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Commit d886c73c authored by Venkatesh Pallipadi's avatar Venkatesh Pallipadi Committed by H. Peter Anvin
Browse files

x86, pat: Sanity check remap_pfn_range for RAM region 



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: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 10876376

arch/x86/mm/pat.c

+21 −3
Original line number Diff line number Diff line
@@ -783,12 +783,30 @@ 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)

		return ret;