Messages in this thread Patch in this message | | | From | Juergen Gross <> | Subject | [PATCH v6 14/16] x86/mtrr: don't let mtrr_type_lookup() return MTRR_TYPE_INVALID | Date | Tue, 2 May 2023 14:09:29 +0200 |
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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> Tested-by: Michael Kelley <mikelley@microsoft.com> --- V2: - always set uniform - set uniform to 1 in case of disabled MTRRs (Linus Torvalds) V3: - adjust include/uapi/asm/mtrr.h comment --- 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 9837fe34e58b..9776a4d576f8 100644 --- a/arch/x86/include/asm/mtrr.h +++ b/arch/x86/include/asm/mtrr.h @@ -78,9 +78,12 @@ 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 376563f2bac1..4aa05c2ffa78 100644 --- a/arch/x86/include/uapi/asm/mtrr.h +++ b/arch/x86/include/uapi/asm/mtrr.h @@ -115,9 +115,9 @@ struct mtrr_state_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 2197e835e98c..bb124f16f88c 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -510,13 +510,13 @@ u8 mtrr_type_lookup(u64 start, u64 end, u8 *uniform) if (!mtrr_state_set) { *uniform = 0; /* Uniformity is unknown. */ - 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++) { if (start >= cache_map[i].end) -- 2.35.3
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