From patchwork Fri Jul 15 00:02:13 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 12918576 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BBB58CCA47B for ; Fri, 15 Jul 2022 00:03:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241046AbiGOAD3 (ORCPT ); Thu, 14 Jul 2022 20:03:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38164 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241052AbiGOAD1 (ORCPT ); Thu, 14 Jul 2022 20:03:27 -0400 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 02E1873596; Thu, 14 Jul 2022 17:03:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1657843406; x=1689379406; h=subject:from:to:cc:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=UDYAt3M3nQnYVxO8RqGbN31McxI7qhhgMZQ6vq7TSG0=; b=IGzOlPatImxk1dS8fbC64OuFYj58x+9BuCpKNYqu6m29DVymkAny6EZ9 pCTsKOj9lzmnCvRTMz8UHS35dOpiTR8XXsnIut+ZA6flFwpASo7GmRJZl 29tJaL4HbZcrFQCmxMYQyh3R+lm+wv2E0m9IBmSTFRj4sbkGzrOyonuYw /akfQ8i9ENH5StCKn3bIJLlsebYXEXc/DG2XHMneDwV/vm2iq/bh8U25A sNTlMieZk/dnqzxqbLJ1IA1ius4ljW7EWoB9OgB/sF09TlMeVBFOq797v tdlehaIvM+AZIfGVsylH6W03mP00eT/B0nWQkymzemC0Rx8upGWeAjaGH A==; X-IronPort-AV: E=McAfee;i="6400,9594,10408"; a="283220083" X-IronPort-AV: E=Sophos;i="5.92,272,1650956400"; d="scan'208";a="283220083" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jul 2022 17:02:14 -0700 X-IronPort-AV: E=Sophos;i="5.92,272,1650956400"; d="scan'208";a="842326104" Received: from jlcone-mobl1.amr.corp.intel.com (HELO dwillia2-xfh.jf.intel.com) ([10.209.2.90]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jul 2022 17:02:13 -0700 Subject: [PATCH v2 16/28] resource: Introduce alloc_free_mem_region() From: Dan Williams To: linux-cxl@vger.kernel.org Cc: Jason Gunthorpe , Matthew Wilcox , Christoph Hellwig , nvdimm@lists.linux.dev, linux-pci@vger.kernel.org Date: Thu, 14 Jul 2022 17:02:13 -0700 Message-ID: <165784333333.1758207.13703329337805274043.stgit@dwillia2-xfh.jf.intel.com> In-Reply-To: <165784324066.1758207.15025479284039479071.stgit@dwillia2-xfh.jf.intel.com> References: <165784324066.1758207.15025479284039479071.stgit@dwillia2-xfh.jf.intel.com> User-Agent: StGit/0.18-3-g996c MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org 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 Link: https://lore.kernel.org/linux-cxl/20220420143406.GY2120790@nvidia.com/ Cc: Matthew Wilcox Cc: Christoph Hellwig Signed-off-by: Dan Williams Reviewed-by: Jonathan Cameron --- include/linux/ioport.h | 2 + kernel/resource.c | 178 +++++++++++++++++++++++++++++++++++++++--------- mm/Kconfig | 5 + 3 files changed, 150 insertions(+), 35 deletions(-) diff --git a/include/linux/ioport.h b/include/linux/ioport.h index 79d1ad6d6275..616b683563a9 100644 --- a/include/linux/ioport.h +++ b/include/linux/ioport.h @@ -330,6 +330,8 @@ struct resource *devm_request_free_mem_region(struct device *dev, struct resource *base, unsigned long size); struct resource *request_free_mem_region(struct resource *base, unsigned long size, const char *name); +struct resource *alloc_free_mem_region(struct resource *base, + unsigned long size, unsigned long align, const char *name); static inline void irqresource_disabled(struct resource *res, u32 irq) { diff --git a/kernel/resource.c b/kernel/resource.c index 53a534db350e..4c5e80b92f2f 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -489,8 +489,9 @@ int __weak page_is_ram(unsigned long pfn) } EXPORT_SYMBOL_GPL(page_is_ram); -static int __region_intersects(resource_size_t start, size_t size, - unsigned long flags, unsigned long desc) +static int __region_intersects(struct resource *parent, resource_size_t start, + size_t size, unsigned long flags, + unsigned long desc) { struct resource res; int type = 0; int other = 0; @@ -499,7 +500,7 @@ static int __region_intersects(resource_size_t start, size_t size, res.start = start; res.end = start + size - 1; - for (p = iomem_resource.child; p ; p = p->sibling) { + for (p = parent->child; p ; p = p->sibling) { bool is_type = (((p->flags & flags) == flags) && ((desc == IORES_DESC_NONE) || (desc == p->desc))); @@ -543,7 +544,7 @@ int region_intersects(resource_size_t start, size_t size, unsigned long flags, int ret; read_lock(&resource_lock); - ret = __region_intersects(start, size, flags, desc); + ret = __region_intersects(&iomem_resource, start, size, flags, desc); read_unlock(&resource_lock); return ret; @@ -1780,62 +1781,139 @@ void resource_list_free(struct list_head *head) } EXPORT_SYMBOL(resource_list_free); -#ifdef CONFIG_DEVICE_PRIVATE -static struct resource *__request_free_mem_region(struct device *dev, - struct resource *base, unsigned long size, const char *name) +#ifdef CONFIG_GET_FREE_REGION +#define GFR_DESCENDING (1UL << 0) +#define GFR_REQUEST_REGION (1UL << 1) +#define GFR_DEFAULT_ALIGN (1UL << PA_SECTION_SHIFT) + +static resource_size_t gfr_start(struct resource *base, resource_size_t size, + resource_size_t align, unsigned long flags) +{ + if (flags & GFR_DESCENDING) { + resource_size_t end; + + end = min_t(resource_size_t, base->end, + (1ULL << MAX_PHYSMEM_BITS) - 1); + return end - size + 1; + } + + return ALIGN(base->start, align); +} + +static bool gfr_continue(struct resource *base, resource_size_t addr, + resource_size_t size, unsigned long flags) +{ + if (flags & GFR_DESCENDING) + return addr > size && addr >= base->start; + /* + * In the ascend case be careful that the last increment by + * @size did not wrap 0. + */ + return addr > addr - size && + addr <= min_t(resource_size_t, base->end, + (1ULL << MAX_PHYSMEM_BITS) - 1); +} + +static resource_size_t gfr_next(resource_size_t addr, resource_size_t size, + unsigned long flags) +{ + if (flags & GFR_DESCENDING) + return addr - size; + return addr + size; +} + +static void remove_free_mem_region(void *_res) +{ + struct resource *res = _res; + + if (res->parent) + remove_resource(res); + free_resource(res); +} + +static struct resource * +get_free_mem_region(struct device *dev, struct resource *base, + resource_size_t size, const unsigned long align, + const char *name, const unsigned long desc, + const unsigned long flags) { - resource_size_t end, addr; + resource_size_t addr; struct resource *res; struct region_devres *dr = NULL; - size = ALIGN(size, 1UL << PA_SECTION_SHIFT); - end = min_t(unsigned long, base->end, (1UL << MAX_PHYSMEM_BITS) - 1); - addr = end - size + 1UL; + size = ALIGN(size, align); res = alloc_resource(GFP_KERNEL); if (!res) return ERR_PTR(-ENOMEM); - if (dev) { + if (dev && (flags & GFR_REQUEST_REGION)) { dr = devres_alloc(devm_region_release, sizeof(struct region_devres), GFP_KERNEL); if (!dr) { free_resource(res); return ERR_PTR(-ENOMEM); } + } else if (dev) { + if (devm_add_action_or_reset(dev, remove_free_mem_region, res)) + return ERR_PTR(-ENOMEM); } write_lock(&resource_lock); - for (; addr > size && addr >= base->start; addr -= size) { - if (__region_intersects(addr, size, 0, IORES_DESC_NONE) != - REGION_DISJOINT) + for (addr = gfr_start(base, size, align, flags); + gfr_continue(base, addr, size, flags); + addr = gfr_next(addr, size, flags)) { + if (__region_intersects(base, addr, size, 0, IORES_DESC_NONE) != + REGION_DISJOINT) continue; - if (__request_region_locked(res, &iomem_resource, addr, size, - name, 0)) - break; + if (flags & GFR_REQUEST_REGION) { + if (__request_region_locked(res, &iomem_resource, addr, + size, name, 0)) + break; - if (dev) { - dr->parent = &iomem_resource; - dr->start = addr; - dr->n = size; - devres_add(dev, dr); - } + if (dev) { + dr->parent = &iomem_resource; + dr->start = addr; + dr->n = size; + devres_add(dev, dr); + } - res->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY; - write_unlock(&resource_lock); + res->desc = desc; + write_unlock(&resource_lock); + + + /* + * A driver is claiming this region so revoke any + * mappings. + */ + revoke_iomem(res); + } else { + res->start = addr; + res->end = addr + size - 1; + res->name = name; + res->desc = desc; + res->flags = IORESOURCE_MEM; + + /* + * Only succeed if the resource hosts an exclusive + * range after the insert + */ + if (__insert_resource(base, res) || res->child) + break; + + write_unlock(&resource_lock); + } - /* - * A driver is claiming this region so revoke any mappings. - */ - revoke_iomem(res); return res; } write_unlock(&resource_lock); - free_resource(res); - if (dr) + if (flags & GFR_REQUEST_REGION) { + free_resource(res); devres_free(dr); + } else if (dev) + devm_release_action(dev, remove_free_mem_region, res); return ERR_PTR(-ERANGE); } @@ -1854,18 +1932,48 @@ static struct resource *__request_free_mem_region(struct device *dev, struct resource *devm_request_free_mem_region(struct device *dev, struct resource *base, unsigned long size) { - return __request_free_mem_region(dev, base, size, dev_name(dev)); + unsigned long flags = GFR_DESCENDING | GFR_REQUEST_REGION; + + return get_free_mem_region(dev, base, size, GFR_DEFAULT_ALIGN, + dev_name(dev), + IORES_DESC_DEVICE_PRIVATE_MEMORY, flags); } EXPORT_SYMBOL_GPL(devm_request_free_mem_region); struct resource *request_free_mem_region(struct resource *base, unsigned long size, const char *name) { - return __request_free_mem_region(NULL, base, size, name); + unsigned long flags = GFR_DESCENDING | GFR_REQUEST_REGION; + + return get_free_mem_region(NULL, base, size, GFR_DEFAULT_ALIGN, name, + IORES_DESC_DEVICE_PRIVATE_MEMORY, flags); } EXPORT_SYMBOL_GPL(request_free_mem_region); -#endif /* CONFIG_DEVICE_PRIVATE */ +/** + * alloc_free_mem_region - find a free region relative to @base + * @base: resource that will parent the new resource + * @size: size in bytes of memory to allocate from @base + * @align: alignment requirements for the allocation + * @name: resource name + * + * Buses like CXL, that can dynamically instantiate new memory regions, + * need a method to allocate physical address space for those regions. + * Allocate and insert a new resource to cover a free, unclaimed by a + * descendant of @base, range in the span of @base. + */ +struct resource *alloc_free_mem_region(struct resource *base, + unsigned long size, unsigned long align, + const char *name) +{ + /* Default of ascending direction and insert resource */ + unsigned long flags = 0; + + return get_free_mem_region(NULL, base, size, align, name, + IORES_DESC_NONE, flags); +} +EXPORT_SYMBOL_NS_GPL(alloc_free_mem_region, CXL); +#endif /* CONFIG_GET_FREE_REGION */ static int __init strict_iomem(char *str) { diff --git a/mm/Kconfig b/mm/Kconfig index 169e64192e48..a5b4fee2e3fd 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -994,9 +994,14 @@ config HMM_MIRROR bool depends on MMU +config GET_FREE_REGION + depends on SPARSEMEM + bool + config DEVICE_PRIVATE bool "Unaddressable device memory (GPU memory, ...)" depends on ZONE_DEVICE + select GET_FREE_REGION help Allows creation of struct pages to represent unaddressable device