From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A472B3AA1AF; Tue, 24 Feb 2026 17:58:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771955897; cv=none; b=MwWu0TKPSFMGzYh3TPDlOkc9G1TeLof6uPRpJrk1PribZGMssomxdlm485PqHTFB/mATheBhBrqaA3F45m7RnzQPrU1LlSNLt3j36cY9iwnhxttAFBq9+zIMfYkX8ssr+aZ6nqUW2Ax9qnWpdJGF7L2fa0mn0E2DbmmIFDdgFQE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771955897; c=relaxed/simple; bh=jFdXe9TNxDV65CtBI3g4s77B3u+dB6FF4nhlglPNKi4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=T3xhhwA/ur2ifSrGO4IXXxYQ9wFv6AV+vNc6xLlr0JVws7jr6TOopwVokYNxwaIS96F1MRSuarXS0Qzzq4YikOm5mtopKesTnkwNWVrrNryFrl6md5sJv03F4DktNEG5eINbwFtgfMHBbgUxcDPX1MbMYY5d0pX7BzQKdDxwYt8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DB181497; Tue, 24 Feb 2026 09:58:08 -0800 (PST) Received: from e134344.cambridge.arm.com (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 458D43F59E; Tue, 24 Feb 2026 09:58:10 -0800 (PST) From: Ben Horgan To: ben.horgan@arm.com Cc: amitsinght@marvell.com, baisheng.gao@unisoc.com, baolin.wang@linux.alibaba.com, carl@os.amperecomputing.com, dave.martin@arm.com, david@kernel.org, dfustini@baylibre.com, fenghuay@nvidia.com, gshan@redhat.com, james.morse@arm.com, jonathan.cameron@huawei.com, kobak@nvidia.com, lcherian@marvell.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, peternewman@google.com, punit.agrawal@oss.qualcomm.com, quic_jiles@quicinc.com, reinette.chatre@intel.com, rohit.mathew@arm.com, scott@os.amperecomputing.com, sdonthineni@nvidia.com, tan.shaopeng@fujitsu.com, xhao@linux.alibaba.com, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, kvmarm@lists.linux.dev, zengheng4@huawei.com, linux-doc@vger.kernel.org, Shaopeng Tan Subject: [PATCH v5 08/41] arm64: mpam: Add cpu_pm notifier to restore MPAM sysregs Date: Tue, 24 Feb 2026 17:56:47 +0000 Message-ID: <20260224175720.2663924-9-ben.horgan@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260224175720.2663924-1-ben.horgan@arm.com> References: <20260224175720.2663924-1-ben.horgan@arm.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: James Morse The MPAM system registers will be lost if the CPU is reset during PSCI's CPU_SUSPEND. Add a PM notifier to restore them. mpam_thread_switch(current) can't be used as this won't make any changes if the in-memory copy says the register already has the correct value. In reality the system register is UNKNOWN out of reset. Tested-by: Gavin Shan Tested-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Zeng Heng Reviewed-by: Shaopeng Tan Reviewed-by: Jonathan Cameron Reviewed-by: Gavin Shan Reviewed-by: Catalin Marinas Signed-off-by: James Morse Signed-off-by: Ben Horgan --- Changes since v3: Always set MPAM1_EL1.MPAMEN rather than relying on it being read only Bail out early if mpam not supported (Gavin) --- arch/arm64/kernel/mpam.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/arch/arm64/kernel/mpam.c b/arch/arm64/kernel/mpam.c index e6feff2324ac..48ec0ffd5999 100644 --- a/arch/arm64/kernel/mpam.c +++ b/arch/arm64/kernel/mpam.c @@ -4,6 +4,7 @@ #include #include +#include #include #include @@ -13,12 +14,44 @@ DEFINE_PER_CPU(u64, arm64_mpam_current); u64 arm64_mpam_global_default; +static int mpam_pm_notifier(struct notifier_block *self, + unsigned long cmd, void *v) +{ + u64 regval; + int cpu = smp_processor_id(); + + switch (cmd) { + case CPU_PM_EXIT: + /* + * Don't use mpam_thread_switch() as the system register + * value has changed under our feet. + */ + regval = READ_ONCE(per_cpu(arm64_mpam_current, cpu)); + write_sysreg_s(regval | MPAM1_EL1_MPAMEN, SYS_MPAM1_EL1); + isb(); + + write_sysreg_s(regval, SYS_MPAM0_EL1); + + return NOTIFY_OK; + default: + return NOTIFY_DONE; + } +} + +static struct notifier_block mpam_pm_nb = { + .notifier_call = mpam_pm_notifier, +}; + static int __init arm64_mpam_register_cpus(void) { u64 mpamidr = read_sanitised_ftr_reg(SYS_MPAMIDR_EL1); u16 partid_max = FIELD_GET(MPAMIDR_EL1_PARTID_MAX, mpamidr); u8 pmg_max = FIELD_GET(MPAMIDR_EL1_PMG_MAX, mpamidr); + if (!system_supports_mpam()) + return 0; + + cpu_pm_register_notifier(&mpam_pm_nb); return mpam_register_requestor(partid_max, pmg_max); } /* Must occur before mpam_msc_driver_init() from subsys_initcall() */ -- 2.43.0