x86, pat: fix warn_on_once() while mapping 0-1MB range with /dev/mem

Jeff Mahoney reported:

> With Suse's hwinfo tool, on -tip:
> WARNING: at arch/x86/mm/pat.c:637 reserve_pfn_range+0x5b/0x26d()

reserve_pfn_range() is not tracking the memory range below 1MB
as non-RAM and as such is inconsistent with similar checks in
reserve_memtype() and free_memtype()

Rename the pagerange_is_ram() to pat_pagerange_is_ram() and add the
"track legacy 1MB region as non RAM" condition.

And also, fix reserve_pfn_range() to return -EINVAL, when the pfn
range is RAM. This is to be consistent with this API design.

Reported-and-tested-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index e9873a2..7765791 100644 (file)
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -57,7 +57,6 @@ typedef struct { pgdval_t pgd; } pgd_t;
 typedef struct { pgprotval_t pgprot; } pgprot_t;
 
 extern int page_is_ram(unsigned long pagenr);
-extern int pagerange_is_ram(unsigned long start, unsigned long end);
 extern int devmem_is_allowed(unsigned long pagenr);
 extern void map_devmem(unsigned long pfn, unsigned long size,
                       pgprot_t vma_prot);

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index af750ab..f45d5e2 100644 (file)
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -134,25 +134,6 @@ int page_is_ram(unsigned long pagenr)
        return 0;
 }
 
-int pagerange_is_ram(unsigned long start, unsigned long end)
-{
-       int ram_page = 0, not_rampage = 0;
-       unsigned long page_nr;
-
-       for (page_nr = (start >> PAGE_SHIFT); page_nr < (end >> PAGE_SHIFT);
-            ++page_nr) {
-               if (page_is_ram(page_nr))
-                       ram_page = 1;
-               else
-                       not_rampage = 1;
-
-               if (ram_page == not_rampage)
-                       return -1;
-       }
-
-       return ram_page;
-}
-
 /*
  * Fix up the linear direct mapping of the kernel to avoid cache attribute
  * conflicts.

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 7b61036..aebbf67 100644 (file)
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -211,6 +211,33 @@ chk_conflict(struct memtype *new, struct memtype *entry, unsigned long *type)
 static struct memtype *cached_entry;
 static u64 cached_start;
 
+static int pat_pagerange_is_ram(unsigned long start, unsigned long end)
+{
+       int ram_page = 0, not_rampage = 0;
+       unsigned long page_nr;
+
+       for (page_nr = (start >> PAGE_SHIFT); page_nr < (end >> PAGE_SHIFT);
+            ++page_nr) {
+               /*
+                * For legacy reasons, physical address range in the legacy ISA
+                * region is tracked as non-RAM. This will allow users of
+                * /dev/mem to map portions of legacy ISA region, even when
+                * some of those portions are listed(or not even listed) with
+                * different e820 types(RAM/reserved/..)
+                */
+               if (page_nr >= (ISA_END_ADDRESS >> PAGE_SHIFT) &&
+                   page_is_ram(page_nr))
+                       ram_page = 1;
+               else
+                       not_rampage = 1;
+
+               if (ram_page == not_rampage)
+                       return -1;
+       }
+
+       return ram_page;
+}
+
 /*
  * For RAM pages, mark the pages as non WB memory type using
  * PageNonWB (PG_arch_1). We allow only one set_memory_uc() or
@@ -336,20 +363,12 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
        if (new_type)
                *new_type = actual_type;
 
-       /*
-        * For legacy reasons, some parts of the physical address range in the
-        * legacy 1MB region is treated as non-RAM (even when listed as RAM in
-        * the e820 tables).  So we will track the memory attributes of this
-        * legacy 1MB region using the linear memtype_list always.
-        */
-       if (end >= ISA_END_ADDRESS) {
-               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;
-       }
+       is_range_ram = pat_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)
@@ -446,19 +465,11 @@ int free_memtype(u64 start, u64 end)
        if (is_ISA_range(start, end - 1))
                return 0;
 
-       /*
-        * For legacy reasons, some parts of the physical address range in the
-        * legacy 1MB region is treated as non-RAM (even when listed as RAM in
-        * the e820 tables).  So we will track the memory attributes of this
-        * legacy 1MB region using the linear memtype_list always.
-        */
-       if (end >= ISA_END_ADDRESS) {
-               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;
-       }
+       is_range_ram = pat_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) {
@@ -626,17 +637,13 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
        unsigned long flags;
        unsigned long want_flags = (pgprot_val(*vma_prot) & _PAGE_CACHE_MASK);
 
-       is_ram = pagerange_is_ram(paddr, paddr + size);
+       is_ram = pat_pagerange_is_ram(paddr, paddr + size);
 
-       if (is_ram != 0) {
-               /*
-                * For mapping RAM pages, drivers need to call
-                * set_memory_[uc|wc|wb] directly, for reserve and free, before
-                * setting up the PTE.
-                */
-               WARN_ON_ONCE(1);
-               return 0;
-       }
+       /*
+        * reserve_pfn_range() doesn't support RAM pages.
+        */
+       if (is_ram != 0)
+               return -EINVAL;
 
        ret = reserve_memtype(paddr, paddr + size, want_flags, &flags);
        if (ret)
@@ -693,7 +700,7 @@ static void free_pfn_range(u64 paddr, unsigned long size)
 {
        int is_ram;
 
-       is_ram = pagerange_is_ram(paddr, paddr + size);
+       is_ram = pat_pagerange_is_ram(paddr, paddr + size);
        if (is_ram == 0)
                free_memtype(paddr, paddr + size);
 }