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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: Ard Biesheuvel , Russell King Cc: Linux ARM , Arnd Bergmann , Linus Walleij , "linux-tegra@vger.kernel.org" , Dmitry Osipenko 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: LO4P123CA0227.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:1a6::16) 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: bf7baef3-b0db-4d0c-7878-08da3d9f5e07 X-MS-TrafficTypeDiagnostic: DM6PR12MB4106: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)(110136005)(2906002)(36756003)(54906003)(508600001)(31686004)(316002)(55236004)(38100700002)(53546011)(6506007)(31696002)(6666004)(86362001)(66476007)(66946007)(4326008)(83380400001)(8676002)(66556008)(5660300002)(2616005)(186003)(6486002)(8936002)(6512007)(26005)(43740500002)(45980500001);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 ... >> > > Thanks for the report. The good news is that the Spectre BHB > protection is finally taking effect on your system. > >> [ 1233.327547] CPU0: Spectre BHB: using loop workaround >> [ 1233.327795] CPU1: Spectre BHB: using loop workaround >> [ 1233.328270] CPU1: Spectre BHB: using loop workaround >> [ 1233.328700] CPU1: Spectre BHB: using loop workaround >> [ 1233.355477] CPU2: Spectre BHB: using loop workaround >> ** 7 printk messages dropped ** >> [ 1233.366271] CPU0: Spectre BHB: using loop workaround >> [ 1233.366580] CPU0: Spectre BHB: using loop workaround >> [ 1233.366815] CPU1: Spectre BHB: using loop workaround >> [ 1233.405475] CPU1: Spectre BHB: using loop workaround >> [ 1233.405874] CPU0: Spectre BHB: using loop workaround >> [ 1233.406041] CPU1: Spectre BHB: using loop workaround >> ** 1 printk messages dropped ** >> >> This is significantly increasing the boot time and causing failures if >> the boot takes too long. >> >> I see that Dmitry has posted a fix for one of these cases [0], but the >> above also needs to be fixed. >> > > Agreed. > > Do we have any idea why this init hook is being called so often? Is > this expected on systems that do agressive suspend/resume for power > management, or is there another existing issue here that is just > coming to light due to the newly added printk() ? So far I have not dug any further, but I do know it is not doing any aggressive suspend/resume. From what Dmitry indicated he saw this during CPU idle transitions and this platform would definitely by exercising CPU idle. Jon -- nvpublic