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 D4ADD23EA8A for ; Fri, 27 Mar 2026 19:15:36 +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=1774638943; cv=none; b=WxCYPM7gA58hwU/vdAborhBB6CGw2IkOoqecEzKjmKxOP1JRyWXsNRA4f3A/UzwqwvrkH3qtLFc6YEkLil/fbMr1uBckqYYY4TMnFsopXO8ULzolWbCrVna2604J2jOScj+J+bRrXkpt9MRxBoscYz5FUC2ww2hKwYOqMyWsQmk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774638943; c=relaxed/simple; bh=pVZsWAwTNhuQGve3K7yHl1CKc5vAbYKswR078p1evoo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kf1/Q/99xl/lwgPIo98dAKn0F0I5vHNDRqtubryVNoc5VSZSKyAB/VcdaOioYWu1HDhidFCVFmlRoWM1TMGj6L1aAXEnBHsnetDZIXYhi7Sny0wJ6+buaxR27P1W2xGeauvayxaanJK/b2WRTgNcXiYPdjKztXh7L7vq8hEMK4c= 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; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=hgQoOoE+; 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="hgQoOoE+" 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 456D639E7; Fri, 27 Mar 2026 12:15:29 -0700 (PDT) Received: from arm.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DDB5C3F99C; Fri, 27 Mar 2026 12:15:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1774638935; bh=pVZsWAwTNhuQGve3K7yHl1CKc5vAbYKswR078p1evoo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hgQoOoE+flJivMYihP+g5wqzHDPcQMNXv8Ff/dJscTn92FOhwbJttWjuei4MqwPyg Zg1OGoNfWxMgyfWOME71ME5u7znoolSFjVqXUtIeJf8TkO0X5IGOM3ibLMXZRqZmST 56j/bhTdh0Erpz1B1D1DA64HMBPid15RoHE0HPVw= Date: Fri, 27 Mar 2026 19:15:31 +0000 From: Catalin Marinas To: linux-arm-kernel@lists.infradead.org Cc: Will Deacon , Marc Zyngier , Oliver Upton , Lorenzo Pieralisi , Sudeep Holla , James Morse , Mark Rutland , Mark Brown , kvmarm@lists.linux.dev Subject: Re: [PATCH v3 4/5] arm64: errata: Work around early CME DVMSync acknowledgement Message-ID: References: <20260323162408.4163113-1-catalin.marinas@arm.com> <20260323162408.4163113-5-catalin.marinas@arm.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260323162408.4163113-5-catalin.marinas@arm.com> On Mon, Mar 23, 2026 at 04:24:04PM +0000, Catalin Marinas wrote: > +void sme_enable_dvmsync(void) > +{ > + if ((!cpumask_available(sme_dvmsync_cpus) && > + !zalloc_cpumask_var(&sme_dvmsync_cpus, GFP_ATOMIC)) || > + (!cpumask_available(sme_active_cpus) && > + !zalloc_cpumask_var(&sme_active_cpus, GFP_ATOMIC))) > + panic("Unable to allocate the cpumasks for SME DVMSync erratum"); > + > + cpumask_set_cpu(smp_processor_id(), sme_dvmsync_cpus); > +} Sashiko (correctly) highlighted a race here. This function, even if the erratum is a local cpu feature, is still called via stop_machine() on all active cpus when the non-boot features are initialised. It only matters if CPUMASK_OFFSTACK is enabled. I'll add a fix, most likely a lock around this to serialise the cpumask initialisation. -- Catalin