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 B37A72D738E for ; Thu, 15 Jan 2026 19:08:56 +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=1768504138; cv=none; b=Iy1miSHx0Q9wVVAieRCz2HR/NbLt/lCn8Hv/BtPW4ixZS0p4yWhO5OvoFmefIhwaJ1HGE/koD2wA/lWuwvqCYuVyK4TuJ8mo1BFpi0qwJi9kpf4+IHde8hYinCxiojfvbQ6cpYh5dGOEVKVjkzuMGW1tSiaUVH/Htj7XcycRjic= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768504138; c=relaxed/simple; bh=oRCS6RtfED9FzzOq2iqQVwNKLaYUe1rjgmRyM0CBbnY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QzE92lk/lkoMbBE5nx3oMFpv0AdO0+VDVV3xGmZcZjZOoiYQINHb2/knOcBrx+KNHdcvHx+jrl8J/C/+nXrA3rlI4vCGR2cBs+3SbqGJ91Iho89fmIfoCxCoz2+se6Yw2hHU23Sv16iRU3G/cU0Xyox0gP9nkH54Ox2rJeP51Fo= 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 3BC101515; Thu, 15 Jan 2026 11:08:49 -0800 (PST) Received: from arm.com (arrakis.cambridge.arm.com [10.1.197.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 933E43F59E; Thu, 15 Jan 2026 11:08:50 -0800 (PST) Date: Thu, 15 Jan 2026 19:08:47 +0000 From: Catalin Marinas To: Ben Horgan 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, will@kernel.org, corbet@lwn.net, maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, kvmarm@lists.linux.dev Subject: Re: [PATCH v3 10/47] arm64: mpam: Initialise and context switch the MPAMSM_EL1 register Message-ID: References: <20260112165914.4086692-1-ben.horgan@arm.com> <20260112165914.4086692-11-ben.horgan@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260112165914.4086692-11-ben.horgan@arm.com> On Mon, Jan 12, 2026 at 04:58:37PM +0000, Ben Horgan wrote: > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index 0cdfb3728f43..2ede543b3eeb 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -2491,6 +2491,8 @@ cpu_enable_mpam(const struct arm64_cpu_capabilities *entry) > regval = READ_ONCE(per_cpu(arm64_mpam_current, cpu)); > > write_sysreg_s(regval, SYS_MPAM1_EL1); > + if (system_supports_sme()) > + write_sysreg_s(regval & (MPAMSM_EL1_PARTID_D | MPAMSM_EL1_PMG_D), SYS_MPAMSM_EL1); > isb(); Do we know for sure that system_supports_sme() returns true at this point (if SME supported)? Digging into the code, system_supports_sme() uses alternative_has_cap_unlikely() which relies on instruction patching. setup_system_capabilities(), IIUC, patches the alternatives after enable_cpu_capabilities(). I think you better use cpus_have_cap(). -- Catalin