From 99c13b8c8896d7bcb92753bf0c63a8de4326e78d Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Tue, 4 Jul 2017 19:04:23 -0400 Subject: x86/mm/pat: Don't report PAT on CPUs that don't support it The pat_enabled() logic is broken on CPUs which do not support PAT and where the initialization code fails to call pat_init(). Due to that the enabled flag stays true and pat_enabled() returns true wrongfully. As a consequence the mappings, e.g. for Xorg, are set up with the wrong caching mode and the required MTRR setups are omitted. To cure this the following changes are required: 1) Make pat_enabled() return true only if PAT initialization was invoked and successful. 2) Invoke init_cache_modes() unconditionally in setup_arch() and remove the extra callsites in pat_disable() and the pat disabled code path in pat_init(). Also rename __pat_enabled to pat_disabled to reflect the real purpose of this variable. Fixes: 9cd25aac1f44 ("x86/mm/pat: Emulate PAT when it is disabled") Signed-off-by: Mikulas Patocka Signed-off-by: Thomas Gleixner Cc: Bernhard Held Cc: Denys Vlasenko Cc: Peter Zijlstra Cc: Brian Gerst Cc: "Luis R. Rodriguez" Cc: Borislav Petkov Cc: Andy Lutomirski Cc: Josh Poimboeuf Cc: Andrew Morton Cc: Linus Torvalds Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1707041749300.3456@file01.intranet.prod.int.rdu2.redhat.com --- arch/x86/mm/pat.c | 28 ++++++++++++---------------- 1 file changed, 12 insertions(+), 16 deletions(-) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 9b78685b66e6..45979502f64b 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -37,14 +37,14 @@ #undef pr_fmt #define pr_fmt(fmt) "" fmt -static bool boot_cpu_done; - -static int __read_mostly __pat_enabled = IS_ENABLED(CONFIG_X86_PAT); -static void init_cache_modes(void); +static bool __read_mostly boot_cpu_done; +static bool __read_mostly pat_disabled = !IS_ENABLED(CONFIG_X86_PAT); +static bool __read_mostly pat_initialized; +static bool __read_mostly init_cm_done; void pat_disable(const char *reason) { - if (!__pat_enabled) + if (pat_disabled) return; if (boot_cpu_done) { @@ -52,10 +52,8 @@ void pat_disable(const char *reason) return; } - __pat_enabled = 0; + pat_disabled = true; pr_info("x86/PAT: %s\n", reason); - - init_cache_modes(); } static int __init nopat(char *str) @@ -67,7 +65,7 @@ early_param("nopat", nopat); bool pat_enabled(void) { - return !!__pat_enabled; + return pat_initialized; } EXPORT_SYMBOL_GPL(pat_enabled); @@ -205,6 +203,8 @@ static void __init_cache_modes(u64 pat) update_cache_mode_entry(i, cache); } pr_info("x86/PAT: Configuration [0-7]: %s\n", pat_msg); + + init_cm_done = true; } #define PAT(x, y) ((u64)PAT_ ## y << ((x)*8)) @@ -225,6 +225,7 @@ static void pat_bsp_init(u64 pat) } wrmsrl(MSR_IA32_CR_PAT, pat); + pat_initialized = true; __init_cache_modes(pat); } @@ -242,10 +243,9 @@ static void pat_ap_init(u64 pat) wrmsrl(MSR_IA32_CR_PAT, pat); } -static void init_cache_modes(void) +void init_cache_modes(void) { u64 pat = 0; - static int init_cm_done; if (init_cm_done) return; @@ -287,8 +287,6 @@ static void init_cache_modes(void) } __init_cache_modes(pat); - - init_cm_done = 1; } /** @@ -306,10 +304,8 @@ void pat_init(void) u64 pat; struct cpuinfo_x86 *c = &boot_cpu_data; - if (!pat_enabled()) { - init_cache_modes(); + if (pat_disabled) return; - } if ((c->x86_vendor == X86_VENDOR_INTEL) && (((c->x86 == 0x6) && (c->x86_model <= 0xd)) || -- cgit v1.2.3