1 files changed, 135 insertions, 2 deletions

diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index fd4c399675df..2d946a8f78b9 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -111,6 +111,133 @@ static void * __init pcpu_alloc_bootmem(unsigned int cpu, unsigned long size,
 }
 
 /*
+ * Remap allocator
+ *
+ * This allocator uses PMD page as unit.  A PMD page is allocated for
+ * each cpu and each is remapped into vmalloc area using PMD mapping.
+ * As PMD page is quite large, only part of it is used for the first
+ * chunk.  Unused part is returned to the bootmem allocator.
+ *
+ * So, the PMD pages are mapped twice - once to the physical mapping
+ * and to the vmalloc area for the first percpu chunk.  The double
+ * mapping does add one more PMD TLB entry pressure but still is much
+ * better than only using 4k mappings while still being NUMA friendly.
+ */
+#ifdef CONFIG_NEED_MULTIPLE_NODES
+static size_t pcpur_size __initdata;
+static void **pcpur_ptrs __initdata;
+
+static struct page * __init pcpur_get_page(unsigned int cpu, int pageno)
+{
+        size_t off = (size_t)pageno << PAGE_SHIFT;
+
+        if (off >= pcpur_size)
+                return NULL;
+
+        return virt_to_page(pcpur_ptrs[cpu] + off);
+}
+
+static ssize_t __init setup_pcpu_remap(size_t static_size)
+{
+        static struct vm_struct vm;
+        pg_data_t *last;
+        size_t ptrs_size;
+        unsigned int cpu;
+        ssize_t ret;
+
+        /*
+         * If large page isn't supported, there's no benefit in doing
+         * this.  Also, on non-NUMA, embedding is better.
+         */
+        if (!cpu_has_pse || pcpu_need_numa())
+                return -EINVAL;
+
+        last = NULL;
+        for_each_possible_cpu(cpu) {
+                int node = early_cpu_to_node(cpu);
+
+                if (node_online(node) && NODE_DATA(node) &&
+                    last && last != NODE_DATA(node))
+                        goto proceed;
+
+                last = NODE_DATA(node);
+        }
+        return -EINVAL;
+
+proceed:
+        /*
+         * Currently supports only single page.  Supporting multiple
+         * pages won't be too difficult if it ever becomes necessary.
+         */
+        pcpur_size = PFN_ALIGN(static_size + PERCPU_DYNAMIC_RESERVE);
+        if (pcpur_size > PMD_SIZE) {
+                pr_warning("PERCPU: static data is larger than large page, "
+                           "can't use large page\n");
+                return -EINVAL;
+        }
+
+        /* allocate pointer array and alloc large pages */
+        ptrs_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpur_ptrs[0]));
+        pcpur_ptrs = alloc_bootmem(ptrs_size);
+
+        for_each_possible_cpu(cpu) {
+                pcpur_ptrs[cpu] = pcpu_alloc_bootmem(cpu, PMD_SIZE, PMD_SIZE);
+                if (!pcpur_ptrs[cpu])
+                        goto enomem;
+
+                /*
+                 * Only use pcpur_size bytes and give back the rest.
+                 *
+                 * Ingo: The 2MB up-rounding bootmem is needed to make
+                 * sure the partial 2MB page is still fully RAM - it's
+                 * not well-specified to have a PAT-incompatible area
+                 * (unmapped RAM, device memory, etc.) in that hole.
+                 */
+                free_bootmem(__pa(pcpur_ptrs[cpu] + pcpur_size),
+                             PMD_SIZE - pcpur_size);
+
+                memcpy(pcpur_ptrs[cpu], __per_cpu_load, static_size);
+        }
+
+        /* allocate address and map */
+        vm.flags = VM_ALLOC;
+        vm.size = num_possible_cpus() * PMD_SIZE;
+        vm_area_register_early(&vm, PMD_SIZE);
+
+        for_each_possible_cpu(cpu) {
+                pmd_t *pmd;
+
+                pmd = populate_extra_pmd((unsigned long)vm.addr
+                                         + cpu * PMD_SIZE);
+                set_pmd(pmd, pfn_pmd(page_to_pfn(virt_to_page(pcpur_ptrs[cpu])),
+                                     PAGE_KERNEL_LARGE));
+        }
+
+        /* we're ready, commit */
+        pr_info("PERCPU: Remapped at %p with large pages, static data "
+                "%zu bytes\n", vm.addr, static_size);
+
+        ret = pcpu_setup_first_chunk(pcpur_get_page, static_size, PMD_SIZE,
+                                     pcpur_size - static_size, vm.addr, NULL);
+        goto out_free_ar;
+
+enomem:
+        for_each_possible_cpu(cpu)
+                if (pcpur_ptrs[cpu])
+                        free_bootmem(__pa(pcpur_ptrs[cpu]), PMD_SIZE);
+        ret = -ENOMEM;
+out_free_ar:
+        free_bootmem(__pa(pcpur_ptrs), ptrs_size);
+        return ret;
+}
+#else
+static ssize_t __init setup_pcpu_remap(size_t static_size)
+{
+        return -EINVAL;
+}
+#endif
+
+/*
  * Embedding allocator
  *
  * The first chunk is sized to just contain the static area plus
@@ -259,8 +386,14 @@ void __init setup_per_cpu_areas(void)
         pr_info("NR_CPUS:%d nr_cpumask_bits:%d nr_cpu_ids:%d nr_node_ids:%d\n",
                 NR_CPUS, nr_cpumask_bits, nr_cpu_ids, nr_node_ids);
 
-        /* allocate percpu area */
-        ret = setup_pcpu_embed(static_size);
+        /*
+         * Allocate percpu area.  If PSE is supported, try to make use
+         * of large page mappings.  Please read comments on top of
+         * each allocator for details.
+         */
+        ret = setup_pcpu_remap(static_size);
+        if (ret < 0)
+                ret = setup_pcpu_embed(static_size);
         if (ret < 0)
                 ret = setup_pcpu_4k(static_size);
         if (ret < 0)