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b=QIOYdnnM35WZBKjEmzGe6iTo4+pwut2F+VYDuDf8dQxDjcEephTZS8UvgowDIbWxC0o0zXKsApV2uSbQA39IpsX4gD7lm8H/dcjN8VIk8DnXL2hELGVSbXEXnU/kibQMUpXyTok7seCjkTvCpB+V30tuMYWy2FR9I+H6ST7p460= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from BL1PR12MB5320.namprd12.prod.outlook.com (2603:10b6:208:314::17) by IA1PR12MB6306.namprd12.prod.outlook.com (2603:10b6:208:3e6::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.245.13; Tue, 28 Jul 2026 20:43:22 +0000 Received: from BL1PR12MB5320.namprd12.prod.outlook.com ([fe80::1876:4a6d:2cf5:b8d1]) by BL1PR12MB5320.namprd12.prod.outlook.com ([fe80::1876:4a6d:2cf5:b8d1%5]) with mapi id 15.21.0270.009; Tue, 28 Jul 2026 20:43:22 +0000 Message-ID: <7495c998-4f3f-4ea5-a383-350584afb42c@amd.com> Date: Tue, 28 Jul 2026 15:43:19 -0500 User-Agent: Mozilla Thunderbird Subject: Re: RE: RE: [PATCH 1/2] x86/resctrl, Documentation: Keep mbm_assign_mode "default" on boot To: "Luck, Tony" , Borislav Petkov Cc: "Chatre, Reinette" , "x86@kernel.org" , "Dave.Martin@arm.com" , "james.morse@arm.com" , "corbet@lwn.net" , "skhan@linuxfoundation.org" , "tglx@kernel.org" , "mingo@redhat.com" , "dave.hansen@linux.intel.com" , "hpa@zytor.com" , "linux-kernel@vger.kernel.org" , "linux-doc@vger.kernel.org" , "Eranian, Stephane" , "peternewman@google.com" References: <8cb66e18e32e4087a9712c1e68ee6da614efe244.1784322818.git.babu.moger@amd.com> <20260728191818.GBamkAeh7BD1d6Gd8X@fat_crate.local> <2c098892-5d4b-402b-bdfb-59e3bf164c8d@amd.com> <73737438-01ed-437e-846a-5aa8bd687462@amd.com> Content-Language: en-US From: Babu Moger In-Reply-To: Content-Type: text/plain; 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>> if (am) >> am->prev_msr = 0; >> } > > Nope. If you want the value reported to the user to start over from zero, > then prev_msr should be set to the current value of the counter. That > would make the next read start from zero. > When an RMID is reallocated, the hardware detects the state transition and the first read returns "Unavailable". At that point, the counter is reset and begins counting again from 0. This is the expected behavior on AMD systems. Therefore, setting prev_msr to 0 is the correct behavior. Thanks Babu