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Tue, 30 Mar 2021 21:25:42 +0000 From: Anthony Yznaga To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: willy@infradead.org, corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, rppt@kernel.org, akpm@linux-foundation.org, hughd@google.com, ebiederm@xmission.com, keescook@chromium.org, ardb@kernel.org, nivedita@alum.mit.edu, jroedel@suse.de, masahiroy@kernel.org, nathan@kernel.org, terrelln@fb.com, vincenzo.frascino@arm.com, martin.b.radev@gmail.com, andreyknvl@google.com, daniel.kiper@oracle.com, rafael.j.wysocki@intel.com, dan.j.williams@intel.com, Jonathan.Cameron@huawei.com, bhe@redhat.com, rminnich@gmail.com, ashish.kalra@amd.com, guro@fb.com, hannes@cmpxchg.org, mhocko@kernel.org, iamjoonsoo.kim@lge.com, vbabka@suse.cz, alex.shi@linux.alibaba.com, david@redhat.com, richard.weiyang@gmail.com, vdavydov.dev@gmail.com, graf@amazon.com, jason.zeng@intel.com, lei.l.li@intel.com, daniel.m.jordan@oracle.com, steven.sistare@oracle.com, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, kexec@lists.infradead.org Subject: [RFC v2 10/43] PKRAM: pass a list of preserved ranges to the next kernel Date: Tue, 30 Mar 2021 14:35:45 -0700 Message-Id: <1617140178-8773-11-git-send-email-anthony.yznaga@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1617140178-8773-1-git-send-email-anthony.yznaga@oracle.com> References: <1617140178-8773-1-git-send-email-anthony.yznaga@oracle.com> X-Originating-IP: [148.87.23.8] X-ClientProxiedBy: BYAPR11CA0099.namprd11.prod.outlook.com (2603:10b6:a03:f4::40) To MN2PR10MB3533.namprd10.prod.outlook.com (2603:10b6:208:118::32) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from ca-qasparc-x86-2.us.oracle.com (148.87.23.8) by BYAPR11CA0099.namprd11.prod.outlook.com (2603:10b6:a03:f4::40) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3977.26 via Frontend Transport; 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identity=mailfrom; envelope-from=""; helo=userp2130.oracle.com; client-ip=156.151.31.86 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617139573-923985 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In order to build a new memblock reserved list during boot that includes ranges preserved by the previous kernel, a list of preserved ranges is passed to the next kernel via the pkram superblock. The ranges are stored in ascending order in a linked list of pages. A more complete memblock list is not prepared to avoid possible conflicts with changes in a newer kernel and to avoid having to allocate a contiguous range larger than a page. Signed-off-by: Anthony Yznaga --- mm/pkram.c | 183 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 176 insertions(+), 7 deletions(-) diff --git a/mm/pkram.c b/mm/pkram.c index a9e6cd8ca084..4cfa236a4126 100644 --- a/mm/pkram.c +++ b/mm/pkram.c @@ -86,6 +86,20 @@ struct pkram_node { #define PKRAM_LOAD 2 #define PKRAM_ACCMODE_MASK 3 +struct pkram_region { + phys_addr_t base; + phys_addr_t size; +}; + +struct pkram_region_list { + __u64 prev_pfn; + __u64 next_pfn; + + struct pkram_region regions[0]; +}; + +#define PKRAM_REGIONS_LIST_MAX \ + ((PAGE_SIZE-sizeof(struct pkram_region_list))/sizeof(struct pkram_region)) /* * The PKRAM super block contains data needed to restore the preserved memory * structure on boot. The pointer to it (pfn) should be passed via the 'pkram' @@ -98,13 +112,20 @@ struct pkram_node { */ struct pkram_super_block { __u64 node_pfn; /* first element of the node list */ + __u64 region_list_pfn; + __u64 nr_regions; }; +static struct pkram_region_list *pkram_regions_list; +static int pkram_init_regions_list(void); +static unsigned long pkram_populate_regions_list(void); + static unsigned long pkram_sb_pfn __initdata; static struct pkram_super_block *pkram_sb; extern int pkram_add_identity_map(struct page *page); extern void pkram_remove_identity_map(struct page *page); +extern void pkram_find_preserved(unsigned long start, unsigned long end, void *private, int (*callback)(unsigned long base, unsigned long size, void *private)); /* * For convenience sake PKRAM nodes are kept in an auxiliary doubly-linked list @@ -862,21 +883,48 @@ static void __pkram_reboot(void) struct page *page; struct pkram_node *node; unsigned long node_pfn = 0; + unsigned long rl_pfn = 0; + unsigned long nr_regions = 0; + int err = 0; - list_for_each_entry_reverse(page, &pkram_nodes, lru) { - node = page_address(page); - if (WARN_ON(node->flags & PKRAM_ACCMODE_MASK)) - continue; - node->node_pfn = node_pfn; - node_pfn = page_to_pfn(page); + if (!list_empty(&pkram_nodes)) { + err = pkram_add_identity_map(virt_to_page(pkram_sb)); + if (err) { + pr_err("PKRAM: failed to add super block to pagetable\n"); + goto done; + } + list_for_each_entry_reverse(page, &pkram_nodes, lru) { + node = page_address(page); + if (WARN_ON(node->flags & PKRAM_ACCMODE_MASK)) + continue; + node->node_pfn = node_pfn; + node_pfn = page_to_pfn(page); + } + err = pkram_init_regions_list(); + if (err) { + pr_err("PKRAM: failed to init regions list\n"); + goto done; + } + nr_regions = pkram_populate_regions_list(); + if (IS_ERR_VALUE(nr_regions)) { + err = nr_regions; + pr_err("PKRAM: failed to populate regions list\n"); + goto done; + } + rl_pfn = page_to_pfn(virt_to_page(pkram_regions_list)); } +done: /* * Zero out pkram_sb completely since it may have been passed from * the previous boot. */ memset(pkram_sb, 0, PAGE_SIZE); - pkram_sb->node_pfn = node_pfn; + if (!err && node_pfn) { + pkram_sb->node_pfn = node_pfn; + pkram_sb->region_list_pfn = rl_pfn; + pkram_sb->nr_regions = nr_regions; + } } static int pkram_reboot(struct notifier_block *notifier, @@ -952,3 +1000,124 @@ static int __init pkram_init(void) return 0; } module_init(pkram_init); + +static int count_region_cb(unsigned long base, unsigned long size, void *private) +{ + unsigned long *nr_regions = (unsigned long *)private; + + (*nr_regions)++; + return 0; +} + +static unsigned long pkram_count_regions(void) +{ + unsigned long nr_regions = 0; + + pkram_find_preserved(0, PHYS_ADDR_MAX, &nr_regions, count_region_cb); + + return nr_regions; +} + +/* + * To faciliate rapidly building a new memblock reserved list during boot + * with the addition of preserved memory ranges a regions list is built + * before reboot. + * The regions list is a linked list of pages with each page containing an + * array of preserved memory ranges. The ranges are stored in each page + * and across the list in address order. A linked list is used rather than + * a single contiguous range to mitigate against the possibility that a + * larger, contiguous allocation may fail due to fragmentation. + * + * Since the pages of the regions list must be preserved and the pkram + * pagetable is used to determine what ranges are preserved, the list pages + * must be allocated and represented in the pkram pagetable before they can + * be populated. Rather than recounting the number of regions after + * allocating pages and repeating until a precise number of pages are + * are allocated, the number of pages needed is estimated. + */ +static int pkram_init_regions_list(void) +{ + struct pkram_region_list *rl; + unsigned long nr_regions; + unsigned long nr_lpages; + struct page *page; + + nr_regions = pkram_count_regions(); + + nr_lpages = DIV_ROUND_UP(nr_regions, PKRAM_REGIONS_LIST_MAX); + nr_regions += nr_lpages; + nr_lpages = DIV_ROUND_UP(nr_regions, PKRAM_REGIONS_LIST_MAX); + + for (; nr_lpages; nr_lpages--) { + page = pkram_alloc_page(GFP_KERNEL | __GFP_ZERO); + if (!page) + return -ENOMEM; + rl = page_address(page); + if (pkram_regions_list) { + rl->next_pfn = page_to_pfn(virt_to_page(pkram_regions_list)); + pkram_regions_list->prev_pfn = page_to_pfn(page); + } + pkram_regions_list = rl; + } + + return 0; +} + +struct pkram_regions_priv { + struct pkram_region_list *curr; + struct pkram_region_list *last; + unsigned long nr_regions; + int idx; +}; + +static int add_region_cb(unsigned long base, unsigned long size, void *private) +{ + struct pkram_regions_priv *priv; + struct pkram_region_list *rl; + int i; + + priv = (struct pkram_regions_priv *)private; + rl = priv->curr; + i = priv->idx; + + if (!rl) { + WARN_ON(1); + return 1; + } + + if (!i) + priv->last = priv->curr; + + rl->regions[i].base = base; + rl->regions[i].size = size; + + priv->nr_regions++; + i++; + if (i == PKRAM_REGIONS_LIST_MAX) { + u64 next_pfn = rl->next_pfn; + + if (next_pfn) + priv->curr = pfn_to_kaddr(next_pfn); + else + priv->curr = NULL; + + i = 0; + } + priv->idx = i; + + return 0; +} + +static unsigned long pkram_populate_regions_list(void) +{ + struct pkram_regions_priv priv = { .curr = pkram_regions_list }; + + pkram_find_preserved(0, PHYS_ADDR_MAX, &priv, add_region_cb); + + /* + * Link the first node to the last populated one. + */ + pkram_regions_list->prev_pfn = page_to_pfn(virt_to_page(priv.last)); + + return priv.nr_regions; +}