s390/mm,vmemmap: use 1MB frames for vmemmap

Use 1MB frames for vmemmap if EDAT1 is available in order to
reduce TLB pressure
Always use a 1MB frame even if its only partially needed for
struct pages. Otherwise we would end up with a mix of large
frame and page mappings, because vmemmap_populate gets called
for each section (256MB -> 3.5MB memmap) separately.
Worst case is that we would waste 512KB.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 25 insertions, 1 deletions

diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
index bf37a094a46..6ed1426d27c 100644
--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -205,7 +205,7 @@ int __meminit vmemmap_populate(struct page *start, unsigned long nr, int node)
         start_addr = (unsigned long) start;
         end_addr = (unsigned long) (start + nr);
 
-        for (address = start_addr; address < end_addr; address += PAGE_SIZE) {
+        for (address = start_addr; address < end_addr;) {
                 pg_dir = pgd_offset_k(address);
                 if (pgd_none(*pg_dir)) {
                         pu_dir = vmem_pud_alloc();
@@ -224,10 +224,33 @@ int __meminit vmemmap_populate(struct page *start, unsigned long nr, int node)
 
                 pm_dir = pmd_offset(pu_dir, address);
                 if (pmd_none(*pm_dir)) {
+#ifdef CONFIG_64BIT
+                        /* Use 1MB frames for vmemmap if available. We always
+                         * use large frames even if they are only partially
+                         * used.
+                         * Otherwise we would have also page tables since
+                         * vmemmap_populate gets called for each section
+                         * separately. */
+                        if (MACHINE_HAS_EDAT1) {
+                                void *new_page;
+
+                                new_page = vmemmap_alloc_block(PMD_SIZE, node);
+                                if (!new_page)
+                                        goto out;
+                                pte = mk_pte_phys(__pa(new_page), PAGE_RW);
+                                pte_val(pte) |= _SEGMENT_ENTRY_LARGE;
+                                pmd_val(*pm_dir) = pte_val(pte);
+                                address = (address + PMD_SIZE) & PMD_MASK;
+                                continue;
+                        }
+#endif
                         pt_dir = vmem_pte_alloc(address);
                         if (!pt_dir)
                                 goto out;
                         pmd_populate(&init_mm, pm_dir, pt_dir);
+                } else if (pmd_large(*pm_dir)) {
+                        address = (address + PMD_SIZE) & PMD_MASK;
+                        continue;
                 }
 
                 pt_dir = pte_offset_kernel(pm_dir, address);
@@ -240,6 +263,7 @@ int __meminit vmemmap_populate(struct page *start, unsigned long nr, int node)
                         pte = pfn_pte(new_page >> PAGE_SHIFT, PAGE_KERNEL);
                         *pt_dir = pte;
                 }
+                address += PAGE_SIZE;
         }
         memset(start, 0, nr * sizeof(struct page));
         ret = 0;