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Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH 1/6] ARM: spectre-bhb: enable for Cortex-A15 Content-Language: en-US To: "Russell King (Oracle)" Cc: Ard Biesheuvel , linux-arm-kernel@lists.infradead.org, arnd@arndb.de, linus.walleij@linaro.org, "linux-tegra@vger.kernel.org" References: <20220328134714.205342-1-ardb@kernel.org> <20220328134714.205342-2-ardb@kernel.org> From: Jon Hunter In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: LO4P123CA0052.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:152::21) To CO6PR12MB5444.namprd12.prod.outlook.com (2603:10b6:5:35e::8) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 3218956d-d7ee-432f-af1c-08da3dadb5a4 X-MS-TrafficTypeDiagnostic: BN6PR12MB1892:EE_ X-Microsoft-Antispam-PRVS: X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CO6PR12MB5444.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230001)(4636009)(366004)(316002)(6916009)(8936002)(66946007)(86362001)(31686004)(36756003)(5660300002)(2906002)(54906003)(966005)(4326008)(66476007)(66556008)(31696002)(8676002)(38100700002)(6486002)(508600001)(26005)(6506007)(6512007)(2616005)(6666004)(186003)(53546011)(55236004)(83380400001)(45980500001)(43740500002);DIR:OUT;SFP:1101; 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So fix that. >>> >>> Signed-off-by: Ard Biesheuvel >>> --- >>> arch/arm/mm/proc-v7-bugs.c | 1 + >>> 1 file changed, 1 insertion(+) >>> >>> diff --git a/arch/arm/mm/proc-v7-bugs.c b/arch/arm/mm/proc-v7-bugs.c >>> index 06dbfb968182..fb9f3eb6bf48 100644 >>> --- a/arch/arm/mm/proc-v7-bugs.c >>> +++ b/arch/arm/mm/proc-v7-bugs.c >>> @@ -288,6 +288,7 @@ void cpu_v7_ca15_ibe(void) >>> { >>> if (check_spectre_auxcr(this_cpu_ptr(&spectre_warned), BIT(0))) >>> cpu_v7_spectre_v2_init(); >>> + cpu_v7_spectre_bhb_init(); >>> } >>> void cpu_v7_bugs_init(void) >> >> >> Since this patch has been merged, I am seeing a ton of messages when booting >> Linux on tegra124-jetson-tk1 ... >> >> [ 1233.327547] CPU0: Spectre BHB: using loop workaround >> [ 1233.327795] CPU1: Spectre BHB: using loop workaround >> [ 1233.328270] CPU1: Spectre BHB: using loop workaround > > Now that you mention this, I vaguely remember some email on the list a > while ago about this being caused by something like cpuidle - but I'm > unable to find it now. > >> [0] https://lore.kernel.org/linux-arm-kernel/20220519161310.1489625-1-dmitry.osipenko@collabora.com/T/ > > That was probably it. I am seeing ... [ 4.415167] CPU0: Spectre BHB: using loop workaround [ 4.417621] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 4.430291] [] (show_stack) from [] (dump_stack+0xc0/0xd4) [ 4.437512] [] (dump_stack) from [] (cpu_v7_spectre_bhb_init+0xd8/0x190) [ 4.445943] [] (cpu_v7_spectre_bhb_init) from [] (cpu_suspend+0xac/0xc8) [ 4.454377] [] (cpu_suspend) from [] (tegra114_idle_power_down+0x74/0x78) [ 4.462898] [] (tegra114_idle_power_down) from [] (cpuidle_enter_state+0x130/0x524) [ 4.472286] [] (cpuidle_enter_state) from [] (do_idle+0x1b0/0x200) [ 4.480199] [] (do_idle) from [] (cpu_startup_entry+0x18/0x1c) [ 4.487762] [] (cpu_startup_entry) from [<801018cc>] (0x801018cc) So definitely CPU idle. > We can't really do this for the other print, because the system status > can change as a result of CPUs being brought online. :( How about making this a pr_debug as opposed to pr_info? Jon -- nvpublic