From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752954AbbAPIHe (ORCPT ); Fri, 16 Jan 2015 03:07:34 -0500 Received: from mga02.intel.com ([134.134.136.20]:29232 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752398AbbAPIH3 (ORCPT ); Fri, 16 Jan 2015 03:07:29 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,409,1418112000"; d="scan'208";a="670932582" Message-ID: <54B8C6BE.7020904@linux.intel.com> Date: Fri, 16 Jan 2015 16:07:26 +0800 From: Jiang Liu Organization: Intel User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Thomas Gleixner , LKML CC: Joerg Roedel , x86@kernel.org, Tony Luck , Borislav Petkov Subject: Re: [patch 06/23] x86/apic: Check x2apic early References: <20150115210458.625399149@linutronix.de> <20150115211702.702479404@linutronix.de> In-Reply-To: <20150115211702.702479404@linutronix.de> Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Thomas, check_x2apic() is a little too early. If system panics in check_x2apic(), it's a blank console if system panics in check_x2apic(). I also tried to disabled x2apic in check_x2apic() if x2apic is enabled by BIOS but kernel doesn't support x2apic. It may continue for a while, but eventually run into livelock with following log messages: [ 222.436829] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2 [ 222.436829] INTR-REMAP:[fault reason 36] Detected reserved fields in the IRTE entry [ 222.452737] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2 [ 222.452737] INTR-REMAP:[fault reason 36] Detected reserved fields in the IRTE entry [ 222.468645] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2 [ 222.468645] INTR-REMAP:[fault reason 36] Detected reserved fields in the IRTE entry [ 222.484554] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2 [ 222.484554] INTR-REMAP:[fault reason 36] Detected reserved fields in the IRTE entry [ 222.500463] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2 [ 222.500463] INTR-REMAP:[fault reason 36] Detected reserved fields in the IRTE entry [ 222.516371] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2 [ 222.516371] INTR-REMAP:[fault reason 36] Detected reserved fields in the IRTE entry [ 222.532285] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2 [ 222.532285] INTR-REMAP:[fault reason 36] Detected reserved fields in the IRTE entry [ 222.548200] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2 So seems we need to revert to original solution. Thanks! Gerry ------------------------------------------------------------------------ On 2015/1/16 5:22, Thomas Gleixner wrote: No point in delaying the x2apic detection for the CONFIG_X86_X2APIC=n case to enable_IR_x2apic(). We rather detect that in the early boot code in check_x2apic(). Signed-off-by: Thomas Gleixner --- arch/x86/include/asm/apic.h | 6 ++---- arch/x86/kernel/apic/apic.c | 33 +++++++++++++++++++-------------- 2 files changed, 21 insertions(+), 18 deletions(-) Index: tip/arch/x86/include/asm/apic.h =================================================================== --- tip.orig/arch/x86/include/asm/apic.h +++ tip/arch/x86/include/asm/apic.h @@ -177,7 +177,6 @@ static inline u64 native_x2apic_icr_read extern int x2apic_mode; extern int x2apic_phys; -extern void check_x2apic(void); extern void enable_x2apic(void); static inline int x2apic_enabled(void) { @@ -193,9 +192,6 @@ static inline void x2apic_force_phys(voi static inline void disable_x2apic(void) { } -static inline void check_x2apic(void) -{ -} static inline void enable_x2apic(void) { } @@ -429,6 +425,7 @@ static inline u32 safe_apic_wait_icr_idl } extern void __init apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v)); +extern void __init check_x2apic(void); #else /* CONFIG_X86_LOCAL_APIC */ @@ -440,6 +437,7 @@ static inline void apic_icr_write(u32 lo static inline void apic_wait_icr_idle(void) { } static inline u32 safe_apic_wait_icr_idle(void) { return 0; } static inline void apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v)) {} +static inline void check_x2apic(void) { } #endif /* CONFIG_X86_LOCAL_APIC */ Index: tip/arch/x86/kernel/apic/apic.c =================================================================== --- tip.orig/arch/x86/kernel/apic/apic.c +++ tip/arch/x86/kernel/apic/apic.c @@ -1541,14 +1541,6 @@ static __init void disable_x2apic(void) x2apic_disabled = 1; } -void check_x2apic(void) -{ - if (x2apic_enabled()) { - pr_info("x2apic enabled by BIOS, switching to x2apic ops\n"); - x2apic_mode = 1; - } -} - void enable_x2apic(void) { u64 msr; @@ -1568,7 +1560,25 @@ void enable_x2apic(void) wrmsrl(MSR_IA32_APICBASE, msr | X2APIC_ENABLE); } } -#endif /* CONFIG_X86_X2APIC */ + +void __init check_x2apic(void) +{ + if (x2apic_enabled()) { + pr_info("x2apic enabled by BIOS, switching to x2apic ops\n"); + x2apic_mode = 1; + } +} +#else /* CONFIG_X86_X2APIC */ +void __init check_x2apic(void) +{ + if (!cpu_has_apic || !apic_is_x2apic_enabled()) + return; + /* + * Checkme: Can we simply turn off x2apic here instead of panic? + */ + panic("BIOS has enabled x2apic but kernel doesn't support x2apic, please disable x2apic in BIOS.\n"); +} +#endif /* !CONFIG_X86_X2APIC */ static int __init try_to_enable_IR(void) { @@ -1620,11 +1630,6 @@ void __init enable_IR_x2apic(void) unsigned long flags; int ret, ir_stat; - if (!IS_ENABLED(CONFIG_X86_X2APIC)) { - if (apic_is_x2apic_enabled()) - panic("BIOS has enabled x2apic but kernel doesn't support x2apic, please disable x2apic in BIOS.\n"); - } - ir_stat = irq_remapping_prepare(); if (ir_stat < 0 && !x2apic_supported()) return;