1 files changed, 106 insertions, 26 deletions

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 2a50e0fa64a5..738fd0f24958 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -7,24 +7,24 @@
  * Loosely based on earlier PAT patchset from Eric Biederman and Andi Kleen.
  */
 
-#include <linux/mm.h>
+#include <linux/seq_file.h>
+#include <linux/bootmem.h>
+#include <linux/debugfs.h>
 #include <linux/kernel.h>
 #include <linux/gfp.h>
+#include <linux/mm.h>
 #include <linux/fs.h>
-#include <linux/bootmem.h>
-#include <linux/debugfs.h>
-#include <linux/seq_file.h>
 
-#include <asm/msr.h>
-#include <asm/tlbflush.h>
+#include <asm/cacheflush.h>
 #include <asm/processor.h>
-#include <asm/page.h>
+#include <asm/tlbflush.h>
 #include <asm/pgtable.h>
-#include <asm/pat.h>
-#include <asm/e820.h>
-#include <asm/cacheflush.h>
 #include <asm/fcntl.h>
+#include <asm/e820.h>
 #include <asm/mtrr.h>
+#include <asm/page.h>
+#include <asm/msr.h>
+#include <asm/pat.h>
 #include <asm/io.h>
 
 #ifdef CONFIG_X86_PAT
@@ -46,6 +46,7 @@ early_param("nopat", nopat);
 
 
 static int debug_enable;
+
 static int __init pat_debug_setup(char *str)
 {
         debug_enable = 1;
@@ -145,14 +146,14 @@ static char *cattr_name(unsigned long flags)
  */
 
 struct memtype {
-        u64 start;
-        u64 end;
-        unsigned long type;
-        struct list_head nd;
+        u64                     start;
+        u64                     end;
+        unsigned long           type;
+        struct list_head        nd;
 };
 
 static LIST_HEAD(memtype_list);
-static DEFINE_SPINLOCK(memtype_lock);   /* protects memtype list */
+static DEFINE_SPINLOCK(memtype_lock);   /* protects memtype list */
 
 /*
  * Does intersection of PAT memory type and MTRR memory type and returns
@@ -180,8 +181,8 @@ static unsigned long pat_x_mtrr_type(u64 start, u64 end, unsigned long req_type)
         return req_type;
 }
 
-static int chk_conflict(struct memtype *new, struct memtype *entry,
-                        unsigned long *type)
+static int
+chk_conflict(struct memtype *new, struct memtype *entry, unsigned long *type)
 {
         if (new->type != entry->type) {
                 if (type) {
@@ -211,6 +212,66 @@ static struct memtype *cached_entry;
 static u64 cached_start;
 
 /*
+ * For RAM pages, mark the pages as non WB memory type using
+ * PageNonWB (PG_arch_1). We allow only one set_memory_uc() or
+ * set_memory_wc() on a RAM page at a time before marking it as WB again.
+ * This is ok, because only one driver will be owning the page and
+ * doing set_memory_*() calls.
+ *
+ * For now, we use PageNonWB to track that the RAM page is being mapped
+ * as non WB. In future, we will have to use one more flag
+ * (or some other mechanism in page_struct) to distinguish between
+ * UC and WC mapping.
+ */
+static int reserve_ram_pages_type(u64 start, u64 end, unsigned long req_type,
+                                  unsigned long *new_type)
+{
+        struct page *page;
+        u64 pfn, end_pfn;
+
+        for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) {
+                page = pfn_to_page(pfn);
+                if (page_mapped(page) || PageNonWB(page))
+                        goto out;
+
+                SetPageNonWB(page);
+        }
+        return 0;
+
+out:
+        end_pfn = pfn;
+        for (pfn = (start >> PAGE_SHIFT); pfn < end_pfn; ++pfn) {
+                page = pfn_to_page(pfn);
+                ClearPageNonWB(page);
+        }
+
+        return -EINVAL;
+}
+
+static int free_ram_pages_type(u64 start, u64 end)
+{
+        struct page *page;
+        u64 pfn, end_pfn;
+
+        for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) {
+                page = pfn_to_page(pfn);
+                if (page_mapped(page) || !PageNonWB(page))
+                        goto out;
+
+                ClearPageNonWB(page);
+        }
+        return 0;
+
+out:
+        end_pfn = pfn;
+        for (pfn = (start >> PAGE_SHIFT); pfn < end_pfn; ++pfn) {
+                page = pfn_to_page(pfn);
+                SetPageNonWB(page);
+        }
+        return -EINVAL;
+}
+
+/*
  * req_type typically has one of the:
  * - _PAGE_CACHE_WB
  * - _PAGE_CACHE_WC
@@ -226,14 +287,15 @@ static u64 cached_start;
  * it will return a negative return value.
  */
 int reserve_memtype(u64 start, u64 end, unsigned long req_type,
-                        unsigned long *new_type)
+                    unsigned long *new_type)
 {
         struct memtype *new, *entry;
         unsigned long actual_type;
         struct list_head *where;
+        int is_range_ram;
         int err = 0;
 
-        BUG_ON(start >= end); /* end is exclusive */
+        BUG_ON(start >= end); /* end is exclusive */
 
         if (!pat_enabled) {
                 /* This is identical to page table setting without PAT */
@@ -266,17 +328,24 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
                         actual_type = _PAGE_CACHE_WB;
                 else
                         actual_type = _PAGE_CACHE_UC_MINUS;
-        } else
+        } else {
                 actual_type = pat_x_mtrr_type(start, end,
                                               req_type & _PAGE_CACHE_MASK);
+        }
+
+        is_range_ram = pagerange_is_ram(start, end);
+        if (is_range_ram == 1)
+                return reserve_ram_pages_type(start, end, req_type, new_type);
+        else if (is_range_ram < 0)
+                return -EINVAL;
 
         new  = kmalloc(sizeof(struct memtype), GFP_KERNEL);
         if (!new)
                 return -ENOMEM;
 
-        new->start = start;
-        new->end = end;
-        new->type = actual_type;
+        new->start      = start;
+        new->end        = end;
+        new->type       = actual_type;
 
         if (new_type)
                 *new_type = actual_type;
@@ -335,6 +404,7 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
                        start, end, cattr_name(new->type), cattr_name(req_type));
                 kfree(new);
                 spin_unlock(&memtype_lock);
+
                 return err;
         }
 
@@ -358,6 +428,7 @@ int free_memtype(u64 start, u64 end)
 {
         struct memtype *entry;
         int err = -EINVAL;
+        int is_range_ram;
 
         if (!pat_enabled)
                 return 0;
@@ -366,6 +437,12 @@ int free_memtype(u64 start, u64 end)
         if (is_ISA_range(start, end - 1))
                 return 0;
 
+        is_range_ram = pagerange_is_ram(start, end);
+        if (is_range_ram == 1)
+                return free_ram_pages_type(start, end);
+        else if (is_range_ram < 0)
+                return -EINVAL;
+
         spin_lock(&memtype_lock);
         list_for_each_entry(entry, &memtype_list, nd) {
                 if (entry->start == start && entry->end == end) {
@@ -386,6 +463,7 @@ int free_memtype(u64 start, u64 end)
         }
 
         dprintk("free_memtype request 0x%Lx-0x%Lx\n", start, end);
+
         return err;
 }
 
@@ -492,9 +570,9 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
 
 void map_devmem(unsigned long pfn, unsigned long size, pgprot_t vma_prot)
 {
+        unsigned long want_flags = (pgprot_val(vma_prot) & _PAGE_CACHE_MASK);
         u64 addr = (u64)pfn << PAGE_SHIFT;
         unsigned long flags;
-        unsigned long want_flags = (pgprot_val(vma_prot) & _PAGE_CACHE_MASK);
 
         reserve_memtype(addr, addr + size, want_flags, &flags);
         if (flags != want_flags) {
@@ -514,7 +592,7 @@ void unmap_devmem(unsigned long pfn, unsigned long size, pgprot_t vma_prot)
         free_memtype(addr, addr + size);
 }
 
-#if defined(CONFIG_DEBUG_FS)
+#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_X86_PAT)
 
 /* get Nth element of the linked list */
 static struct memtype *memtype_get_idx(loff_t pos)
@@ -537,6 +615,7 @@ static struct memtype *memtype_get_idx(loff_t pos)
         }
         spin_unlock(&memtype_lock);
         kfree(print_entry);
+
         return NULL;
 }
 
@@ -567,6 +646,7 @@ static int memtype_seq_show(struct seq_file *seq, void *v)
         seq_printf(seq, "%s @ 0x%Lx-0x%Lx\n", cattr_name(print_entry->type),
                         print_entry->start, print_entry->end);
         kfree(print_entry);
+
         return 0;
 }
 
@@ -598,4 +678,4 @@ static int __init pat_memtype_list_init(void)
 
 late_initcall(pat_memtype_list_init);
 
-#endif /* CONFIG_DEBUG_FS */
+#endif /* CONFIG_DEBUG_FS && CONFIG_X86_PAT */