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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 5 Jun 2019 08:42:06 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x557g53L52166888 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 5 Jun 2019 07:42:05 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 71FE04C040; Wed, 5 Jun 2019 07:42:05 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 22F054C046; Wed, 5 Jun 2019 07:42:05 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 5 Jun 2019 07:42:05 +0000 (GMT) Received: from [10.61.2.125] (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id C2B1DA00F6; Wed, 5 Jun 2019 17:42:03 +1000 (AEST) Subject: Re: [PATCH v5] powerpc/64s: support nospectre_v2 cmdline option To: "Christopher M. Riedl" , linuxppc-dev@ozlabs.org References: <20190524024647.381-1-cmr@informatik.wtf> From: Andrew Donnellan Date: Wed, 5 Jun 2019 17:42:03 +1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190524024647.381-1-cmr@informatik.wtf> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-AU Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19060507-0020-0000-0000-00000345DE6F X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19060507-0021-0000-0000-00002198EBB8 Message-Id: <98c47360-c89c-5f4d-1c32-f6ac0ddd7f1e@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-06-05_06:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906050050 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 24/5/19 12:46 pm, Christopher M. Riedl wrote: > Add support for disabling the kernel implemented spectre v2 mitigation > (count cache flush on context switch) via the nospectre_v2 and > mitigations=off cmdline options. > > Suggested-by: Michael Ellerman > Signed-off-by: Christopher M. Riedl > Reviewed-by: Andrew Donnellan snowpatch is whinging about this breaking the build for some reason... https://patchwork.ozlabs.org/patch/1104583/ > --- > v4->v5: > Fix checkpatch complaint > arch/powerpc/kernel/security.c | 19 ++++++++++++++++--- > 1 file changed, 16 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c > index e1c9cf079503..7cfcb294b11c 100644 > --- a/arch/powerpc/kernel/security.c > +++ b/arch/powerpc/kernel/security.c > @@ -28,7 +28,7 @@ static enum count_cache_flush_type count_cache_flush_type = COUNT_CACHE_FLUSH_NO > bool barrier_nospec_enabled; > static bool no_nospec; > static bool btb_flush_enabled; > -#ifdef CONFIG_PPC_FSL_BOOK3E > +#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_BOOK3S_64) > static bool no_spectrev2; > #endif > > @@ -114,7 +114,7 @@ static __init int security_feature_debugfs_init(void) > device_initcall(security_feature_debugfs_init); > #endif /* CONFIG_DEBUG_FS */ > > -#ifdef CONFIG_PPC_FSL_BOOK3E > +#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_BOOK3S_64) > static int __init handle_nospectre_v2(char *p) > { > no_spectrev2 = true; > @@ -122,6 +122,9 @@ static int __init handle_nospectre_v2(char *p) > return 0; > } > early_param("nospectre_v2", handle_nospectre_v2); > +#endif /* CONFIG_PPC_FSL_BOOK3E || CONFIG_PPC_BOOK3S_64 */ > + > +#ifdef CONFIG_PPC_FSL_BOOK3E > void setup_spectre_v2(void) > { > if (no_spectrev2 || cpu_mitigations_off()) > @@ -399,7 +402,17 @@ static void toggle_count_cache_flush(bool enable) > > void setup_count_cache_flush(void) > { > - toggle_count_cache_flush(true); > + bool enable = true; > + > + if (no_spectrev2 || cpu_mitigations_off()) { > + if (security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED) || > + security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED)) > + pr_warn("Spectre v2 mitigations not under software control, can't disable\n"); > + > + enable = false; > + } > + > + toggle_count_cache_flush(enable); > } > > #ifdef CONFIG_DEBUG_FS > -- Andrew Donnellan OzLabs, ADL Canberra ajd@linux.ibm.com IBM Australia Limited