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Peter Anvin" , Linus Torvalds , Michael Kelley Subject: [PATCH v5 13/15] x86/mtrr: don't let mtrr_type_lookup() return MTRR_TYPE_INVALID Date: Sat, 1 Apr 2023 08:36:50 +0200 Message-Id: <20230401063652.23522-14-jgross@suse.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230401063652.23522-1-jgross@suse.com> References: <20230401063652.23522-1-jgross@suse.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.5 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1761959311068410448?= X-GMAIL-MSGID: =?utf-8?q?1761959311068410448?= 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 Tested-by: Michael Kelley --- 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 6decb18e22ed..b17a66da1237 100644 --- a/arch/x86/include/asm/mtrr.h +++ b/arch/x86/include/asm/mtrr.h @@ -77,9 +77,12 @@ 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 5d502b926dd8..178253d117c6 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -463,13 +463,13 @@ 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)