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Date: Tue, 22 Sep 2026 09:29:30 +0200 Message-Id: <20260922-cci_enxio-v1-0-00bade212729@arm.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAFousmoC/yWMQQrCMBAAv1L2bKBJoVKvgg/wKlI2m61dwbRkq xRK/26ixxmG2UA5CSucqg0Sf0RlihnsoQIaMT7YSMgMrnZt3TlriKTnuMpkhiY0NnRITEfI/Zx 4kPX3usH1cob7X+rbP5mWcimZR2XjE0Yai3qhLpxg379llFLciwAAAA== X-Change-ID: 20260921-cci_enxio-f3d31d9acec7 To: Andrew Morton , Conor Dooley , Jonathan Cameron , Yicong Yang Cc: linux-kernel@vger.kernel.org, Bence Csokas X-Mailer: b4 0.15.2 X-ClientProxiedBy: LO4P123CA0024.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:151::11) To GV1PR08MB10455.eurprd08.prod.outlook.com (2603:10a6:150:16f::10) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-TrafficTypeDiagnostic: GV1PR08MB10455:EE_|DB9PR08MB8676:EE_|DB1PEPF000509F0:EE_|AM9PR08MB6659:EE_ X-MS-Office365-Filtering-Correlation-Id: c89d229a-2894-4630-46c5-08df187b53e4 x-checkrecipientrouted: true NoDisclaimer: true X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam-Untrusted: BCL:0;ARA:13230040|366016|1800799024|23010399003|376014|10067099003|56012099006|18002099003|11063799006; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: HB/kOmtTLZcZyWlyVvvWLm/jNraxGPpuah+FHrN7peBreVdayEDNya2gZ+dL1zxTLUcD8m507qYNco1jMHv/Vj9Sx2V/AcoPOPk6t/TBFxQxbCZJqpv/438/9k/Hc8Ru6lH8aSidoB9nnWOC3vpzimhOrdauwD8xym0dWEnacDmkLtkiA8qE1qRhp1IuYzvJ3r7rHtk2kQM45sqGP4qLNu28J5WnYrii0pRbLovaUYhSuq+32x20JiG4Wdnbb9ab+1/UbzvueRhWvE6x7FcvcbVyUCAWcxzqFOgaPGrv50Uxv3p+ahUHxRWyDYDMC01Ye/4JOXowIo8DQ4CBZeLmrPxDbGw8gCc6+pLR+DQjzv1wZLgmEjSVpiZCGLpJT7OY3ERlz7lLPfHIS2nkZbvceg58uEsFzM4/BfesRNzSt73YIPeupImdSMiy+rpG37SL X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Sep 2026 07:30:07.6459 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c89d229a-2894-4630-46c5-08df187b53e4 X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[4.158.2.129];Helo=[outbound-uk1.az.dlp.m.darktrace.com] X-MS-Exchange-CrossTenant-AuthSource: DB1PEPF000509F0.eurprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM9PR08MB6659 I noticed cpu_cache_invalidate_memregion() returns 0 if there are no registered `cache_coherency_ops_inst`s, which I find counter-intuitive. Is this intended? >From what I've seen, there are no in-tree users who do not check cpu_cache_has_invalidate_memregion(). However, IMO the better solution would be if the function would perform this check, and not the callee. Furthermore, arch/x86/mm/pat/set_memory.c also implements this function, but actually does the feature check, and WARNs and returns -ENXIO if it fails that check. As part of this RFC, I'll attach a patch that provides a low-overhead fix. Signed-off-by: Bence Csokas --- Bence Csokas (1): cache: Make cpu_cache_invalidate_memregion() error out if there are no handlers lib/cache_maint.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- base-commit: 93f51579e7df248780214094418f205253383cc5 change-id: 20260921-cci_enxio-f3d31d9acec7 Best regards, -- Bence Csokas