The RISC-V advanced interrupt architecture (AIA) specification
defines a new MSI controller called incoming message signalled
interrupt controller (IMSIC) which manages MSI on per-HART (or
per-CPU) basis. It also supports IPIs as software injected MSIs.
(For more details refer https://github.com/riscv/riscv-aia)
Add an early irqchip driver for RISC-V IMSIC which sets up the
IMSIC state and provide IPIs.
Signed-off-by: Anup Patel <[email protected]>
---
drivers/irqchip/Kconfig | 7 +
drivers/irqchip/Makefile | 1 +
drivers/irqchip/irq-riscv-imsic-early.c | 201 ++++++
drivers/irqchip/irq-riscv-imsic-state.c | 870 ++++++++++++++++++++++++
drivers/irqchip/irq-riscv-imsic-state.h | 107 +++
include/linux/irqchip/riscv-imsic.h | 87 +++
6 files changed, 1273 insertions(+)
create mode 100644 drivers/irqchip/irq-riscv-imsic-early.c
create mode 100644 drivers/irqchip/irq-riscv-imsic-state.c
create mode 100644 drivers/irqchip/irq-riscv-imsic-state.h
create mode 100644 include/linux/irqchip/riscv-imsic.h
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index f7149d0f3d45..85f86e31c996 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -546,6 +546,13 @@ config SIFIVE_PLIC
select IRQ_DOMAIN_HIERARCHY
select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
+config RISCV_IMSIC
+ bool
+ depends on RISCV
+ select IRQ_DOMAIN_HIERARCHY
+ select GENERIC_IRQ_MATRIX_ALLOCATOR
+ select GENERIC_MSI_IRQ
+
config EXYNOS_IRQ_COMBINER
bool "Samsung Exynos IRQ combiner support" if COMPILE_TEST
depends on (ARCH_EXYNOS && ARM) || COMPILE_TEST
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index ffd945fe71aa..d714724387ce 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -95,6 +95,7 @@ obj-$(CONFIG_QCOM_MPM) += irq-qcom-mpm.o
obj-$(CONFIG_CSKY_MPINTC) += irq-csky-mpintc.o
obj-$(CONFIG_CSKY_APB_INTC) += irq-csky-apb-intc.o
obj-$(CONFIG_RISCV_INTC) += irq-riscv-intc.o
+obj-$(CONFIG_RISCV_IMSIC) += irq-riscv-imsic-state.o irq-riscv-imsic-early.o
obj-$(CONFIG_SIFIVE_PLIC) += irq-sifive-plic.o
obj-$(CONFIG_IMX_IRQSTEER) += irq-imx-irqsteer.o
obj-$(CONFIG_IMX_INTMUX) += irq-imx-intmux.o
diff --git a/drivers/irqchip/irq-riscv-imsic-early.c b/drivers/irqchip/irq-riscv-imsic-early.c
new file mode 100644
index 000000000000..079be5c0eec3
--- /dev/null
+++ b/drivers/irqchip/irq-riscv-imsic-early.c
@@ -0,0 +1,201 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ * Copyright (C) 2022 Ventana Micro Systems Inc.
+ */
+
+#define pr_fmt(fmt) "riscv-imsic: " fmt
+#include <linux/cpu.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+
+#include "irq-riscv-imsic-state.h"
+
+static int imsic_parent_irq;
+
+#ifdef CONFIG_SMP
+static void imsic_ipi_send(unsigned int cpu)
+{
+ struct imsic_local_config *local = per_cpu_ptr(imsic->global.local, cpu);
+
+ writel_relaxed(IMSIC_IPI_ID, local->msi_va);
+}
+
+static void imsic_ipi_starting_cpu(void)
+{
+ /* Enable IPIs for current CPU. */
+ __imsic_id_set_enable(IMSIC_IPI_ID);
+}
+
+static void imsic_ipi_dying_cpu(void)
+{
+ /* Disable IPIs for current CPU. */
+ __imsic_id_clear_enable(IMSIC_IPI_ID);
+}
+
+static int __init imsic_ipi_domain_init(void)
+{
+ int virq;
+
+ /* Create IMSIC IPI multiplexing */
+ virq = ipi_mux_create(IMSIC_NR_IPI, imsic_ipi_send);
+ if (virq <= 0)
+ return virq < 0 ? virq : -ENOMEM;
+
+ /* Set vIRQ range */
+ riscv_ipi_set_virq_range(virq, IMSIC_NR_IPI, true);
+
+ /* Announce that IMSIC is providing IPIs */
+ pr_info("%pfwP: providing IPIs using interrupt %d\n", imsic->fwnode, IMSIC_IPI_ID);
+
+ return 0;
+}
+#else
+static void imsic_ipi_starting_cpu(void) { }
+static void imsic_ipi_dying_cpu(void) { }
+static int __init imsic_ipi_domain_init(void) { return 0; }
+#endif
+
+/*
+ * To handle an interrupt, we read the TOPEI CSR and write zero in one
+ * instruction. If TOPEI CSR is non-zero then we translate TOPEI.ID to
+ * Linux interrupt number and let Linux IRQ subsystem handle it.
+ */
+static void imsic_handle_irq(struct irq_desc *desc)
+{
+ struct irq_chip *chip = irq_desc_get_chip(desc);
+ int err, cpu = smp_processor_id();
+ struct imsic_vector *vec;
+ unsigned long local_id;
+
+ chained_irq_enter(chip, desc);
+
+ while ((local_id = csr_swap(CSR_TOPEI, 0))) {
+ local_id >>= TOPEI_ID_SHIFT;
+
+ if (local_id == IMSIC_IPI_ID) {
+ if (IS_ENABLED(CONFIG_SMP))
+ ipi_mux_process();
+ continue;
+ }
+
+ if (unlikely(!imsic->base_domain))
+ continue;
+
+ vec = imsic_vector_from_local_id(cpu, local_id);
+ if (!vec) {
+ pr_warn_ratelimited("vector not found for local ID 0x%lx\n", local_id);
+ continue;
+ }
+
+ err = generic_handle_domain_irq(imsic->base_domain, vec->hwirq);
+ if (unlikely(err))
+ pr_warn_ratelimited("hwirq 0x%x mapping not found\n", vec->hwirq);
+ }
+
+ chained_irq_exit(chip, desc);
+}
+
+static int imsic_starting_cpu(unsigned int cpu)
+{
+ /* Mark per-CPU IMSIC state as online */
+ imsic_state_online();
+
+ /* Enable per-CPU parent interrupt */
+ enable_percpu_irq(imsic_parent_irq, irq_get_trigger_type(imsic_parent_irq));
+
+ /* Setup IPIs */
+ imsic_ipi_starting_cpu();
+
+ /*
+ * Interrupts identities might have been enabled/disabled while
+ * this CPU was not running so sync-up local enable/disable state.
+ */
+ imsic_local_sync_all();
+
+ /* Enable local interrupt delivery */
+ imsic_local_delivery(true);
+
+ return 0;
+}
+
+static int imsic_dying_cpu(unsigned int cpu)
+{
+ /* Cleanup IPIs */
+ imsic_ipi_dying_cpu();
+
+ /* Mark per-CPU IMSIC state as offline */
+ imsic_state_offline();
+
+ return 0;
+}
+
+static int __init imsic_early_probe(struct fwnode_handle *fwnode)
+{
+ struct irq_domain *domain;
+ int rc;
+
+ /* Find parent domain and register chained handler */
+ domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(), DOMAIN_BUS_ANY);
+ if (!domain) {
+ pr_err("%pfwP: Failed to find INTC domain\n", fwnode);
+ return -ENOENT;
+ }
+ imsic_parent_irq = irq_create_mapping(domain, RV_IRQ_EXT);
+ if (!imsic_parent_irq) {
+ pr_err("%pfwP: Failed to create INTC mapping\n", fwnode);
+ return -ENOENT;
+ }
+
+ /* Initialize IPI domain */
+ rc = imsic_ipi_domain_init();
+ if (rc) {
+ pr_err("%pfwP: Failed to initialize IPI domain\n", fwnode);
+ return rc;
+ }
+
+ /* Setup chained handler to the parent domain interrupt */
+ irq_set_chained_handler(imsic_parent_irq, imsic_handle_irq);
+
+ /*
+ * Setup cpuhp state (must be done after setting imsic_parent_irq)
+ *
+ * Don't disable per-CPU IMSIC file when CPU goes offline
+ * because this affects IPI and the masking/unmasking of
+ * virtual IPIs is done via generic IPI-Mux
+ */
+ cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "irqchip/riscv/imsic:starting",
+ imsic_starting_cpu, imsic_dying_cpu);
+
+ return 0;
+}
+
+static int __init imsic_early_dt_init(struct device_node *node, struct device_node *parent)
+{
+ struct fwnode_handle *fwnode = &node->fwnode;
+ int rc;
+
+ /* Setup IMSIC state */
+ rc = imsic_setup_state(fwnode);
+ if (rc) {
+ pr_err("%pfwP: failed to setup state (error %d)\n", fwnode, rc);
+ return rc;
+ }
+
+ /* Do early setup of IPIs */
+ rc = imsic_early_probe(fwnode);
+ if (rc)
+ return rc;
+
+ /* Ensure that OF platform device gets probed */
+ of_node_clear_flag(node, OF_POPULATED);
+ return 0;
+}
+
+IRQCHIP_DECLARE(riscv_imsic, "riscv,imsics", imsic_early_dt_init);
diff --git a/drivers/irqchip/irq-riscv-imsic-state.c b/drivers/irqchip/irq-riscv-imsic-state.c
new file mode 100644
index 000000000000..0c19ffb9ca3e
--- /dev/null
+++ b/drivers/irqchip/irq-riscv-imsic-state.c
@@ -0,0 +1,870 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ * Copyright (C) 2022 Ventana Micro Systems Inc.
+ */
+
+#define pr_fmt(fmt) "riscv-imsic: " fmt
+#include <linux/cpu.h>
+#include <linux/bitmap.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <asm/hwcap.h>
+
+#include "irq-riscv-imsic-state.h"
+
+#define IMSIC_DISABLE_EIDELIVERY 0
+#define IMSIC_ENABLE_EIDELIVERY 1
+#define IMSIC_DISABLE_EITHRESHOLD 1
+#define IMSIC_ENABLE_EITHRESHOLD 0
+
+static inline void imsic_csr_write(unsigned long reg, unsigned long val)
+{
+ csr_write(CSR_ISELECT, reg);
+ csr_write(CSR_IREG, val);
+}
+
+static inline unsigned long imsic_csr_read(unsigned long reg)
+{
+ csr_write(CSR_ISELECT, reg);
+ return csr_read(CSR_IREG);
+}
+
+static inline unsigned long imsic_csr_read_clear(unsigned long reg, unsigned long val)
+{
+ csr_write(CSR_ISELECT, reg);
+ return csr_read_clear(CSR_IREG, val);
+}
+
+static inline void imsic_csr_set(unsigned long reg, unsigned long val)
+{
+ csr_write(CSR_ISELECT, reg);
+ csr_set(CSR_IREG, val);
+}
+
+static inline void imsic_csr_clear(unsigned long reg, unsigned long val)
+{
+ csr_write(CSR_ISELECT, reg);
+ csr_clear(CSR_IREG, val);
+}
+
+struct imsic_priv *imsic;
+
+const struct imsic_global_config *imsic_get_global_config(void)
+{
+ return imsic ? &imsic->global : NULL;
+}
+EXPORT_SYMBOL_GPL(imsic_get_global_config);
+
+static bool __imsic_eix_read_clear(unsigned long id, bool pend)
+{
+ unsigned long isel, imask;
+
+ isel = id / BITS_PER_LONG;
+ isel *= BITS_PER_LONG / IMSIC_EIPx_BITS;
+ isel += pend ? IMSIC_EIP0 : IMSIC_EIE0;
+ imask = BIT(id & (__riscv_xlen - 1));
+
+ return !!(imsic_csr_read_clear(isel, imask) & imask);
+}
+
+static inline bool __imsic_id_read_clear_enabled(unsigned long id)
+{
+ return __imsic_eix_read_clear(id, false);
+}
+
+static inline bool __imsic_id_read_clear_pending(unsigned long id)
+{
+ return __imsic_eix_read_clear(id, true);
+}
+
+void __imsic_eix_update(unsigned long base_id, unsigned long num_id, bool pend, bool val)
+{
+ unsigned long id = base_id, last_id = base_id + num_id;
+ unsigned long i, isel, ireg;
+
+ while (id < last_id) {
+ isel = id / BITS_PER_LONG;
+ isel *= BITS_PER_LONG / IMSIC_EIPx_BITS;
+ isel += pend ? IMSIC_EIP0 : IMSIC_EIE0;
+
+ /*
+ * Prepare the ID mask to be programmed in the
+ * IMSIC EIEx and EIPx registers. These registers
+ * are XLEN-wide and we must not touch IDs which
+ * are < base_id and >= (base_id + num_id).
+ */
+ ireg = 0;
+ for (i = id & (__riscv_xlen - 1); id < last_id && i < __riscv_xlen; i++) {
+ ireg |= BIT(i);
+ id++;
+ }
+
+ /*
+ * The IMSIC EIEx and EIPx registers are indirectly
+ * accessed via using ISELECT and IREG CSRs so we
+ * need to access these CSRs without getting preempted.
+ *
+ * All existing users of this function call this
+ * function with local IRQs disabled so we don't
+ * need to do anything special here.
+ */
+ if (val)
+ imsic_csr_set(isel, ireg);
+ else
+ imsic_csr_clear(isel, ireg);
+ }
+}
+
+static void __imsic_local_sync(struct imsic_local_priv *lpriv)
+{
+ struct imsic_local_config *mlocal;
+ struct imsic_vector *vec, *mvec;
+ int i;
+
+ lockdep_assert_held(&lpriv->lock);
+
+ /* This pairs with the barrier in __imsic_remote_sync(). */
+ smp_mb();
+
+ for_each_set_bit(i, lpriv->dirty_bitmap, imsic->global.nr_ids + 1) {
+ if (!i || i == IMSIC_IPI_ID)
+ goto skip;
+ vec = &lpriv->vectors[i];
+
+ if (READ_ONCE(vec->enable))
+ __imsic_id_set_enable(i);
+ else
+ __imsic_id_clear_enable(i);
+
+ /*
+ * If the ID was being moved to a new ID on some other CPU
+ * then we can get a MSI during the movement so check the
+ * ID pending bit and re-trigger the new ID on other CPU
+ * using MMIO write.
+ */
+ mvec = READ_ONCE(vec->move);
+ WRITE_ONCE(vec->move, NULL);
+ if (mvec && mvec != vec) {
+ if (__imsic_id_read_clear_pending(i)) {
+ mlocal = per_cpu_ptr(imsic->global.local, mvec->cpu);
+ writel_relaxed(mvec->local_id, mlocal->msi_va);
+ }
+
+ imsic_vector_free(&lpriv->vectors[i]);
+ }
+
+skip:
+ bitmap_clear(lpriv->dirty_bitmap, i, 1);
+ }
+}
+
+void imsic_local_sync_all(void)
+{
+ struct imsic_local_priv *lpriv = this_cpu_ptr(imsic->lpriv);
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&lpriv->lock, flags);
+ bitmap_fill(lpriv->dirty_bitmap, imsic->global.nr_ids + 1);
+ __imsic_local_sync(lpriv);
+ raw_spin_unlock_irqrestore(&lpriv->lock, flags);
+}
+
+void imsic_local_delivery(bool enable)
+{
+ if (enable) {
+ imsic_csr_write(IMSIC_EITHRESHOLD, IMSIC_ENABLE_EITHRESHOLD);
+ imsic_csr_write(IMSIC_EIDELIVERY, IMSIC_ENABLE_EIDELIVERY);
+ return;
+ }
+
+ imsic_csr_write(IMSIC_EIDELIVERY, IMSIC_DISABLE_EIDELIVERY);
+ imsic_csr_write(IMSIC_EITHRESHOLD, IMSIC_DISABLE_EITHRESHOLD);
+}
+
+#ifdef CONFIG_SMP
+static void imsic_local_timer_callback(struct timer_list *timer)
+{
+ struct imsic_local_priv *lpriv = this_cpu_ptr(imsic->lpriv);
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&lpriv->lock, flags);
+ __imsic_local_sync(lpriv);
+ raw_spin_unlock_irqrestore(&lpriv->lock, flags);
+}
+
+static void __imsic_remote_sync(struct imsic_local_priv *lpriv, unsigned int cpu)
+{
+ lockdep_assert_held(&lpriv->lock);
+
+ /*
+ * Ensure that changes to vector enable, vector move and
+ * dirty bitmap are visible to the target CPU.
+ *
+ * This pairs with the barrier in __imsic_local_sync().
+ */
+ smp_mb();
+
+ /*
+ * We schedule a timer on the target CPU if the target CPU is not
+ * same as the current CPU. An offline CPU will unconditionally
+ * synchronize IDs through imsic_starting_cpu() when the
+ * CPU is brought up.
+ */
+ if (cpu_online(cpu)) {
+ if (cpu == smp_processor_id()) {
+ __imsic_local_sync(lpriv);
+ return;
+ }
+
+ if (!timer_pending(&lpriv->timer)) {
+ lpriv->timer.expires = jiffies + 1;
+ add_timer_on(&lpriv->timer, cpu);
+ }
+ }
+}
+#else
+static void __imsic_remote_sync(struct imsic_local_priv *lpriv, unsigned int cpu)
+{
+ lockdep_assert_held(&lpriv->lock);
+ __imsic_local_sync(lpriv);
+}
+#endif
+
+void imsic_vector_mask(struct imsic_vector *vec)
+{
+ struct imsic_local_priv *lpriv;
+
+ lpriv = per_cpu_ptr(imsic->lpriv, vec->cpu);
+ if (WARN_ON_ONCE(&lpriv->vectors[vec->local_id] != vec))
+ return;
+
+ /*
+ * This function is called through Linux irq subsystem with
+ * irqs disabled so no need to save/restore irq flags.
+ */
+
+ raw_spin_lock(&lpriv->lock);
+
+ vec->enable = false;
+ bitmap_set(lpriv->dirty_bitmap, vec->local_id, 1);
+ __imsic_remote_sync(lpriv, vec->cpu);
+
+ raw_spin_unlock(&lpriv->lock);
+}
+
+void imsic_vector_unmask(struct imsic_vector *vec)
+{
+ struct imsic_local_priv *lpriv;
+
+ lpriv = per_cpu_ptr(imsic->lpriv, vec->cpu);
+ if (WARN_ON_ONCE(&lpriv->vectors[vec->local_id] != vec))
+ return;
+
+ /*
+ * This function is called through Linux irq subsystem with
+ * irqs disabled so no need to save/restore irq flags.
+ */
+
+ raw_spin_lock(&lpriv->lock);
+
+ vec->enable = true;
+ bitmap_set(lpriv->dirty_bitmap, vec->local_id, 1);
+ __imsic_remote_sync(lpriv, vec->cpu);
+
+ raw_spin_unlock(&lpriv->lock);
+}
+
+static bool imsic_vector_move_update(struct imsic_local_priv *lpriv, struct imsic_vector *vec,
+ bool new_enable, struct imsic_vector *new_move)
+{
+ unsigned long flags;
+ bool enabled;
+
+ raw_spin_lock_irqsave(&lpriv->lock, flags);
+
+ /* Update enable and move details */
+ enabled = READ_ONCE(vec->enable);
+ WRITE_ONCE(vec->enable, new_enable);
+ WRITE_ONCE(vec->move, new_move);
+
+ /* Mark the vector as dirty and synchronize */
+ bitmap_set(lpriv->dirty_bitmap, vec->local_id, 1);
+ __imsic_remote_sync(lpriv, vec->cpu);
+
+ raw_spin_unlock_irqrestore(&lpriv->lock, flags);
+
+ return enabled;
+}
+
+void imsic_vector_move(struct imsic_vector *old_vec, struct imsic_vector *new_vec)
+{
+ struct imsic_local_priv *old_lpriv, *new_lpriv;
+ bool enabled;
+
+ if (WARN_ON_ONCE(old_vec->cpu == new_vec->cpu))
+ return;
+
+ old_lpriv = per_cpu_ptr(imsic->lpriv, old_vec->cpu);
+ if (WARN_ON_ONCE(&old_lpriv->vectors[old_vec->local_id] != old_vec))
+ return;
+
+ new_lpriv = per_cpu_ptr(imsic->lpriv, new_vec->cpu);
+ if (WARN_ON_ONCE(&new_lpriv->vectors[new_vec->local_id] != new_vec))
+ return;
+
+ /*
+ * Move and re-trigger the new vector based on the pending
+ * state of the old vector because we might get a device
+ * interrupt on the old vector while device was being moved
+ * to the new vector.
+ */
+ enabled = imsic_vector_move_update(old_lpriv, old_vec, false, new_vec);
+ imsic_vector_move_update(new_lpriv, new_vec, enabled, new_vec);
+}
+
+#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+void imsic_vector_debug_show(struct seq_file *m, struct imsic_vector *vec, int ind)
+{
+ struct imsic_local_priv *lpriv;
+ struct imsic_vector *mvec;
+ bool is_enabled;
+
+ lpriv = per_cpu_ptr(imsic->lpriv, vec->cpu);
+ if (WARN_ON_ONCE(&lpriv->vectors[vec->local_id] != vec))
+ return;
+
+ is_enabled = imsic_vector_isenabled(vec);
+ mvec = imsic_vector_get_move(vec);
+
+ seq_printf(m, "%*starget_cpu : %5u\n", ind, "", vec->cpu);
+ seq_printf(m, "%*starget_local_id : %5u\n", ind, "", vec->local_id);
+ seq_printf(m, "%*sis_reserved : %5u\n", ind, "",
+ (vec->local_id <= IMSIC_IPI_ID) ? 1 : 0);
+ seq_printf(m, "%*sis_enabled : %5u\n", ind, "", is_enabled ? 1 : 0);
+ seq_printf(m, "%*sis_move_pending : %5u\n", ind, "", mvec ? 1 : 0);
+ if (mvec) {
+ seq_printf(m, "%*smove_cpu : %5u\n", ind, "", mvec->cpu);
+ seq_printf(m, "%*smove_local_id : %5u\n", ind, "", mvec->local_id);
+ }
+}
+
+void imsic_vector_debug_show_summary(struct seq_file *m, int ind)
+{
+ irq_matrix_debug_show(m, imsic->matrix, ind);
+}
+#endif
+
+struct imsic_vector *imsic_vector_from_local_id(unsigned int cpu, unsigned int local_id)
+{
+ struct imsic_local_priv *lpriv = per_cpu_ptr(imsic->lpriv, cpu);
+
+ if (!lpriv || imsic->global.nr_ids < local_id)
+ return NULL;
+
+ return &lpriv->vectors[local_id];
+}
+
+struct imsic_vector *imsic_vector_alloc(unsigned int hwirq, const struct cpumask *mask)
+{
+ struct imsic_vector *vec = NULL;
+ struct imsic_local_priv *lpriv;
+ unsigned long flags;
+ unsigned int cpu;
+ int local_id;
+
+ raw_spin_lock_irqsave(&imsic->matrix_lock, flags);
+ local_id = irq_matrix_alloc(imsic->matrix, mask, false, &cpu);
+ raw_spin_unlock_irqrestore(&imsic->matrix_lock, flags);
+ if (local_id < 0)
+ return NULL;
+
+ lpriv = per_cpu_ptr(imsic->lpriv, cpu);
+ vec = &lpriv->vectors[local_id];
+ vec->hwirq = hwirq;
+ vec->enable = false;
+ vec->move = NULL;
+
+ return vec;
+}
+
+void imsic_vector_free(struct imsic_vector *vec)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&imsic->matrix_lock, flags);
+ vec->hwirq = UINT_MAX;
+ irq_matrix_free(imsic->matrix, vec->cpu, vec->local_id, false);
+ raw_spin_unlock_irqrestore(&imsic->matrix_lock, flags);
+}
+
+static void __init imsic_local_cleanup(void)
+{
+ struct imsic_local_priv *lpriv;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ lpriv = per_cpu_ptr(imsic->lpriv, cpu);
+
+ bitmap_free(lpriv->dirty_bitmap);
+ kfree(lpriv->vectors);
+ }
+
+ free_percpu(imsic->lpriv);
+}
+
+static int __init imsic_local_init(void)
+{
+ struct imsic_global_config *global = &imsic->global;
+ struct imsic_local_priv *lpriv;
+ struct imsic_vector *vec;
+ int cpu, i;
+
+ /* Allocate per-CPU private state */
+ imsic->lpriv = alloc_percpu(typeof(*imsic->lpriv));
+ if (!imsic->lpriv)
+ return -ENOMEM;
+
+ /* Setup per-CPU private state */
+ for_each_possible_cpu(cpu) {
+ lpriv = per_cpu_ptr(imsic->lpriv, cpu);
+
+ raw_spin_lock_init(&lpriv->lock);
+
+ /* Allocate dirty bitmap */
+ lpriv->dirty_bitmap = bitmap_zalloc(global->nr_ids + 1, GFP_KERNEL);
+ if (!lpriv->dirty_bitmap)
+ goto fail_local_cleanup;
+
+#ifdef CONFIG_SMP
+ /* Setup lazy timer for synchronization */
+ timer_setup(&lpriv->timer, imsic_local_timer_callback, TIMER_PINNED);
+#endif
+
+ /* Allocate vector array */
+ lpriv->vectors = kcalloc(global->nr_ids + 1, sizeof(*lpriv->vectors),
+ GFP_KERNEL);
+ if (!lpriv->vectors)
+ goto fail_local_cleanup;
+
+ /* Setup vector array */
+ for (i = 0; i <= global->nr_ids; i++) {
+ vec = &lpriv->vectors[i];
+ vec->cpu = cpu;
+ vec->local_id = i;
+ vec->hwirq = UINT_MAX;
+ }
+ }
+
+ return 0;
+
+fail_local_cleanup:
+ imsic_local_cleanup();
+ return -ENOMEM;
+}
+
+void imsic_state_online(void)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&imsic->matrix_lock, flags);
+ irq_matrix_online(imsic->matrix);
+ raw_spin_unlock_irqrestore(&imsic->matrix_lock, flags);
+}
+
+void imsic_state_offline(void)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&imsic->matrix_lock, flags);
+ irq_matrix_offline(imsic->matrix);
+ raw_spin_unlock_irqrestore(&imsic->matrix_lock, flags);
+
+#ifdef CONFIG_SMP
+ struct imsic_local_priv *lpriv = this_cpu_ptr(imsic->lpriv);
+
+ raw_spin_lock_irqsave(&lpriv->lock, flags);
+ WARN_ON_ONCE(try_to_del_timer_sync(&lpriv->timer) < 0);
+ raw_spin_unlock_irqrestore(&lpriv->lock, flags);
+#endif
+}
+
+static int __init imsic_matrix_init(void)
+{
+ struct imsic_global_config *global = &imsic->global;
+
+ raw_spin_lock_init(&imsic->matrix_lock);
+ imsic->matrix = irq_alloc_matrix(global->nr_ids + 1,
+ 0, global->nr_ids + 1);
+ if (!imsic->matrix)
+ return -ENOMEM;
+
+ /* Reserve ID#0 because it is special and never implemented */
+ irq_matrix_assign_system(imsic->matrix, 0, false);
+
+ /* Reserve IPI ID because it is special and used internally */
+ irq_matrix_assign_system(imsic->matrix, IMSIC_IPI_ID, false);
+
+ return 0;
+}
+
+static int __init imsic_get_parent_hartid(struct fwnode_handle *fwnode,
+ u32 index, unsigned long *hartid)
+{
+ struct of_phandle_args parent;
+ int rc;
+
+ /*
+ * Currently, only OF fwnode is supported so extend this
+ * function for ACPI support.
+ */
+ if (!is_of_node(fwnode))
+ return -EINVAL;
+
+ rc = of_irq_parse_one(to_of_node(fwnode), index, &parent);
+ if (rc)
+ return rc;
+
+ /*
+ * Skip interrupts other than external interrupts for
+ * current privilege level.
+ */
+ if (parent.args[0] != RV_IRQ_EXT)
+ return -EINVAL;
+
+ return riscv_of_parent_hartid(parent.np, hartid);
+}
+
+static int __init imsic_get_mmio_resource(struct fwnode_handle *fwnode,
+ u32 index, struct resource *res)
+{
+ /*
+ * Currently, only OF fwnode is supported so extend this
+ * function for ACPI support.
+ */
+ if (!is_of_node(fwnode))
+ return -EINVAL;
+
+ return of_address_to_resource(to_of_node(fwnode), index, res);
+}
+
+static int __init imsic_parse_fwnode(struct fwnode_handle *fwnode,
+ struct imsic_global_config *global,
+ u32 *nr_parent_irqs,
+ u32 *nr_mmios)
+{
+ unsigned long hartid;
+ struct resource res;
+ int rc;
+ u32 i;
+
+ /*
+ * Currently, only OF fwnode is supported so extend this
+ * function for ACPI support.
+ */
+ if (!is_of_node(fwnode))
+ return -EINVAL;
+
+ *nr_parent_irqs = 0;
+ *nr_mmios = 0;
+
+ /* Find number of parent interrupts */
+ while (!imsic_get_parent_hartid(fwnode, *nr_parent_irqs, &hartid))
+ (*nr_parent_irqs)++;
+ if (!*nr_parent_irqs) {
+ pr_err("%pfwP: no parent irqs available\n", fwnode);
+ return -EINVAL;
+ }
+
+ /* Find number of guest index bits in MSI address */
+ rc = of_property_read_u32(to_of_node(fwnode), "riscv,guest-index-bits",
+ &global->guest_index_bits);
+ if (rc)
+ global->guest_index_bits = 0;
+
+ /* Find number of HART index bits */
+ rc = of_property_read_u32(to_of_node(fwnode), "riscv,hart-index-bits",
+ &global->hart_index_bits);
+ if (rc) {
+ /* Assume default value */
+ global->hart_index_bits = __fls(*nr_parent_irqs);
+ if (BIT(global->hart_index_bits) < *nr_parent_irqs)
+ global->hart_index_bits++;
+ }
+
+ /* Find number of group index bits */
+ rc = of_property_read_u32(to_of_node(fwnode), "riscv,group-index-bits",
+ &global->group_index_bits);
+ if (rc)
+ global->group_index_bits = 0;
+
+ /*
+ * Find first bit position of group index.
+ * If not specified assumed the default APLIC-IMSIC configuration.
+ */
+ rc = of_property_read_u32(to_of_node(fwnode), "riscv,group-index-shift",
+ &global->group_index_shift);
+ if (rc)
+ global->group_index_shift = IMSIC_MMIO_PAGE_SHIFT * 2;
+
+ /* Find number of interrupt identities */
+ rc = of_property_read_u32(to_of_node(fwnode), "riscv,num-ids",
+ &global->nr_ids);
+ if (rc) {
+ pr_err("%pfwP: number of interrupt identities not found\n", fwnode);
+ return rc;
+ }
+
+ /* Find number of guest interrupt identities */
+ rc = of_property_read_u32(to_of_node(fwnode), "riscv,num-guest-ids",
+ &global->nr_guest_ids);
+ if (rc)
+ global->nr_guest_ids = global->nr_ids;
+
+ /* Sanity check guest index bits */
+ i = BITS_PER_LONG - IMSIC_MMIO_PAGE_SHIFT;
+ if (i < global->guest_index_bits) {
+ pr_err("%pfwP: guest index bits too big\n", fwnode);
+ return -EINVAL;
+ }
+
+ /* Sanity check HART index bits */
+ i = BITS_PER_LONG - IMSIC_MMIO_PAGE_SHIFT - global->guest_index_bits;
+ if (i < global->hart_index_bits) {
+ pr_err("%pfwP: HART index bits too big\n", fwnode);
+ return -EINVAL;
+ }
+
+ /* Sanity check group index bits */
+ i = BITS_PER_LONG - IMSIC_MMIO_PAGE_SHIFT -
+ global->guest_index_bits - global->hart_index_bits;
+ if (i < global->group_index_bits) {
+ pr_err("%pfwP: group index bits too big\n", fwnode);
+ return -EINVAL;
+ }
+
+ /* Sanity check group index shift */
+ i = global->group_index_bits + global->group_index_shift - 1;
+ if (i >= BITS_PER_LONG) {
+ pr_err("%pfwP: group index shift too big\n", fwnode);
+ return -EINVAL;
+ }
+
+ /* Sanity check number of interrupt identities */
+ if (global->nr_ids < IMSIC_MIN_ID ||
+ global->nr_ids >= IMSIC_MAX_ID ||
+ (global->nr_ids & IMSIC_MIN_ID) != IMSIC_MIN_ID) {
+ pr_err("%pfwP: invalid number of interrupt identities\n", fwnode);
+ return -EINVAL;
+ }
+
+ /* Sanity check number of guest interrupt identities */
+ if (global->nr_guest_ids < IMSIC_MIN_ID ||
+ global->nr_guest_ids >= IMSIC_MAX_ID ||
+ (global->nr_guest_ids & IMSIC_MIN_ID) != IMSIC_MIN_ID) {
+ pr_err("%pfwP: invalid number of guest interrupt identities\n", fwnode);
+ return -EINVAL;
+ }
+
+ /* Compute base address */
+ rc = imsic_get_mmio_resource(fwnode, 0, &res);
+ if (rc) {
+ pr_err("%pfwP: first MMIO resource not found\n", fwnode);
+ return -EINVAL;
+ }
+ global->base_addr = res.start;
+ global->base_addr &= ~(BIT(global->guest_index_bits +
+ global->hart_index_bits +
+ IMSIC_MMIO_PAGE_SHIFT) - 1);
+ global->base_addr &= ~((BIT(global->group_index_bits) - 1) <<
+ global->group_index_shift);
+
+ /* Find number of MMIO register sets */
+ while (!imsic_get_mmio_resource(fwnode, *nr_mmios, &res))
+ (*nr_mmios)++;
+
+ return 0;
+}
+
+int __init imsic_setup_state(struct fwnode_handle *fwnode)
+{
+ u32 i, j, index, nr_parent_irqs, nr_mmios, nr_handlers = 0;
+ struct imsic_global_config *global;
+ struct imsic_local_config *local;
+ void __iomem **mmios_va = NULL;
+ struct resource *mmios = NULL;
+ unsigned long reloff, hartid;
+ phys_addr_t base_addr;
+ int rc, cpu;
+
+ /*
+ * Only one IMSIC instance allowed in a platform for clean
+ * implementation of SMP IRQ affinity and per-CPU IPIs.
+ *
+ * This means on a multi-socket (or multi-die) platform we
+ * will have multiple MMIO regions for one IMSIC instance.
+ */
+ if (imsic) {
+ pr_err("%pfwP: already initialized hence ignoring\n", fwnode);
+ return -EALREADY;
+ }
+
+ if (!riscv_isa_extension_available(NULL, SxAIA)) {
+ pr_err("%pfwP: AIA support not available\n", fwnode);
+ return -ENODEV;
+ }
+
+ imsic = kzalloc(sizeof(*imsic), GFP_KERNEL);
+ if (!imsic)
+ return -ENOMEM;
+ imsic->fwnode = fwnode;
+ global = &imsic->global;
+
+ global->local = alloc_percpu(typeof(*global->local));
+ if (!global->local) {
+ rc = -ENOMEM;
+ goto out_free_priv;
+ }
+
+ /* Parse IMSIC fwnode */
+ rc = imsic_parse_fwnode(fwnode, global, &nr_parent_irqs, &nr_mmios);
+ if (rc)
+ goto out_free_local;
+
+ /* Allocate MMIO resource array */
+ mmios = kcalloc(nr_mmios, sizeof(*mmios), GFP_KERNEL);
+ if (!mmios) {
+ rc = -ENOMEM;
+ goto out_free_local;
+ }
+
+ /* Allocate MMIO virtual address array */
+ mmios_va = kcalloc(nr_mmios, sizeof(*mmios_va), GFP_KERNEL);
+ if (!mmios_va) {
+ rc = -ENOMEM;
+ goto out_iounmap;
+ }
+
+ /* Parse and map MMIO register sets */
+ for (i = 0; i < nr_mmios; i++) {
+ rc = imsic_get_mmio_resource(fwnode, i, &mmios[i]);
+ if (rc) {
+ pr_err("%pfwP: unable to parse MMIO regset %d\n", fwnode, i);
+ goto out_iounmap;
+ }
+
+ base_addr = mmios[i].start;
+ base_addr &= ~(BIT(global->guest_index_bits +
+ global->hart_index_bits +
+ IMSIC_MMIO_PAGE_SHIFT) - 1);
+ base_addr &= ~((BIT(global->group_index_bits) - 1) <<
+ global->group_index_shift);
+ if (base_addr != global->base_addr) {
+ rc = -EINVAL;
+ pr_err("%pfwP: address mismatch for regset %d\n", fwnode, i);
+ goto out_iounmap;
+ }
+
+ mmios_va[i] = ioremap(mmios[i].start, resource_size(&mmios[i]));
+ if (!mmios_va[i]) {
+ rc = -EIO;
+ pr_err("%pfwP: unable to map MMIO regset %d\n", fwnode, i);
+ goto out_iounmap;
+ }
+ }
+
+ /* Initialize local (or per-CPU )state */
+ rc = imsic_local_init();
+ if (rc) {
+ pr_err("%pfwP: failed to initialize local state\n",
+ fwnode);
+ goto out_iounmap;
+ }
+
+ /* Configure handlers for target CPUs */
+ for (i = 0; i < nr_parent_irqs; i++) {
+ rc = imsic_get_parent_hartid(fwnode, i, &hartid);
+ if (rc) {
+ pr_warn("%pfwP: hart ID for parent irq%d not found\n", fwnode, i);
+ continue;
+ }
+
+ cpu = riscv_hartid_to_cpuid(hartid);
+ if (cpu < 0) {
+ pr_warn("%pfwP: invalid cpuid for parent irq%d\n", fwnode, i);
+ continue;
+ }
+
+ /* Find MMIO location of MSI page */
+ index = nr_mmios;
+ reloff = i * BIT(global->guest_index_bits) *
+ IMSIC_MMIO_PAGE_SZ;
+ for (j = 0; nr_mmios; j++) {
+ if (reloff < resource_size(&mmios[j])) {
+ index = j;
+ break;
+ }
+
+ /*
+ * MMIO region size may not be aligned to
+ * BIT(global->guest_index_bits) * IMSIC_MMIO_PAGE_SZ
+ * if holes are present.
+ */
+ reloff -= ALIGN(resource_size(&mmios[j]),
+ BIT(global->guest_index_bits) * IMSIC_MMIO_PAGE_SZ);
+ }
+ if (index >= nr_mmios) {
+ pr_warn("%pfwP: MMIO not found for parent irq%d\n", fwnode, i);
+ continue;
+ }
+
+ local = per_cpu_ptr(global->local, cpu);
+ local->msi_pa = mmios[index].start + reloff;
+ local->msi_va = mmios_va[index] + reloff;
+
+ nr_handlers++;
+ }
+
+ /* If no CPU handlers found then can't take interrupts */
+ if (!nr_handlers) {
+ pr_err("%pfwP: No CPU handlers found\n", fwnode);
+ rc = -ENODEV;
+ goto out_local_cleanup;
+ }
+
+ /* Initialize matrix allocator */
+ rc = imsic_matrix_init();
+ if (rc) {
+ pr_err("%pfwP: failed to create matrix allocator\n", fwnode);
+ goto out_local_cleanup;
+ }
+
+ /* We don't need MMIO arrays anymore so let's free-up */
+ kfree(mmios_va);
+ kfree(mmios);
+
+ return 0;
+
+out_local_cleanup:
+ imsic_local_cleanup();
+out_iounmap:
+ for (i = 0; i < nr_mmios; i++) {
+ if (mmios_va[i])
+ iounmap(mmios_va[i]);
+ }
+ kfree(mmios_va);
+ kfree(mmios);
+out_free_local:
+ free_percpu(imsic->global.local);
+out_free_priv:
+ kfree(imsic);
+ imsic = NULL;
+ return rc;
+}
diff --git a/drivers/irqchip/irq-riscv-imsic-state.h b/drivers/irqchip/irq-riscv-imsic-state.h
new file mode 100644
index 000000000000..8ec9649d0d01
--- /dev/null
+++ b/drivers/irqchip/irq-riscv-imsic-state.h
@@ -0,0 +1,107 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ * Copyright (C) 2022 Ventana Micro Systems Inc.
+ */
+
+#ifndef _IRQ_RISCV_IMSIC_STATE_H
+#define _IRQ_RISCV_IMSIC_STATE_H
+
+#include <linux/irqchip/riscv-imsic.h>
+#include <linux/irqdomain.h>
+#include <linux/fwnode.h>
+#include <linux/timer.h>
+
+#define IMSIC_IPI_ID 1
+#define IMSIC_NR_IPI 8
+
+struct imsic_vector {
+ /* Fixed details of the vector */
+ unsigned int cpu;
+ unsigned int local_id;
+ /* Details saved by driver in the vector */
+ unsigned int hwirq;
+ /* Details accessed using local lock held */
+ bool enable;
+ struct imsic_vector *move;
+};
+
+struct imsic_local_priv {
+ /* Local lock to protect vector enable/move variables and dirty bitmap */
+ raw_spinlock_t lock;
+
+ /* Local dirty bitmap for synchronization */
+ unsigned long *dirty_bitmap;
+
+#ifdef CONFIG_SMP
+ /* Local timer for synchronization */
+ struct timer_list timer;
+#endif
+
+ /* Local vector table */
+ struct imsic_vector *vectors;
+};
+
+struct imsic_priv {
+ /* Device details */
+ struct fwnode_handle *fwnode;
+
+ /* Global configuration common for all HARTs */
+ struct imsic_global_config global;
+
+ /* Per-CPU state */
+ struct imsic_local_priv __percpu *lpriv;
+
+ /* State of IRQ matrix allocator */
+ raw_spinlock_t matrix_lock;
+ struct irq_matrix *matrix;
+
+ /* IRQ domains (created by platform driver) */
+ struct irq_domain *base_domain;
+};
+
+extern struct imsic_priv *imsic;
+
+void __imsic_eix_update(unsigned long base_id, unsigned long num_id, bool pend, bool val);
+
+static inline void __imsic_id_set_enable(unsigned long id)
+{
+ __imsic_eix_update(id, 1, false, true);
+}
+
+static inline void __imsic_id_clear_enable(unsigned long id)
+{
+ __imsic_eix_update(id, 1, false, false);
+}
+
+void imsic_local_sync_all(void);
+void imsic_local_delivery(bool enable);
+
+void imsic_vector_mask(struct imsic_vector *vec);
+void imsic_vector_unmask(struct imsic_vector *vec);
+
+static inline bool imsic_vector_isenabled(struct imsic_vector *vec)
+{
+ return READ_ONCE(vec->enable);
+}
+
+static inline struct imsic_vector *imsic_vector_get_move(struct imsic_vector *vec)
+{
+ return READ_ONCE(vec->move);
+}
+
+void imsic_vector_move(struct imsic_vector *old_vec, struct imsic_vector *new_vec);
+
+struct imsic_vector *imsic_vector_from_local_id(unsigned int cpu, unsigned int local_id);
+
+struct imsic_vector *imsic_vector_alloc(unsigned int hwirq, const struct cpumask *mask);
+void imsic_vector_free(struct imsic_vector *vector);
+
+void imsic_vector_debug_show(struct seq_file *m, struct imsic_vector *vec, int ind);
+void imsic_vector_debug_show_summary(struct seq_file *m, int ind);
+
+void imsic_state_online(void);
+void imsic_state_offline(void);
+int imsic_setup_state(struct fwnode_handle *fwnode);
+
+#endif
diff --git a/include/linux/irqchip/riscv-imsic.h b/include/linux/irqchip/riscv-imsic.h
new file mode 100644
index 000000000000..faf0b800b1b0
--- /dev/null
+++ b/include/linux/irqchip/riscv-imsic.h
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ * Copyright (C) 2022 Ventana Micro Systems Inc.
+ */
+#ifndef __LINUX_IRQCHIP_RISCV_IMSIC_H
+#define __LINUX_IRQCHIP_RISCV_IMSIC_H
+
+#include <linux/types.h>
+#include <linux/bitops.h>
+#include <asm/csr.h>
+
+#define IMSIC_MMIO_PAGE_SHIFT 12
+#define IMSIC_MMIO_PAGE_SZ BIT(IMSIC_MMIO_PAGE_SHIFT)
+#define IMSIC_MMIO_PAGE_LE 0x00
+#define IMSIC_MMIO_PAGE_BE 0x04
+
+#define IMSIC_MIN_ID 63
+#define IMSIC_MAX_ID 2048
+
+#define IMSIC_EIDELIVERY 0x70
+
+#define IMSIC_EITHRESHOLD 0x72
+
+#define IMSIC_EIP0 0x80
+#define IMSIC_EIP63 0xbf
+#define IMSIC_EIPx_BITS 32
+
+#define IMSIC_EIE0 0xc0
+#define IMSIC_EIE63 0xff
+#define IMSIC_EIEx_BITS 32
+
+#define IMSIC_FIRST IMSIC_EIDELIVERY
+#define IMSIC_LAST IMSIC_EIE63
+
+#define IMSIC_MMIO_SETIPNUM_LE 0x00
+#define IMSIC_MMIO_SETIPNUM_BE 0x04
+
+struct imsic_local_config {
+ phys_addr_t msi_pa;
+ void __iomem *msi_va;
+};
+
+struct imsic_global_config {
+ /*
+ * MSI Target Address Scheme
+ *
+ * XLEN-1 12 0
+ * | | |
+ * -------------------------------------------------------------
+ * |xxxxxx|Group Index|xxxxxxxxxxx|HART Index|Guest Index| 0 |
+ * -------------------------------------------------------------
+ */
+
+ /* Bits representing Guest index, HART index, and Group index */
+ u32 guest_index_bits;
+ u32 hart_index_bits;
+ u32 group_index_bits;
+ u32 group_index_shift;
+
+ /* Global base address matching all target MSI addresses */
+ phys_addr_t base_addr;
+
+ /* Number of interrupt identities */
+ u32 nr_ids;
+
+ /* Number of guest interrupt identities */
+ u32 nr_guest_ids;
+
+ /* Per-CPU IMSIC addresses */
+ struct imsic_local_config __percpu *local;
+};
+
+#ifdef CONFIG_RISCV_IMSIC
+
+const struct imsic_global_config *imsic_get_global_config(void);
+
+#else
+
+static inline const struct imsic_global_config *imsic_get_global_config(void)
+{
+ return NULL;
+}
+
+#endif
+
+#endif
--
2.34.1
Anup Patel <[email protected]> writes:
> diff --git a/drivers/irqchip/irq-riscv-imsic-state.c b/drivers/irqchip/irq-riscv-imsic-state.c
> new file mode 100644
> index 000000000000..0c19ffb9ca3e
> --- /dev/null
> +++ b/drivers/irqchip/irq-riscv-imsic-state.c
> @@ -0,0 +1,870 @@
[...]
> +static void __imsic_local_sync(struct imsic_local_priv *lpriv)
> +{
> + struct imsic_local_config *mlocal;
> + struct imsic_vector *vec, *mvec;
> + int i;
> +
> + lockdep_assert_held(&lpriv->lock);
> +
> + /* This pairs with the barrier in __imsic_remote_sync(). */
> + smp_mb();
I'm trying to figure out why this barrier is needed? All the updates are
done behind the spinlocks. If there're some ordering constraints that
I'm missing, please document them.
> +
> + for_each_set_bit(i, lpriv->dirty_bitmap, imsic->global.nr_ids + 1) {
> + if (!i || i == IMSIC_IPI_ID)
> + goto skip;
> + vec = &lpriv->vectors[i];
> +
> + if (READ_ONCE(vec->enable))
> + __imsic_id_set_enable(i);
> + else
> + __imsic_id_clear_enable(i);
> +
> + /*
> + * If the ID was being moved to a new ID on some other CPU
> + * then we can get a MSI during the movement so check the
> + * ID pending bit and re-trigger the new ID on other CPU
> + * using MMIO write.
> + */
> + mvec = READ_ONCE(vec->move);
> + WRITE_ONCE(vec->move, NULL);
mvec = xchg(&vec->move, NULL) ?
> + if (mvec && mvec != vec) {
> + if (__imsic_id_read_clear_pending(i)) {
> + mlocal = per_cpu_ptr(imsic->global.local, mvec->cpu);
> + writel_relaxed(mvec->local_id, mlocal->msi_va);
> + }
> +
> + imsic_vector_free(&lpriv->vectors[i]);
> + }
> +
> +skip:
> + bitmap_clear(lpriv->dirty_bitmap, i, 1);
> + }
> +}
> +
> +void imsic_local_sync_all(void)
> +{
> + struct imsic_local_priv *lpriv = this_cpu_ptr(imsic->lpriv);
> + unsigned long flags;
> +
> + raw_spin_lock_irqsave(&lpriv->lock, flags);
> + bitmap_fill(lpriv->dirty_bitmap, imsic->global.nr_ids + 1);
> + __imsic_local_sync(lpriv);
> + raw_spin_unlock_irqrestore(&lpriv->lock, flags);
> +}
> +
> +void imsic_local_delivery(bool enable)
> +{
> + if (enable) {
> + imsic_csr_write(IMSIC_EITHRESHOLD, IMSIC_ENABLE_EITHRESHOLD);
> + imsic_csr_write(IMSIC_EIDELIVERY, IMSIC_ENABLE_EIDELIVERY);
> + return;
> + }
> +
> + imsic_csr_write(IMSIC_EIDELIVERY, IMSIC_DISABLE_EIDELIVERY);
> + imsic_csr_write(IMSIC_EITHRESHOLD, IMSIC_DISABLE_EITHRESHOLD);
> +}
> +
> +#ifdef CONFIG_SMP
> +static void imsic_local_timer_callback(struct timer_list *timer)
> +{
> + struct imsic_local_priv *lpriv = this_cpu_ptr(imsic->lpriv);
> + unsigned long flags;
> +
> + raw_spin_lock_irqsave(&lpriv->lock, flags);
> + __imsic_local_sync(lpriv);
> + raw_spin_unlock_irqrestore(&lpriv->lock, flags);
> +}
> +
> +static void __imsic_remote_sync(struct imsic_local_priv *lpriv, unsigned int cpu)
> +{
> + lockdep_assert_held(&lpriv->lock);
> +
> + /*
> + * Ensure that changes to vector enable, vector move and
> + * dirty bitmap are visible to the target CPU.
..which case the spinlock(s) are enough, no?
> + *
> + * This pairs with the barrier in __imsic_local_sync().
> + */
> + smp_mb();
> +
> + /*
> + * We schedule a timer on the target CPU if the target CPU is not
> + * same as the current CPU. An offline CPU will unconditionally
> + * synchronize IDs through imsic_starting_cpu() when the
> + * CPU is brought up.
> + */
> + if (cpu_online(cpu)) {
> + if (cpu == smp_processor_id()) {
> + __imsic_local_sync(lpriv);
> + return;
> + }
Maybe move this if-clause out from the cpu_online(), and only have
something like
if (cpu_online(cpu) && !timer_pending(&lpriv->timer)) { ... }
inside the CONFIG_SMP guard...
> +
> + if (!timer_pending(&lpriv->timer)) {
> + lpriv->timer.expires = jiffies + 1;
> + add_timer_on(&lpriv->timer, cpu);
> + }
> + }
> +}
> +#else
> +static void __imsic_remote_sync(struct imsic_local_priv *lpriv, unsigned int cpu)
> +{
> + lockdep_assert_held(&lpriv->lock);
> + __imsic_local_sync(lpriv);
> +}
> +#endif
..where we can get rid of this special !SMP all together for this
function.
> +
> +void imsic_vector_mask(struct imsic_vector *vec)
> +{
> + struct imsic_local_priv *lpriv;
> +
> + lpriv = per_cpu_ptr(imsic->lpriv, vec->cpu);
> + if (WARN_ON_ONCE(&lpriv->vectors[vec->local_id] != vec))
> + return;
> +
> + /*
> + * This function is called through Linux irq subsystem with
> + * irqs disabled so no need to save/restore irq flags.
> + */
> +
> + raw_spin_lock(&lpriv->lock);
> +
> + vec->enable = false;
Should have WRITE_ONCE to make the checkers happy.
> + bitmap_set(lpriv->dirty_bitmap, vec->local_id, 1);
> + __imsic_remote_sync(lpriv, vec->cpu);
> +
> + raw_spin_unlock(&lpriv->lock);
> +}
> +
> +void imsic_vector_unmask(struct imsic_vector *vec)
> +{
> + struct imsic_local_priv *lpriv;
> +
> + lpriv = per_cpu_ptr(imsic->lpriv, vec->cpu);
> + if (WARN_ON_ONCE(&lpriv->vectors[vec->local_id] != vec))
> + return;
> +
> + /*
> + * This function is called through Linux irq subsystem with
> + * irqs disabled so no need to save/restore irq flags.
> + */
> +
> + raw_spin_lock(&lpriv->lock);
> +
> + vec->enable = true;
Dito.
> + bitmap_set(lpriv->dirty_bitmap, vec->local_id, 1);
> + __imsic_remote_sync(lpriv, vec->cpu);
> +
> + raw_spin_unlock(&lpriv->lock);
> +}
> +
> +static bool imsic_vector_move_update(struct imsic_local_priv *lpriv, struct imsic_vector *vec,
> + bool new_enable, struct imsic_vector *new_move)
> +{
> + unsigned long flags;
> + bool enabled;
> +
> + raw_spin_lock_irqsave(&lpriv->lock, flags);
> +
> + /* Update enable and move details */
> + enabled = READ_ONCE(vec->enable);
> + WRITE_ONCE(vec->enable, new_enable);
Again, xchg() would be easier to read.
Björn
On Thu, Feb 22, 2024 at 6:43 PM Björn Töpel <bjorn@kernelorg> wrote:
>
> Anup Patel <[email protected]> writes:
>
> > diff --git a/drivers/irqchip/irq-riscv-imsic-state.c b/drivers/irqchip/irq-riscv-imsic-state.c
> > new file mode 100644
> > index 000000000000..0c19ffb9ca3e
> > --- /dev/null
> > +++ b/drivers/irqchip/irq-riscv-imsic-state.c
> > @@ -0,0 +1,870 @@
>
> [...]
>
> > +static void __imsic_local_sync(struct imsic_local_priv *lpriv)
> > +{
> > + struct imsic_local_config *mlocal;
> > + struct imsic_vector *vec, *mvec;
> > + int i;
> > +
> > + lockdep_assert_held(&lpriv->lock);
> > +
> > + /* This pairs with the barrier in __imsic_remote_sync(). */
> > + smp_mb();
>
> I'm trying to figure out why this barrier is needed? All the updates are
> done behind the spinlocks. If there're some ordering constraints that
> I'm missing, please document them.
>
> > +
> > + for_each_set_bit(i, lpriv->dirty_bitmap, imsic->global.nr_ids + 1) {
> > + if (!i || i == IMSIC_IPI_ID)
> > + goto skip;
> > + vec = &lpriv->vectors[i];
> > +
> > + if (READ_ONCE(vec->enable))
> > + __imsic_id_set_enable(i);
> > + else
> > + __imsic_id_clear_enable(i);
> > +
> > + /*
> > + * If the ID was being moved to a new ID on some other CPU
> > + * then we can get a MSI during the movement so check the
> > + * ID pending bit and re-trigger the new ID on other CPU
> > + * using MMIO write.
> > + */
> > + mvec = READ_ONCE(vec->move);
> > + WRITE_ONCE(vec->move, NULL);
>
> mvec = xchg(&vec->move, NULL) ?
The __imsic_local_sync() is called with spinlock held.
>
> > + if (mvec && mvec != vec) {
> > + if (__imsic_id_read_clear_pending(i)) {
> > + mlocal = per_cpu_ptr(imsic->global.local, mvec->cpu);
> > + writel_relaxed(mvec->local_id, mlocal->msi_va);
> > + }
> > +
> > + imsic_vector_free(&lpriv->vectors[i]);
> > + }
> > +
> > +skip:
> > + bitmap_clear(lpriv->dirty_bitmap, i, 1);
> > + }
> > +}
> > +
> > +void imsic_local_sync_all(void)
> > +{
> > + struct imsic_local_priv *lpriv = this_cpu_ptr(imsic->lpriv);
> > + unsigned long flags;
> > +
> > + raw_spin_lock_irqsave(&lpriv->lock, flags);
> > + bitmap_fill(lpriv->dirty_bitmap, imsic->global.nr_ids + 1);
> > + __imsic_local_sync(lpriv);
> > + raw_spin_unlock_irqrestore(&lpriv->lock, flags);
> > +}
> > +
> > +void imsic_local_delivery(bool enable)
> > +{
> > + if (enable) {
> > + imsic_csr_write(IMSIC_EITHRESHOLD, IMSIC_ENABLE_EITHRESHOLD);
> > + imsic_csr_write(IMSIC_EIDELIVERY, IMSIC_ENABLE_EIDELIVERY);
> > + return;
> > + }
> > +
> > + imsic_csr_write(IMSIC_EIDELIVERY, IMSIC_DISABLE_EIDELIVERY);
> > + imsic_csr_write(IMSIC_EITHRESHOLD, IMSIC_DISABLE_EITHRESHOLD);
> > +}
> > +
> > +#ifdef CONFIG_SMP
> > +static void imsic_local_timer_callback(struct timer_list *timer)
> > +{
> > + struct imsic_local_priv *lpriv = this_cpu_ptr(imsic->lpriv);
> > + unsigned long flags;
> > +
> > + raw_spin_lock_irqsave(&lpriv->lock, flags);
> > + __imsic_local_sync(lpriv);
> > + raw_spin_unlock_irqrestore(&lpriv->lock, flags);
> > +}
> > +
> > +static void __imsic_remote_sync(struct imsic_local_priv *lpriv, unsigned int cpu)
> > +{
> > + lockdep_assert_held(&lpriv->lock);
> > +
> > + /*
> > + * Ensure that changes to vector enable, vector move and
> > + * dirty bitmap are visible to the target CPU.
>
> ...which case the spinlock(s) are enough, no?
spinlocks are not fences.
If the timer wheel on the target cpu is already running and we don't
have a fence here then the target cpu might not see the changes
done by this cpu.
>
> > + *
> > + * This pairs with the barrier in __imsic_local_sync().
> > + */
> > + smp_mb();
> > +
> > + /*
> > + * We schedule a timer on the target CPU if the target CPU is not
> > + * same as the current CPU. An offline CPU will unconditionally
> > + * synchronize IDs through imsic_starting_cpu() when the
> > + * CPU is brought up.
> > + */
> > + if (cpu_online(cpu)) {
> > + if (cpu == smp_processor_id()) {
> > + __imsic_local_sync(lpriv);
> > + return;
> > + }
>
> Maybe move this if-clause out from the cpu_online(), and only have
> something like
> if (cpu_online(cpu) && !timer_pending(&lpriv->timer)) { ... }
> inside the CONFIG_SMP guard...
>
> > +
> > + if (!timer_pending(&lpriv->timer)) {
> > + lpriv->timer.expires = jiffies + 1;
> > + add_timer_on(&lpriv->timer, cpu);
> > + }
> > + }
> > +}
> > +#else
> > +static void __imsic_remote_sync(struct imsic_local_priv *lpriv, unsigned int cpu)
> > +{
> > + lockdep_assert_held(&lpriv->lock);
> > + __imsic_local_sync(lpriv);
> > +}
> > +#endif
>
> ...where we can get rid of this special !SMP all together for this
> function.
I failed to understand what is wrong the current code.
>
> > +
> > +void imsic_vector_mask(struct imsic_vector *vec)
> > +{
> > + struct imsic_local_priv *lpriv;
> > +
> > + lpriv = per_cpu_ptr(imsic->lpriv, vec->cpu);
> > + if (WARN_ON_ONCE(&lpriv->vectors[vec->local_id] != vec))
> > + return;
> > +
> > + /*
> > + * This function is called through Linux irq subsystem with
> > + * irqs disabled so no need to save/restore irq flags.
> > + */
> > +
> > + raw_spin_lock(&lpriv->lock);
> > +
> > + vec->enable = false;
>
> Should have WRITE_ONCE to make the checkers happy.
Okay, I will update.
>
> > + bitmap_set(lpriv->dirty_bitmap, vec->local_id, 1);
> > + __imsic_remote_sync(lpriv, vec->cpu);
> > +
> > + raw_spin_unlock(&lpriv->lock);
> > +}
> > +
> > +void imsic_vector_unmask(struct imsic_vector *vec)
> > +{
> > + struct imsic_local_priv *lpriv;
> > +
> > + lpriv = per_cpu_ptr(imsic->lpriv, vec->cpu);
> > + if (WARN_ON_ONCE(&lpriv->vectors[vec->local_id] != vec))
> > + return;
> > +
> > + /*
> > + * This function is called through Linux irq subsystem with
> > + * irqs disabled so no need to save/restore irq flags.
> > + */
> > +
> > + raw_spin_lock(&lpriv->lock);
> > +
> > + vec->enable = true;
>
> Dito.
Okay, I will update.
>
> > + bitmap_set(lpriv->dirty_bitmap, vec->local_id, 1);
> > + __imsic_remote_sync(lpriv, vec->cpu);
> > +
> > + raw_spin_unlock(&lpriv->lock);
> > +}
> > +
> > +static bool imsic_vector_move_update(struct imsic_local_priv *lpriv, struct imsic_vector *vec,
> > + bool new_enable, struct imsic_vector *new_move)
> > +{
> > + unsigned long flags;
> > + bool enabled;
> > +
> > + raw_spin_lock_irqsave(&lpriv->lock, flags);
> > +
> > + /* Update enable and move details */
> > + enabled = READ_ONCE(vec->enable);
> > + WRITE_ONCE(vec->enable, new_enable);
>
> Again, xchg() would be easier to read.
why ? spinlock is not enough?
Regards,
Anup
Anup Patel <[email protected]> writes:
> On Thu, Feb 22, 2024 at 6:43 PM Björn Töpel <[email protected]> wrote:
>>
>> Anup Patel <[email protected]> writes:
>>
>> > diff --git a/drivers/irqchip/irq-riscv-imsic-state.c b/drivers/irqchip/irq-riscv-imsic-state.c
>> > new file mode 100644
>> > index 000000000000..0c19ffb9ca3e
>> > --- /dev/null
>> > +++ b/drivers/irqchip/irq-riscv-imsic-state.c
>> > @@ -0,0 +1,870 @@
>>
>> [...]
>>
>> > +static void __imsic_local_sync(struct imsic_local_priv *lpriv)
>> > +{
>> > + struct imsic_local_config *mlocal;
>> > + struct imsic_vector *vec, *mvec;
>> > + int i;
>> > +
>> > + lockdep_assert_held(&lpriv->lock);
>> > +
>> > + /* This pairs with the barrier in __imsic_remote_sync(). */
>> > + smp_mb();
>>
>> I'm trying to figure out why this barrier is needed? All the updates are
>> done behind the spinlocks. If there're some ordering constraints that
>> I'm missing, please document them.
>>
>> > +
>> > + for_each_set_bit(i, lpriv->dirty_bitmap, imsic->global.nr_ids + 1) {
>> > + if (!i || i == IMSIC_IPI_ID)
>> > + goto skip;
>> > + vec = &lpriv->vectors[i];
>> > +
>> > + if (READ_ONCE(vec->enable))
>> > + __imsic_id_set_enable(i);
>> > + else
>> > + __imsic_id_clear_enable(i);
>> > +
>> > + /*
>> > + * If the ID was being moved to a new ID on some other CPU
>> > + * then we can get a MSI during the movement so check the
>> > + * ID pending bit and re-trigger the new ID on other CPU
>> > + * using MMIO write.
>> > + */
>> > + mvec = READ_ONCE(vec->move);
>> > + WRITE_ONCE(vec->move, NULL);
>>
>> mvec = xchg(&vec->move, NULL) ?
>
> The __imsic_local_sync() is called with spinlock held.
Yeah, this was a readability comment.
>> > + if (mvec && mvec != vec) {
>> > + if (__imsic_id_read_clear_pending(i)) {
>> > + mlocal = per_cpu_ptr(imsic->global.local, mvec->cpu);
>> > + writel_relaxed(mvec->local_id, mlocal->msi_va);
>> > + }
>> > +
>> > + imsic_vector_free(&lpriv->vectors[i]);
>> > + }
>> > +
>> > +skip:
>> > + bitmap_clear(lpriv->dirty_bitmap, i, 1);
>> > + }
>> > +}
>> > +
>> > +void imsic_local_sync_all(void)
>> > +{
>> > + struct imsic_local_priv *lpriv = this_cpu_ptr(imsic->lpriv);
>> > + unsigned long flags;
>> > +
>> > + raw_spin_lock_irqsave(&lpriv->lock, flags);
>> > + bitmap_fill(lpriv->dirty_bitmap, imsic->global.nr_ids + 1);
>> > + __imsic_local_sync(lpriv);
>> > + raw_spin_unlock_irqrestore(&lpriv->lock, flags);
>> > +}
>> > +
>> > +void imsic_local_delivery(bool enable)
>> > +{
>> > + if (enable) {
>> > + imsic_csr_write(IMSIC_EITHRESHOLD, IMSIC_ENABLE_EITHRESHOLD);
>> > + imsic_csr_write(IMSIC_EIDELIVERY, IMSIC_ENABLE_EIDELIVERY);
>> > + return;
>> > + }
>> > +
>> > + imsic_csr_write(IMSIC_EIDELIVERY, IMSIC_DISABLE_EIDELIVERY);
>> > + imsic_csr_write(IMSIC_EITHRESHOLD, IMSIC_DISABLE_EITHRESHOLD);
>> > +}
>> > +
>> > +#ifdef CONFIG_SMP
>> > +static void imsic_local_timer_callback(struct timer_list *timer)
>> > +{
>> > + struct imsic_local_priv *lpriv = this_cpu_ptr(imsic->lpriv);
>> > + unsigned long flags;
>> > +
>> > + raw_spin_lock_irqsave(&lpriv->lock, flags);
>> > + __imsic_local_sync(lpriv);
>> > + raw_spin_unlock_irqrestore(&lpriv->lock, flags);
>> > +}
>> > +
>> > +static void __imsic_remote_sync(struct imsic_local_priv *lpriv, unsigned int cpu)
>> > +{
>> > + lockdep_assert_held(&lpriv->lock);
>> > +
>> > + /*
>> > + * Ensure that changes to vector enable, vector move and
>> > + * dirty bitmap are visible to the target CPU.
>>
>> ...which case the spinlock(s) are enough, no?
>
> spinlocks are not fences.
They are indeed, and it would be hard to use them as locks otherwise
(acq/rel -- good ol' Documentation/memory-barriers.txt).
> If the timer wheel on the target cpu is already running and we don't
> have a fence here then the target cpu might not see the changes
> done by this cpu.
Remove the smp_mb() pair, the spinlocks are enough for this scenario!
>> > + *
>> > + * This pairs with the barrier in __imsic_local_sync().
>> > + */
>> > + smp_mb();
>> > +
>> > + /*
>> > + * We schedule a timer on the target CPU if the target CPU is not
>> > + * same as the current CPU. An offline CPU will unconditionally
>> > + * synchronize IDs through imsic_starting_cpu() when the
>> > + * CPU is brought up.
>> > + */
>> > + if (cpu_online(cpu)) {
>> > + if (cpu == smp_processor_id()) {
>> > + __imsic_local_sync(lpriv);
>> > + return;
>> > + }
>>
>> Maybe move this if-clause out from the cpu_online(), and only have
>> something like
>> if (cpu_online(cpu) && !timer_pending(&lpriv->timer)) { ... }
>> inside the CONFIG_SMP guard...
>>
>> > +
>> > + if (!timer_pending(&lpriv->timer)) {
>> > + lpriv->timer.expires = jiffies + 1;
>> > + add_timer_on(&lpriv->timer, cpu);
>> > + }
>> > + }
>> > +}
>> > +#else
>> > +static void __imsic_remote_sync(struct imsic_local_priv *lpriv, unsigned int cpu)
>> > +{
>> > + lockdep_assert_held(&lpriv->lock);
>> > + __imsic_local_sync(lpriv);
>> > +}
>> > +#endif
>>
>> ...where we can get rid of this special !SMP all together for this
>> function.
>
> I failed to understand what is wrong the current code.
Oh, nothing is wrong. Just trying to get rid of some ifdeffery.
>> > +void imsic_vector_mask(struct imsic_vector *vec)
>> > +{
>> > + struct imsic_local_priv *lpriv;
>> > +
>> > + lpriv = per_cpu_ptr(imsic->lpriv, vec->cpu);
>> > + if (WARN_ON_ONCE(&lpriv->vectors[vec->local_id] != vec))
>> > + return;
>> > +
>> > + /*
>> > + * This function is called through Linux irq subsystem with
>> > + * irqs disabled so no need to save/restore irq flags.
>> > + */
>> > +
>> > + raw_spin_lock(&lpriv->lock);
>> > +
>> > + vec->enable = false;
>>
>> Should have WRITE_ONCE to make the checkers happy.
>
> Okay, I will update.
>
>>
>> > + bitmap_set(lpriv->dirty_bitmap, vec->local_id, 1);
>> > + __imsic_remote_sync(lpriv, vec->cpu);
>> > +
>> > + raw_spin_unlock(&lpriv->lock);
>> > +}
>> > +
>> > +void imsic_vector_unmask(struct imsic_vector *vec)
>> > +{
>> > + struct imsic_local_priv *lpriv;
>> > +
>> > + lpriv = per_cpu_ptr(imsic->lpriv, vec->cpu);
>> > + if (WARN_ON_ONCE(&lpriv->vectors[vec->local_id] != vec))
>> > + return;
>> > +
>> > + /*
>> > + * This function is called through Linux irq subsystem with
>> > + * irqs disabled so no need to save/restore irq flags.
>> > + */
>> > +
>> > + raw_spin_lock(&lpriv->lock);
>> > +
>> > + vec->enable = true;
>>
>> Dito.
>
> Okay, I will update.
>
>>
>> > + bitmap_set(lpriv->dirty_bitmap, vec->local_id, 1);
>> > + __imsic_remote_sync(lpriv, vec->cpu);
>> > +
>> > + raw_spin_unlock(&lpriv->lock);
>> > +}
>> > +
>> > +static bool imsic_vector_move_update(struct imsic_local_priv *lpriv, struct imsic_vector *vec,
>> > + bool new_enable, struct imsic_vector *new_move)
>> > +{
>> > + unsigned long flags;
>> > + bool enabled;
>> > +
>> > + raw_spin_lock_irqsave(&lpriv->lock, flags);
>> > +
>> > + /* Update enable and move details */
>> > + enabled = READ_ONCE(vec->enable);
>> > + WRITE_ONCE(vec->enable, new_enable);
>>
>> Again, xchg() would be easier to read.
>
> why ? spinlock is not enough?
They're enough! Just readbaility/personal taste.
I'm running tests for this series now! Would be awesome to have the
series land for 6.9!
Cheers,
Björn
On Thu, Feb 22 2024 at 15:09, Anup Patel wrote:
> + /*
> + * Setup cpuhp state (must be done after setting imsic_parent_irq)
> + *
> + * Don't disable per-CPU IMSIC file when CPU goes offline
> + * because this affects IPI and the masking/unmasking of
> + * virtual IPIs is done via generic IPI-Mux
> + */
> + cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "irqchip/riscv/imsic:starting",
> + imsic_starting_cpu, imsic_dying_cpu);
This is not really correct. IPIs should be working right away when a CPU
comes online and on the unplug side until it really goes offline.
So this wants to be in the starting range, i.e. between CPUHP_AP_OFFLINE
and CPUHP_AP_ONLINE. No?
Thanks,
tglx
On Fri, Feb 23, 2024 at 1:58 PM Thomas Gleixner <[email protected]> wrote:
>
> On Thu, Feb 22 2024 at 15:09, Anup Patel wrote:
> > + /*
> > + * Setup cpuhp state (must be done after setting imsic_parent_irq)
> > + *
> > + * Don't disable per-CPU IMSIC file when CPU goes offline
> > + * because this affects IPI and the masking/unmasking of
> > + * virtual IPIs is done via generic IPI-Mux
> > + */
> > + cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "irqchip/riscv/imsic:starting",
> > + imsic_starting_cpu, imsic_dying_cpu);
>
> This is not really correct. IPIs should be working right away when a CPU
> comes online and on the unplug side until it really goes offline.
>
> So this wants to be in the starting range, i.e. between CPUHP_AP_OFFLINE
> and CPUHP_AP_ONLINE. No?
Yes, it has to be as early as possible but I was not sure about
introducing yet another driver specific CPUHP_AP_xyz state
considering CPUHP_AP_ONLINE_DYN worked fine.
Since you suggested, let me introduce
CPUHP_AP_IRQ_RISCV_IMSIC_STARTING in the next revision.
Regards,
Anup