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Wed, 06 May 2026 19:27:35 +0000 (GMT) Received: from smtpav06.dal12v.mail.ibm.com (smtpav06.dal12v.mail.ibm.com [10.241.53.105]) by smtprelay02.dal12v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 646JRYae29229716 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 6 May 2026 19:27:34 GMT Received: from smtpav06.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B3EBC58055; Wed, 6 May 2026 19:27:34 +0000 (GMT) Received: from smtpav06.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 16C7C58043; Wed, 6 May 2026 19:27:34 +0000 (GMT) Received: from [9.67.175.186] (unknown [9.67.175.186]) by smtpav06.dal12v.mail.ibm.com (Postfix) with ESMTP; Wed, 6 May 2026 19:27:33 +0000 (GMT) Message-ID: Date: Wed, 6 May 2026 14:27:33 -0500 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] powerpc/pseries/iommu: Add TCEs for 16GB pages when RAM is pre-mapped To: Harsh Prateek Bora , maddy@linux.ibm.com Cc: linuxppc-dev@lists.ozlabs.org, ritesh.list@gmail.com, donettom@linux.ibm.com, vaibhav@linux.ibm.com, sbhat@linux.ibm.com References: <20260504205459.39185-1-gbatra@linux.ibm.com> <83e821e1-2a71-4d8e-a40a-59ed7b333e95@linux.ibm.com> <36506ccd-5448-4ed6-a1be-aa89d80c4d43@linux.ibm.com> Content-Language: en-US From: Gaurav Batra In-Reply-To: <36506ccd-5448-4ed6-a1be-aa89d80c4d43@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA2MDE4NyBTYWx0ZWRfX5GwHuDCGCZ7h tOf+BLZbi00DNUilz14x0Ch+chm1NmYX2pFyCku3RwrIgQLoJRsT/c+t/Jm/5inmxX+XozH1qWb Ag7VJM5kjIw6IXnI2b0iN+12vJeslntuCelgzllY5K6ZnPaQcMucmxg2mE0OI+PwMgmlmzt1o8Y 2FIpwoH26bfz2K4qt3JQla7EHDfdenQrGdkFojLItakkJrVYJuNc3O5NvKnI38vQnZSOFtcchHy e/DX+N27qdFWd+CDg6oD949CTo8UALis3e3D64QV2rnj2l6rwK4R+ST2ehQxCmzEvggXSAGFreW otrvEnEh7Yv6DxHqxYwmSkJPLZ9zwBdmcvUL7QF0R6h+nv7rpt6XoIYczxxwq1hXU3jOIi0+aqS rPfv0znX4bxWCw6ENgpIU8qTBpVd/crZbzJBwyTJzQ/8DcJfPhwA5uhgEj6UGlO1G4FblACwJFu hxShTuGc3CKTsXNTAFQ== X-Proofpoint-GUID: svwMJgHo9Mc2arHtotHESGs-ua6IfpMq X-Proofpoint-ORIG-GUID: OvVXdHMqcUNCvbmhEuucfO_JjWW_ot1H X-Authority-Analysis: v=2.4 cv=eu/vCIpX c=1 sm=1 tr=0 ts=69fb9628 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=IODWg27a4XDs8XJ6STcA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-06_01,2026-05-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 phishscore=0 lowpriorityscore=0 clxscore=1015 adultscore=0 suspectscore=0 malwarescore=0 bulkscore=0 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605060187 On 5/5/26 11:04 PM, Harsh Prateek Bora wrote: > > > On 06/05/26 2:31 am, Gaurav Batra wrote: >> >> On 5/5/26 1:49 PM, Harsh Prateek Bora wrote: >>> >>> >>> On 05/05/26 2:24 am, Gaurav Batra wrote: >>>> @@ -2431,7 +2437,7 @@ static int iommu_mem_notifier(struct >>>> notifier_block *nb, unsigned long action, >>>>           spin_lock(&dma_win_list_lock); >>>>           list_for_each_entry(window, &dma_win_list, list) { >>>>               if (window->direct && (arg->start_pfn << PAGE_SHIFT) < >>>> -                ddw_memory_hotplug_max()) { >>>> +                pseries_ddw_max_ram) { >>>>                   ret |= tce_setrange_multi_pSeriesLP(arg->start_pfn, >>>>                           arg->nr_pages, window->prop); >>> >>> I think not only start_pfn, but end_pfn also needs to be within allowed >>> range, which may require clamping arg->nr_pages if crossing the limits. >> The reason to only check for start_pfn is because the range given >> will either be in the RAM or pmemory. It can never cross the boundary > > Usually as an API, we do not trust the caller, hence the check for > start_pfn. However, if at all we need to go ahead with that assumption, > may be document that as a code comment and/or in the commit log also? I will document it. I am wondering, if instead of capping it to start+nrpages, maybe, return an error. If in the future, we get an error, this needs to be investigated. > >>> >>>>               } >>>> @@ -2444,7 +2450,7 @@ static int iommu_mem_notifier(struct >>>> notifier_block *nb, unsigned long action, >>>>           spin_lock(&dma_win_list_lock); >>>>           list_for_each_entry(window, &dma_win_list, list) { >>>>               if (window->direct && (arg->start_pfn << PAGE_SHIFT) < >>>> -                ddw_memory_hotplug_max()) { >>>> +                pseries_ddw_max_ram) { >>>>                   ret |= >>>> tce_clearrange_multi_pSeriesLP(arg->start_pfn, >>>>                           arg->nr_pages, window->prop); >>>>               } >>> >