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Subject[PATCH 10/10] x86, PAT: Sanity check remap_pfn_range for RAM region
Date
Add sanity check for remap_pfn_range of RAM regions using
lookup_memtype(). Previously, we did not have anyway to get the type of
RAM memory regions as they were tracked using a single bit in
page_struct (WB, nonWB). Now we can get the actual type from page struct
(WB, WC, UC_MINUS) and make sure the requester gets that type.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
---
arch/x86/mm/pat.c | 24 +++++++++++++++++++++---
1 files changed, 21 insertions(+), 3 deletions(-)
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index b629f75..a6cace0 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -783,11 +783,29 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
is_ram = pat_pagerange_is_ram(paddr, paddr + size);

/*
- * reserve_pfn_range() doesn't support RAM pages. Maintain the current
- * behavior with RAM pages by returning success.
+ * reserve_pfn_range() for RAM pages. We do not refcount to keep
+ * track of number of mappings of RAM pages. We can assert that
+ * the type requested matches the type of first page in the range.
*/
- if (is_ram != 0)
+ if (is_ram) {
+ if (!pat_enabled)
+ return 0;
+
+ flags = lookup_memtype(paddr);
+ if (want_flags != flags) {
+ printk(KERN_WARNING
+ "%s:%d map pfn RAM range req %s for %Lx-%Lx, got %s\n",
+ current->comm, current->pid,
+ cattr_name(want_flags),
+ (unsigned long long)paddr,
+ (unsigned long long)(paddr + size),
+ cattr_name(flags));
+ *vma_prot = __pgprot((pgprot_val(*vma_prot) &
+ (~_PAGE_CACHE_MASK)) |
+ flags);
+ }
return 0;
+ }

ret = reserve_memtype(paddr, paddr + size, want_flags, &flags);
if (ret)
--
1.6.0.6


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