Commit-ID: 9dac6290945142e6b87d9f027edfee676dcfbfda Gitweb: http://git.kernel.org/tip/9dac6290945142e6b87d9f027edfee676dcfbfda Author: Borislav Petkov <bp@xxxxxxx> AuthorDate: Thu, 4 Jun 2015 18:55:09 +0200 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Sun, 7 Jun 2015 15:28:52 +0200 x86/mm/pat: Untangle pat_init() Split it into a BSP and AP version which makes the PAT initialization path actually readable again. Signed-off-by: Borislav Petkov <bp@xxxxxxx> Reviewed-by: Toshi Kani <toshi.kani@xxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Elliott@xxxxxx Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Luis R. Rodriguez <mcgrof@xxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: arnd@xxxxxxxx Cc: hch@xxxxxx Cc: hmh@xxxxxxxxxx Cc: jgross@xxxxxxxx Cc: konrad.wilk@xxxxxxxxxx Cc: linux-mm <linux-mm@xxxxxxxxx> Cc: linux-nvdimm@xxxxxxxxxxxx Cc: stefan.bader@xxxxxxxxxxxxx Cc: yigal@xxxxxxxxxxxxx Link: http://lkml.kernel.org/r/1433436928-31903-2-git-send-email-bp@xxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/mm/pat.c | 69 ++++++++++++++++++++++++++++++++----------------------- 1 file changed, 40 insertions(+), 29 deletions(-) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index a1c9654..476d078 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -36,6 +36,8 @@ #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 inline void pat_disable(const char *reason) @@ -194,31 +196,47 @@ void pat_init_cache_modes(void) #define PAT(x, y) ((u64)PAT_ ## y << ((x)*8)) -void pat_init(void) +static void pat_bsp_init(u64 pat) { - u64 pat; - bool boot_cpu = !boot_pat_state; + if (!cpu_has_pat) { + pat_disable("PAT not supported by CPU."); + return; + } - if (!pat_enabled()) + rdmsrl(MSR_IA32_CR_PAT, boot_pat_state); + if (!boot_pat_state) { + pat_disable("PAT MSR is 0, disabled."); return; + } + wrmsrl(MSR_IA32_CR_PAT, pat); + + pat_init_cache_modes(); +} + +static void pat_ap_init(u64 pat) +{ if (!cpu_has_pat) { - if (!boot_pat_state) { - pat_disable("PAT not supported by CPU."); - return; - } else { - /* - * If this happens we are on a secondary CPU, but - * switched to PAT on the boot CPU. We have no way to - * undo PAT. - */ - pr_err("x86/PAT: PAT enabled, but not supported by secondary CPU\n"); - BUG(); - } + /* + * If this happens we are on a secondary CPU, but switched to + * PAT on the boot CPU. We have no way to undo PAT. + */ + panic("x86/PAT: PAT enabled, but not supported by secondary CPU\n"); } - /* Set PWT to Write-Combining. All other bits stay the same */ + wrmsrl(MSR_IA32_CR_PAT, pat); +} + +void pat_init(void) +{ + u64 pat; + + if (!pat_enabled()) + return; + /* + * Set PWT to Write-Combining. All other bits stay the same: + * * PTE encoding used in Linux: * PAT * |PCD @@ -233,19 +251,12 @@ void pat_init(void) pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) | PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC); - /* Boot CPU check */ - if (!boot_pat_state) { - rdmsrl(MSR_IA32_CR_PAT, boot_pat_state); - if (!boot_pat_state) { - pat_disable("PAT read returns always zero, disabled."); - return; - } + if (!boot_cpu_done) { + pat_bsp_init(pat); + boot_cpu_done = true; + } else { + pat_ap_init(pat); } - - wrmsrl(MSR_IA32_CR_PAT, pat); - - if (boot_cpu) - pat_init_cache_modes(); } #undef PAT -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>