From patchwork Sun Jun 21 14:25:37 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 223614 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5AEEAC433E0 for ; Sun, 21 Jun 2020 14:26:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B14220890 for ; Sun, 21 Jun 2020 14:26:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592749562; bh=W0GxbCl0T6tlIURC2FrWHy0pl7O2r2pLvdotzPz142k=; h=From:To:Cc:Subject:Date:List-ID:From; b=xEnPAzdxMxjw6e0RcXc969FNd5o0R7EwZKQzkhgTUnaac1RueaaAJ5Lbd/hUowryz 9/fDG2pv+XwARKZpsWu324yJmfALiFjozT+dHcpnUC2o63Tsvp2+vNgdUbfoZsMV7G 0N3Mu8GdRrMJY4gdBU3fj/Z8yuLRZscz1a/Dr+YE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730129AbgFUO0B (ORCPT ); Sun, 21 Jun 2020 10:26:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:60804 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730120AbgFUO0B (ORCPT ); Sun, 21 Jun 2020 10:26:01 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 02ECD2083E; Sun, 21 Jun 2020 14:26:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592749561; bh=W0GxbCl0T6tlIURC2FrWHy0pl7O2r2pLvdotzPz142k=; h=From:To:Cc:Subject:Date:From; b=niQc58EJh7aqd2Rg73A6I9LirIVVVZpJv5bB7kacWxGD6weZMCUkjN5OQImAXUaRu 7AFFXZEL9t9bAGVG+sLBSSfSq/YsixTIdoiK/R4Xookn0JIdT6QiaUkiPv61wSm7JY SeOgaGnPdd6SsMA057+6q5cQ3sdo8GEkSXK0WF6Q= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=hot-poop.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jn0v1-0056g4-EX; Sun, 21 Jun 2020 15:25:59 +0100 From: Marc Zyngier To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Thomas Gleixner , Jason Cooper , stable@vger.kernel.org Subject: [PATCH] irqchip/gic: Atomically update affinity Date: Sun, 21 Jun 2020 15:25:37 +0100 Message-Id: <20200621142537.784191-1-maz@kernel.org> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, tglx@linutronix.de, jason@lakedaemon.net, stable@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The GIC driver uses a RMW sequence to update the affinity, and relies on the gic_lock_irqsave/gic_unlock_irqrestore sequences to update it atomically. But these sequences only expand into anything meaningful if the BL_SWITCHER option is selected, which almost never happens. It also turns out that using a RMW and locks is just as silly, as the GIC distributor supports byte accesses for the GICD_TARGETRn registers, which when used make the update atomic by definition. Drop the terminally broken code and replace it by a byte write. Fixes: 04c8b0f82c7d ("irqchip/gic: Make locking a BL_SWITCHER only feature") Cc: stable@vger.kernel.org Signed-off-by: Marc Zyngier --- drivers/irqchip/irq-gic.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c index 00de05abd3c3..c17fabd6741e 100644 --- a/drivers/irqchip/irq-gic.c +++ b/drivers/irqchip/irq-gic.c @@ -329,10 +329,8 @@ static int gic_irq_set_vcpu_affinity(struct irq_data *d, void *vcpu) static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val, bool force) { - void __iomem *reg = gic_dist_base(d) + GIC_DIST_TARGET + (gic_irq(d) & ~3); - unsigned int cpu, shift = (gic_irq(d) % 4) * 8; - u32 val, mask, bit; - unsigned long flags; + void __iomem *reg = gic_dist_base(d) + GIC_DIST_TARGET + gic_irq(d); + unsigned int cpu; if (!force) cpu = cpumask_any_and(mask_val, cpu_online_mask); @@ -342,13 +340,7 @@ static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val, if (cpu >= NR_GIC_CPU_IF || cpu >= nr_cpu_ids) return -EINVAL; - gic_lock_irqsave(flags); - mask = 0xff << shift; - bit = gic_cpu_map[cpu] << shift; - val = readl_relaxed(reg) & ~mask; - writel_relaxed(val | bit, reg); - gic_unlock_irqrestore(flags); - + writeb_relaxed(gic_cpu_map[cpu], reg); irq_data_update_effective_affinity(d, cpumask_of(cpu)); return IRQ_SET_MASK_OK_DONE;