Break the requirement that device-dax instances are physically contiguous. With this constraint removed it allows fragmented available capacity to be fully allocated.
This capability is useful to mitigate the "noisy neighbor" problem with memory-side-cache management for virtual machines, or any other scenario where a platform address boundary also designates a performance boundary. For example a direct mapped memory side cache might rotate cache colors at 1GB boundaries. With dis-contiguous allocations a device-dax instance could be configured to contain only 1 cache color.
It also satisfies Joao's use case (see link) for partitioning memory for exclusive guest access. It allows for a future potential mode where the host kernel need not allocate 'struct page' capacity up-front.
Link: https://lore.kernel.org/lkml/20200110190313.17144-1-joao.m.martins@oracle.co... Reported-by: Joao Martins joao.m.martins@oracle.com Signed-off-by: Dan Williams dan.j.williams@intel.com --- drivers/dax/bus.c | 230 +++++++++++++++++++++++++++++++--------- drivers/dax/dax-private.h | 9 +- drivers/dax/device.c | 55 ++++++---- drivers/dax/kmem.c | 132 +++++++++++++++-------- tools/testing/nvdimm/dax-dev.c | 20 ++- 5 files changed, 319 insertions(+), 127 deletions(-)
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index 00fa73a8dfb4..f342e36c69a1 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -136,15 +136,27 @@ static bool is_static(struct dax_region *dax_region) return (dax_region->res.flags & IORESOURCE_DAX_STATIC) != 0; }
+static u64 dev_dax_size(struct dev_dax *dev_dax) +{ + u64 size = 0; + int i; + + device_lock_assert(&dev_dax->dev); + + for (i = 0; i < dev_dax->nr_range; i++) + size += range_len(&dev_dax->ranges[i].range); + + return size; +} + static int dax_bus_probe(struct device *dev) { struct dax_device_driver *dax_drv = to_dax_drv(dev->driver); struct dev_dax *dev_dax = to_dev_dax(dev); struct dax_region *dax_region = dev_dax->region; - struct range *range = &dev_dax->range; int rc;
- if (range_len(range) == 0 || dev_dax->id < 0) + if (dev_dax_size(dev_dax) == 0 || dev_dax->id < 0) return -ENXIO;
rc = dax_drv->probe(dev_dax); @@ -354,15 +366,19 @@ void kill_dev_dax(struct dev_dax *dev_dax) } EXPORT_SYMBOL_GPL(kill_dev_dax);
-static void free_dev_dax_range(struct dev_dax *dev_dax) +static void free_dev_dax_ranges(struct dev_dax *dev_dax) { struct dax_region *dax_region = dev_dax->region; - struct range *range = &dev_dax->range; + int i;
device_lock_assert(dax_region->dev); - if (range_len(range)) + for (i = 0; i < dev_dax->nr_range; i++) { + struct range *range = &dev_dax->ranges[i].range; + __release_region(&dax_region->res, range->start, range_len(range)); + } + dev_dax->nr_range = 0; }
static void unregister_dev_dax(void *dev) @@ -372,7 +388,7 @@ static void unregister_dev_dax(void *dev) dev_dbg(dev, "%s\n", __func__);
kill_dev_dax(dev_dax); - free_dev_dax_range(dev_dax); + free_dev_dax_ranges(dev_dax); device_del(dev); put_device(dev); } @@ -423,7 +439,7 @@ static ssize_t delete_store(struct device *dev, struct device_attribute *attr, device_lock(dev); device_lock(victim); dev_dax = to_dev_dax(victim); - if (victim->driver || range_len(&dev_dax->range)) + if (victim->driver || dev_dax_size(dev_dax)) rc = -EBUSY; else { /* @@ -569,51 +585,83 @@ static int alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start, struct dax_region *dax_region = dev_dax->region; struct resource *res = &dax_region->res; struct device *dev = &dev_dax->dev; + struct dev_dax_range *ranges; + unsigned long pgoff = 0; struct resource *alloc; + int i;
device_lock_assert(dax_region->dev);
/* handle the seed alloc special case */ if (!size) { - dev_dax->range = (struct range) { - .start = res->start, - .end = res->start - 1, - }; + if (dev_WARN_ONCE(dev, dev_dax->nr_range, + "0-size allocation must be first\n")) + return -EBUSY; + /* nr_range == 0 is elsewhere special cased as 0-size device */ return 0; }
+ ranges = krealloc(dev_dax->ranges, sizeof(*ranges) + * (dev_dax->nr_range + 1), GFP_KERNEL); + if (!ranges) + return -ENOMEM; + alloc = __request_region(res, start, size, dev_name(dev), 0); - if (!alloc) + if (!alloc && !dev_dax->nr_range) { + /* + * If we adjusted an existing @ranges leave it alone, + * but if this was an empty set of ranges nothing else + * will release @ranges, so do it now. + */ + kfree(ranges); return -ENOMEM; + }
- dev_dax->range = (struct range) { - .start = alloc->start, - .end = alloc->end, + for (i = 0; i < dev_dax->nr_range; i++) + pgoff += PHYS_PFN(range_len(&ranges[i].range)); + dev_dax->ranges = ranges; + ranges[dev_dax->nr_range++] = (struct dev_dax_range) { + .pgoff = pgoff, + .range = { + .start = alloc->start, + .end = alloc->end, + }, };
+ dev_dbg(dev, "alloc range[%d]: %pa:%pa\n", dev_dax->nr_range - 1, + &alloc->start, &alloc->end); + return 0; }
static int adjust_dev_dax_range(struct dev_dax *dev_dax, struct resource *res, resource_size_t size) { + int last_range = dev_dax->nr_range - 1; + struct dev_dax_range *dax_range = &dev_dax->ranges[last_range]; struct dax_region *dax_region = dev_dax->region; - struct range *range = &dev_dax->range; - int rc = 0; + bool is_shrink = resource_size(res) > size; + struct range *range = &dax_range->range; + struct device *dev = &dev_dax->dev; + int rc;
device_lock_assert(dax_region->dev);
- if (size) - rc = adjust_resource(res, range->start, size); - else - __release_region(&dax_region->res, range->start, range_len(range)); + if (dev_WARN_ONCE(dev, !size, "deletion is handled by dev_dax_shrink\n")) + return -EINVAL; + + rc = adjust_resource(res, range->start, size); if (rc) return rc;
- dev_dax->range = (struct range) { + *range = (struct range) { .start = range->start, .end = range->start + size - 1, };
+ dev_dbg(dev, "%s range[%d]: %#llx:%#llx\n", is_shrink ? "shrink" : "extend", + last_range, (unsigned long long) range->start, + (unsigned long long) range->end); + return 0; }
@@ -621,7 +669,11 @@ static ssize_t size_show(struct device *dev, struct device_attribute *attr, char *buf) { struct dev_dax *dev_dax = to_dev_dax(dev); - unsigned long long size = range_len(&dev_dax->range); + unsigned long long size; + + device_lock(dev); + size = dev_dax_size(dev_dax); + device_unlock(dev);
return sprintf(buf, "%llu\n", size); } @@ -639,32 +691,82 @@ static bool alloc_is_aligned(struct dax_region *dax_region,
static int dev_dax_shrink(struct dev_dax *dev_dax, resource_size_t size) { + resource_size_t to_shrink = dev_dax_size(dev_dax) - size; struct dax_region *dax_region = dev_dax->region; - struct range *range = &dev_dax->range; - struct resource *res, *adjust = NULL; struct device *dev = &dev_dax->dev; - - for_each_dax_region_resource(dax_region, res) - if (strcmp(res->name, dev_name(dev)) == 0 - && res->start == range->start) { - adjust = res; - break; + int i; + + for (i = dev_dax->nr_range - 1; i >= 0; i--) { + struct range *range = &dev_dax->ranges[i].range; + struct resource *adjust = NULL, *res; + resource_size_t shrink; + + shrink = min(to_shrink, range_len(range)); + if (shrink >= range_len(range)) { + __release_region(&dax_region->res, range->start, + range_len(range)); + dev_dax->nr_range--; + dev_dbg(dev, "delete range[%d]: %#llx:%#llx\n", i, + (unsigned long long) range->start, + (unsigned long long) range->end); + to_shrink -= shrink; + if (!to_shrink) + break; + continue; }
- if (dev_WARN_ONCE(dev, !adjust, "failed to find matching resource\n")) - return -ENXIO; - return adjust_dev_dax_range(dev_dax, adjust, size); + for_each_dax_region_resource(dax_region, res) + if (strcmp(res->name, dev_name(dev)) == 0 + && res->start == range->start) { + adjust = res; + break; + } + + if (dev_WARN_ONCE(dev, !adjust || i != dev_dax->nr_range - 1, + "failed to find matching resource\n")) + return -ENXIO; + return adjust_dev_dax_range(dev_dax, adjust, range_len(range) + - shrink); + } + return 0; +} + +/* + * Only allow adjustments that preserve the relative pgoff of existing + * allocations. I.e. the dev_dax->ranges array is ordered by increasing pgoff. + */ +static bool adjust_ok(struct dev_dax *dev_dax, struct resource *res) +{ + struct dev_dax_range *last; + int i; + + if (dev_dax->nr_range == 0) + return false; + if (strcmp(res->name, dev_name(&dev_dax->dev)) != 0) + return false; + last = &dev_dax->ranges[dev_dax->nr_range - 1]; + if (last->range.start != res->start || last->range.end != res->end) + return false; + for (i = 0; i < dev_dax->nr_range - 1; i++) { + struct dev_dax_range *dax_range = &dev_dax->ranges[i]; + + if (dax_range->pgoff > last->pgoff) + return false; + } + + return true; }
static ssize_t dev_dax_resize(struct dax_region *dax_region, struct dev_dax *dev_dax, resource_size_t size) { resource_size_t avail = dax_region_avail_size(dax_region), to_alloc; - resource_size_t dev_size = range_len(&dev_dax->range); + resource_size_t dev_size = dev_dax_size(dev_dax); struct resource *region_res = &dax_region->res; struct device *dev = &dev_dax->dev; - const char *name = dev_name(dev); struct resource *res, *first; + resource_size_t alloc = 0; + int rc;
if (dev->driver) return -EBUSY; @@ -685,35 +787,47 @@ static ssize_t dev_dax_resize(struct dax_region *dax_region, * may involve adjusting the end of an existing resource, or * allocating a new resource. */ +retry: first = region_res->child; if (!first) return alloc_dev_dax_range(dev_dax, dax_region->res.start, to_alloc); - for (res = first; to_alloc && res; res = res->sibling) { + + rc = -ENOSPC; + for (res = first; res; res = res->sibling) { struct resource *next = res->sibling; - resource_size_t free;
/* space at the beginning of the region */ - free = 0; - if (res == first && res->start > dax_region->res.start) - free = res->start - dax_region->res.start; - if (free >= to_alloc && dev_size == 0) - return alloc_dev_dax_range(dev_dax, dax_region->res.start, to_alloc); + if (res == first && res->start > dax_region->res.start) { + alloc = min(res->start - dax_region->res.start, to_alloc); + rc = alloc_dev_dax_range(dev_dax, dax_region->res.start, alloc); + break; + }
- free = 0; + alloc = 0; /* space between allocations */ if (next && next->start > res->end + 1) - free = next->start - res->end + 1; + alloc = min(next->start - (res->end + 1), to_alloc);
/* space at the end of the region */ - if (free < to_alloc && !next && res->end < region_res->end) - free = region_res->end - res->end; + if (!alloc && !next && res->end < region_res->end) + alloc = min(region_res->end - res->end, to_alloc);
- if (free >= to_alloc && strcmp(name, res->name) == 0) - return adjust_dev_dax_range(dev_dax, res, resource_size(res) + to_alloc); - else if (free >= to_alloc && dev_size == 0) - return alloc_dev_dax_range(dev_dax, res->end + 1, to_alloc); + if (!alloc) + continue; + + if (adjust_ok(dev_dax, res)) { + rc = adjust_dev_dax_range(dev_dax, res, resource_size(res) + alloc); + break; + } + rc = alloc_dev_dax_range(dev_dax, res->end + 1, alloc); + break; } - return -ENOSPC; + if (rc) + return rc; + to_alloc -= alloc; + if (to_alloc) + goto retry; + return 0; }
static ssize_t size_store(struct device *dev, struct device_attribute *attr, @@ -767,8 +881,15 @@ static ssize_t resource_show(struct device *dev, struct device_attribute *attr, char *buf) { struct dev_dax *dev_dax = to_dev_dax(dev); + struct dax_region *dax_region = dev_dax->region; + unsigned long long start; + + if (dev_dax->nr_range < 1) + start = dax_region->res.start; + else + start = dev_dax->ranges[0].range.start;
- return sprintf(buf, "%#llx\n", dev_dax->range.start); + return sprintf(buf, "%#llx\n", start); } static DEVICE_ATTR(resource, 0400, resource_show, NULL);
@@ -833,6 +954,7 @@ static void dev_dax_release(struct device *dev) put_dax(dax_dev); free_dev_dax_id(dev_dax); dax_region_put(dax_region); + kfree(dev_dax->ranges); kfree(dev_dax->pgmap); kfree(dev_dax); } @@ -941,7 +1063,7 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data) err_alloc_dax: kfree(dev_dax->pgmap); err_pgmap: - free_dev_dax_range(dev_dax); + free_dev_dax_ranges(dev_dax); err_range: free_dev_dax_id(dev_dax); err_id: diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h index 0cbb2ec81ca7..f863287107fd 100644 --- a/drivers/dax/dax-private.h +++ b/drivers/dax/dax-private.h @@ -49,7 +49,8 @@ struct dax_region { * @id: ida allocated id * @dev - device core * @pgmap - pgmap for memmap setup / lifetime (driver owned) - * @range: resource range for the instance + * @nr_range: size of @ranges + * @ranges: resource-span + pgoff tuples for the instance */ struct dev_dax { struct dax_region *region; @@ -58,7 +59,11 @@ struct dev_dax { int id; struct device dev; struct dev_pagemap *pgmap; - struct range range; + int nr_range; + struct dev_dax_range { + unsigned long pgoff; + struct range range; + } *ranges; };
static inline struct dev_dax *to_dev_dax(struct device *dev) diff --git a/drivers/dax/device.c b/drivers/dax/device.c index f3755df4ae29..2bfc5c83e3b0 100644 --- a/drivers/dax/device.c +++ b/drivers/dax/device.c @@ -55,15 +55,22 @@ static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma, __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff, unsigned long size) { - struct range *range = &dev_dax->range; - phys_addr_t phys; - - phys = pgoff * PAGE_SIZE + range->start; - if (phys >= range->start && phys <= range->end) { + int i; + + for (i = 0; i < dev_dax->nr_range; i++) { + struct dev_dax_range *dax_range = &dev_dax->ranges[i]; + struct range *range = &dax_range->range; + unsigned long long pgoff_end; + phys_addr_t phys; + + pgoff_end = dax_range->pgoff + PHYS_PFN(range_len(range)) - 1; + if (pgoff < dax_range->pgoff || pgoff > pgoff_end) + continue; + phys = PFN_PHYS(pgoff - dax_range->pgoff) + range->start; if (phys + size - 1 <= range->end) return phys; + break; } - return -1; }
@@ -395,30 +402,40 @@ static void dev_dax_kill(void *dev_dax) int dev_dax_probe(struct dev_dax *dev_dax) { struct dax_device *dax_dev = dev_dax->dax_dev; - struct range *range = &dev_dax->range; struct device *dev = &dev_dax->dev; struct dev_pagemap *pgmap; struct inode *inode; struct cdev *cdev; void *addr; - int rc; - - /* 1:1 map region resource range to device-dax instance range */ - if (!devm_request_mem_region(dev, range->start, range_len(range), - dev_name(dev))) { - dev_warn(dev, "could not reserve range: %#llx - %#llx\n", - range->start, range->end); - return -EBUSY; - } + int rc, i;
pgmap = dev_dax->pgmap; + if (dev_WARN_ONCE(dev, pgmap && dev_dax->nr_range > 1, + "static pgmap / multi-range device conflict\n")) + return -EINVAL; + if (!pgmap) { - pgmap = devm_kzalloc(dev, sizeof(*pgmap), GFP_KERNEL); + pgmap = devm_kzalloc(dev, sizeof(*pgmap) + sizeof(struct range) + * (dev_dax->nr_range - 1), GFP_KERNEL); if (!pgmap) return -ENOMEM; - pgmap->range = *range; - pgmap->nr_range = 1; + pgmap->nr_range = dev_dax->nr_range; + } + + for (i = 0; i < dev_dax->nr_range; i++) { + struct range *range = &dev_dax->ranges[i].range; + + if (!devm_request_mem_region(dev, range->start, + range_len(range), dev_name(dev))) { + dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve range\n", + i, range->start, range->end); + return -EBUSY; + } + /* don't update the range for static pgmap */ + if (!dev_dax->pgmap) + pgmap->ranges[i] = *range; } + pgmap->type = MEMORY_DEVICE_DEVDAX; addr = devm_memremap_pages(dev, pgmap); if (IS_ERR(addr)) diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c index b1be8a53b26a..7dcb2902e9b1 100644 --- a/drivers/dax/kmem.c +++ b/drivers/dax/kmem.c @@ -19,25 +19,28 @@ static const char *kmem_name; /* Set if any memory will remain added when the driver will be unloaded. */ static bool any_hotremove_failed;
-static struct range dax_kmem_range(struct dev_dax *dev_dax) +static int dax_kmem_range(struct dev_dax *dev_dax, int i, struct range *r) { - struct range range; + struct dev_dax_range *dax_range = &dev_dax->ranges[i]; + struct range *range = &dax_range->range;
/* memory-block align the hotplug range */ - range.start = ALIGN(dev_dax->range.start, memory_block_size_bytes()); - range.end = ALIGN_DOWN(dev_dax->range.end + 1, - memory_block_size_bytes()) - 1; - return range; + r->start = ALIGN(range->start, memory_block_size_bytes()); + r->end = ALIGN_DOWN(range->end + 1, memory_block_size_bytes()) - 1; + if (r->start >= r->end) { + r->start = range->start; + r->end = range->end; + return -ENOSPC; + } + return 0; }
int dev_dax_kmem_probe(struct dev_dax *dev_dax) { - struct range range = dax_kmem_range(dev_dax); int numa_node = dev_dax->target_node; struct device *dev = &dev_dax->dev; - struct resource *res; + int i, mapped = 0; char *res_name; - int rc;
/* * Ensure good NUMA information for the persistent memory. @@ -55,32 +58,56 @@ int dev_dax_kmem_probe(struct dev_dax *dev_dax) if (!res_name) return -ENOMEM;
- res = request_mem_region(range.start, range_len(&range), res_name); - if (!res) { - dev_warn(dev, "could not reserve region [%#llx-%#llx]\n", - range.start, range.end); - kfree(res_name); - return -EBUSY; - } - - /* - * Temporarily clear busy to allow add_memory_driver_managed() - * to claim it. - */ - res->flags &= ~IORESOURCE_BUSY; - - /* - * Ensure that future kexec'd kernels will not treat this as RAM - * automatically. - */ - rc = add_memory_driver_managed(numa_node, res->start, - resource_size(res), kmem_name); - - res->flags |= IORESOURCE_BUSY; - if (rc) { - release_mem_region(range.start, range_len(&range)); - kfree(res_name); - return rc; + for (i = 0; i < dev_dax->nr_range; i++) { + struct resource *res; + struct range range; + int rc; + + rc = dax_kmem_range(dev_dax, i, &range); + if (rc) { + dev_info(dev, "mapping%d: %#llx-%#llx too small after alignment\n", + i, range.start, range.end); + continue; + } + + res = request_mem_region(range.start, range_len(&range), res_name); + if (!res) { + dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve region\n", + i, range.start, range.end); + /* + * Once some memory has been onlined we can't + * assume that it can be un-onlined safely. + */ + if (mapped) + continue; + kfree(res_name); + return -EBUSY; + } + + /* + * Temporarily clear busy to allow + * add_memory_driver_managed() to claim it. + */ + res->flags &= ~IORESOURCE_BUSY; + + /* + * Ensure that future kexec'd kernels will not treat + * this as RAM automatically. + */ + rc = add_memory_driver_managed(numa_node, range.start, + range_len(&range), kmem_name); + + res->flags |= IORESOURCE_BUSY; + if (rc) { + dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n", + i, range.start, range.end); + release_mem_region(range.start, range_len(&range)); + if (mapped) + continue; + kfree(res_name); + return rc; + } + mapped++; }
dev_set_drvdata(dev, res_name); @@ -91,10 +118,9 @@ int dev_dax_kmem_probe(struct dev_dax *dev_dax) #ifdef CONFIG_MEMORY_HOTREMOVE static void dax_kmem_release(struct dev_dax *dev_dax) { - int rc; + int i, success = 0; struct device *dev = &dev_dax->dev; const char *res_name = dev_get_drvdata(dev); - struct range range = dax_kmem_range(dev_dax);
/* * We have one shot for removing memory, if some memory blocks were not @@ -102,17 +128,31 @@ static void dax_kmem_release(struct dev_dax *dev_dax) * there is no way to hotremove this memory until reboot because device * unbind will proceed regardless of the remove_memory result. */ - rc = remove_memory(dev_dax->target_node, range.start, range_len(&range)); - if (rc == 0) { - release_mem_region(range.start, range_len(&range)); - dev_set_drvdata(dev, NULL); - kfree(res_name); - return; + for (i = 0; i < dev_dax->nr_range; i++) { + struct range range; + int rc; + + rc = dax_kmem_range(dev_dax, i, &range); + if (rc) + continue; + + rc = remove_memory(dev_dax->target_node, range.start, + range_len(&range)); + if (rc == 0) { + release_mem_region(range.start, range_len(&range)); + success++; + continue; + } + any_hotremove_failed = true; + dev_err(dev, + "mapping%d: %#llx-%#llx cannot be hotremoved until the next reboot\n", + i, range.start, range.end); }
- any_hotremove_failed = true; - dev_err(dev, "%#llx-%#llx cannot be hotremoved until the next reboot\n", - range.start, range.end); + if (success >= dev_dax->nr_range) { + kfree(res_name); + dev_set_drvdata(dev, NULL); + } } #else static void dax_kmem_release(struct dev_dax *dev_dax) diff --git a/tools/testing/nvdimm/dax-dev.c b/tools/testing/nvdimm/dax-dev.c index 38d8e55c4a0d..fb342a8c98d3 100644 --- a/tools/testing/nvdimm/dax-dev.c +++ b/tools/testing/nvdimm/dax-dev.c @@ -9,11 +9,18 @@ phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff, unsigned long size) { - struct range *range = &dev_dax->range; - phys_addr_t addr; + int i;
- addr = pgoff * PAGE_SIZE + range->start; - if (addr >= range->start && addr <= range->end) { + for (i = 0; i < dev_dax->nr_range; i++) { + struct dev_dax_range *dax_range = &dev_dax->ranges[i]; + struct range *range = &dax_range->range; + unsigned long long pgoff_end; + phys_addr_t addr; + + pgoff_end = dax_range->pgoff + PHYS_PFN(range_len(range)) - 1; + if (pgoff < dax_range->pgoff || pgoff > pgoff_end) + continue; + addr = PFN_PHYS(pgoff - dax_range->pgoff) + range->start; if (addr + size - 1 <= range->end) { if (get_nfit_res(addr)) { struct page *page; @@ -23,9 +30,10 @@ phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
page = vmalloc_to_page((void *)addr); return PFN_PHYS(page_to_pfn(page)); - } else - return addr; + } + return addr; } + break; } return -1; }