From patchwork Tue Feb 6 12:27:09 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lad Prabhakar X-Patchwork-Id: 13547178 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id E108EC48297 for ; Tue, 6 Feb 2024 12:28:25 +0000 (UTC) Received: from relmlie5.idc.renesas.com (relmlie5.idc.renesas.com [210.160.252.171]) by mx.groups.io with SMTP id smtpd.web11.20171.1707222496328553437 for ; Tue, 06 Feb 2024 04:28:16 -0800 Authentication-Results: mx.groups.io; dkim=none (message not signed); spf=pass (domain: bp.renesas.com, ip: 210.160.252.171, mailfrom: prabhakar.mahadev-lad.rj@bp.renesas.com) X-IronPort-AV: E=Sophos;i="6.05,247,1701097200"; d="scan'208";a="193048743" Received: from unknown (HELO relmlir5.idc.renesas.com) ([10.200.68.151]) by relmlie5.idc.renesas.com with ESMTP; 06 Feb 2024 21:28:15 +0900 Received: from Ubuntu-22.. (unknown [10.226.93.78]) by relmlir5.idc.renesas.com (Postfix) with ESMTP id 427FE4005E16; Tue, 6 Feb 2024 21:28:13 +0900 (JST) From: Lad Prabhakar To: cip-dev@lists.cip-project.org, Nobuhiro Iwamatsu , Pavel Machek Cc: Biju Das Subject: [PATCH v2 5.10.y-cip 19/44] irqchip/sifive-plic: Separate the enable and mask operations Date: Tue, 6 Feb 2024 12:27:09 +0000 Message-Id: <20240206122734.13477-20-prabhakar.mahadev-lad.rj@bp.renesas.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240206122734.13477-1-prabhakar.mahadev-lad.rj@bp.renesas.com> References: <20240206122734.13477-1-prabhakar.mahadev-lad.rj@bp.renesas.com> MIME-Version: 1.0 List-Id: X-Webhook-Received: from li982-79.members.linode.com [45.33.32.79] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Tue, 06 Feb 2024 12:28:25 -0000 X-Groupsio-URL: https://lists.cip-project.org/g/cip-dev/message/14803 From: Samuel Holland commit a1706a1c5062e0908528170f853601ed53f428c8 upstream. The PLIC has two per-IRQ checks before sending an IRQ to a hart context. First, it checks that the IRQ's priority is nonzero. Then, it checks that the enable bit is set for that combination of IRQ and context. Currently, the PLIC driver sets both the priority value and the enable bit in its (un)mask operations. However, modifying the enable bit is problematic for two reasons: 1) The enable bits are packed, so changes are not atomic and require taking a spinlock. 2) The following requirement from the PLIC spec, which explains the racy (un)mask operations in plic_irq_eoi(): If the completion ID does not match an interrupt source that is currently enabled for the target, the completion is silently ignored. Both of these problems are solved by using the priority value to mask IRQs. Each IRQ has a separate priority register, so writing the priority value is atomic. And since the enable bit remains set while an IRQ is masked, the EOI operation works normally. The enable bits are still used to control the IRQ's affinity. Signed-off-by: Samuel Holland Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20220701202440.59059-3-samuel@sholland.org Signed-off-by: Lad Prabhakar Reviewed-by: Nobuhiro Iwamatsu --- drivers/irqchip/irq-sifive-plic.c | 55 +++++++++++++++++++------------ 1 file changed, 34 insertions(+), 21 deletions(-) diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c index 364023c776d43..2673f726f85d8 100644 --- a/drivers/irqchip/irq-sifive-plic.c +++ b/drivers/irqchip/irq-sifive-plic.c @@ -108,9 +108,7 @@ static inline void plic_irq_toggle(const struct cpumask *mask, struct irq_data *d, int enable) { int cpu; - struct plic_priv *priv = irq_data_get_irq_chip_data(d); - writel(enable, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID); for_each_cpu(cpu, mask) { struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu); @@ -118,16 +116,37 @@ static inline void plic_irq_toggle(const struct cpumask *mask, } } -static void plic_irq_unmask(struct irq_data *d) +static void plic_irq_enable(struct irq_data *d) { plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 1); } -static void plic_irq_mask(struct irq_data *d) +static void plic_irq_disable(struct irq_data *d) { plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 0); } +static void plic_irq_unmask(struct irq_data *d) +{ + struct plic_priv *priv = irq_data_get_irq_chip_data(d); + + writel(1, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID); +} + +static void plic_irq_mask(struct irq_data *d) +{ + struct plic_priv *priv = irq_data_get_irq_chip_data(d); + + writel(0, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID); +} + +static void plic_irq_eoi(struct irq_data *d) +{ + struct plic_handler *handler = this_cpu_ptr(&plic_handlers); + + writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM); +} + #ifdef CONFIG_SMP static int plic_set_affinity(struct irq_data *d, const struct cpumask *mask_val, bool force) @@ -146,32 +165,21 @@ static int plic_set_affinity(struct irq_data *d, if (cpu >= nr_cpu_ids) return -EINVAL; - plic_irq_mask(d); + plic_irq_disable(d); irq_data_update_effective_affinity(d, cpumask_of(cpu)); - if (!irqd_irq_masked(d)) - plic_irq_unmask(d); + if (!irqd_irq_disabled(d)) + plic_irq_enable(d); return IRQ_SET_MASK_OK_DONE; } #endif -static void plic_irq_eoi(struct irq_data *d) -{ - struct plic_handler *handler = this_cpu_ptr(&plic_handlers); - - if (irqd_irq_masked(d)) { - plic_irq_unmask(d); - writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM); - plic_irq_mask(d); - } else { - writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM); - } -} - static struct irq_chip plic_edge_chip = { .name = "SiFive PLIC", + .irq_enable = plic_irq_enable, + .irq_disable = plic_irq_disable, .irq_ack = plic_irq_eoi, .irq_mask = plic_irq_mask, .irq_unmask = plic_irq_unmask, @@ -184,6 +192,8 @@ static struct irq_chip plic_edge_chip = { static struct irq_chip plic_chip = { .name = "SiFive PLIC", + .irq_enable = plic_irq_enable, + .irq_disable = plic_irq_disable, .irq_mask = plic_irq_mask, .irq_unmask = plic_irq_unmask, .irq_eoi = plic_irq_eoi, @@ -431,8 +441,11 @@ static int __init __plic_init(struct device_node *node, i * CONTEXT_ENABLE_SIZE; handler->priv = priv; done: - for (hwirq = 1; hwirq <= nr_irqs; hwirq++) + for (hwirq = 1; hwirq <= nr_irqs; hwirq++) { plic_toggle(handler, hwirq, 0); + writel(1, priv->regs + PRIORITY_BASE + + hwirq * PRIORITY_PER_ID); + } nr_handlers++; }