcount is 1 then page is freed and refcount is stable as nobody
* holds a reference on the page.
*/
if (count == 1) {
/* Clear Active bit in case of parallel mark_page_accessed */
__ClearPageActive(page);
__ClearPageWaiters(page);
mem_cgroup_uncharge(page);
page->pgmap->page_free(page, page->pgmap->data);
} else if (!count)
__put_page(page);
}
EXPORT_SYMBOL(__put_devmap_managed_page);
#endif /* CONFIG_DEV_PAGEMAP_OPS */
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