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Commit a7f07cfb authored by Venkatesh Pallipadi's avatar Venkatesh Pallipadi Committed by H. Peter Anvin
Browse files

x86, mtrr: Refactor MTRR type overlap check code 



Move the MTRR type overlap check into a new function. No functional change in
this patch. Just making it easier to add multiple region overlap check in
the following patch.

Signed-off-by: default avatarVenkatesh Pallipadi <venki@google.com>
LKML-Reference: <1284159350-19841-2-git-send-email-venki@google.com>
Reviewed-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 2bfc96a1

arch/x86/kernel/cpu/mtrr/generic.c

+29 −15
Original line number Diff line number Diff line
@@ -64,6 +64,33 @@ static inline void k8_check_syscfg_dram_mod_en(void) 
	}

}



/*

 * Check and return the effective type for MTRR-MTRR type overlap.

 * Returns 1 if the effective type is UNCACHEABLE, else returns 0

 */

static int check_type_overlap(u8 *prev, u8 *curr)

{

	if (*prev == MTRR_TYPE_UNCACHABLE || *curr == MTRR_TYPE_UNCACHABLE) {

		*prev = MTRR_TYPE_UNCACHABLE;

		*curr = MTRR_TYPE_UNCACHABLE;

		return 1;

	}



	if ((*prev == MTRR_TYPE_WRBACK && *curr == MTRR_TYPE_WRTHROUGH) ||

	    (*prev == MTRR_TYPE_WRTHROUGH && *curr == MTRR_TYPE_WRBACK)) {

		*prev = MTRR_TYPE_WRTHROUGH;

		*curr = MTRR_TYPE_WRTHROUGH;

	}



	if (*prev != *curr) {

		*prev = MTRR_TYPE_UNCACHABLE;

		*curr = MTRR_TYPE_UNCACHABLE;

		return 1;

	}



	return 0;

}



/*

 * Returns the effective MTRR type for the region

 * Error returns:
@@ -138,21 +165,8 @@ u8 mtrr_type_lookup(u64 start, u64 end) 
			continue;

		}



		if (prev_match == MTRR_TYPE_UNCACHABLE ||

		    curr_match == MTRR_TYPE_UNCACHABLE) {

			return MTRR_TYPE_UNCACHABLE;

		}



		if ((prev_match == MTRR_TYPE_WRBACK &&

		     curr_match == MTRR_TYPE_WRTHROUGH) ||

		    (prev_match == MTRR_TYPE_WRTHROUGH &&

		     curr_match == MTRR_TYPE_WRBACK)) {

			prev_match = MTRR_TYPE_WRTHROUGH;

			curr_match = MTRR_TYPE_WRTHROUGH;

		}



		if (prev_match != curr_match)

			return MTRR_TYPE_UNCACHABLE;

		if (check_type_overlap(&prev_match, &curr_match))

			return curr_match;

	}



	if (mtrr_tom2) {