From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14A06C433B4 for ; Sun, 9 May 2021 00:01:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CBD516141D for ; Sun, 9 May 2021 00:01:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229649AbhEHXlk (ORCPT ); Sat, 8 May 2021 19:41:40 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:34137 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229601AbhEHXlj (ORCPT ); Sat, 8 May 2021 19:41:39 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=laijs@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0UYBf8LZ_1620517234; Received: from C02XQCBJJG5H.local(mailfrom:laijs@linux.alibaba.com fp:SMTPD_---0UYBf8LZ_1620517234) by smtp.aliyun-inc.com(127.0.0.1); Sun, 09 May 2021 07:40:35 +0800 Subject: Re: [patch 1/2] x86/cpu: Init exception handling from cpu_init_secondary() To: Thomas Gleixner , LKML Cc: x86@kernel.org, Joerg Roedel , Borislav Petkov References: <20210507110210.147106915@linutronix.de> <20210507114000.429303187@linutronix.de> From: Lai Jiangshan Message-ID: Date: Sun, 9 May 2021 07:40:34 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210507114000.429303187@linutronix.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/5/7 19:02, Thomas Gleixner wrote: > From: Borislav Petkov > > SEV-ES guests require properly setup task register with which the TSS > descriptor in the GDT can be located so that the IST-type #VC exception > handler which they need to function properly, can be executed. > > This setup needs to happen before attempting to load microcode in > ucode_cpu_init() on secondary CPUs which can cause such #VC exceptions. > > Simplify the machinery by running that exception setup from a new function > cpu_init_secondary() and explicitly call cpu_init_exception_handling() for > the boot CPU before cpu_init(). The latter prepares for fixing and > simplifying the exception/IST setup on the boot CPU. > > There should be no functional changes resulting from this patch. > > [ tglx: Reworked it so cpu_init_exception_handling() stays separate ] > > Signed-off-by: Borislav Petkov > Signed-off-by: Thomas Gleixner > > --- > arch/x86/include/asm/processor.h | 1 + > arch/x86/kernel/cpu/common.c | 24 +++++++++++------------- > arch/x86/kernel/traps.c | 4 +--- > 3 files changed, 13 insertions(+), 16 deletions(-) > > --- a/arch/x86/include/asm/processor.h > +++ b/arch/x86/include/asm/processor.h > @@ -663,6 +663,7 @@ extern void load_direct_gdt(int); > extern void load_fixmap_gdt(int); > extern void load_percpu_segment(int); > extern void cpu_init(void); > +extern void cpu_init_secondary(void); > extern void cpu_init_exception_handling(void); > extern void cr4_init(void); > > --- a/arch/x86/kernel/cpu/common.c > +++ b/arch/x86/kernel/cpu/common.c > @@ -1938,13 +1938,12 @@ void cpu_init_exception_handling(void) > > /* > * cpu_init() initializes state that is per-CPU. Some data is already > - * initialized (naturally) in the bootstrap process, such as the GDT > - * and IDT. We reload them nevertheless, this function acts as a > - * 'CPU state barrier', nothing should get across. > + * initialized (naturally) in the bootstrap process, such as the GDT. We > + * reload it nevertheless, this function acts as a 'CPU state barrier', > + * nothing should get across. > */ > void cpu_init(void) > { > - struct tss_struct *tss = this_cpu_ptr(&cpu_tss_rw); > struct task_struct *cur = current; > int cpu = raw_smp_processor_id(); > > @@ -1957,8 +1956,6 @@ void cpu_init(void) > early_cpu_to_node(cpu) != NUMA_NO_NODE) > set_numa_node(early_cpu_to_node(cpu)); > #endif > - setup_getcpu(cpu); > - > pr_debug("Initializing CPU#%d\n", cpu); > > if (IS_ENABLED(CONFIG_X86_64) || cpu_feature_enabled(X86_FEATURE_VME) || > @@ -1970,7 +1967,6 @@ void cpu_init(void) > * and set up the GDT descriptor: > */ > switch_to_new_gdt(cpu); > - load_current_idt(); > > if (IS_ENABLED(CONFIG_X86_64)) { > loadsegment(fs, 0); > @@ -1990,12 +1986,6 @@ void cpu_init(void) > initialize_tlbstate_and_flush(); > enter_lazy_tlb(&init_mm, cur); > > - /* Initialize the TSS. */ > - tss_setup_ist(tss); > - tss_setup_io_bitmap(tss); > - set_tss_desc(cpu, &get_cpu_entry_area(cpu)->tss.x86_tss); > - > - load_TR_desc(); > /* > * sp0 points to the entry trampoline stack regardless of what task > * is running. > @@ -2017,6 +2007,14 @@ void cpu_init(void) > load_fixmap_gdt(cpu); > } > > +#ifdef CONFIG_SMP > +void cpu_init_secondary(void) > +{ > + cpu_init_exception_handling(); > + cpu_init(); > +} > +#endif Hello No code invokes this function in this patch. Forgot to invoke it from start_secondary() or somewhere? Thanks Lai > + > /* > * The microcode loader calls this upon late microcode load to recheck features, > * only when microcode has been updated. Caller holds microcode_mutex and CPU > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -1162,9 +1162,7 @@ void __init trap_init(void) > > idt_setup_traps(); > > - /* > - * Should be a barrier for any external CPU state: > - */ > + cpu_init_exception_handling(); > cpu_init(); > > idt_setup_ist_traps(); >