From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f197.google.com (mail-qt0-f197.google.com [209.85.216.197]) by kanga.kvack.org (Postfix) with ESMTP id C86E12803BF for ; Mon, 22 May 2017 12:52:25 -0400 (EDT) Received: by mail-qt0-f197.google.com with SMTP id 25so52498514qtx.11 for ; Mon, 22 May 2017 09:52:25 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id h184si18185621qkc.11.2017.05.22.09.52.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 22 May 2017 09:52:24 -0700 (PDT) From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= Subject: [HMM 09/15] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE v4 Date: Mon, 22 May 2017 12:52:00 -0400 Message-Id: <20170522165206.6284-10-jglisse@redhat.com> In-Reply-To: <20170522165206.6284-1-jglisse@redhat.com> References: <20170522165206.6284-1-jglisse@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: John Hubbard , David Nellans , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Evgeny Baskakov , Mark Hairgrove , Sherry Cheung , Subhash Gutti This introduce a simple struct and associated helpers for device driver to use when hotpluging un-addressable device memory as ZONE_DEVICE. It will find a unuse physical address range and trigger memory hotplug for it which allocates and initialize struct page for the device memory. Changed since v3: - s/device unaddressable/device private/ Changed since v2: - s/SECTION_SIZE/PA_SECTION_SIZE Changed since v1: - change to adapt to new add_pages() helper - make this x86-64 only for now Signed-off-by: JA(C)rA'me Glisse Signed-off-by: Evgeny Baskakov Signed-off-by: John Hubbard Signed-off-by: Mark Hairgrove Signed-off-by: Sherry Cheung Signed-off-by: Subhash Gutti --- include/linux/hmm.h | 114 +++++++++++++++ mm/Kconfig | 9 ++ mm/hmm.c | 414 +++++++++++++++++++++++++++++++++++++++++++++++++++- 3 files changed, 536 insertions(+), 1 deletion(-) diff --git a/include/linux/hmm.h b/include/linux/hmm.h index 248a6e0..0865afd 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -72,6 +72,11 @@ #if IS_ENABLED(CONFIG_HMM) +#include +#include +#include + + struct hmm; /* @@ -322,6 +327,115 @@ int hmm_vma_fault(struct vm_area_struct *vma, #endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */ +#if IS_ENABLED(CONFIG_HMM_DEVMEM) +struct hmm_devmem; + +struct page *hmm_vma_alloc_locked_page(struct vm_area_struct *vma, + unsigned long addr); + +/* + * struct hmm_devmem_ops - callback for ZONE_DEVICE memory events + * + * @free: call when refcount on page reach 1 and thus is no longer use + * @fault: call when there is a page fault to unaddressable memory + */ +struct hmm_devmem_ops { + void (*free)(struct hmm_devmem *devmem, struct page *page); + int (*fault)(struct hmm_devmem *devmem, + struct vm_area_struct *vma, + unsigned long addr, + struct page *page, + unsigned int flags, + pmd_t *pmdp); +}; + +/* + * struct hmm_devmem - track device memory + * + * @completion: completion object for device memory + * @pfn_first: first pfn for this resource (set by hmm_devmem_add()) + * @pfn_last: last pfn for this resource (set by hmm_devmem_add()) + * @resource: IO resource reserved for this chunk of memory + * @pagemap: device page map for that chunk + * @device: device to bind resource to + * @ops: memory operations callback + * @ref: per CPU refcount + * + * This an helper structure for device drivers that do not wish to implement + * the gory details related to hotplugging new memoy and allocating struct + * pages. + * + * Device drivers can directly use ZONE_DEVICE memory on their own if they + * wish to do so. + */ +struct hmm_devmem { + struct completion completion; + unsigned long pfn_first; + unsigned long pfn_last; + struct resource *resource; + struct device *device; + struct dev_pagemap pagemap; + const struct hmm_devmem_ops *ops; + struct percpu_ref ref; +}; + +/* + * To add (hotplug) device memory, HMM assumes that there is no real resource + * that reserves a range in the physical address space (this is intended to be + * use by unaddressable device memory). It will reserve a physical range big + * enough and allocate struct page for it. + * + * The device driver can wrap the hmm_devmem struct inside a private device + * driver struct. The device driver must call hmm_devmem_remove() before the + * device goes away and before freeing the hmm_devmem struct memory. + */ +struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, + struct device *device, + unsigned long size); +void hmm_devmem_remove(struct hmm_devmem *devmem); + +int hmm_devmem_fault_range(struct hmm_devmem *devmem, + struct vm_area_struct *vma, + const struct migrate_vma_ops *ops, + unsigned long *src, + unsigned long *dst, + unsigned long start, + unsigned long addr, + unsigned long end, + void *private); + +/* + * hmm_devmem_page_set_drvdata - set per-page driver data field + * + * @page: pointer to struct page + * @data: driver data value to set + * + * Because page can not be on lru we have an unsigned long that driver can use + * to store a per page field. This just a simple helper to do that. + */ +static inline void hmm_devmem_page_set_drvdata(struct page *page, + unsigned long data) +{ + unsigned long *drvdata = (unsigned long *)&page->pgmap; + + drvdata[1] = data; +} + +/* + * hmm_devmem_page_get_drvdata - get per page driver data field + * + * @page: pointer to struct page + * Return: driver data value + */ +static inline unsigned long hmm_devmem_page_get_drvdata(struct page *page) +{ + unsigned long *drvdata = (unsigned long *)&page->pgmap; + + return drvdata[1]; +} +#endif /* IS_ENABLED(CONFIG_HMM_DEVMEM) */ + + /* Below are for HMM internal use only! Not to be used by device driver! */ void hmm_mm_destroy(struct mm_struct *mm); diff --git a/mm/Kconfig b/mm/Kconfig index d49d816..feb1eb2 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -314,6 +314,15 @@ config HMM_MIRROR page tables (at PAGE_SIZE granularity), and must be able to recover from the resulting potential page faults. +config HMM_DEVMEM + bool "HMM device memory helpers (to leverage ZONE_DEVICE)" + depends on ARCH_HAS_HMM + select HMM + help + HMM devmem is a set of helper routines to leverage the ZONE_DEVICE + feature. This is just to avoid having device drivers to replicating a lot + of boiler plate code. See Documentation/vm/hmm.txt. + config PHYS_ADDR_T_64BIT def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT diff --git a/mm/hmm.c b/mm/hmm.c index ed97051..939a62e 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -23,9 +23,15 @@ #include #include #include +#include +#include #include #include +#include #include +#include + +#define PA_SECTION_SIZE (1UL << PA_SECTION_SHIFT) static const struct mmu_notifier_ops hmm_mmu_notifier_ops; @@ -427,7 +433,15 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, * This is a special swap entry, ignore migration, use * device and report anything else as error. */ - if (is_migration_entry(entry)) { + if (is_device_private_entry(entry)) { + pfns[i] = hmm_pfn_t_from_pfn(swp_offset(entry)); + if (is_write_device_private_entry(entry)) { + pfns[i] |= HMM_PFN_WRITE; + } else if (write_fault) + goto fault; + pfns[i] |= HMM_PFN_DEVICE_UNADDRESSABLE; + pfns[i] |= flag; + } else if (is_migration_entry(entry)) { if (hmm_vma_walk->fault) { pte_unmap(ptep); hmm_vma_walk->last = addr; @@ -721,3 +735,401 @@ int hmm_vma_fault(struct vm_area_struct *vma, } EXPORT_SYMBOL(hmm_vma_fault); #endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */ + + +#if IS_ENABLED(CONFIG_HMM_DEVMEM) +struct page *hmm_vma_alloc_locked_page(struct vm_area_struct *vma, + unsigned long addr) +{ + struct page *page; + + page = alloc_page_vma(GFP_HIGHUSER, vma, addr); + if (!page) + return NULL; + lock_page(page); + return page; +} +EXPORT_SYMBOL(hmm_vma_alloc_locked_page); + + +static void hmm_devmem_ref_release(struct percpu_ref *ref) +{ + struct hmm_devmem *devmem; + + devmem = container_of(ref, struct hmm_devmem, ref); + complete(&devmem->completion); +} + +static void hmm_devmem_ref_exit(void *data) +{ + struct percpu_ref *ref = data; + struct hmm_devmem *devmem; + + devmem = container_of(ref, struct hmm_devmem, ref); + percpu_ref_exit(ref); + devm_remove_action(devmem->device, &hmm_devmem_ref_exit, data); +} + +static void hmm_devmem_ref_kill(void *data) +{ + struct percpu_ref *ref = data; + struct hmm_devmem *devmem; + + devmem = container_of(ref, struct hmm_devmem, ref); + percpu_ref_kill(ref); + wait_for_completion(&devmem->completion); + devm_remove_action(devmem->device, &hmm_devmem_ref_kill, data); +} + +static int hmm_devmem_fault(struct vm_area_struct *vma, + unsigned long addr, + struct page *page, + unsigned int flags, + pmd_t *pmdp) +{ + struct hmm_devmem *devmem = page->pgmap->data; + + return devmem->ops->fault(devmem, vma, addr, page, flags, pmdp); +} + +static void hmm_devmem_free(struct page *page, void *data) +{ + struct hmm_devmem *devmem = data; + + devmem->ops->free(devmem, page); +} + +static DEFINE_MUTEX(hmm_devmem_lock); +static RADIX_TREE(hmm_devmem_radix, GFP_KERNEL); + +static void hmm_devmem_radix_release(struct resource *resource) +{ + resource_size_t key, align_start, align_size, align_end; + + align_start = resource->start & ~(PA_SECTION_SIZE - 1); + align_size = ALIGN(resource_size(resource), PA_SECTION_SIZE); + align_end = align_start + align_size - 1; + + mutex_lock(&hmm_devmem_lock); + for (key = resource->start; + key <= resource->end; + key += PA_SECTION_SIZE) + radix_tree_delete(&hmm_devmem_radix, key >> PA_SECTION_SHIFT); + mutex_unlock(&hmm_devmem_lock); +} + +static void hmm_devmem_release(struct device *dev, void *data) +{ + struct hmm_devmem *devmem = data; + struct resource *resource = devmem->resource; + unsigned long start_pfn, npages; + struct zone *zone; + struct page *page; + + if (percpu_ref_tryget_live(&devmem->ref)) { + dev_WARN(dev, "%s: page mapping is still live!\n", __func__); + percpu_ref_put(&devmem->ref); + } + + /* pages are dead and unused, undo the arch mapping */ + start_pfn = (resource->start & ~(PA_SECTION_SIZE - 1)) >> PAGE_SHIFT; + npages = ALIGN(resource_size(resource), PA_SECTION_SIZE) >> PAGE_SHIFT; + + page = pfn_to_page(start_pfn); + zone = page_zone(page); + + mem_hotplug_begin(); + __remove_pages(zone, start_pfn, npages); + mem_hotplug_done(); + + hmm_devmem_radix_release(resource); +} + +static struct hmm_devmem *hmm_devmem_find(resource_size_t phys) +{ + WARN_ON_ONCE(!rcu_read_lock_held()); + + return radix_tree_lookup(&hmm_devmem_radix, phys >> PA_SECTION_SHIFT); +} + +static int hmm_devmem_pages_create(struct hmm_devmem *devmem) +{ + resource_size_t key, align_start, align_size, align_end; + struct device *device = devmem->device; + int ret, nid, is_ram; + unsigned long pfn; + + align_start = devmem->resource->start & ~(PA_SECTION_SIZE - 1); + align_size = ALIGN(devmem->resource->start + + resource_size(devmem->resource), + PA_SECTION_SIZE) - align_start; + + 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__, devmem->resource); + return -ENXIO; + } + if (is_ram == REGION_INTERSECTS) + return -ENXIO; + + devmem->pagemap.type = MEMORY_DEVICE_PRIVATE; + devmem->pagemap.res = devmem->resource; + devmem->pagemap.page_fault = hmm_devmem_fault; + devmem->pagemap.page_free = hmm_devmem_free; + devmem->pagemap.dev = devmem->device; + devmem->pagemap.ref = &devmem->ref; + devmem->pagemap.data = devmem; + + mutex_lock(&hmm_devmem_lock); + align_end = align_start + align_size - 1; + for (key = align_start; key <= align_end; key += PA_SECTION_SIZE) { + struct hmm_devmem *dup; + + rcu_read_lock(); + dup = hmm_devmem_find(key); + rcu_read_unlock(); + if (dup) { + dev_err(device, "%s: collides with mapping for %s\n", + __func__, dev_name(dup->device)); + mutex_unlock(&hmm_devmem_lock); + ret = -EBUSY; + goto error; + } + ret = radix_tree_insert(&hmm_devmem_radix, + key >> PA_SECTION_SHIFT, + devmem); + if (ret) { + dev_err(device, "%s: failed: %d\n", __func__, ret); + mutex_unlock(&hmm_devmem_lock); + goto error_radix; + } + } + mutex_unlock(&hmm_devmem_lock); + + nid = dev_to_node(device); + if (nid < 0) + nid = numa_mem_id(); + + mem_hotplug_begin(); + ret = add_pages(nid, align_start >> PAGE_SHIFT, + align_size >> PAGE_SHIFT, false); + if (ret) { + mem_hotplug_done(); + goto error_add_memory; + } + move_pfn_range_to_zone(&NODE_DATA(nid)->node_zones[ZONE_DEVICE], + align_start >> PAGE_SHIFT, + align_size >> PAGE_SHIFT); + mem_hotplug_done(); + + for (pfn = devmem->pfn_first; pfn < devmem->pfn_last; pfn++) { + 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. Therefore, + * seed the storage with LIST_POISON* values. + */ + list_del(&page->lru); + page->pgmap = &devmem->pagemap; + } + return 0; + +error_add_memory: + untrack_pfn(NULL, PHYS_PFN(align_start), align_size); +error_radix: + hmm_devmem_radix_release(devmem->resource); +error: + return ret; +} + +static int hmm_devmem_match(struct device *dev, void *data, void *match_data) +{ + struct hmm_devmem *devmem = data; + + return devmem->resource == match_data; +} + +static void hmm_devmem_pages_remove(struct hmm_devmem *devmem) +{ + devres_release(devmem->device, &hmm_devmem_release, + &hmm_devmem_match, devmem->resource); +} + +/* + * hmm_devmem_add() - hotplug ZONE_DEVICE memory for device memory + * + * @ops: memory event device driver callback (see struct hmm_devmem_ops) + * @device: device struct to bind the resource too + * @size: size in bytes of the device memory to add + * Returns: pointer to new hmm_devmem struct ERR_PTR otherwise + * + * This first finds an empty range of physical address big enough to contain the + * new resource, and then hotplugs it as ZONE_DEVICE memory, which in turn + * allocates struct pages. It does not do anything beyond that; all events + * affecting the memory will go through the various callbacks provided by + * hmm_devmem_ops struct. + */ +struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, + struct device *device, + unsigned long size) +{ + struct hmm_devmem *devmem; + resource_size_t addr; + int ret; + + devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem), + GFP_KERNEL, dev_to_node(device)); + if (!devmem) + return ERR_PTR(-ENOMEM); + + init_completion(&devmem->completion); + devmem->pfn_first = -1UL; + devmem->pfn_last = -1UL; + devmem->resource = NULL; + devmem->device = device; + devmem->ops = ops; + + ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release, + 0, GFP_KERNEL); + if (ret) + goto error_percpu_ref; + + ret = devm_add_action(device, hmm_devmem_ref_exit, &devmem->ref); + if (ret) + goto error_devm_add_action; + + size = ALIGN(size, PA_SECTION_SIZE); + addr = min((unsigned long)iomem_resource.end, 1UL << MAX_PHYSMEM_BITS); + addr = addr - size + 1UL; + + /* + * FIXME add a new helper to quickly walk resource tree and find free + * range + * + * FIXME what about ioport_resource resource ? + */ + for (; addr > size && addr >= iomem_resource.start; addr -= size) { + ret = region_intersects(addr, size, 0, IORES_DESC_NONE); + if (ret != REGION_DISJOINT) + continue; + + devmem->resource = devm_request_mem_region(device, addr, size, + dev_name(device)); + if (!devmem->resource) { + ret = -ENOMEM; + goto error_no_resource; + } + break; + } + if (!devmem->resource) { + ret = -ERANGE; + goto error_no_resource; + } + + devmem->resource->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY; + devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT; + devmem->pfn_last = devmem->pfn_first + + (resource_size(devmem->resource) >> PAGE_SHIFT); + + ret = hmm_devmem_pages_create(devmem); + if (ret) + goto error_pages; + + devres_add(device, devmem); + + ret = devm_add_action(device, hmm_devmem_ref_kill, &devmem->ref); + if (ret) { + hmm_devmem_remove(devmem); + return ERR_PTR(ret); + } + + return devmem; + +error_pages: + devm_release_mem_region(device, devmem->resource->start, + resource_size(devmem->resource)); +error_no_resource: +error_devm_add_action: + hmm_devmem_ref_kill(&devmem->ref); + hmm_devmem_ref_exit(&devmem->ref); +error_percpu_ref: + devres_free(devmem); + return ERR_PTR(ret); +} +EXPORT_SYMBOL(hmm_devmem_add); + +/* + * hmm_devmem_remove() - remove device memory (kill and free ZONE_DEVICE) + * + * @devmem: hmm_devmem struct use to track and manage the ZONE_DEVICE memory + * + * This will hot-unplug memory that was hotplugged by hmm_devmem_add on behalf + * of the device driver. It will free struct page and remove the resource that + * reserved the physical address range for this device memory. + */ +void hmm_devmem_remove(struct hmm_devmem *devmem) +{ + resource_size_t start, size; + struct device *device; + + if (!devmem) + return; + + device = devmem->device; + start = devmem->resource->start; + size = resource_size(devmem->resource); + + hmm_devmem_ref_kill(&devmem->ref); + hmm_devmem_ref_exit(&devmem->ref); + hmm_devmem_pages_remove(devmem); + + devm_release_mem_region(device, start, size); +} +EXPORT_SYMBOL(hmm_devmem_remove); + +/* + * hmm_devmem_fault_range() - migrate back a virtual range of memory + * + * @devmem: hmm_devmem struct use to track and manage the ZONE_DEVICE memory + * @vma: virtual memory area containing the range to be migrated + * @ops: migration callback for allocating destination memory and copying + * @src: array of unsigned long containing source pfns + * @dst: array of unsigned long containing destination pfns + * @start: start address of the range to migrate (inclusive) + * @addr: fault address (must be inside the range) + * @end: end address of the range to migrate (exclusive) + * @private: pointer passed back to each of the callback + * Returns: 0 on success, VM_FAULT_SIGBUS on error + * + * This is a wrapper around migrate_vma() which checks the migration status + * for a given fault address and returns the corresponding page fault handler + * status. That will be 0 on success, or VM_FAULT_SIGBUS if migration failed + * for the faulting address. + * + * This is a helper intendend to be used by the ZONE_DEVICE fault handler. + */ +int hmm_devmem_fault_range(struct hmm_devmem *devmem, + struct vm_area_struct *vma, + const struct migrate_vma_ops *ops, + unsigned long *src, + unsigned long *dst, + unsigned long start, + unsigned long addr, + unsigned long end, + void *private) +{ + if (migrate_vma(ops, vma, start, end, src, dst, private)) + return VM_FAULT_SIGBUS; + + if (dst[(addr - start) >> PAGE_SHIFT] & MIGRATE_PFN_ERROR) + return VM_FAULT_SIGBUS; + + return 0; +} +EXPORT_SYMBOL(hmm_devmem_fault_range); +#endif /* IS_ENABLED(CONFIG_HMM_DEVMEM) */ -- 2.9.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org