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resource: Introduce alloc_free_mem_region()
The core of devm_request_free_mem_region() is a helper that searches for free space in iomem_resource and performs __request_region_locked() on the result of that search. The policy choices of the implementation conform to what CONFIG_DEVICE_PRIVATE users want which is memory that is immediately marked busy, and a preference to search for the first-fit free range in descending order from the top of the physical address space. CXL has a need for a similar allocator, but with the following tweaks: 1/ Search for free space in ascending order 2/ Search for free space relative to a given CXL window 3/ 'insert' rather than 'request' the new resource given downstream drivers from the CXL Region driver (like the pmem or dax drivers) are responsible for request_mem_region() when they activate the memory range. Rework __request_free_mem_region() into get_free_mem_region() which takes a set of GFR_* (Get Free Region) flags to control the allocation policy (ascending vs descending), and "busy" policy (insert_resource() vs request_region()). As part of the consolidation of the legacy GFR_REQUEST_REGION case with the new default of just inserting a new resource into the free space some minor cleanups like not checking for NULL before calling devres_free() (which does its own check) is included. Suggested-by: Jason Gunthorpe <jgg@nvidia.com> Link: https://lore.kernel.org/linux-cxl/20220420143406.GY2120790@nvidia.com/ Cc: Matthew Wilcox <willy@infradead.org> Cc: Christoph Hellwig <hch@lst.de> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Link: https://lore.kernel.org/r/165784333333.1758207.13703329337805274043.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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@ -330,6 +330,8 @@ struct resource *devm_request_free_mem_region(struct device *dev,
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struct resource *base, unsigned long size);
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struct resource *request_free_mem_region(struct resource *base,
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unsigned long size, const char *name);
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struct resource *alloc_free_mem_region(struct resource *base,
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unsigned long size, unsigned long align, const char *name);
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static inline void irqresource_disabled(struct resource *res, u32 irq)
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{
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@ -489,8 +489,9 @@ int __weak page_is_ram(unsigned long pfn)
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}
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EXPORT_SYMBOL_GPL(page_is_ram);
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static int __region_intersects(resource_size_t start, size_t size,
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unsigned long flags, unsigned long desc)
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static int __region_intersects(struct resource *parent, resource_size_t start,
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size_t size, unsigned long flags,
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unsigned long desc)
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{
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struct resource res;
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int type = 0; int other = 0;
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@ -499,7 +500,7 @@ static int __region_intersects(resource_size_t start, size_t size,
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res.start = start;
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res.end = start + size - 1;
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for (p = iomem_resource.child; p ; p = p->sibling) {
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for (p = parent->child; p ; p = p->sibling) {
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bool is_type = (((p->flags & flags) == flags) &&
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((desc == IORES_DESC_NONE) ||
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(desc == p->desc)));
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@ -543,7 +544,7 @@ int region_intersects(resource_size_t start, size_t size, unsigned long flags,
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int ret;
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read_lock(&resource_lock);
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ret = __region_intersects(start, size, flags, desc);
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ret = __region_intersects(&iomem_resource, start, size, flags, desc);
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read_unlock(&resource_lock);
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return ret;
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@ -1780,62 +1781,139 @@ void resource_list_free(struct list_head *head)
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}
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EXPORT_SYMBOL(resource_list_free);
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#ifdef CONFIG_DEVICE_PRIVATE
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static struct resource *__request_free_mem_region(struct device *dev,
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struct resource *base, unsigned long size, const char *name)
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#ifdef CONFIG_GET_FREE_REGION
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#define GFR_DESCENDING (1UL << 0)
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#define GFR_REQUEST_REGION (1UL << 1)
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#define GFR_DEFAULT_ALIGN (1UL << PA_SECTION_SHIFT)
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static resource_size_t gfr_start(struct resource *base, resource_size_t size,
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resource_size_t align, unsigned long flags)
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{
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resource_size_t end, addr;
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if (flags & GFR_DESCENDING) {
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resource_size_t end;
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end = min_t(resource_size_t, base->end,
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(1ULL << MAX_PHYSMEM_BITS) - 1);
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return end - size + 1;
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}
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return ALIGN(base->start, align);
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}
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static bool gfr_continue(struct resource *base, resource_size_t addr,
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resource_size_t size, unsigned long flags)
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{
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if (flags & GFR_DESCENDING)
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return addr > size && addr >= base->start;
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/*
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* In the ascend case be careful that the last increment by
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* @size did not wrap 0.
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*/
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return addr > addr - size &&
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addr <= min_t(resource_size_t, base->end,
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(1ULL << MAX_PHYSMEM_BITS) - 1);
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}
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static resource_size_t gfr_next(resource_size_t addr, resource_size_t size,
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unsigned long flags)
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{
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if (flags & GFR_DESCENDING)
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return addr - size;
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return addr + size;
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}
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static void remove_free_mem_region(void *_res)
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{
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struct resource *res = _res;
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if (res->parent)
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remove_resource(res);
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free_resource(res);
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}
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static struct resource *
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get_free_mem_region(struct device *dev, struct resource *base,
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resource_size_t size, const unsigned long align,
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const char *name, const unsigned long desc,
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const unsigned long flags)
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{
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resource_size_t addr;
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struct resource *res;
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struct region_devres *dr = NULL;
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size = ALIGN(size, 1UL << PA_SECTION_SHIFT);
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end = min_t(unsigned long, base->end, (1UL << MAX_PHYSMEM_BITS) - 1);
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addr = end - size + 1UL;
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size = ALIGN(size, align);
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res = alloc_resource(GFP_KERNEL);
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if (!res)
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return ERR_PTR(-ENOMEM);
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if (dev) {
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if (dev && (flags & GFR_REQUEST_REGION)) {
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dr = devres_alloc(devm_region_release,
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sizeof(struct region_devres), GFP_KERNEL);
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if (!dr) {
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free_resource(res);
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return ERR_PTR(-ENOMEM);
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}
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} else if (dev) {
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if (devm_add_action_or_reset(dev, remove_free_mem_region, res))
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return ERR_PTR(-ENOMEM);
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}
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write_lock(&resource_lock);
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for (; addr > size && addr >= base->start; addr -= size) {
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if (__region_intersects(addr, size, 0, IORES_DESC_NONE) !=
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REGION_DISJOINT)
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for (addr = gfr_start(base, size, align, flags);
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gfr_continue(base, addr, size, flags);
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addr = gfr_next(addr, size, flags)) {
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if (__region_intersects(base, addr, size, 0, IORES_DESC_NONE) !=
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REGION_DISJOINT)
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continue;
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if (__request_region_locked(res, &iomem_resource, addr, size,
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name, 0))
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break;
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if (flags & GFR_REQUEST_REGION) {
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if (__request_region_locked(res, &iomem_resource, addr,
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size, name, 0))
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break;
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if (dev) {
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dr->parent = &iomem_resource;
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dr->start = addr;
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dr->n = size;
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devres_add(dev, dr);
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if (dev) {
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dr->parent = &iomem_resource;
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dr->start = addr;
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dr->n = size;
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devres_add(dev, dr);
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}
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res->desc = desc;
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write_unlock(&resource_lock);
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/*
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* A driver is claiming this region so revoke any
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* mappings.
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*/
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revoke_iomem(res);
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} else {
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res->start = addr;
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res->end = addr + size - 1;
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res->name = name;
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res->desc = desc;
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res->flags = IORESOURCE_MEM;
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/*
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* Only succeed if the resource hosts an exclusive
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* range after the insert
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*/
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if (__insert_resource(base, res) || res->child)
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break;
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write_unlock(&resource_lock);
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}
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res->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY;
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write_unlock(&resource_lock);
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/*
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* A driver is claiming this region so revoke any mappings.
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*/
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revoke_iomem(res);
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return res;
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}
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write_unlock(&resource_lock);
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free_resource(res);
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if (dr)
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if (flags & GFR_REQUEST_REGION) {
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free_resource(res);
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devres_free(dr);
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} else if (dev)
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devm_release_action(dev, remove_free_mem_region, res);
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return ERR_PTR(-ERANGE);
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}
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@ -1854,18 +1932,48 @@ static struct resource *__request_free_mem_region(struct device *dev,
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struct resource *devm_request_free_mem_region(struct device *dev,
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struct resource *base, unsigned long size)
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{
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return __request_free_mem_region(dev, base, size, dev_name(dev));
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unsigned long flags = GFR_DESCENDING | GFR_REQUEST_REGION;
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return get_free_mem_region(dev, base, size, GFR_DEFAULT_ALIGN,
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dev_name(dev),
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IORES_DESC_DEVICE_PRIVATE_MEMORY, flags);
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}
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EXPORT_SYMBOL_GPL(devm_request_free_mem_region);
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struct resource *request_free_mem_region(struct resource *base,
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unsigned long size, const char *name)
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{
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return __request_free_mem_region(NULL, base, size, name);
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unsigned long flags = GFR_DESCENDING | GFR_REQUEST_REGION;
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return get_free_mem_region(NULL, base, size, GFR_DEFAULT_ALIGN, name,
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IORES_DESC_DEVICE_PRIVATE_MEMORY, flags);
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}
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EXPORT_SYMBOL_GPL(request_free_mem_region);
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#endif /* CONFIG_DEVICE_PRIVATE */
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/**
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* alloc_free_mem_region - find a free region relative to @base
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* @base: resource that will parent the new resource
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* @size: size in bytes of memory to allocate from @base
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* @align: alignment requirements for the allocation
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* @name: resource name
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*
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* Buses like CXL, that can dynamically instantiate new memory regions,
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* need a method to allocate physical address space for those regions.
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* Allocate and insert a new resource to cover a free, unclaimed by a
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* descendant of @base, range in the span of @base.
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*/
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struct resource *alloc_free_mem_region(struct resource *base,
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unsigned long size, unsigned long align,
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const char *name)
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{
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/* Default of ascending direction and insert resource */
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unsigned long flags = 0;
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return get_free_mem_region(NULL, base, size, align, name,
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IORES_DESC_NONE, flags);
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}
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EXPORT_SYMBOL_NS_GPL(alloc_free_mem_region, CXL);
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#endif /* CONFIG_GET_FREE_REGION */
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static int __init strict_iomem(char *str)
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{
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@ -994,9 +994,14 @@ config HMM_MIRROR
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bool
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depends on MMU
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config GET_FREE_REGION
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depends on SPARSEMEM
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bool
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config DEVICE_PRIVATE
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bool "Unaddressable device memory (GPU memory, ...)"
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depends on ZONE_DEVICE
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select GET_FREE_REGION
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help
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Allows creation of struct pages to represent unaddressable device
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