Commit 1ca12099 authored by Juergen Gross's avatar Juergen Gross Committed by Borislav Petkov (AMD)
Browse files

x86/mtrr: Add get_effective_type() service function 



Add a service function for obtaining the effective cache mode of
overlapping MTRR registers.

Make use of that function in check_type_overlap().

Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Tested-by: default avatarMichael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20230502120931.20719-11-jgross@suse.com


Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
parent 961c6a43

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

+19 −20
Original line number Diff line number Diff line
@@ -80,31 +80,30 @@ static u64 get_mtrr_size(u64 mask) 
	return size;

}



/*

 * 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)

static u8 get_effective_type(u8 type1, u8 type2)

{

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

		*prev = MTRR_TYPE_UNCACHABLE;

		*curr = MTRR_TYPE_UNCACHABLE;

		return 1;

	}

	if (type1 == MTRR_TYPE_UNCACHABLE || type2 == MTRR_TYPE_UNCACHABLE)

		return MTRR_TYPE_UNCACHABLE;



	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 ((type1 == MTRR_TYPE_WRBACK && type2 == MTRR_TYPE_WRTHROUGH) ||

	    (type1 == MTRR_TYPE_WRTHROUGH && type2 == MTRR_TYPE_WRBACK))

		return MTRR_TYPE_WRTHROUGH;



	if (*prev != *curr) {

		*prev = MTRR_TYPE_UNCACHABLE;

		*curr = MTRR_TYPE_UNCACHABLE;

		return 1;

	if (type1 != type2)

		return MTRR_TYPE_UNCACHABLE;



	return type1;

}



	return 0;

/*

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

 * Returns true if the effective type is UNCACHEABLE, else returns false

 */

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

{

	*prev = *curr = get_effective_type(*curr, *prev);



	return *prev == MTRR_TYPE_UNCACHABLE;

}



/**