From 973df1942068c0cc72244ce7dce5e5aeca03ad5f Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Tue, 2 May 2023 14:09:29 +0200 Subject: [PATCH] x86/mtrr: Don't let mtrr_type_lookup() return MTRR_TYPE_INVALID 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 Signed-off-by: Juergen Gross Signed-off-by: Borislav Petkov (AMD) Tested-by: Michael Kelley Link: https://lore.kernel.org/r/20230502120931.20719-15-jgross@suse.com Signed-off-by: Borislav Petkov (AMD) --- arch/x86/include/asm/mtrr.h | 7 +++++-- arch/x86/include/uapi/asm/mtrr.h | 6 +++--- arch/x86/kernel/cpu/mtrr/generic.c | 4 ++-- 3 files changed, 10 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/mtrr.h b/arch/x86/include/asm/mtrr.h index 1bae790..5a758ee 100644 --- a/arch/x86/include/asm/mtrr.h +++ b/arch/x86/include/asm/mtrr.h @@ -86,9 +86,12 @@ static inline void mtrr_overwrite_state(struct mtrr_var_range *var, 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) diff --git a/arch/x86/include/uapi/asm/mtrr.h b/arch/x86/include/uapi/asm/mtrr.h index ab194c8..3a8a8eb 100644 --- a/arch/x86/include/uapi/asm/mtrr.h +++ b/arch/x86/include/uapi/asm/mtrr.h @@ -107,9 +107,9 @@ typedef __u8 mtrr_type; #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 diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index 4443e71..f6b426d 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -508,13 +508,13 @@ u8 mtrr_type_lookup(u64 start, u64 end, u8 *uniform) 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. */ -- 2.7.4