mtrr_type_lookup() should always return a valid memory type. In case
there is no information available, it should return the default UC.
This will remove the last case where mtrr_type_lookup() can return
MTRR_TYPE_INVALID, so adjust the comment in include/uapi/asm/mtrr.h.
Note that removing the MTRR_TYPE_INVALID #define from that header
could break user code, so it has to stay.
At the same time the mtrr_type_lookup() stub for the !CONFIG_MTRR
case should set uniform to 1, as if the memory range would be
covered by no MTRR at all.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20230502120931.20719-15-jgross@suse.com
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
static inline u8 mtrr_type_lookup(u64 addr, u64 end, u8 *uniform)
{
/*
- * Return no-MTRRs:
+ * Return the default MTRR type, without any known other types in
+ * that range.
*/
- return MTRR_TYPE_INVALID;
+ *uniform = 1;
+
+ return MTRR_TYPE_UNCACHABLE;
}
#define mtrr_save_fixed_ranges(arg) do {} while (0)
#define mtrr_save_state() do {} while (0)
#define MTRR_NUM_TYPES 7
/*
- * Invalid MTRR memory type. mtrr_type_lookup() returns this value when
- * MTRRs are disabled. Note, this value is allocated from the reserved
- * values (0x7-0xff) of the MTRR memory types.
+ * Invalid MTRR memory type. No longer used outside of MTRR code.
+ * Note, this value is allocated from the reserved values (0x7-0xff) of
+ * the MTRR memory types.
*/
#define MTRR_TYPE_INVALID 0xff
if (!mtrr_state_set) {
/* Uniformity is unknown. */
*uniform = 0;
- return MTRR_TYPE_INVALID;
+ return MTRR_TYPE_UNCACHABLE;
}
*uniform = 1;
if (!(mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED))
- return MTRR_TYPE_INVALID;
+ return MTRR_TYPE_UNCACHABLE;
for (i = 0; i < cache_map_n && start < end; i++) {
/* Region after current map entry? -> continue with next one. */