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Tue, 17 Nov 2020 00:41:18 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP for ; Tue, 17 Nov 2020 00:41:18 +0000 (GMT) Received: from [9.206.209.35] (unknown [9.206.209.35]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id 9FC3BA012A; Tue, 17 Nov 2020 11:41:17 +1100 (AEDT) Subject: Re: [PATCH] ocxl: Mmio invalidation support To: Christophe Lombard , linuxppc-dev@lists.ozlabs.org, fbarrat@linux.vnet.ibm.com References: <20201113153333.290505-1-clombard@linux.vnet.ibm.com> From: Andrew Donnellan Message-ID: <76002af5-6ada-ad2c-0470-e2cdc5b360c2@linux.ibm.com> Date: Tue, 17 Nov 2020 11:41:17 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201113153333.290505-1-clombard@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312, 18.0.737 definitions=2020-11-16_13:2020-11-13, 2020-11-16 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=686 suspectscore=0 impostorscore=0 spamscore=0 priorityscore=1501 adultscore=0 phishscore=0 malwarescore=0 mlxscore=0 bulkscore=0 lowpriorityscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011160147 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 14/11/20 2:33 am, Christophe Lombard wrote: > OpenCAPI 4.0/5.0 with TLBI/SLBI Snooping, is not used due to performance > problems caused by the PAU having to process all incoming TLBI/SLBI > commands which will cause them to back up on the PowerBus. > > When the Address Translation Mode requires TLB and SLB Invalidate > operations to be initiated using MMIO registers, a set of registers like > the following is used: > • XTS MMIO ATSD0 LPARID register > • XTS MMIO ATSD0 AVA register > • XTS MMIO ATSD0 launch register, write access initiates a shoot down > • XTS MMIO ATSD0 status register > > The MMIO based mechanism also blocks the NPU/PAU from snooping TLBIE > commands from the PowerBus. > > The Shootdown commands (ATSD) will be generated using MMIO registers > in the NPU/PAU and sent to the device. > > Signed-off-by: Christophe Lombard snowpatch has reported some minor checkpatch issues: https://openpower.xyz/job/snowpatch/job/snowpatch-linux-checkpatch/16267//artifact/linux/checkpatch.log -- Andrew Donnellan OzLabs, ADL Canberra ajd@linux.ibm.com IBM Australia Limited