[PATCH v16 0/9] RISC-V IPI Improvements

[PATCH v16 0/9] RISC-V IPI Improvements

[Anup Patel]

This series aims to improve IPI support in Linux RISC-V in following ways:
 1) Treat IPIs as normal per-CPU interrupts instead of having custom RISC-V
    specific hooks. This also makes Linux RISC-V IPI support aligned with
    other architectures.
 2) Remote TLB flushes and icache flushes should prefer local IPIs instead
    of SBI calls whenever we have specialized hardware (such as RISC-V AIA
    IMSIC and RISC-V SWI) which allows S-mode software to directly inject
    IPIs without any assistance from M-mode runtime firmware.

These patches were originally part of the "Linux RISC-V ACLINT Support"
series but this now a separate series so that it can be merged independently
of the "Linux RISC-V ACLINT Support" series.
(Refer, https://lore.kernel.org/lkml/20211007123632.697666-1-anup.patel@wdc.com/)

These patches are also a preparatory patches for the up-coming:
 1) Linux RISC-V AIA support
 2) Linux RISC-V SWI support

These patches can also be found in riscv_ipi_imp_v16 branch at:
https://github.com/avpatel/linux.git

Changes since v15:
 - Rebased on Linux-6.2-rc2
 - Added Reviewed-by and Tested-by tags to some of the patches.

Changes since v14:
 - Minor fixes in commit description of PATCH3 (as suggested by tglx)
 - Don't disable parent IPI when CPU goes offline for SBI IPI driver and
   CLINT driver in PATCH4.
 - Include Apple AIC driver changes from Marc Z as PATCH9

Changes since v13:
 - Included changes suggested by Marc Z in PATCH3
 - Use chained handlers in PATCH4
 - Added new PATCH8 to have empty irq_eoi() in RISC-V INTC driver. This
   avoids the unnecessary mask/unmask dance at time of handling interrupts.

Changes since v12:
 - Rebased on Linux-6.1-rc7
 - Bring-back the IPI optimization in ipi_mux_send_mask() for PATCH3
 - Call ipi_mux_send() for one target CPU at a time in PATCH3

Changes since v11:
 - Removed ipi_mux_pre/post_handle() callbacks in PATCH3
 - Removed sturct ipi_mux_ops in PATCH3
 - Removed parent_virq and data pointer from everywhere in PATCH3
 - Removed struct ipi_mux_control in PATCH3
 - Improved function signature of ipi_mux_send() callback in PATCH3
 - Used unsigned type with atomic operation in PATCH3

Changes since v10:
 - Rebased on Linux-6.1-rc5
 - Drop the "!(pending & ibit)" check in ipi_mux_send_mask() of PATCH3
 - Disable local interrupts in ipi_mux_send_mask() of PATCH3 because we
   can be preempted while using a per-CPU temporary variable.

Changes since v9:
 - Rebased on Linux-6.1-rc3
 - Updated header comment block of ipi-mux.c in PATCH3
 - Use a struct for global data of ipi-mux.c in PATCH3
 - Add per-CPU temp cpumask for sending IPIs in PATCH3
 - Drop the use of fwspec in PATCH3
 - Use static key for ipi_mux_pre_handle() and ipi_mux_post_handle()
   in PATCH3
 - Remove redundant pr_warn_ratelimited() called by ipi_mux_process()
   in PATCH3
 - Remove CPUHP thingy from ipi_mux_create() in PATCH3

Changes since v8:
 - Rebased on Linux-6.0-rc3
 - Use dummy percpu data as parameter for request_percpu_irq() in PATCH4.

Changes since v7:
 - Rebased on Linux-6.0-rc1
 - Use atomic operations to track per-CPU pending and enabled IPIs in PATCH3.
   (Note: this is inspired from IPI muxing implemented in
    drivers/irqchip/irq-apple-aic.c)
 - Made "struct ipi_mux_ops" (added by PATCH3) flexible so that
   drivers/irqchip/irq-apple-aic.c can adopt it in future.

Changes since v6:
 - Rebased on Linux-5.19-rc7
 - Added documentation for struct ipi_mux_ops in PATCH3
 - Dropped dummy irq_mask()/unmask() in PATCH3
 - Added const for "ipi_mux_chip" in PATCH3
 - Removed "type" initialization from ipi_mux_domain_alloc() in PATCH3
 - Dropped translate() from "ipi_mux_domain_ops" in PATCH3
 - Improved barrier documentation in ipi_mux_process() of PATCH3
 - Added percpu check in ipi_mux_create() for parent_virq of PATCH3
 - Added nr_ipi parameter in ipi_mux_create() of PATCH3

Changes since v5:
 - Rebased on Linux-5.18-rc3
 - Used kernel doc style in PATCH3
 - Removed redundant loop in ipi_mux_process() of PATCH3
 - Removed "RISC-V" prefix form ipi_mux_chip.name of PATCH3
 - Removed use of "this patch" in PATCH3 commit description
 - Addressed few other nit comments in PATCH3

Changes since v4:
 - Rebased on Linux-5.17
 - Includes new PATCH3 which adds mechanism to multiplex a single HW IPI

Changes since v3:
 - Rebased on Linux-5.17-rc6
 - Updated PATCH2 to not export riscv_set_intc_hwnode_fn()
 - Simplified riscv_intc_hwnode() in PATCH2

Changes since v2:
 - Rebased on Linux-5.17-rc4
 - Updated PATCH2 to not create synthetic INTC fwnode and instead provide
   a function which allows drivers to directly discover INTC fwnode

Changes since v1:
 - Use synthetic fwnode for INTC instead of irq_set_default_host() in PATCH2

Anup Patel (8):
  RISC-V: Clear SIP bit only when using SBI IPI operations
  irqchip/riscv-intc: Allow drivers to directly discover INTC hwnode
  genirq: Add mechanism to multiplex a single HW IPI
  RISC-V: Treat IPIs as normal Linux IRQs
  RISC-V: Allow marking IPIs as suitable for remote FENCEs
  RISC-V: Use IPIs for remote TLB flush when possible
  RISC-V: Use IPIs for remote icache flush when possible
  irqchip/riscv-intc: Add empty irq_eoi() for chained irq handlers

Marc Zyngier (1):
  irqchip/apple-aic: Move over to core ipi-mux

 arch/riscv/Kconfig                |   2 +
 arch/riscv/include/asm/irq.h      |   4 +
 arch/riscv/include/asm/sbi.h      |   9 +-
 arch/riscv/include/asm/smp.h      |  49 +++++--
 arch/riscv/kernel/Makefile        |   1 +
 arch/riscv/kernel/cpu-hotplug.c   |   3 +-
 arch/riscv/kernel/irq.c           |  21 ++-
 arch/riscv/kernel/sbi-ipi.c       |  77 +++++++++++
 arch/riscv/kernel/sbi.c           | 100 +++------------
 arch/riscv/kernel/smp.c           | 171 ++++++++++++------------
 arch/riscv/kernel/smpboot.c       |   5 +-
 arch/riscv/mm/cacheflush.c        |   5 +-
 arch/riscv/mm/tlbflush.c          |  93 +++++++++++---
 drivers/clocksource/timer-clint.c |  65 +++++++---
 drivers/irqchip/Kconfig           |   2 +
 drivers/irqchip/irq-apple-aic.c   | 161 ++---------------------
 drivers/irqchip/irq-riscv-intc.c  |  71 ++++++----
 include/linux/irq.h               |   3 +
 kernel/irq/Kconfig                |   5 +
 kernel/irq/Makefile               |   1 +
 kernel/irq/ipi-mux.c              | 207 ++++++++++++++++++++++++++++++
 21 files changed, 654 insertions(+), 401 deletions(-)
 create mode 100644 arch/riscv/kernel/sbi-ipi.c
 create mode 100644 kernel/irq/ipi-mux.c

-- 
2.34.1

[PATCH v16 1/9] RISC-V: Clear SIP bit only when using SBI IPI operations

[Anup Patel]

The software interrupt pending (i.e. [M|S]SIP) bit is writeable for
S-mode but read-only for M-mode so we clear this bit only when using
SBI IPI operations.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
---
 arch/riscv/kernel/sbi.c | 8 +++++++-
 arch/riscv/kernel/smp.c | 2 --
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index 5c87db8fdff2..ac99a70ead6a 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -646,8 +646,14 @@ static void sbi_send_cpumask_ipi(const struct cpumask *target)
 	sbi_send_ipi(target);
 }
 
+static void sbi_ipi_clear(void)
+{
+	csr_clear(CSR_IP, IE_SIE);
+}
+
 static const struct riscv_ipi_ops sbi_ipi_ops = {
-	.ipi_inject = sbi_send_cpumask_ipi
+	.ipi_inject = sbi_send_cpumask_ipi,
+	.ipi_clear = sbi_ipi_clear
 };
 
 void __init sbi_init(void)
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index 8c3b59f1f9b8..8a12768c09ee 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -112,8 +112,6 @@ void riscv_clear_ipi(void)
 {
 	if (ipi_ops && ipi_ops->ipi_clear)
 		ipi_ops->ipi_clear();
-
-	csr_clear(CSR_IP, IE_SIE);
 }
 EXPORT_SYMBOL_GPL(riscv_clear_ipi);
 
-- 
2.34.1

[PATCH v16 2/9] irqchip/riscv-intc: Allow drivers to directly discover INTC hwnode

[Anup Patel]

Various RISC-V drivers (such as SBI IPI, SBI Timer, SBI PMU, and
KVM RISC-V) don't have associated DT node but these drivers need
standard per-CPU (local) interrupts defined by the RISC-V privileged
specification.

We add riscv_get_intc_hwnode() in arch/riscv which allows RISC-V
drivers not having DT node to discover INTC hwnode which in-turn
helps these drivers to map per-CPU (local) interrupts provided
by the INTC driver.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
---
 arch/riscv/include/asm/irq.h     |  4 ++++
 arch/riscv/kernel/irq.c          | 18 ++++++++++++++++++
 drivers/irqchip/irq-riscv-intc.c |  7 +++++++
 3 files changed, 29 insertions(+)

diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
index e4c435509983..43b9ebfbd943 100644
--- a/arch/riscv/include/asm/irq.h
+++ b/arch/riscv/include/asm/irq.h
@@ -12,6 +12,10 @@
 
 #include <asm-generic/irq.h>
 
+void riscv_set_intc_hwnode_fn(struct fwnode_handle *(*fn)(void));
+
+struct fwnode_handle *riscv_get_intc_hwnode(void);
+
 extern void __init init_IRQ(void);
 
 #endif /* _ASM_RISCV_IRQ_H */
diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index 7207fa08d78f..96d3171f0ca1 100644
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -7,9 +7,27 @@
 
 #include <linux/interrupt.h>
 #include <linux/irqchip.h>
+#include <linux/irqdomain.h>
+#include <linux/module.h>
 #include <linux/seq_file.h>
 #include <asm/smp.h>
 
+static struct fwnode_handle *(*__get_intc_node)(void);
+
+void riscv_set_intc_hwnode_fn(struct fwnode_handle *(*fn)(void))
+{
+	__get_intc_node = fn;
+}
+
+struct fwnode_handle *riscv_get_intc_hwnode(void)
+{
+	if (__get_intc_node)
+		return __get_intc_node();
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(riscv_get_intc_hwnode);
+
 int arch_show_interrupts(struct seq_file *p, int prec)
 {
 	show_ipi_stats(p, prec);
diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c
index 499e5f81b3fe..9066467e99e4 100644
--- a/drivers/irqchip/irq-riscv-intc.c
+++ b/drivers/irqchip/irq-riscv-intc.c
@@ -92,6 +92,11 @@ static const struct irq_domain_ops riscv_intc_domain_ops = {
 	.xlate	= irq_domain_xlate_onecell,
 };
 
+static struct fwnode_handle *riscv_intc_hwnode(void)
+{
+	return intc_domain->fwnode;
+}
+
 static int __init riscv_intc_init(struct device_node *node,
 				  struct device_node *parent)
 {
@@ -126,6 +131,8 @@ static int __init riscv_intc_init(struct device_node *node,
 		return rc;
 	}
 
+	riscv_set_intc_hwnode_fn(riscv_intc_hwnode);
+
 	cpuhp_setup_state(CPUHP_AP_IRQ_RISCV_STARTING,
 			  "irqchip/riscv/intc:starting",
 			  riscv_intc_cpu_starting,
-- 
2.34.1

[PATCH v16 3/9] genirq: Add mechanism to multiplex a single HW IPI

[Anup Patel]

All RISC-V platforms have a single HW IPI provided by the INTC local
interrupt controller. The HW method to trigger INTC IPI can be through
external irqchip (e.g. RISC-V AIA), through platform specific device
(e.g. SiFive CLINT timer), or through firmware (e.g. SBI IPI call).

To support multiple IPIs on RISC-V, add a generic IPI multiplexing
mechanism which help us create multiple virtual IPIs using a single
HW IPI. This generic IPI multiplexing is inspired by the Apple AIC
irqchip driver and it is shared by various RISC-V irqchip drivers.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Hector Martin <marcan@marcan.st>
Tested-by: Hector Martin <marcan@marcan.st>
---
 include/linux/irq.h  |   3 +
 kernel/irq/Kconfig   |   5 ++
 kernel/irq/Makefile  |   1 +
 kernel/irq/ipi-mux.c | 207 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 216 insertions(+)
 create mode 100644 kernel/irq/ipi-mux.c

diff --git a/include/linux/irq.h b/include/linux/irq.h
index c3eb89606c2b..b1b28affb32a 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -1266,6 +1266,9 @@ int __ipi_send_mask(struct irq_desc *desc, const struct cpumask *dest);
 int ipi_send_single(unsigned int virq, unsigned int cpu);
 int ipi_send_mask(unsigned int virq, const struct cpumask *dest);
 
+void ipi_mux_process(void);
+int ipi_mux_create(unsigned int nr_ipi, void (*mux_send)(unsigned int cpu));
+
 #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
 /*
  * Registers a generic IRQ handling function as the top-level IRQ handler in
diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index b64c44ae4c25..2531f3496ab6 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -86,6 +86,11 @@ config GENERIC_IRQ_IPI
 	depends on SMP
 	select IRQ_DOMAIN_HIERARCHY
 
+# Generic IRQ IPI Mux support
+config GENERIC_IRQ_IPI_MUX
+	bool
+	depends on SMP
+
 # Generic MSI hierarchical interrupt domain support
 config GENERIC_MSI_IRQ
 	bool
diff --git a/kernel/irq/Makefile b/kernel/irq/Makefile
index b4f53717d143..f19d3080bf11 100644
--- a/kernel/irq/Makefile
+++ b/kernel/irq/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_GENERIC_IRQ_MIGRATION) += cpuhotplug.o
 obj-$(CONFIG_PM_SLEEP) += pm.o
 obj-$(CONFIG_GENERIC_MSI_IRQ) += msi.o
 obj-$(CONFIG_GENERIC_IRQ_IPI) += ipi.o
+obj-$(CONFIG_GENERIC_IRQ_IPI_MUX) += ipi-mux.o
 obj-$(CONFIG_SMP) += affinity.o
 obj-$(CONFIG_GENERIC_IRQ_DEBUGFS) += debugfs.o
 obj-$(CONFIG_GENERIC_IRQ_MATRIX_ALLOCATOR) += matrix.o
diff --git a/kernel/irq/ipi-mux.c b/kernel/irq/ipi-mux.c
new file mode 100644
index 000000000000..3a403c3a785d
--- /dev/null
+++ b/kernel/irq/ipi-mux.c
@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Multiplex several virtual IPIs over a single HW IPI.
+ *
+ * Copyright The Asahi Linux Contributors
+ * Copyright (c) 2022 Ventana Micro Systems Inc.
+ */
+
+#define pr_fmt(fmt) "ipi-mux: " fmt
+#include <linux/cpu.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/jump_label.h>
+#include <linux/percpu.h>
+#include <linux/smp.h>
+
+struct ipi_mux_cpu {
+	atomic_t			enable;
+	atomic_t			bits;
+};
+
+static struct ipi_mux_cpu __percpu *ipi_mux_pcpu;
+static struct irq_domain *ipi_mux_domain;
+static void (*ipi_mux_send)(unsigned int cpu);
+
+static void ipi_mux_mask(struct irq_data *d)
+{
+	struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu);
+
+	atomic_andnot(BIT(irqd_to_hwirq(d)), &icpu->enable);
+}
+
+static void ipi_mux_unmask(struct irq_data *d)
+{
+	struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu);
+	u32 ibit = BIT(irqd_to_hwirq(d));
+
+	atomic_or(ibit, &icpu->enable);
+
+	/*
+	 * The atomic_or() above must complete before the atomic_read()
+	 * below to avoid racing ipi_mux_send_mask().
+	 */
+	smp_mb__after_atomic();
+
+	/* If a pending IPI was unmasked, raise a parent IPI immediately. */
+	if (atomic_read(&icpu->bits) & ibit)
+		ipi_mux_send(smp_processor_id());
+}
+
+static void ipi_mux_send_mask(struct irq_data *d, const struct cpumask *mask)
+{
+	struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu);
+	u32 ibit = BIT(irqd_to_hwirq(d));
+	unsigned long pending;
+	int cpu;
+
+	for_each_cpu(cpu, mask) {
+		icpu = per_cpu_ptr(ipi_mux_pcpu, cpu);
+
+		/*
+		 * This sequence is the mirror of the one in ipi_mux_unmask();
+		 * see the comment there. Additionally, release semantics
+		 * ensure that the vIPI flag set is ordered after any shared
+		 * memory accesses that precede it. This therefore also pairs
+		 * with the atomic_fetch_andnot in ipi_mux_process().
+		 */
+		pending = atomic_fetch_or_release(ibit, &icpu->bits);
+
+		/*
+		 * The atomic_fetch_or_release() above must complete
+		 * before the atomic_read() below to avoid racing with
+		 * ipi_mux_unmask().
+		 */
+		smp_mb__after_atomic();
+
+		/*
+		 * The flag writes must complete before the physical IPI is
+		 * issued to another CPU. This is implied by the control
+		 * dependency on the result of atomic_read() below, which is
+		 * itself already ordered after the vIPI flag write.
+		 */
+		if (!(pending & ibit) && (atomic_read(&icpu->enable) & ibit))
+			ipi_mux_send(cpu);
+	}
+}
+
+static const struct irq_chip ipi_mux_chip = {
+	.name		= "IPI Mux",
+	.irq_mask	= ipi_mux_mask,
+	.irq_unmask	= ipi_mux_unmask,
+	.ipi_send_mask	= ipi_mux_send_mask,
+};
+
+static int ipi_mux_domain_alloc(struct irq_domain *d, unsigned int virq,
+				unsigned int nr_irqs, void *arg)
+{
+	int i;
+
+	for (i = 0; i < nr_irqs; i++) {
+		irq_set_percpu_devid(virq + i);
+		irq_domain_set_info(d, virq + i, i, &ipi_mux_chip, NULL,
+				    handle_percpu_devid_irq, NULL, NULL);
+	}
+
+	return 0;
+}
+
+static const struct irq_domain_ops ipi_mux_domain_ops = {
+	.alloc		= ipi_mux_domain_alloc,
+	.free		= irq_domain_free_irqs_top,
+};
+
+/**
+ * ipi_mux_process - Process multiplexed virtual IPIs
+ */
+void ipi_mux_process(void)
+{
+	struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu);
+	irq_hw_number_t hwirq;
+	unsigned long ipis;
+	unsigned int en;
+
+	/*
+	 * Reading enable mask does not need to be ordered as long as
+	 * this function is called from interrupt handler because only
+	 * the CPU itself can change it's own enable mask.
+	 */
+	en = atomic_read(&icpu->enable);
+
+	/*
+	 * Clear the IPIs we are about to handle. This pairs with the
+	 * atomic_fetch_or_release() in ipi_mux_send_mask().
+	 */
+	ipis = atomic_fetch_andnot(en, &icpu->bits) & en;
+
+	for_each_set_bit(hwirq, &ipis, BITS_PER_TYPE(int))
+		generic_handle_domain_irq(ipi_mux_domain, hwirq);
+}
+
+/**
+ * ipi_mux_create - Create virtual IPIs multiplexed on top of a single
+ * parent IPI.
+ * @nr_ipi:		number of virtual IPIs to create. This should
+ *			be <= BITS_PER_TYPE(int)
+ * @mux_send:		callback to trigger parent IPI for a particular CPU
+ *
+ * Returns first virq of the newly created virtual IPIs upon success
+ * or <=0 upon failure
+ */
+int ipi_mux_create(unsigned int nr_ipi, void (*mux_send)(unsigned int cpu))
+{
+	struct fwnode_handle *fwnode;
+	struct irq_domain *domain;
+	int rc;
+
+	if (ipi_mux_domain)
+		return -EEXIST;
+
+	if (BITS_PER_TYPE(int) < nr_ipi || !mux_send)
+		return -EINVAL;
+
+	ipi_mux_pcpu = alloc_percpu(typeof(*ipi_mux_pcpu));
+	if (!ipi_mux_pcpu)
+		return -ENOMEM;
+
+	fwnode = irq_domain_alloc_named_fwnode("IPI-Mux");
+	if (!fwnode) {
+		pr_err("unable to create IPI Mux fwnode\n");
+		rc = -ENOMEM;
+		goto fail_free_cpu;
+	}
+
+	domain = irq_domain_create_linear(fwnode, nr_ipi,
+					  &ipi_mux_domain_ops, NULL);
+	if (!domain) {
+		pr_err("unable to add IPI Mux domain\n");
+		rc = -ENOMEM;
+		goto fail_free_fwnode;
+	}
+
+	domain->flags |= IRQ_DOMAIN_FLAG_IPI_SINGLE;
+	irq_domain_update_bus_token(domain, DOMAIN_BUS_IPI);
+
+	rc = __irq_domain_alloc_irqs(domain, -1, nr_ipi,
+				     NUMA_NO_NODE, NULL, false, NULL);
+	if (rc <= 0) {
+		pr_err("unable to alloc IRQs from IPI Mux domain\n");
+		goto fail_free_domain;
+	}
+
+	ipi_mux_domain = domain;
+	ipi_mux_send = mux_send;
+
+	return rc;
+
+fail_free_domain:
+	irq_domain_remove(domain);
+fail_free_fwnode:
+	irq_domain_free_fwnode(fwnode);
+fail_free_cpu:
+	free_percpu(ipi_mux_pcpu);
+	return rc;
+}
-- 
2.34.1

[irqchip: irq/irqchip-next] genirq: Add mechanism to multiplex a single HW IPI

[irqchip-bot for Anup Patel]

The following commit has been merged into the irq/irqchip-next branch of irqchip:

Commit-ID:     835a486cd9f55790dee9f6b67ce0057d49f15da5
Gitweb:        https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms/835a486cd9f55790dee9f6b67ce0057d49f15da5
Author:        Anup Patel <apatel@ventanamicro.com>
AuthorDate:    Tue, 03 Jan 2023 19:42:15 +05:30
Committer:     Marc Zyngier <maz@kernel.org>
CommitterDate: Sun, 05 Feb 2023 10:57:55 

genirq: Add mechanism to multiplex a single HW IPI

All RISC-V platforms have a single HW IPI provided by the INTC local
interrupt controller. The HW method to trigger INTC IPI can be through
external irqchip (e.g. RISC-V AIA), through platform specific device
(e.g. SiFive CLINT timer), or through firmware (e.g. SBI IPI call).

To support multiple IPIs on RISC-V, add a generic IPI multiplexing
mechanism which help us create multiple virtual IPIs using a single
HW IPI. This generic IPI multiplexing is inspired by the Apple AIC
irqchip driver and it is shared by various RISC-V irqchip drivers.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Hector Martin <marcan@marcan.st>
Tested-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230103141221.772261-4-apatel@ventanamicro.com
---
 include/linux/irq.h  |   3 +-
 kernel/irq/Kconfig   |   5 +-
 kernel/irq/Makefile  |   1 +-
 kernel/irq/ipi-mux.c | 207 ++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 216 insertions(+)
 create mode 100644 kernel/irq/ipi-mux.c

diff --git a/include/linux/irq.h b/include/linux/irq.h
index c3eb896..b1b28af 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -1266,6 +1266,9 @@ int __ipi_send_mask(struct irq_desc *desc, const struct cpumask *dest);
 int ipi_send_single(unsigned int virq, unsigned int cpu);
 int ipi_send_mask(unsigned int virq, const struct cpumask *dest);
 
+void ipi_mux_process(void);
+int ipi_mux_create(unsigned int nr_ipi, void (*mux_send)(unsigned int cpu));
+
 #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
 /*
  * Registers a generic IRQ handling function as the top-level IRQ handler in
diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index b64c44a..2531f34 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -86,6 +86,11 @@ config GENERIC_IRQ_IPI
 	depends on SMP
 	select IRQ_DOMAIN_HIERARCHY
 
+# Generic IRQ IPI Mux support
+config GENERIC_IRQ_IPI_MUX
+	bool
+	depends on SMP
+
 # Generic MSI hierarchical interrupt domain support
 config GENERIC_MSI_IRQ
 	bool
diff --git a/kernel/irq/Makefile b/kernel/irq/Makefile
index b4f5371..f19d308 100644
--- a/kernel/irq/Makefile
+++ b/kernel/irq/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_GENERIC_IRQ_MIGRATION) += cpuhotplug.o
 obj-$(CONFIG_PM_SLEEP) += pm.o
 obj-$(CONFIG_GENERIC_MSI_IRQ) += msi.o
 obj-$(CONFIG_GENERIC_IRQ_IPI) += ipi.o
+obj-$(CONFIG_GENERIC_IRQ_IPI_MUX) += ipi-mux.o
 obj-$(CONFIG_SMP) += affinity.o
 obj-$(CONFIG_GENERIC_IRQ_DEBUGFS) += debugfs.o
 obj-$(CONFIG_GENERIC_IRQ_MATRIX_ALLOCATOR) += matrix.o
diff --git a/kernel/irq/ipi-mux.c b/kernel/irq/ipi-mux.c
new file mode 100644
index 0000000..3a403c3
--- /dev/null
+++ b/kernel/irq/ipi-mux.c
@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Multiplex several virtual IPIs over a single HW IPI.
+ *
+ * Copyright The Asahi Linux Contributors
+ * Copyright (c) 2022 Ventana Micro Systems Inc.
+ */
+
+#define pr_fmt(fmt) "ipi-mux: " fmt
+#include <linux/cpu.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/jump_label.h>
+#include <linux/percpu.h>
+#include <linux/smp.h>
+
+struct ipi_mux_cpu {
+	atomic_t			enable;
+	atomic_t			bits;
+};
+
+static struct ipi_mux_cpu __percpu *ipi_mux_pcpu;
+static struct irq_domain *ipi_mux_domain;
+static void (*ipi_mux_send)(unsigned int cpu);
+
+static void ipi_mux_mask(struct irq_data *d)
+{
+	struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu);
+
+	atomic_andnot(BIT(irqd_to_hwirq(d)), &icpu->enable);
+}
+
+static void ipi_mux_unmask(struct irq_data *d)
+{
+	struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu);
+	u32 ibit = BIT(irqd_to_hwirq(d));
+
+	atomic_or(ibit, &icpu->enable);
+
+	/*
+	 * The atomic_or() above must complete before the atomic_read()
+	 * below to avoid racing ipi_mux_send_mask().
+	 */
+	smp_mb__after_atomic();
+
+	/* If a pending IPI was unmasked, raise a parent IPI immediately. */
+	if (atomic_read(&icpu->bits) & ibit)
+		ipi_mux_send(smp_processor_id());
+}
+
+static void ipi_mux_send_mask(struct irq_data *d, const struct cpumask *mask)
+{
+	struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu);
+	u32 ibit = BIT(irqd_to_hwirq(d));
+	unsigned long pending;
+	int cpu;
+
+	for_each_cpu(cpu, mask) {
+		icpu = per_cpu_ptr(ipi_mux_pcpu, cpu);
+
+		/*
+		 * This sequence is the mirror of the one in ipi_mux_unmask();
+		 * see the comment there. Additionally, release semantics
+		 * ensure that the vIPI flag set is ordered after any shared
+		 * memory accesses that precede it. This therefore also pairs
+		 * with the atomic_fetch_andnot in ipi_mux_process().
+		 */
+		pending = atomic_fetch_or_release(ibit, &icpu->bits);
+
+		/*
+		 * The atomic_fetch_or_release() above must complete
+		 * before the atomic_read() below to avoid racing with
+		 * ipi_mux_unmask().
+		 */
+		smp_mb__after_atomic();
+
+		/*
+		 * The flag writes must complete before the physical IPI is
+		 * issued to another CPU. This is implied by the control
+		 * dependency on the result of atomic_read() below, which is
+		 * itself already ordered after the vIPI flag write.
+		 */
+		if (!(pending & ibit) && (atomic_read(&icpu->enable) & ibit))
+			ipi_mux_send(cpu);
+	}
+}
+
+static const struct irq_chip ipi_mux_chip = {
+	.name		= "IPI Mux",
+	.irq_mask	= ipi_mux_mask,
+	.irq_unmask	= ipi_mux_unmask,
+	.ipi_send_mask	= ipi_mux_send_mask,
+};
+
+static int ipi_mux_domain_alloc(struct irq_domain *d, unsigned int virq,
+				unsigned int nr_irqs, void *arg)
+{
+	int i;
+
+	for (i = 0; i < nr_irqs; i++) {
+		irq_set_percpu_devid(virq + i);
+		irq_domain_set_info(d, virq + i, i, &ipi_mux_chip, NULL,
+				    handle_percpu_devid_irq, NULL, NULL);
+	}
+
+	return 0;
+}
+
+static const struct irq_domain_ops ipi_mux_domain_ops = {
+	.alloc		= ipi_mux_domain_alloc,
+	.free		= irq_domain_free_irqs_top,
+};
+
+/**
+ * ipi_mux_process - Process multiplexed virtual IPIs
+ */
+void ipi_mux_process(void)
+{
+	struct ipi_mux_cpu *icpu = this_cpu_ptr(ipi_mux_pcpu);
+	irq_hw_number_t hwirq;
+	unsigned long ipis;
+	unsigned int en;
+
+	/*
+	 * Reading enable mask does not need to be ordered as long as
+	 * this function is called from interrupt handler because only
+	 * the CPU itself can change it's own enable mask.
+	 */
+	en = atomic_read(&icpu->enable);
+
+	/*
+	 * Clear the IPIs we are about to handle. This pairs with the
+	 * atomic_fetch_or_release() in ipi_mux_send_mask().
+	 */
+	ipis = atomic_fetch_andnot(en, &icpu->bits) & en;
+
+	for_each_set_bit(hwirq, &ipis, BITS_PER_TYPE(int))
+		generic_handle_domain_irq(ipi_mux_domain, hwirq);
+}
+
+/**
+ * ipi_mux_create - Create virtual IPIs multiplexed on top of a single
+ * parent IPI.
+ * @nr_ipi:		number of virtual IPIs to create. This should
+ *			be <= BITS_PER_TYPE(int)
+ * @mux_send:		callback to trigger parent IPI for a particular CPU
+ *
+ * Returns first virq of the newly created virtual IPIs upon success
+ * or <=0 upon failure
+ */
+int ipi_mux_create(unsigned int nr_ipi, void (*mux_send)(unsigned int cpu))
+{
+	struct fwnode_handle *fwnode;
+	struct irq_domain *domain;
+	int rc;
+
+	if (ipi_mux_domain)
+		return -EEXIST;
+
+	if (BITS_PER_TYPE(int) < nr_ipi || !mux_send)
+		return -EINVAL;
+
+	ipi_mux_pcpu = alloc_percpu(typeof(*ipi_mux_pcpu));
+	if (!ipi_mux_pcpu)
+		return -ENOMEM;
+
+	fwnode = irq_domain_alloc_named_fwnode("IPI-Mux");
+	if (!fwnode) {
+		pr_err("unable to create IPI Mux fwnode\n");
+		rc = -ENOMEM;
+		goto fail_free_cpu;
+	}
+
+	domain = irq_domain_create_linear(fwnode, nr_ipi,
+					  &ipi_mux_domain_ops, NULL);
+	if (!domain) {
+		pr_err("unable to add IPI Mux domain\n");
+		rc = -ENOMEM;
+		goto fail_free_fwnode;
+	}
+
+	domain->flags |= IRQ_DOMAIN_FLAG_IPI_SINGLE;
+	irq_domain_update_bus_token(domain, DOMAIN_BUS_IPI);
+
+	rc = __irq_domain_alloc_irqs(domain, -1, nr_ipi,
+				     NUMA_NO_NODE, NULL, false, NULL);
+	if (rc <= 0) {
+		pr_err("unable to alloc IRQs from IPI Mux domain\n");
+		goto fail_free_domain;
+	}
+
+	ipi_mux_domain = domain;
+	ipi_mux_send = mux_send;
+
+	return rc;
+
+fail_free_domain:
+	irq_domain_remove(domain);
+fail_free_fwnode:
+	irq_domain_free_fwnode(fwnode);
+fail_free_cpu:
+	free_percpu(ipi_mux_pcpu);
+	return rc;
+}

[PATCH v16 4/9] RISC-V: Treat IPIs as normal Linux IRQs

[Anup Patel]

Currently, the RISC-V kernel provides arch specific hooks (i.e.
struct riscv_ipi_ops) to register IPI handling methods. The stats
gathering of IPIs is also arch specific in the RISC-V kernel.

Other architectures (such as ARM, ARM64, and MIPS) have moved away
from custom arch specific IPI handling methods. Currently, these
architectures have Linux irqchip drivers providing a range of Linux
IRQ numbers to be used as IPIs and IPI triggering is done using
generic IPI APIs. This approach allows architectures to treat IPIs
as normal Linux IRQs and IPI stats gathering is done by the generic
Linux IRQ subsystem.

We extend the RISC-V IPI handling as-per above approach so that arch
specific IPI handling methods (struct riscv_ipi_ops) can be removed
and the IPI handling is done through the Linux IRQ subsystem.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 arch/riscv/Kconfig                |   2 +
 arch/riscv/include/asm/sbi.h      |   9 +-
 arch/riscv/include/asm/smp.h      |  35 ++++---
 arch/riscv/kernel/Makefile        |   1 +
 arch/riscv/kernel/cpu-hotplug.c   |   3 +-
 arch/riscv/kernel/irq.c           |   3 +-
 arch/riscv/kernel/sbi-ipi.c       |  77 ++++++++++++++
 arch/riscv/kernel/sbi.c           | 106 +++-----------------
 arch/riscv/kernel/smp.c           | 160 +++++++++++++++---------------
 arch/riscv/kernel/smpboot.c       |   5 +-
 drivers/clocksource/timer-clint.c |  65 +++++++++---
 drivers/irqchip/Kconfig           |   1 +
 drivers/irqchip/irq-riscv-intc.c  |  55 +++++-----
 13 files changed, 283 insertions(+), 239 deletions(-)
 create mode 100644 arch/riscv/kernel/sbi-ipi.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index e2b656043abf..d153e1cd890b 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -61,6 +61,8 @@ config RISCV
 	select GENERIC_GETTIMEOFDAY if HAVE_GENERIC_VDSO
 	select GENERIC_IDLE_POLL_SETUP
 	select GENERIC_IOREMAP if MMU
+	select GENERIC_IRQ_IPI if SMP
+	select GENERIC_IRQ_IPI_MUX if SMP
 	select GENERIC_IRQ_MULTI_HANDLER
 	select GENERIC_IRQ_SHOW
 	select GENERIC_IRQ_SHOW_LEVEL
diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index 4ca7fbacff42..2f9db8c4aed8 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -268,8 +268,7 @@ long sbi_get_marchid(void);
 long sbi_get_mimpid(void);
 void sbi_set_timer(uint64_t stime_value);
 void sbi_shutdown(void);
-void sbi_clear_ipi(void);
-int sbi_send_ipi(const struct cpumask *cpu_mask);
+void sbi_send_ipi(unsigned int cpu);
 int sbi_remote_fence_i(const struct cpumask *cpu_mask);
 int sbi_remote_sfence_vma(const struct cpumask *cpu_mask,
 			   unsigned long start,
@@ -332,4 +331,10 @@ unsigned long riscv_cached_mvendorid(unsigned int cpu_id);
 unsigned long riscv_cached_marchid(unsigned int cpu_id);
 unsigned long riscv_cached_mimpid(unsigned int cpu_id);
 
+#if IS_ENABLED(CONFIG_SMP) && IS_ENABLED(CONFIG_RISCV_SBI)
+void sbi_ipi_init(void);
+#else
+static inline void sbi_ipi_init(void) { }
+#endif
+
 #endif /* _ASM_RISCV_SBI_H */
diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
index 3831b638ecab..4fe7a8854c2e 100644
--- a/arch/riscv/include/asm/smp.h
+++ b/arch/riscv/include/asm/smp.h
@@ -15,11 +15,6 @@
 struct seq_file;
 extern unsigned long boot_cpu_hartid;
 
-struct riscv_ipi_ops {
-	void (*ipi_inject)(const struct cpumask *target);
-	void (*ipi_clear)(void);
-};
-
 #ifdef CONFIG_SMP
 /*
  * Mapping between linux logical cpu index and hartid.
@@ -33,9 +28,6 @@ void show_ipi_stats(struct seq_file *p, int prec);
 /* SMP initialization hook for setup_arch */
 void __init setup_smp(void);
 
-/* Called from C code, this handles an IPI. */
-void handle_IPI(struct pt_regs *regs);
-
 /* Hook for the generic smp_call_function_many() routine. */
 void arch_send_call_function_ipi_mask(struct cpumask *mask);
 
@@ -44,11 +36,17 @@ void arch_send_call_function_single_ipi(int cpu);
 
 int riscv_hartid_to_cpuid(unsigned long hartid);
 
-/* Set custom IPI operations */
-void riscv_set_ipi_ops(const struct riscv_ipi_ops *ops);
+/* Enable IPI for CPU hotplug */
+void riscv_ipi_enable(void);
+
+/* Disable IPI for CPU hotplug */
+void riscv_ipi_disable(void);
 
-/* Clear IPI for current CPU */
-void riscv_clear_ipi(void);
+/* Check if IPI interrupt numbers are available */
+bool riscv_ipi_have_virq_range(void);
+
+/* Set the IPI interrupt numbers for arch (called by irqchip drivers) */
+void riscv_ipi_set_virq_range(int virq, int nr);
 
 /* Check other CPUs stop or not */
 bool smp_crash_stop_failed(void);
@@ -85,11 +83,20 @@ static inline unsigned long cpuid_to_hartid_map(int cpu)
 	return boot_cpu_hartid;
 }
 
-static inline void riscv_set_ipi_ops(const struct riscv_ipi_ops *ops)
+static inline void riscv_ipi_enable(void)
 {
 }
 
-static inline void riscv_clear_ipi(void)
+static inline void riscv_ipi_disable(void)
+{
+}
+
+static inline bool riscv_ipi_have_virq_range(void)
+{
+	return false;
+}
+
+static inline void riscv_ipi_set_virq_range(int virq, int nr)
 {
 }
 
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 4cf303a779ab..67f542be1bea 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -74,6 +74,7 @@ obj-$(CONFIG_PERF_EVENTS)	+= perf_callchain.o
 obj-$(CONFIG_HAVE_PERF_REGS)	+= perf_regs.o
 obj-$(CONFIG_RISCV_SBI)		+= sbi.o
 ifeq ($(CONFIG_RISCV_SBI), y)
+obj-$(CONFIG_SMP)		+= sbi-ipi.o
 obj-$(CONFIG_SMP) += cpu_ops_sbi.o
 endif
 obj-$(CONFIG_HOTPLUG_CPU)	+= cpu-hotplug.o
diff --git a/arch/riscv/kernel/cpu-hotplug.c b/arch/riscv/kernel/cpu-hotplug.c
index f7a832e3a1d1..39235cf50652 100644
--- a/arch/riscv/kernel/cpu-hotplug.c
+++ b/arch/riscv/kernel/cpu-hotplug.c
@@ -13,7 +13,7 @@
 #include <asm/irq.h>
 #include <asm/cpu_ops.h>
 #include <asm/numa.h>
-#include <asm/sbi.h>
+#include <asm/smp.h>
 
 bool cpu_has_hotplug(unsigned int cpu)
 {
@@ -43,6 +43,7 @@ int __cpu_disable(void)
 	remove_cpu_topology(cpu);
 	numa_remove_cpu(cpu);
 	set_cpu_online(cpu, false);
+	riscv_ipi_disable();
 	irq_migrate_all_off_this_cpu();
 
 	return ret;
diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index 96d3171f0ca1..eb9a68a539e6 100644
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -10,7 +10,7 @@
 #include <linux/irqdomain.h>
 #include <linux/module.h>
 #include <linux/seq_file.h>
-#include <asm/smp.h>
+#include <asm/sbi.h>
 
 static struct fwnode_handle *(*__get_intc_node)(void);
 
@@ -39,4 +39,5 @@ void __init init_IRQ(void)
 	irqchip_init();
 	if (!handle_arch_irq)
 		panic("No interrupt controller found.");
+	sbi_ipi_init();
 }
diff --git a/arch/riscv/kernel/sbi-ipi.c b/arch/riscv/kernel/sbi-ipi.c
new file mode 100644
index 000000000000..41981ab88493
--- /dev/null
+++ b/arch/riscv/kernel/sbi-ipi.c
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Multiplex several IPIs over a single HW IPI.
+ *
+ * Copyright (c) 2022 Ventana Micro Systems Inc.
+ */
+
+#define pr_fmt(fmt) "riscv: " fmt
+#include <linux/cpu.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <asm/sbi.h>
+
+static int sbi_ipi_virq;
+
+static void sbi_ipi_handle(struct irq_desc *desc)
+{
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+
+	chained_irq_enter(chip, desc);
+
+	csr_clear(CSR_IP, IE_SIE);
+	ipi_mux_process();
+
+	chained_irq_exit(chip, desc);
+}
+
+static int sbi_ipi_starting_cpu(unsigned int cpu)
+{
+	enable_percpu_irq(sbi_ipi_virq, irq_get_trigger_type(sbi_ipi_virq));
+	return 0;
+}
+
+void __init sbi_ipi_init(void)
+{
+	int virq;
+	struct irq_domain *domain;
+
+	if (riscv_ipi_have_virq_range())
+		return;
+
+	domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(),
+					  DOMAIN_BUS_ANY);
+	if (!domain) {
+		pr_err("unable to find INTC IRQ domain\n");
+		return;
+	}
+
+	sbi_ipi_virq = irq_create_mapping(domain, RV_IRQ_SOFT);
+	if (!sbi_ipi_virq) {
+		pr_err("unable to create INTC IRQ mapping\n");
+		return;
+	}
+
+	virq = ipi_mux_create(BITS_PER_BYTE, sbi_send_ipi);
+	if (virq <= 0) {
+		pr_err("unable to create muxed IPIs\n");
+		irq_dispose_mapping(sbi_ipi_virq);
+		return;
+	}
+
+	irq_set_chained_handler(sbi_ipi_virq, sbi_ipi_handle);
+
+	/*
+	 * Don't disable IPI when CPU goes offline because
+	 * the masking/unmasking of virtual IPIs is done
+	 * via generic IPI-Mux
+	 */
+	cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
+			  "irqchip/sbi-ipi:starting",
+			  sbi_ipi_starting_cpu, NULL);
+
+	riscv_ipi_set_virq_range(virq, BITS_PER_BYTE);
+	pr_info("providing IPIs using SBI IPI extension\n");
+}
diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index ac99a70ead6a..92b9b759ab3d 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -17,7 +17,7 @@ unsigned long sbi_spec_version __ro_after_init = SBI_SPEC_VERSION_DEFAULT;
 EXPORT_SYMBOL(sbi_spec_version);
 
 static void (*__sbi_set_timer)(uint64_t stime) __ro_after_init;
-static int (*__sbi_send_ipi)(const struct cpumask *cpu_mask) __ro_after_init;
+static void (*__sbi_send_ipi)(unsigned int cpu) __ro_after_init;
 static int (*__sbi_rfence)(int fid, const struct cpumask *cpu_mask,
 			   unsigned long start, unsigned long size,
 			   unsigned long arg4, unsigned long arg5) __ro_after_init;
@@ -130,17 +130,6 @@ void sbi_shutdown(void)
 }
 EXPORT_SYMBOL(sbi_shutdown);
 
-/**
- * sbi_clear_ipi() - Clear any pending IPIs for the calling hart.
- *
- * Return: None
- */
-void sbi_clear_ipi(void)
-{
-	sbi_ecall(SBI_EXT_0_1_CLEAR_IPI, 0, 0, 0, 0, 0, 0, 0);
-}
-EXPORT_SYMBOL(sbi_clear_ipi);
-
 /**
  * __sbi_set_timer_v01() - Program the timer for next timer event.
  * @stime_value: The value after which next timer event should fire.
@@ -157,17 +146,12 @@ static void __sbi_set_timer_v01(uint64_t stime_value)
 #endif
 }
 
-static int __sbi_send_ipi_v01(const struct cpumask *cpu_mask)
+static void __sbi_send_ipi_v01(unsigned int cpu)
 {
-	unsigned long hart_mask;
-
-	if (!cpu_mask || cpumask_empty(cpu_mask))
-		cpu_mask = cpu_online_mask;
-	hart_mask = __sbi_v01_cpumask_to_hartmask(cpu_mask);
-
+	unsigned long hart_mask =
+		__sbi_v01_cpumask_to_hartmask(cpumask_of(cpu));
 	sbi_ecall(SBI_EXT_0_1_SEND_IPI, 0, (unsigned long)(&hart_mask),
 		  0, 0, 0, 0, 0);
-	return 0;
 }
 
 static int __sbi_rfence_v01(int fid, const struct cpumask *cpu_mask,
@@ -216,12 +200,10 @@ static void __sbi_set_timer_v01(uint64_t stime_value)
 		sbi_major_version(), sbi_minor_version());
 }
 
-static int __sbi_send_ipi_v01(const struct cpumask *cpu_mask)
+static void __sbi_send_ipi_v01(unsigned int cpu)
 {
 	pr_warn("IPI extension is not available in SBI v%lu.%lu\n",
 		sbi_major_version(), sbi_minor_version());
-
-	return 0;
 }
 
 static int __sbi_rfence_v01(int fid, const struct cpumask *cpu_mask,
@@ -248,55 +230,18 @@ static void __sbi_set_timer_v02(uint64_t stime_value)
 #endif
 }
 
-static int __sbi_send_ipi_v02(const struct cpumask *cpu_mask)
+static void __sbi_send_ipi_v02(unsigned int cpu)
 {
-	unsigned long hartid, cpuid, hmask = 0, hbase = 0, htop = 0;
-	struct sbiret ret = {0};
 	int result;
+	struct sbiret ret = {0};
 
-	if (!cpu_mask || cpumask_empty(cpu_mask))
-		cpu_mask = cpu_online_mask;
-
-	for_each_cpu(cpuid, cpu_mask) {
-		hartid = cpuid_to_hartid_map(cpuid);
-		if (hmask) {
-			if (hartid + BITS_PER_LONG <= htop ||
-			    hbase + BITS_PER_LONG <= hartid) {
-				ret = sbi_ecall(SBI_EXT_IPI,
-						SBI_EXT_IPI_SEND_IPI, hmask,
-						hbase, 0, 0, 0, 0);
-				if (ret.error)
-					goto ecall_failed;
-				hmask = 0;
-			} else if (hartid < hbase) {
-				/* shift the mask to fit lower hartid */
-				hmask <<= hbase - hartid;
-				hbase = hartid;
-			}
-		}
-		if (!hmask) {
-			hbase = hartid;
-			htop = hartid;
-		} else if (hartid > htop) {
-			htop = hartid;
-		}
-		hmask |= BIT(hartid - hbase);
-	}
-
-	if (hmask) {
-		ret = sbi_ecall(SBI_EXT_IPI, SBI_EXT_IPI_SEND_IPI,
-				hmask, hbase, 0, 0, 0, 0);
-		if (ret.error)
-			goto ecall_failed;
+	ret = sbi_ecall(SBI_EXT_IPI, SBI_EXT_IPI_SEND_IPI,
+			1UL, cpuid_to_hartid_map(cpu), 0, 0, 0, 0);
+	if (ret.error) {
+		result = sbi_err_map_linux_errno(ret.error);
+		pr_err("%s: hbase = [%lu] failed (error [%d])\n",
+			__func__, cpuid_to_hartid_map(cpu), result);
 	}
-
-	return 0;
-
-ecall_failed:
-	result = sbi_err_map_linux_errno(ret.error);
-	pr_err("%s: hbase = [%lu] hmask = [0x%lx] failed (error [%d])\n",
-	       __func__, hbase, hmask, result);
-	return result;
 }
 
 static int __sbi_rfence_v02_call(unsigned long fid, unsigned long hmask,
@@ -410,13 +355,11 @@ void sbi_set_timer(uint64_t stime_value)
 
 /**
  * sbi_send_ipi() - Send an IPI to any hart.
- * @cpu_mask: A cpu mask containing all the target harts.
- *
- * Return: 0 on success, appropriate linux error code otherwise.
+ * @cpu: Logical id of the target CPU.
  */
-int sbi_send_ipi(const struct cpumask *cpu_mask)
+void sbi_send_ipi(unsigned int cpu)
 {
-	return __sbi_send_ipi(cpu_mask);
+	__sbi_send_ipi(cpu);
 }
 EXPORT_SYMBOL(sbi_send_ipi);
 
@@ -641,21 +584,6 @@ long sbi_get_mimpid(void)
 }
 EXPORT_SYMBOL_GPL(sbi_get_mimpid);
 
-static void sbi_send_cpumask_ipi(const struct cpumask *target)
-{
-	sbi_send_ipi(target);
-}
-
-static void sbi_ipi_clear(void)
-{
-	csr_clear(CSR_IP, IE_SIE);
-}
-
-static const struct riscv_ipi_ops sbi_ipi_ops = {
-	.ipi_inject = sbi_send_cpumask_ipi,
-	.ipi_clear = sbi_ipi_clear
-};
-
 void __init sbi_init(void)
 {
 	int ret;
@@ -702,6 +630,4 @@ void __init sbi_init(void)
 		__sbi_send_ipi	= __sbi_send_ipi_v01;
 		__sbi_rfence	= __sbi_rfence_v01;
 	}
-
-	riscv_set_ipi_ops(&sbi_ipi_ops);
 }
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index 8a12768c09ee..47e7ecfedb4d 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -13,14 +13,15 @@
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/kexec.h>
+#include <linux/percpu.h>
 #include <linux/profile.h>
 #include <linux/smp.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
 #include <linux/delay.h>
+#include <linux/irq.h>
 #include <linux/irq_work.h>
 
-#include <asm/sbi.h>
 #include <asm/tlbflush.h>
 #include <asm/cacheflush.h>
 #include <asm/cpu_ops.h>
@@ -44,11 +45,10 @@ void __init smp_setup_processor_id(void)
 	cpuid_to_hartid_map(0) = boot_cpu_hartid;
 }
 
-/* A collection of single bit ipi messages.  */
-static struct {
-	unsigned long stats[IPI_MAX] ____cacheline_aligned;
-	unsigned long bits ____cacheline_aligned;
-} ipi_data[NR_CPUS] __cacheline_aligned;
+static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev);
+static int ipi_virq_base __ro_after_init;
+static int nr_ipi __ro_after_init = IPI_MAX;
+static struct irq_desc *ipi_desc[IPI_MAX] __read_mostly;
 
 int riscv_hartid_to_cpuid(unsigned long hartid)
 {
@@ -100,46 +100,14 @@ static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
 }
 #endif
 
-static const struct riscv_ipi_ops *ipi_ops __ro_after_init;
-
-void riscv_set_ipi_ops(const struct riscv_ipi_ops *ops)
-{
-	ipi_ops = ops;
-}
-EXPORT_SYMBOL_GPL(riscv_set_ipi_ops);
-
-void riscv_clear_ipi(void)
-{
-	if (ipi_ops && ipi_ops->ipi_clear)
-		ipi_ops->ipi_clear();
-}
-EXPORT_SYMBOL_GPL(riscv_clear_ipi);
-
 static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
 {
-	int cpu;
-
-	smp_mb__before_atomic();
-	for_each_cpu(cpu, mask)
-		set_bit(op, &ipi_data[cpu].bits);
-	smp_mb__after_atomic();
-
-	if (ipi_ops && ipi_ops->ipi_inject)
-		ipi_ops->ipi_inject(mask);
-	else
-		pr_warn("SMP: IPI inject method not available\n");
+	__ipi_send_mask(ipi_desc[op], mask);
 }
 
 static void send_ipi_single(int cpu, enum ipi_message_type op)
 {
-	smp_mb__before_atomic();
-	set_bit(op, &ipi_data[cpu].bits);
-	smp_mb__after_atomic();
-
-	if (ipi_ops && ipi_ops->ipi_inject)
-		ipi_ops->ipi_inject(cpumask_of(cpu));
-	else
-		pr_warn("SMP: IPI inject method not available\n");
+	__ipi_send_mask(ipi_desc[op], cpumask_of(cpu));
 }
 
 #ifdef CONFIG_IRQ_WORK
@@ -149,59 +117,89 @@ void arch_irq_work_raise(void)
 }
 #endif
 
-void handle_IPI(struct pt_regs *regs)
+static irqreturn_t handle_IPI(int irq, void *data)
+{
+	int ipi = irq - ipi_virq_base;
+
+	switch (ipi) {
+	case IPI_RESCHEDULE:
+		scheduler_ipi();
+		break;
+	case IPI_CALL_FUNC:
+		generic_smp_call_function_interrupt();
+		break;
+	case IPI_CPU_STOP:
+		ipi_stop();
+		break;
+	case IPI_CPU_CRASH_STOP:
+		ipi_cpu_crash_stop(smp_processor_id(), get_irq_regs());
+		break;
+	case IPI_IRQ_WORK:
+		irq_work_run();
+		break;
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+	case IPI_TIMER:
+		tick_receive_broadcast();
+		break;
+#endif
+	default:
+		pr_warn("CPU%d: unhandled IPI%d\n", smp_processor_id(), ipi);
+		break;
+	}
+
+	return IRQ_HANDLED;
+}
+
+void riscv_ipi_enable(void)
 {
-	unsigned int cpu = smp_processor_id();
-	unsigned long *pending_ipis = &ipi_data[cpu].bits;
-	unsigned long *stats = ipi_data[cpu].stats;
+	int i;
 
-	riscv_clear_ipi();
+	if (WARN_ON_ONCE(!ipi_virq_base))
+		return;
 
-	while (true) {
-		unsigned long ops;
+	for (i = 0; i < nr_ipi; i++)
+		enable_percpu_irq(ipi_virq_base + i, 0);
+}
 
-		/* Order bit clearing and data access. */
-		mb();
+void riscv_ipi_disable(void)
+{
+	int i;
 
-		ops = xchg(pending_ipis, 0);
-		if (ops == 0)
-			return;
+	if (WARN_ON_ONCE(!ipi_virq_base))
+		return;
 
-		if (ops & (1 << IPI_RESCHEDULE)) {
-			stats[IPI_RESCHEDULE]++;
-			scheduler_ipi();
-		}
+	for (i = 0; i < nr_ipi; i++)
+		disable_percpu_irq(ipi_virq_base + i);
+}
 
-		if (ops & (1 << IPI_CALL_FUNC)) {
-			stats[IPI_CALL_FUNC]++;
-			generic_smp_call_function_interrupt();
-		}
+bool riscv_ipi_have_virq_range(void)
+{
+	return (ipi_virq_base) ? true : false;
+}
 
-		if (ops & (1 << IPI_CPU_STOP)) {
-			stats[IPI_CPU_STOP]++;
-			ipi_stop();
-		}
+void riscv_ipi_set_virq_range(int virq, int nr)
+{
+	int i, err;
 
-		if (ops & (1 << IPI_CPU_CRASH_STOP)) {
-			ipi_cpu_crash_stop(cpu, get_irq_regs());
-		}
+	if (WARN_ON(ipi_virq_base))
+		return;
 
-		if (ops & (1 << IPI_IRQ_WORK)) {
-			stats[IPI_IRQ_WORK]++;
-			irq_work_run();
-		}
+	WARN_ON(nr < IPI_MAX);
+	nr_ipi = min(nr, IPI_MAX);
+	ipi_virq_base = virq;
 
-#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
-		if (ops & (1 << IPI_TIMER)) {
-			stats[IPI_TIMER]++;
-			tick_receive_broadcast();
-		}
-#endif
-		BUG_ON((ops >> IPI_MAX) != 0);
+	/* Request IPIs */
+	for (i = 0; i < nr_ipi; i++) {
+		err = request_percpu_irq(ipi_virq_base + i, handle_IPI,
+					 "IPI", &ipi_dummy_dev);
+		WARN_ON(err);
 
-		/* Order data access and bit testing. */
-		mb();
+		ipi_desc[i] = irq_to_desc(ipi_virq_base + i);
+		irq_set_status_flags(ipi_virq_base + i, IRQ_HIDDEN);
 	}
+
+	/* Enabled IPIs for boot CPU immediately */
+	riscv_ipi_enable();
 }
 
 static const char * const ipi_names[] = {
@@ -221,7 +219,7 @@ void show_ipi_stats(struct seq_file *p, int prec)
 		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
 			   prec >= 4 ? " " : "");
 		for_each_online_cpu(cpu)
-			seq_printf(p, "%10lu ", ipi_data[cpu].stats[i]);
+			seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
 		seq_printf(p, " %s\n", ipi_names[i]);
 	}
 }
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 3373df413c88..9cbdb960515b 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -30,7 +30,6 @@
 #include <asm/numa.h>
 #include <asm/tlbflush.h>
 #include <asm/sections.h>
-#include <asm/sbi.h>
 #include <asm/smp.h>
 
 #include "head.h"
@@ -157,12 +156,12 @@ asmlinkage __visible void smp_callin(void)
 	struct mm_struct *mm = &init_mm;
 	unsigned int curr_cpuid = smp_processor_id();
 
-	riscv_clear_ipi();
-
 	/* All kernel threads share the same mm context.  */
 	mmgrab(mm);
 	current->active_mm = mm;
 
+	riscv_ipi_enable();
+
 	store_cpu_topology(curr_cpuid);
 	notify_cpu_starting(curr_cpuid);
 	numa_add_cpu(curr_cpuid);
diff --git a/drivers/clocksource/timer-clint.c b/drivers/clocksource/timer-clint.c
index 6cfe2ab73eb0..7ccc16dd6a76 100644
--- a/drivers/clocksource/timer-clint.c
+++ b/drivers/clocksource/timer-clint.c
@@ -17,6 +17,9 @@
 #include <linux/sched_clock.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
 #include <linux/of_irq.h>
 #include <linux/smp.h>
 #include <linux/timex.h>
@@ -31,6 +34,7 @@
 
 /* CLINT manages IPI and Timer for RISC-V M-mode  */
 static u32 __iomem *clint_ipi_base;
+static unsigned int clint_ipi_irq;
 static u64 __iomem *clint_timer_cmp;
 static u64 __iomem *clint_timer_val;
 static unsigned long clint_timer_freq;
@@ -41,12 +45,10 @@ u64 __iomem *clint_time_val;
 EXPORT_SYMBOL(clint_time_val);
 #endif
 
-static void clint_send_ipi(const struct cpumask *target)
+#ifdef CONFIG_SMP
+static void clint_send_ipi(unsigned int cpu)
 {
-	unsigned int cpu;
-
-	for_each_cpu(cpu, target)
-		writel(1, clint_ipi_base + cpuid_to_hartid_map(cpu));
+	writel(1, clint_ipi_base + cpuid_to_hartid_map(cpu));
 }
 
 static void clint_clear_ipi(void)
@@ -54,10 +56,18 @@ static void clint_clear_ipi(void)
 	writel(0, clint_ipi_base + cpuid_to_hartid_map(smp_processor_id()));
 }
 
-static struct riscv_ipi_ops clint_ipi_ops = {
-	.ipi_inject = clint_send_ipi,
-	.ipi_clear = clint_clear_ipi,
-};
+static void clint_ipi_interrupt(struct irq_desc *desc)
+{
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+
+	chained_irq_enter(chip, desc);
+
+	clint_clear_ipi();
+	ipi_mux_process();
+
+	chained_irq_exit(chip, desc);
+}
+#endif
 
 #ifdef CONFIG_64BIT
 #define clint_get_cycles()	readq_relaxed(clint_timer_val)
@@ -125,12 +135,19 @@ static int clint_timer_starting_cpu(unsigned int cpu)
 
 	enable_percpu_irq(clint_timer_irq,
 			  irq_get_trigger_type(clint_timer_irq));
+	enable_percpu_irq(clint_ipi_irq,
+			  irq_get_trigger_type(clint_ipi_irq));
 	return 0;
 }
 
 static int clint_timer_dying_cpu(unsigned int cpu)
 {
 	disable_percpu_irq(clint_timer_irq);
+	/*
+	 * Don't disable IPI when CPU goes offline because
+	 * the masking/unmasking of virtual IPIs is done
+	 * via generic IPI-Mux
+	 */
 	return 0;
 }
 
@@ -170,6 +187,12 @@ static int __init clint_timer_init_dt(struct device_node *np)
 			return -ENODEV;
 		}
 
+		/* Find parent irq domain and map ipi irq */
+		if (!clint_ipi_irq &&
+		    oirq.args[0] == RV_IRQ_SOFT &&
+		    irq_find_host(oirq.np))
+			clint_ipi_irq = irq_of_parse_and_map(np, i);
+
 		/* Find parent irq domain and map timer irq */
 		if (!clint_timer_irq &&
 		    oirq.args[0] == RV_IRQ_TIMER &&
@@ -177,9 +200,9 @@ static int __init clint_timer_init_dt(struct device_node *np)
 			clint_timer_irq = irq_of_parse_and_map(np, i);
 	}
 
-	/* If CLINT timer irq not found then fail */
-	if (!clint_timer_irq) {
-		pr_err("%pOFP: timer irq not found\n", np);
+	/* If CLINT ipi or timer irq not found then fail */
+	if (!clint_ipi_irq || !clint_timer_irq) {
+		pr_err("%pOFP: ipi/timer irq not found\n", np);
 		return -ENODEV;
 	}
 
@@ -219,6 +242,19 @@ static int __init clint_timer_init_dt(struct device_node *np)
 		goto fail_iounmap;
 	}
 
+#ifdef CONFIG_SMP
+	rc = ipi_mux_create(BITS_PER_BYTE, clint_send_ipi);
+	if (rc <= 0) {
+		pr_err("unable to create muxed IPIs\n");
+		rc = (rc < 0) ? rc : -ENODEV;
+		goto fail_free_irq;
+	}
+
+	irq_set_chained_handler(clint_ipi_irq, clint_ipi_interrupt);
+	riscv_ipi_set_virq_range(rc, BITS_PER_BYTE);
+	clint_clear_ipi();
+#endif
+
 	rc = cpuhp_setup_state(CPUHP_AP_CLINT_TIMER_STARTING,
 				"clockevents/clint/timer:starting",
 				clint_timer_starting_cpu,
@@ -228,13 +264,10 @@ static int __init clint_timer_init_dt(struct device_node *np)
 		goto fail_free_irq;
 	}
 
-	riscv_set_ipi_ops(&clint_ipi_ops);
-	clint_clear_ipi();
-
 	return 0;
 
 fail_free_irq:
-	free_irq(clint_timer_irq, &clint_clock_event);
+	free_percpu_irq(clint_timer_irq, &clint_clock_event);
 fail_iounmap:
 	iounmap(base);
 	return rc;
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index caa952c40ff9..0e3a7749d87c 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -540,6 +540,7 @@ config TI_PRUSS_INTC
 config RISCV_INTC
 	bool
 	depends on RISCV
+	select IRQ_DOMAIN_HIERARCHY
 
 config SIFIVE_PLIC
 	bool
diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c
index 9066467e99e4..784d25645704 100644
--- a/drivers/irqchip/irq-riscv-intc.c
+++ b/drivers/irqchip/irq-riscv-intc.c
@@ -26,20 +26,7 @@ static asmlinkage void riscv_intc_irq(struct pt_regs *regs)
 	if (unlikely(cause >= BITS_PER_LONG))
 		panic("unexpected interrupt cause");
 
-	switch (cause) {
-#ifdef CONFIG_SMP
-	case RV_IRQ_SOFT:
-		/*
-		 * We only use software interrupts to pass IPIs, so if a
-		 * non-SMP system gets one, then we don't know what to do.
-		 */
-		handle_IPI(regs);
-		break;
-#endif
-	default:
-		generic_handle_domain_irq(intc_domain, cause);
-		break;
-	}
+	generic_handle_domain_irq(intc_domain, cause);
 }
 
 /*
@@ -59,18 +46,6 @@ static void riscv_intc_irq_unmask(struct irq_data *d)
 	csr_set(CSR_IE, BIT(d->hwirq));
 }
 
-static int riscv_intc_cpu_starting(unsigned int cpu)
-{
-	csr_set(CSR_IE, BIT(RV_IRQ_SOFT));
-	return 0;
-}
-
-static int riscv_intc_cpu_dying(unsigned int cpu)
-{
-	csr_clear(CSR_IE, BIT(RV_IRQ_SOFT));
-	return 0;
-}
-
 static struct irq_chip riscv_intc_chip = {
 	.name = "RISC-V INTC",
 	.irq_mask = riscv_intc_irq_mask,
@@ -87,9 +62,32 @@ static int riscv_intc_domain_map(struct irq_domain *d, unsigned int irq,
 	return 0;
 }
 
+static int riscv_intc_domain_alloc(struct irq_domain *domain,
+				   unsigned int virq, unsigned int nr_irqs,
+				   void *arg)
+{
+	int i, ret;
+	irq_hw_number_t hwirq;
+	unsigned int type = IRQ_TYPE_NONE;
+	struct irq_fwspec *fwspec = arg;
+
+	ret = irq_domain_translate_onecell(domain, fwspec, &hwirq, &type);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < nr_irqs; i++) {
+		ret = riscv_intc_domain_map(domain, virq + i, hwirq + i);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 static const struct irq_domain_ops riscv_intc_domain_ops = {
 	.map	= riscv_intc_domain_map,
 	.xlate	= irq_domain_xlate_onecell,
+	.alloc	= riscv_intc_domain_alloc
 };
 
 static struct fwnode_handle *riscv_intc_hwnode(void)
@@ -133,11 +131,6 @@ static int __init riscv_intc_init(struct device_node *node,
 
 	riscv_set_intc_hwnode_fn(riscv_intc_hwnode);
 
-	cpuhp_setup_state(CPUHP_AP_IRQ_RISCV_STARTING,
-			  "irqchip/riscv/intc:starting",
-			  riscv_intc_cpu_starting,
-			  riscv_intc_cpu_dying);
-
 	pr_info("%d local interrupts mapped\n", BITS_PER_LONG);
 
 	return 0;
-- 
2.34.1

[PATCH v16 5/9] RISC-V: Allow marking IPIs as suitable for remote FENCEs

[Anup Patel]

To do remote FENCEs (i.e. remote TLB flushes) using IPI calls on the
RISC-V kernel, we need hardware mechanism to directly inject IPI from
the supervisor mode (i.e. RISC-V kernel) instead of using SBI calls.

The upcoming AIA IMSIC devices allow direct IPI injection from the
supervisor mode (i.e. RISC-V kernel). To support this, we extend the
riscv_ipi_set_virq_range() function so that IPI provider (i.e. irqchip
drivers can mark IPIs as suitable for remote FENCEs.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
---
 arch/riscv/include/asm/smp.h      | 18 ++++++++++++++++--
 arch/riscv/kernel/sbi-ipi.c       |  2 +-
 arch/riscv/kernel/smp.c           | 11 ++++++++++-
 drivers/clocksource/timer-clint.c |  2 +-
 4 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
index 4fe7a8854c2e..c4b77017ec58 100644
--- a/arch/riscv/include/asm/smp.h
+++ b/arch/riscv/include/asm/smp.h
@@ -16,6 +16,9 @@ struct seq_file;
 extern unsigned long boot_cpu_hartid;
 
 #ifdef CONFIG_SMP
+
+#include <linux/jump_label.h>
+
 /*
  * Mapping between linux logical cpu index and hartid.
  */
@@ -46,7 +49,12 @@ void riscv_ipi_disable(void);
 bool riscv_ipi_have_virq_range(void);
 
 /* Set the IPI interrupt numbers for arch (called by irqchip drivers) */
-void riscv_ipi_set_virq_range(int virq, int nr);
+void riscv_ipi_set_virq_range(int virq, int nr, bool use_for_rfence);
+
+/* Check if we can use IPIs for remote FENCEs */
+DECLARE_STATIC_KEY_FALSE(riscv_ipi_for_rfence);
+#define riscv_use_ipi_for_rfence() \
+	static_branch_unlikely(&riscv_ipi_for_rfence)
 
 /* Check other CPUs stop or not */
 bool smp_crash_stop_failed(void);
@@ -96,10 +104,16 @@ static inline bool riscv_ipi_have_virq_range(void)
 	return false;
 }
 
-static inline void riscv_ipi_set_virq_range(int virq, int nr)
+static inline void riscv_ipi_set_virq_range(int virq, int nr,
+					    bool use_for_rfence)
 {
 }
 
+static inline bool riscv_use_ipi_for_rfence(void)
+{
+	return false;
+}
+
 #endif /* CONFIG_SMP */
 
 #if defined(CONFIG_HOTPLUG_CPU) && (CONFIG_SMP)
diff --git a/arch/riscv/kernel/sbi-ipi.c b/arch/riscv/kernel/sbi-ipi.c
index 41981ab88493..a4559695ce62 100644
--- a/arch/riscv/kernel/sbi-ipi.c
+++ b/arch/riscv/kernel/sbi-ipi.c
@@ -72,6 +72,6 @@ void __init sbi_ipi_init(void)
 			  "irqchip/sbi-ipi:starting",
 			  sbi_ipi_starting_cpu, NULL);
 
-	riscv_ipi_set_virq_range(virq, BITS_PER_BYTE);
+	riscv_ipi_set_virq_range(virq, BITS_PER_BYTE, false);
 	pr_info("providing IPIs using SBI IPI extension\n");
 }
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index 47e7ecfedb4d..5f985a197eff 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -177,7 +177,10 @@ bool riscv_ipi_have_virq_range(void)
 	return (ipi_virq_base) ? true : false;
 }
 
-void riscv_ipi_set_virq_range(int virq, int nr)
+DEFINE_STATIC_KEY_FALSE(riscv_ipi_for_rfence);
+EXPORT_SYMBOL_GPL(riscv_ipi_for_rfence);
+
+void riscv_ipi_set_virq_range(int virq, int nr, bool use_for_rfence)
 {
 	int i, err;
 
@@ -200,6 +203,12 @@ void riscv_ipi_set_virq_range(int virq, int nr)
 
 	/* Enabled IPIs for boot CPU immediately */
 	riscv_ipi_enable();
+
+	/* Update RFENCE static key */
+	if (use_for_rfence)
+		static_branch_enable(&riscv_ipi_for_rfence);
+	else
+		static_branch_disable(&riscv_ipi_for_rfence);
 }
 
 static const char * const ipi_names[] = {
diff --git a/drivers/clocksource/timer-clint.c b/drivers/clocksource/timer-clint.c
index 7ccc16dd6a76..9a55e733ae99 100644
--- a/drivers/clocksource/timer-clint.c
+++ b/drivers/clocksource/timer-clint.c
@@ -251,7 +251,7 @@ static int __init clint_timer_init_dt(struct device_node *np)
 	}
 
 	irq_set_chained_handler(clint_ipi_irq, clint_ipi_interrupt);
-	riscv_ipi_set_virq_range(rc, BITS_PER_BYTE);
+	riscv_ipi_set_virq_range(rc, BITS_PER_BYTE, true);
 	clint_clear_ipi();
 #endif
 
-- 
2.34.1

[PATCH v16 6/9] RISC-V: Use IPIs for remote TLB flush when possible

[Anup Patel]

If we have specialized interrupt controller (such as AIA IMSIC) which
allows supervisor mode to directly inject IPIs without any assistance
from M-mode or HS-mode then using such specialized interrupt controller,
we can do remote TLB flushes directly from supervisor mode instead of
using the SBI RFENCE calls.

This patch extends remote TLB flush functions to use supervisor mode
IPIs whenever direct supervisor mode IPIs.are supported by interrupt
controller.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
---
 arch/riscv/mm/tlbflush.c | 93 +++++++++++++++++++++++++++++++++-------
 1 file changed, 78 insertions(+), 15 deletions(-)

diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index ce7dfc81bb3f..91078377344d 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -7,14 +7,62 @@
 #include <asm/mmu_context.h>
 #include <asm/tlbflush.h>
 
+static inline void local_flush_tlb_range(unsigned long start,
+		unsigned long size, unsigned long stride)
+{
+	if (size <= stride)
+		local_flush_tlb_page(start);
+	else
+		local_flush_tlb_all();
+}
+
+static inline void local_flush_tlb_range_asid(unsigned long start,
+		unsigned long size, unsigned long stride, unsigned long asid)
+{
+	if (size <= stride)
+		local_flush_tlb_page_asid(start, asid);
+	else
+		local_flush_tlb_all_asid(asid);
+}
+
+static void __ipi_flush_tlb_all(void *info)
+{
+	local_flush_tlb_all();
+}
+
 void flush_tlb_all(void)
 {
-	sbi_remote_sfence_vma(NULL, 0, -1);
+	if (riscv_use_ipi_for_rfence())
+		on_each_cpu(__ipi_flush_tlb_all, NULL, 1);
+	else
+		sbi_remote_sfence_vma(NULL, 0, -1);
+}
+
+struct flush_tlb_range_data {
+	unsigned long asid;
+	unsigned long start;
+	unsigned long size;
+	unsigned long stride;
+};
+
+static void __ipi_flush_tlb_range_asid(void *info)
+{
+	struct flush_tlb_range_data *d = info;
+
+	local_flush_tlb_range_asid(d->start, d->size, d->stride, d->asid);
+}
+
+static void __ipi_flush_tlb_range(void *info)
+{
+	struct flush_tlb_range_data *d = info;
+
+	local_flush_tlb_range(d->start, d->size, d->stride);
 }
 
-static void __sbi_tlb_flush_range(struct mm_struct *mm, unsigned long start,
-				  unsigned long size, unsigned long stride)
+static void __flush_tlb_range(struct mm_struct *mm, unsigned long start,
+			      unsigned long size, unsigned long stride)
 {
+	struct flush_tlb_range_data ftd;
 	struct cpumask *pmask = &mm->context.tlb_stale_mask;
 	struct cpumask *cmask = mm_cpumask(mm);
 	unsigned int cpuid;
@@ -39,19 +87,34 @@ static void __sbi_tlb_flush_range(struct mm_struct *mm, unsigned long start,
 		cpumask_andnot(pmask, pmask, cmask);
 
 		if (broadcast) {
-			sbi_remote_sfence_vma_asid(cmask, start, size, asid);
-		} else if (size <= stride) {
-			local_flush_tlb_page_asid(start, asid);
+			if (riscv_use_ipi_for_rfence()) {
+				ftd.asid = asid;
+				ftd.start = start;
+				ftd.size = size;
+				ftd.stride = stride;
+				on_each_cpu_mask(cmask,
+						 __ipi_flush_tlb_range_asid,
+						 &ftd, 1);
+			} else
+				sbi_remote_sfence_vma_asid(cmask,
+							   start, size, asid);
 		} else {
-			local_flush_tlb_all_asid(asid);
+			local_flush_tlb_range_asid(start, size, stride, asid);
 		}
 	} else {
 		if (broadcast) {
-			sbi_remote_sfence_vma(cmask, start, size);
-		} else if (size <= stride) {
-			local_flush_tlb_page(start);
+			if (riscv_use_ipi_for_rfence()) {
+				ftd.asid = 0;
+				ftd.start = start;
+				ftd.size = size;
+				ftd.stride = stride;
+				on_each_cpu_mask(cmask,
+						 __ipi_flush_tlb_range,
+						 &ftd, 1);
+			} else
+				sbi_remote_sfence_vma(cmask, start, size);
 		} else {
-			local_flush_tlb_all();
+			local_flush_tlb_range(start, size, stride);
 		}
 	}
 
@@ -60,23 +123,23 @@ static void __sbi_tlb_flush_range(struct mm_struct *mm, unsigned long start,
 
 void flush_tlb_mm(struct mm_struct *mm)
 {
-	__sbi_tlb_flush_range(mm, 0, -1, PAGE_SIZE);
+	__flush_tlb_range(mm, 0, -1, PAGE_SIZE);
 }
 
 void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 {
-	__sbi_tlb_flush_range(vma->vm_mm, addr, PAGE_SIZE, PAGE_SIZE);
+	__flush_tlb_range(vma->vm_mm, addr, PAGE_SIZE, PAGE_SIZE);
 }
 
 void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 		     unsigned long end)
 {
-	__sbi_tlb_flush_range(vma->vm_mm, start, end - start, PAGE_SIZE);
+	__flush_tlb_range(vma->vm_mm, start, end - start, PAGE_SIZE);
 }
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 void flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
 			unsigned long end)
 {
-	__sbi_tlb_flush_range(vma->vm_mm, start, end - start, PMD_SIZE);
+	__flush_tlb_range(vma->vm_mm, start, end - start, PMD_SIZE);
 }
 #endif
-- 
2.34.1

[PATCH v16 7/9] RISC-V: Use IPIs for remote icache flush when possible

[Anup Patel]

If we have specialized interrupt controller (such as AIA IMSIC) which
allows supervisor mode to directly inject IPIs without any assistance
from M-mode or HS-mode then using such specialized interrupt controller,
we can do remote icache flushe directly from supervisor mode instead of
using the SBI RFENCE calls.

This patch extends remote icache flush functions to use supervisor mode
IPIs whenever direct supervisor mode IPIs.are supported by interrupt
controller.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
---
 arch/riscv/mm/cacheflush.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
index 3cc07ed45aeb..b093727494eb 100644
--- a/arch/riscv/mm/cacheflush.c
+++ b/arch/riscv/mm/cacheflush.c
@@ -19,7 +19,7 @@ void flush_icache_all(void)
 {
 	local_flush_icache_all();
 
-	if (IS_ENABLED(CONFIG_RISCV_SBI))
+	if (IS_ENABLED(CONFIG_RISCV_SBI) && !riscv_use_ipi_for_rfence())
 		sbi_remote_fence_i(NULL);
 	else
 		on_each_cpu(ipi_remote_fence_i, NULL, 1);
@@ -67,7 +67,8 @@ void flush_icache_mm(struct mm_struct *mm, bool local)
 		 * with flush_icache_deferred().
 		 */
 		smp_mb();
-	} else if (IS_ENABLED(CONFIG_RISCV_SBI)) {
+	} else if (IS_ENABLED(CONFIG_RISCV_SBI) &&
+		   !riscv_use_ipi_for_rfence()) {
 		sbi_remote_fence_i(&others);
 	} else {
 		on_each_cpu_mask(&others, ipi_remote_fence_i, NULL, 1);
-- 
2.34.1

[PATCH v16 8/9] irqchip/riscv-intc: Add empty irq_eoi() for chained irq handlers

[Anup Patel]

We add empty irq_eoi() in RISC-V INTC driver for child irqchip
drivers (such as PLIC, SBI IPI, CLINT, APLIC, IMSIC, etc) which
implement chained handlers for parent per-HART local interrupts.
This hels us avoid unnecessary mask/unmask of per-HART local
interrupts at the time of handling interrupts.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 drivers/irqchip/irq-riscv-intc.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c
index 784d25645704..f229e3e66387 100644
--- a/drivers/irqchip/irq-riscv-intc.c
+++ b/drivers/irqchip/irq-riscv-intc.c
@@ -46,10 +46,27 @@ static void riscv_intc_irq_unmask(struct irq_data *d)
 	csr_set(CSR_IE, BIT(d->hwirq));
 }
 
+static void riscv_intc_irq_eoi(struct irq_data *d)
+{
+	/*
+	 * The RISC-V INTC driver uses handle_percpu_devid_irq() flow
+	 * for the per-HART local interrupts and child irqchip drivers
+	 * (such as PLIC, SBI IPI, CLINT, APLIC, IMSIC, etc) implement
+	 * chained handlers for the per-HART local interrupts.
+	 *
+	 * In the absence of irq_eoi(), the chained_irq_enter() and
+	 * chained_irq_exit() functions (used by child irqchip drivers)
+	 * will do unnecessary mask/unmask of per-HART local interrupts
+	 * at the time of handling interrupts. To avoid this, we provide
+	 * an empty irq_eoi() callback for RISC-V INTC irqchip.
+	 */
+}
+
 static struct irq_chip riscv_intc_chip = {
 	.name = "RISC-V INTC",
 	.irq_mask = riscv_intc_irq_mask,
 	.irq_unmask = riscv_intc_irq_unmask,
+	.irq_eoi = riscv_intc_irq_eoi,
 };
 
 static int riscv_intc_domain_map(struct irq_domain *d, unsigned int irq,
-- 
2.34.1

[PATCH v16 9/9] irqchip/apple-aic: Move over to core ipi-mux

[Anup Patel]

From: Marc Zyngier <maz@kernel.org>

Now that the complexity of the AIC IPI mux has been copied into
the core code for the benefit of the riscv architecture,
shrink the AIC driver by the same amount by using that infrastructure.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Acked-by: Hector Martin <marcan@marcan.st>
---
 drivers/irqchip/Kconfig         |   1 +
 drivers/irqchip/irq-apple-aic.c | 161 ++------------------------------
 2 files changed, 9 insertions(+), 153 deletions(-)

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 0e3a7749d87c..9e65345ca3f6 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -659,6 +659,7 @@ config APPLE_AIC
 	bool "Apple Interrupt Controller (AIC)"
 	depends on ARM64
 	depends on ARCH_APPLE || COMPILE_TEST
+	select GENERIC_IRQ_IPI_MUX
 	help
 	  Support for the Apple Interrupt Controller found on Apple Silicon SoCs,
 	  such as the M1.
diff --git a/drivers/irqchip/irq-apple-aic.c b/drivers/irqchip/irq-apple-aic.c
index ae3437f03e6c..eabb3b92965b 100644
--- a/drivers/irqchip/irq-apple-aic.c
+++ b/drivers/irqchip/irq-apple-aic.c
@@ -292,7 +292,6 @@ struct aic_irq_chip {
 	void __iomem *base;
 	void __iomem *event;
 	struct irq_domain *hw_domain;
-	struct irq_domain *ipi_domain;
 	struct {
 		cpumask_t aff;
 	} *fiq_aff[AIC_NR_FIQ];
@@ -307,9 +306,6 @@ struct aic_irq_chip {
 
 static DEFINE_PER_CPU(uint32_t, aic_fiq_unmasked);
 
-static DEFINE_PER_CPU(atomic_t, aic_vipi_flag);
-static DEFINE_PER_CPU(atomic_t, aic_vipi_enable);
-
 static struct aic_irq_chip *aic_irqc;
 
 static void aic_handle_ipi(struct pt_regs *regs);
@@ -751,98 +747,8 @@ static void aic_ipi_send_fast(int cpu)
 	isb();
 }
 
-static void aic_ipi_mask(struct irq_data *d)
-{
-	u32 irq_bit = BIT(irqd_to_hwirq(d));
-
-	/* No specific ordering requirements needed here. */
-	atomic_andnot(irq_bit, this_cpu_ptr(&aic_vipi_enable));
-}
-
-static void aic_ipi_unmask(struct irq_data *d)
-{
-	struct aic_irq_chip *ic = irq_data_get_irq_chip_data(d);
-	u32 irq_bit = BIT(irqd_to_hwirq(d));
-
-	atomic_or(irq_bit, this_cpu_ptr(&aic_vipi_enable));
-
-	/*
-	 * The atomic_or() above must complete before the atomic_read()
-	 * below to avoid racing aic_ipi_send_mask().
-	 */
-	smp_mb__after_atomic();
-
-	/*
-	 * If a pending vIPI was unmasked, raise a HW IPI to ourselves.
-	 * No barriers needed here since this is a self-IPI.
-	 */
-	if (atomic_read(this_cpu_ptr(&aic_vipi_flag)) & irq_bit) {
-		if (static_branch_likely(&use_fast_ipi))
-			aic_ipi_send_fast(smp_processor_id());
-		else
-			aic_ic_write(ic, AIC_IPI_SEND, AIC_IPI_SEND_CPU(smp_processor_id()));
-	}
-}
-
-static void aic_ipi_send_mask(struct irq_data *d, const struct cpumask *mask)
-{
-	struct aic_irq_chip *ic = irq_data_get_irq_chip_data(d);
-	u32 irq_bit = BIT(irqd_to_hwirq(d));
-	u32 send = 0;
-	int cpu;
-	unsigned long pending;
-
-	for_each_cpu(cpu, mask) {
-		/*
-		 * This sequence is the mirror of the one in aic_ipi_unmask();
-		 * see the comment there. Additionally, release semantics
-		 * ensure that the vIPI flag set is ordered after any shared
-		 * memory accesses that precede it. This therefore also pairs
-		 * with the atomic_fetch_andnot in aic_handle_ipi().
-		 */
-		pending = atomic_fetch_or_release(irq_bit, per_cpu_ptr(&aic_vipi_flag, cpu));
-
-		/*
-		 * The atomic_fetch_or_release() above must complete before the
-		 * atomic_read() below to avoid racing aic_ipi_unmask().
-		 */
-		smp_mb__after_atomic();
-
-		if (!(pending & irq_bit) &&
-		    (atomic_read(per_cpu_ptr(&aic_vipi_enable, cpu)) & irq_bit)) {
-			if (static_branch_likely(&use_fast_ipi))
-				aic_ipi_send_fast(cpu);
-			else
-				send |= AIC_IPI_SEND_CPU(cpu);
-		}
-	}
-
-	/*
-	 * The flag writes must complete before the physical IPI is issued
-	 * to another CPU. This is implied by the control dependency on
-	 * the result of atomic_read_acquire() above, which is itself
-	 * already ordered after the vIPI flag write.
-	 */
-	if (send)
-		aic_ic_write(ic, AIC_IPI_SEND, send);
-}
-
-static struct irq_chip ipi_chip = {
-	.name = "AIC-IPI",
-	.irq_mask = aic_ipi_mask,
-	.irq_unmask = aic_ipi_unmask,
-	.ipi_send_mask = aic_ipi_send_mask,
-};
-
-/*
- * IPI IRQ domain
- */
-
 static void aic_handle_ipi(struct pt_regs *regs)
 {
-	int i;
-	unsigned long enabled, firing;
-
 	/*
 	 * Ack the IPI. We need to order this after the AIC event read, but
 	 * that is enforced by normal MMIO ordering guarantees.
@@ -857,27 +763,7 @@ static void aic_handle_ipi(struct pt_regs *regs)
 		aic_ic_write(aic_irqc, AIC_IPI_ACK, AIC_IPI_OTHER);
 	}
 
-	/*
-	 * The mask read does not need to be ordered. Only we can change
-	 * our own mask anyway, so no races are possible here, as long as
-	 * we are properly in the interrupt handler (which is covered by
-	 * the barrier that is part of the top-level AIC handler's readl()).
-	 */
-	enabled = atomic_read(this_cpu_ptr(&aic_vipi_enable));
-
-	/*
-	 * Clear the IPIs we are about to handle. This pairs with the
-	 * atomic_fetch_or_release() in aic_ipi_send_mask(), and needs to be
-	 * ordered after the aic_ic_write() above (to avoid dropping vIPIs) and
-	 * before IPI handling code (to avoid races handling vIPIs before they
-	 * are signaled). The former is taken care of by the release semantics
-	 * of the write portion, while the latter is taken care of by the
-	 * acquire semantics of the read portion.
-	 */
-	firing = atomic_fetch_andnot(enabled, this_cpu_ptr(&aic_vipi_flag)) & enabled;
-
-	for_each_set_bit(i, &firing, AIC_NR_SWIPI)
-		generic_handle_domain_irq(aic_irqc->ipi_domain, i);
+	ipi_mux_process();
 
 	/*
 	 * No ordering needed here; at worst this just changes the timing of
@@ -887,55 +773,24 @@ static void aic_handle_ipi(struct pt_regs *regs)
 		aic_ic_write(aic_irqc, AIC_IPI_MASK_CLR, AIC_IPI_OTHER);
 }
 
-static int aic_ipi_alloc(struct irq_domain *d, unsigned int virq,
-			 unsigned int nr_irqs, void *args)
+static void aic_ipi_send_single(unsigned int cpu)
 {
-	int i;
-
-	for (i = 0; i < nr_irqs; i++) {
-		irq_set_percpu_devid(virq + i);
-		irq_domain_set_info(d, virq + i, i, &ipi_chip, d->host_data,
-				    handle_percpu_devid_irq, NULL, NULL);
-	}
-
-	return 0;
-}
-
-static void aic_ipi_free(struct irq_domain *d, unsigned int virq, unsigned int nr_irqs)
-{
-	/* Not freeing IPIs */
+	if (static_branch_likely(&use_fast_ipi))
+		aic_ipi_send_fast(cpu);
+	else
+		aic_ic_write(aic_irqc, AIC_IPI_SEND, AIC_IPI_SEND_CPU(cpu));
 }
 
-static const struct irq_domain_ops aic_ipi_domain_ops = {
-	.alloc = aic_ipi_alloc,
-	.free = aic_ipi_free,
-};
-
 static int __init aic_init_smp(struct aic_irq_chip *irqc, struct device_node *node)
 {
-	struct irq_domain *ipi_domain;
 	int base_ipi;
 
-	ipi_domain = irq_domain_create_linear(irqc->hw_domain->fwnode, AIC_NR_SWIPI,
-					      &aic_ipi_domain_ops, irqc);
-	if (WARN_ON(!ipi_domain))
-		return -ENODEV;
-
-	ipi_domain->flags |= IRQ_DOMAIN_FLAG_IPI_SINGLE;
-	irq_domain_update_bus_token(ipi_domain, DOMAIN_BUS_IPI);
-
-	base_ipi = __irq_domain_alloc_irqs(ipi_domain, -1, AIC_NR_SWIPI,
-					   NUMA_NO_NODE, NULL, false, NULL);
-
-	if (WARN_ON(!base_ipi)) {
-		irq_domain_remove(ipi_domain);
+	base_ipi = ipi_mux_create(AIC_NR_SWIPI, aic_ipi_send_single);
+	if (WARN_ON(base_ipi <= 0))
 		return -ENODEV;
-	}
 
 	set_smp_ipi_range(base_ipi, AIC_NR_SWIPI);
 
-	irqc->ipi_domain = ipi_domain;
-
 	return 0;
 }
 
-- 
2.34.1

[irqchip: irq/irqchip-next] irqchip/apple-aic: Move over to core ipi-mux

[irqchip-bot for Marc Zyngier]

The following commit has been merged into the irq/irqchip-next branch of irqchip:

Commit-ID:     c19f897194288ec286bb52001b9ee9551876a614
Gitweb:        https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms/c19f897194288ec286bb52001b9ee9551876a614
Author:        Marc Zyngier <maz@kernel.org>
AuthorDate:    Tue, 03 Jan 2023 19:42:21 +05:30
Committer:     Marc Zyngier <maz@kernel.org>
CommitterDate: Sun, 05 Feb 2023 10:58:18 

irqchip/apple-aic: Move over to core ipi-mux

Now that the complexity of the AIC IPI mux has been copied into
the core code for the benefit of the riscv architecture,
shrink the AIC driver by the same amount by using that infrastructure.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Acked-by: Hector Martin <marcan@marcan.st>
Link: https://lore.kernel.org/r/20230103141221.772261-10-apatel@ventanamicro.com
---
 drivers/irqchip/Kconfig         |   1 +-
 drivers/irqchip/irq-apple-aic.c | 161 +------------------------------
 2 files changed, 9 insertions(+), 153 deletions(-)

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index caa952c..cbf5047 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -658,6 +658,7 @@ config APPLE_AIC
 	bool "Apple Interrupt Controller (AIC)"
 	depends on ARM64
 	depends on ARCH_APPLE || COMPILE_TEST
+	select GENERIC_IRQ_IPI_MUX
 	help
 	  Support for the Apple Interrupt Controller found on Apple Silicon SoCs,
 	  such as the M1.
diff --git a/drivers/irqchip/irq-apple-aic.c b/drivers/irqchip/irq-apple-aic.c
index ae3437f..eabb3b9 100644
--- a/drivers/irqchip/irq-apple-aic.c
+++ b/drivers/irqchip/irq-apple-aic.c
@@ -292,7 +292,6 @@ struct aic_irq_chip {
 	void __iomem *base;
 	void __iomem *event;
 	struct irq_domain *hw_domain;
-	struct irq_domain *ipi_domain;
 	struct {
 		cpumask_t aff;
 	} *fiq_aff[AIC_NR_FIQ];
@@ -307,9 +306,6 @@ struct aic_irq_chip {
 
 static DEFINE_PER_CPU(uint32_t, aic_fiq_unmasked);
 
-static DEFINE_PER_CPU(atomic_t, aic_vipi_flag);
-static DEFINE_PER_CPU(atomic_t, aic_vipi_enable);
-
 static struct aic_irq_chip *aic_irqc;
 
 static void aic_handle_ipi(struct pt_regs *regs);
@@ -751,98 +747,8 @@ static void aic_ipi_send_fast(int cpu)
 	isb();
 }
 
-static void aic_ipi_mask(struct irq_data *d)
-{
-	u32 irq_bit = BIT(irqd_to_hwirq(d));
-
-	/* No specific ordering requirements needed here. */
-	atomic_andnot(irq_bit, this_cpu_ptr(&aic_vipi_enable));
-}
-
-static void aic_ipi_unmask(struct irq_data *d)
-{
-	struct aic_irq_chip *ic = irq_data_get_irq_chip_data(d);
-	u32 irq_bit = BIT(irqd_to_hwirq(d));
-
-	atomic_or(irq_bit, this_cpu_ptr(&aic_vipi_enable));
-
-	/*
-	 * The atomic_or() above must complete before the atomic_read()
-	 * below to avoid racing aic_ipi_send_mask().
-	 */
-	smp_mb__after_atomic();
-
-	/*
-	 * If a pending vIPI was unmasked, raise a HW IPI to ourselves.
-	 * No barriers needed here since this is a self-IPI.
-	 */
-	if (atomic_read(this_cpu_ptr(&aic_vipi_flag)) & irq_bit) {
-		if (static_branch_likely(&use_fast_ipi))
-			aic_ipi_send_fast(smp_processor_id());
-		else
-			aic_ic_write(ic, AIC_IPI_SEND, AIC_IPI_SEND_CPU(smp_processor_id()));
-	}
-}
-
-static void aic_ipi_send_mask(struct irq_data *d, const struct cpumask *mask)
-{
-	struct aic_irq_chip *ic = irq_data_get_irq_chip_data(d);
-	u32 irq_bit = BIT(irqd_to_hwirq(d));
-	u32 send = 0;
-	int cpu;
-	unsigned long pending;
-
-	for_each_cpu(cpu, mask) {
-		/*
-		 * This sequence is the mirror of the one in aic_ipi_unmask();
-		 * see the comment there. Additionally, release semantics
-		 * ensure that the vIPI flag set is ordered after any shared
-		 * memory accesses that precede it. This therefore also pairs
-		 * with the atomic_fetch_andnot in aic_handle_ipi().
-		 */
-		pending = atomic_fetch_or_release(irq_bit, per_cpu_ptr(&aic_vipi_flag, cpu));
-
-		/*
-		 * The atomic_fetch_or_release() above must complete before the
-		 * atomic_read() below to avoid racing aic_ipi_unmask().
-		 */
-		smp_mb__after_atomic();
-
-		if (!(pending & irq_bit) &&
-		    (atomic_read(per_cpu_ptr(&aic_vipi_enable, cpu)) & irq_bit)) {
-			if (static_branch_likely(&use_fast_ipi))
-				aic_ipi_send_fast(cpu);
-			else
-				send |= AIC_IPI_SEND_CPU(cpu);
-		}
-	}
-
-	/*
-	 * The flag writes must complete before the physical IPI is issued
-	 * to another CPU. This is implied by the control dependency on
-	 * the result of atomic_read_acquire() above, which is itself
-	 * already ordered after the vIPI flag write.
-	 */
-	if (send)
-		aic_ic_write(ic, AIC_IPI_SEND, send);
-}
-
-static struct irq_chip ipi_chip = {
-	.name = "AIC-IPI",
-	.irq_mask = aic_ipi_mask,
-	.irq_unmask = aic_ipi_unmask,
-	.ipi_send_mask = aic_ipi_send_mask,
-};
-
-/*
- * IPI IRQ domain
- */
-
 static void aic_handle_ipi(struct pt_regs *regs)
 {
-	int i;
-	unsigned long enabled, firing;
-
 	/*
 	 * Ack the IPI. We need to order this after the AIC event read, but
 	 * that is enforced by normal MMIO ordering guarantees.
@@ -857,27 +763,7 @@ static void aic_handle_ipi(struct pt_regs *regs)
 		aic_ic_write(aic_irqc, AIC_IPI_ACK, AIC_IPI_OTHER);
 	}
 
-	/*
-	 * The mask read does not need to be ordered. Only we can change
-	 * our own mask anyway, so no races are possible here, as long as
-	 * we are properly in the interrupt handler (which is covered by
-	 * the barrier that is part of the top-level AIC handler's readl()).
-	 */
-	enabled = atomic_read(this_cpu_ptr(&aic_vipi_enable));
-
-	/*
-	 * Clear the IPIs we are about to handle. This pairs with the
-	 * atomic_fetch_or_release() in aic_ipi_send_mask(), and needs to be
-	 * ordered after the aic_ic_write() above (to avoid dropping vIPIs) and
-	 * before IPI handling code (to avoid races handling vIPIs before they
-	 * are signaled). The former is taken care of by the release semantics
-	 * of the write portion, while the latter is taken care of by the
-	 * acquire semantics of the read portion.
-	 */
-	firing = atomic_fetch_andnot(enabled, this_cpu_ptr(&aic_vipi_flag)) & enabled;
-
-	for_each_set_bit(i, &firing, AIC_NR_SWIPI)
-		generic_handle_domain_irq(aic_irqc->ipi_domain, i);
+	ipi_mux_process();
 
 	/*
 	 * No ordering needed here; at worst this just changes the timing of
@@ -887,55 +773,24 @@ static void aic_handle_ipi(struct pt_regs *regs)
 		aic_ic_write(aic_irqc, AIC_IPI_MASK_CLR, AIC_IPI_OTHER);
 }
 
-static int aic_ipi_alloc(struct irq_domain *d, unsigned int virq,
-			 unsigned int nr_irqs, void *args)
+static void aic_ipi_send_single(unsigned int cpu)
 {
-	int i;
-
-	for (i = 0; i < nr_irqs; i++) {
-		irq_set_percpu_devid(virq + i);
-		irq_domain_set_info(d, virq + i, i, &ipi_chip, d->host_data,
-				    handle_percpu_devid_irq, NULL, NULL);
-	}
-
-	return 0;
-}
-
-static void aic_ipi_free(struct irq_domain *d, unsigned int virq, unsigned int nr_irqs)
-{
-	/* Not freeing IPIs */
+	if (static_branch_likely(&use_fast_ipi))
+		aic_ipi_send_fast(cpu);
+	else
+		aic_ic_write(aic_irqc, AIC_IPI_SEND, AIC_IPI_SEND_CPU(cpu));
 }
 
-static const struct irq_domain_ops aic_ipi_domain_ops = {
-	.alloc = aic_ipi_alloc,
-	.free = aic_ipi_free,
-};
-
 static int __init aic_init_smp(struct aic_irq_chip *irqc, struct device_node *node)
 {
-	struct irq_domain *ipi_domain;
 	int base_ipi;
 
-	ipi_domain = irq_domain_create_linear(irqc->hw_domain->fwnode, AIC_NR_SWIPI,
-					      &aic_ipi_domain_ops, irqc);
-	if (WARN_ON(!ipi_domain))
-		return -ENODEV;
-
-	ipi_domain->flags |= IRQ_DOMAIN_FLAG_IPI_SINGLE;
-	irq_domain_update_bus_token(ipi_domain, DOMAIN_BUS_IPI);
-
-	base_ipi = __irq_domain_alloc_irqs(ipi_domain, -1, AIC_NR_SWIPI,
-					   NUMA_NO_NODE, NULL, false, NULL);
-
-	if (WARN_ON(!base_ipi)) {
-		irq_domain_remove(ipi_domain);
+	base_ipi = ipi_mux_create(AIC_NR_SWIPI, aic_ipi_send_single);
+	if (WARN_ON(base_ipi <= 0))
 		return -ENODEV;
-	}
 
 	set_smp_ipi_range(base_ipi, AIC_NR_SWIPI);
 
-	irqc->ipi_domain = ipi_domain;
-
 	return 0;
 }
 

Re: [PATCH v16 0/9] RISC-V IPI Improvements

[Anup Patel]

Hi Marc,

On Tue, Jan 3, 2023 at 7:42 PM Anup Patel <apatel@ventanamicro.com> wrote:
>
> This series aims to improve IPI support in Linux RISC-V in following ways:
>  1) Treat IPIs as normal per-CPU interrupts instead of having custom RISC-V
>     specific hooks. This also makes Linux RISC-V IPI support aligned with
>     other architectures.
>  2) Remote TLB flushes and icache flushes should prefer local IPIs instead
>     of SBI calls whenever we have specialized hardware (such as RISC-V AIA
>     IMSIC and RISC-V SWI) which allows S-mode software to directly inject
>     IPIs without any assistance from M-mode runtime firmware.
>
> These patches were originally part of the "Linux RISC-V ACLINT Support"
> series but this now a separate series so that it can be merged independently
> of the "Linux RISC-V ACLINT Support" series.
> (Refer, https://lore.kernel.org/lkml/20211007123632.697666-1-anup.patel@wdc.com/)
>
> These patches are also a preparatory patches for the up-coming:
>  1) Linux RISC-V AIA support
>  2) Linux RISC-V SWI support
>
> These patches can also be found in riscv_ipi_imp_v16 branch at:
> https://github.com/avpatel/linux.git
>
> Changes since v15:
>  - Rebased on Linux-6.2-rc2
>  - Added Reviewed-by and Tested-by tags to some of the patches.
>
> Changes since v14:
>  - Minor fixes in commit description of PATCH3 (as suggested by tglx)
>  - Don't disable parent IPI when CPU goes offline for SBI IPI driver and
>    CLINT driver in PATCH4.
>  - Include Apple AIC driver changes from Marc Z as PATCH9
>
> Changes since v13:
>  - Included changes suggested by Marc Z in PATCH3
>  - Use chained handlers in PATCH4
>  - Added new PATCH8 to have empty irq_eoi() in RISC-V INTC driver. This
>    avoids the unnecessary mask/unmask dance at time of handling interrupts.
>
> Changes since v12:
>  - Rebased on Linux-6.1-rc7
>  - Bring-back the IPI optimization in ipi_mux_send_mask() for PATCH3
>  - Call ipi_mux_send() for one target CPU at a time in PATCH3
>
> Changes since v11:
>  - Removed ipi_mux_pre/post_handle() callbacks in PATCH3
>  - Removed sturct ipi_mux_ops in PATCH3
>  - Removed parent_virq and data pointer from everywhere in PATCH3
>  - Removed struct ipi_mux_control in PATCH3
>  - Improved function signature of ipi_mux_send() callback in PATCH3
>  - Used unsigned type with atomic operation in PATCH3
>
> Changes since v10:
>  - Rebased on Linux-6.1-rc5
>  - Drop the "!(pending & ibit)" check in ipi_mux_send_mask() of PATCH3
>  - Disable local interrupts in ipi_mux_send_mask() of PATCH3 because we
>    can be preempted while using a per-CPU temporary variable.
>
> Changes since v9:
>  - Rebased on Linux-6.1-rc3
>  - Updated header comment block of ipi-mux.c in PATCH3
>  - Use a struct for global data of ipi-mux.c in PATCH3
>  - Add per-CPU temp cpumask for sending IPIs in PATCH3
>  - Drop the use of fwspec in PATCH3
>  - Use static key for ipi_mux_pre_handle() and ipi_mux_post_handle()
>    in PATCH3
>  - Remove redundant pr_warn_ratelimited() called by ipi_mux_process()
>    in PATCH3
>  - Remove CPUHP thingy from ipi_mux_create() in PATCH3
>
> Changes since v8:
>  - Rebased on Linux-6.0-rc3
>  - Use dummy percpu data as parameter for request_percpu_irq() in PATCH4.
>
> Changes since v7:
>  - Rebased on Linux-6.0-rc1
>  - Use atomic operations to track per-CPU pending and enabled IPIs in PATCH3.
>    (Note: this is inspired from IPI muxing implemented in
>     drivers/irqchip/irq-apple-aic.c)
>  - Made "struct ipi_mux_ops" (added by PATCH3) flexible so that
>    drivers/irqchip/irq-apple-aic.c can adopt it in future.
>
> Changes since v6:
>  - Rebased on Linux-5.19-rc7
>  - Added documentation for struct ipi_mux_ops in PATCH3
>  - Dropped dummy irq_mask()/unmask() in PATCH3
>  - Added const for "ipi_mux_chip" in PATCH3
>  - Removed "type" initialization from ipi_mux_domain_alloc() in PATCH3
>  - Dropped translate() from "ipi_mux_domain_ops" in PATCH3
>  - Improved barrier documentation in ipi_mux_process() of PATCH3
>  - Added percpu check in ipi_mux_create() for parent_virq of PATCH3
>  - Added nr_ipi parameter in ipi_mux_create() of PATCH3
>
> Changes since v5:
>  - Rebased on Linux-5.18-rc3
>  - Used kernel doc style in PATCH3
>  - Removed redundant loop in ipi_mux_process() of PATCH3
>  - Removed "RISC-V" prefix form ipi_mux_chip.name of PATCH3
>  - Removed use of "this patch" in PATCH3 commit description
>  - Addressed few other nit comments in PATCH3
>
> Changes since v4:
>  - Rebased on Linux-5.17
>  - Includes new PATCH3 which adds mechanism to multiplex a single HW IPI
>
> Changes since v3:
>  - Rebased on Linux-5.17-rc6
>  - Updated PATCH2 to not export riscv_set_intc_hwnode_fn()
>  - Simplified riscv_intc_hwnode() in PATCH2
>
> Changes since v2:
>  - Rebased on Linux-5.17-rc4
>  - Updated PATCH2 to not create synthetic INTC fwnode and instead provide
>    a function which allows drivers to directly discover INTC fwnode
>
> Changes since v1:
>  - Use synthetic fwnode for INTC instead of irq_set_default_host() in PATCH2
>
> Anup Patel (8):
>   RISC-V: Clear SIP bit only when using SBI IPI operations
>   irqchip/riscv-intc: Allow drivers to directly discover INTC hwnode
>   genirq: Add mechanism to multiplex a single HW IPI
>   RISC-V: Treat IPIs as normal Linux IRQs
>   RISC-V: Allow marking IPIs as suitable for remote FENCEs
>   RISC-V: Use IPIs for remote TLB flush when possible
>   RISC-V: Use IPIs for remote icache flush when possible
>   irqchip/riscv-intc: Add empty irq_eoi() for chained irq handlers
>
> Marc Zyngier (1):
>   irqchip/apple-aic: Move over to core ipi-mux
>
>  arch/riscv/Kconfig                |   2 +
>  arch/riscv/include/asm/irq.h      |   4 +
>  arch/riscv/include/asm/sbi.h      |   9 +-
>  arch/riscv/include/asm/smp.h      |  49 +++++--
>  arch/riscv/kernel/Makefile        |   1 +
>  arch/riscv/kernel/cpu-hotplug.c   |   3 +-
>  arch/riscv/kernel/irq.c           |  21 ++-
>  arch/riscv/kernel/sbi-ipi.c       |  77 +++++++++++
>  arch/riscv/kernel/sbi.c           | 100 +++------------
>  arch/riscv/kernel/smp.c           | 171 ++++++++++++------------
>  arch/riscv/kernel/smpboot.c       |   5 +-
>  arch/riscv/mm/cacheflush.c        |   5 +-
>  arch/riscv/mm/tlbflush.c          |  93 +++++++++++---
>  drivers/clocksource/timer-clint.c |  65 +++++++---
>  drivers/irqchip/Kconfig           |   2 +
>  drivers/irqchip/irq-apple-aic.c   | 161 ++---------------------
>  drivers/irqchip/irq-riscv-intc.c  |  71 ++++++----
>  include/linux/irq.h               |   3 +
>  kernel/irq/Kconfig                |   5 +
>  kernel/irq/Makefile               |   1 +
>  kernel/irq/ipi-mux.c              | 207 ++++++++++++++++++++++++++++++
>  21 files changed, 654 insertions(+), 401 deletions(-)
>  create mode 100644 arch/riscv/kernel/sbi-ipi.c
>  create mode 100644 kernel/irq/ipi-mux.c
>
> --
> 2.34.1
>

Friendly ping ?

Regards,
Anup

Re: [PATCH v16 0/9] RISC-V IPI Improvements

[Anup Patel]

Hi Marc,

On Thu, Jan 12, 2023 at 5:47 PM Anup Patel <apatel@ventanamicro.com> wrote:
>
> Hi Marc,
>
> On Tue, Jan 3, 2023 at 7:42 PM Anup Patel <apatel@ventanamicro.com> wrote:
> >
> > This series aims to improve IPI support in Linux RISC-V in following ways:
> >  1) Treat IPIs as normal per-CPU interrupts instead of having custom RISC-V
> >     specific hooks. This also makes Linux RISC-V IPI support aligned with
> >     other architectures.
> >  2) Remote TLB flushes and icache flushes should prefer local IPIs instead
> >     of SBI calls whenever we have specialized hardware (such as RISC-V AIA
> >     IMSIC and RISC-V SWI) which allows S-mode software to directly inject
> >     IPIs without any assistance from M-mode runtime firmware.
> >
> > These patches were originally part of the "Linux RISC-V ACLINT Support"
> > series but this now a separate series so that it can be merged independently
> > of the "Linux RISC-V ACLINT Support" series.
> > (Refer, https://lore.kernel.org/lkml/20211007123632.697666-1-anup.patel@wdc.com/)
> >
> > These patches are also a preparatory patches for the up-coming:
> >  1) Linux RISC-V AIA support
> >  2) Linux RISC-V SWI support
> >
> > These patches can also be found in riscv_ipi_imp_v16 branch at:
> > https://github.com/avpatel/linux.git
> >
> > Changes since v15:
> >  - Rebased on Linux-6.2-rc2
> >  - Added Reviewed-by and Tested-by tags to some of the patches.
> >
> > Changes since v14:
> >  - Minor fixes in commit description of PATCH3 (as suggested by tglx)
> >  - Don't disable parent IPI when CPU goes offline for SBI IPI driver and
> >    CLINT driver in PATCH4.
> >  - Include Apple AIC driver changes from Marc Z as PATCH9
> >
> > Changes since v13:
> >  - Included changes suggested by Marc Z in PATCH3
> >  - Use chained handlers in PATCH4
> >  - Added new PATCH8 to have empty irq_eoi() in RISC-V INTC driver. This
> >    avoids the unnecessary mask/unmask dance at time of handling interrupts.
> >
> > Changes since v12:
> >  - Rebased on Linux-6.1-rc7
> >  - Bring-back the IPI optimization in ipi_mux_send_mask() for PATCH3
> >  - Call ipi_mux_send() for one target CPU at a time in PATCH3
> >
> > Changes since v11:
> >  - Removed ipi_mux_pre/post_handle() callbacks in PATCH3
> >  - Removed sturct ipi_mux_ops in PATCH3
> >  - Removed parent_virq and data pointer from everywhere in PATCH3
> >  - Removed struct ipi_mux_control in PATCH3
> >  - Improved function signature of ipi_mux_send() callback in PATCH3
> >  - Used unsigned type with atomic operation in PATCH3
> >
> > Changes since v10:
> >  - Rebased on Linux-6.1-rc5
> >  - Drop the "!(pending & ibit)" check in ipi_mux_send_mask() of PATCH3
> >  - Disable local interrupts in ipi_mux_send_mask() of PATCH3 because we
> >    can be preempted while using a per-CPU temporary variable.
> >
> > Changes since v9:
> >  - Rebased on Linux-6.1-rc3
> >  - Updated header comment block of ipi-mux.c in PATCH3
> >  - Use a struct for global data of ipi-mux.c in PATCH3
> >  - Add per-CPU temp cpumask for sending IPIs in PATCH3
> >  - Drop the use of fwspec in PATCH3
> >  - Use static key for ipi_mux_pre_handle() and ipi_mux_post_handle()
> >    in PATCH3
> >  - Remove redundant pr_warn_ratelimited() called by ipi_mux_process()
> >    in PATCH3
> >  - Remove CPUHP thingy from ipi_mux_create() in PATCH3
> >
> > Changes since v8:
> >  - Rebased on Linux-6.0-rc3
> >  - Use dummy percpu data as parameter for request_percpu_irq() in PATCH4.
> >
> > Changes since v7:
> >  - Rebased on Linux-6.0-rc1
> >  - Use atomic operations to track per-CPU pending and enabled IPIs in PATCH3.
> >    (Note: this is inspired from IPI muxing implemented in
> >     drivers/irqchip/irq-apple-aic.c)
> >  - Made "struct ipi_mux_ops" (added by PATCH3) flexible so that
> >    drivers/irqchip/irq-apple-aic.c can adopt it in future.
> >
> > Changes since v6:
> >  - Rebased on Linux-5.19-rc7
> >  - Added documentation for struct ipi_mux_ops in PATCH3
> >  - Dropped dummy irq_mask()/unmask() in PATCH3
> >  - Added const for "ipi_mux_chip" in PATCH3
> >  - Removed "type" initialization from ipi_mux_domain_alloc() in PATCH3
> >  - Dropped translate() from "ipi_mux_domain_ops" in PATCH3
> >  - Improved barrier documentation in ipi_mux_process() of PATCH3
> >  - Added percpu check in ipi_mux_create() for parent_virq of PATCH3
> >  - Added nr_ipi parameter in ipi_mux_create() of PATCH3
> >
> > Changes since v5:
> >  - Rebased on Linux-5.18-rc3
> >  - Used kernel doc style in PATCH3
> >  - Removed redundant loop in ipi_mux_process() of PATCH3
> >  - Removed "RISC-V" prefix form ipi_mux_chip.name of PATCH3
> >  - Removed use of "this patch" in PATCH3 commit description
> >  - Addressed few other nit comments in PATCH3
> >
> > Changes since v4:
> >  - Rebased on Linux-5.17
> >  - Includes new PATCH3 which adds mechanism to multiplex a single HW IPI
> >
> > Changes since v3:
> >  - Rebased on Linux-5.17-rc6
> >  - Updated PATCH2 to not export riscv_set_intc_hwnode_fn()
> >  - Simplified riscv_intc_hwnode() in PATCH2
> >
> > Changes since v2:
> >  - Rebased on Linux-5.17-rc4
> >  - Updated PATCH2 to not create synthetic INTC fwnode and instead provide
> >    a function which allows drivers to directly discover INTC fwnode
> >
> > Changes since v1:
> >  - Use synthetic fwnode for INTC instead of irq_set_default_host() in PATCH2
> >
> > Anup Patel (8):
> >   RISC-V: Clear SIP bit only when using SBI IPI operations
> >   irqchip/riscv-intc: Allow drivers to directly discover INTC hwnode
> >   genirq: Add mechanism to multiplex a single HW IPI
> >   RISC-V: Treat IPIs as normal Linux IRQs
> >   RISC-V: Allow marking IPIs as suitable for remote FENCEs
> >   RISC-V: Use IPIs for remote TLB flush when possible
> >   RISC-V: Use IPIs for remote icache flush when possible
> >   irqchip/riscv-intc: Add empty irq_eoi() for chained irq handlers
> >
> > Marc Zyngier (1):
> >   irqchip/apple-aic: Move over to core ipi-mux
> >
> >  arch/riscv/Kconfig                |   2 +
> >  arch/riscv/include/asm/irq.h      |   4 +
> >  arch/riscv/include/asm/sbi.h      |   9 +-
> >  arch/riscv/include/asm/smp.h      |  49 +++++--
> >  arch/riscv/kernel/Makefile        |   1 +
> >  arch/riscv/kernel/cpu-hotplug.c   |   3 +-
> >  arch/riscv/kernel/irq.c           |  21 ++-
> >  arch/riscv/kernel/sbi-ipi.c       |  77 +++++++++++
> >  arch/riscv/kernel/sbi.c           | 100 +++------------
> >  arch/riscv/kernel/smp.c           | 171 ++++++++++++------------
> >  arch/riscv/kernel/smpboot.c       |   5 +-
> >  arch/riscv/mm/cacheflush.c        |   5 +-
> >  arch/riscv/mm/tlbflush.c          |  93 +++++++++++---
> >  drivers/clocksource/timer-clint.c |  65 +++++++---
> >  drivers/irqchip/Kconfig           |   2 +
> >  drivers/irqchip/irq-apple-aic.c   | 161 ++---------------------
> >  drivers/irqchip/irq-riscv-intc.c  |  71 ++++++----
> >  include/linux/irq.h               |   3 +
> >  kernel/irq/Kconfig                |   5 +
> >  kernel/irq/Makefile               |   1 +
> >  kernel/irq/ipi-mux.c              | 207 ++++++++++++++++++++++++++++++
> >  21 files changed, 654 insertions(+), 401 deletions(-)
> >  create mode 100644 arch/riscv/kernel/sbi-ipi.c
> >  create mode 100644 kernel/irq/ipi-mux.c
> >
> > --
> > 2.34.1
> >
>
> Friendly ping ?

Any further comments on this series ?

Regards,
Anup

Re: [PATCH v16 0/9] RISC-V IPI Improvements

[Marc Zyngier]

On Tue, 03 Jan 2023 14:12:12 +0000,
Anup Patel <apatel@ventanamicro.com> wrote:
> 
> This series aims to improve IPI support in Linux RISC-V in following ways:
>  1) Treat IPIs as normal per-CPU interrupts instead of having custom RISC-V
>     specific hooks. This also makes Linux RISC-V IPI support aligned with
>     other architectures.
>  2) Remote TLB flushes and icache flushes should prefer local IPIs instead
>     of SBI calls whenever we have specialized hardware (such as RISC-V AIA
>     IMSIC and RISC-V SWI) which allows S-mode software to directly inject
>     IPIs without any assistance from M-mode runtime firmware.

[...]

I'm queuing patches 3 and 9 via the irqchip tree as they are
standalone.

For the rest, I need an Ack from the riscv maintainers as they change
a large amount of arch-specific code, and the couple of irqchip
patches depend on these changes.

Palmer, Paul?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH v16 0/9] RISC-V IPI Improvements

[Palmer Dabbelt]

On Sun, 05 Feb 2023 03:04:14 PST (-0800), Marc Zyngier wrote:
> On Tue, 03 Jan 2023 14:12:12 +0000,
> Anup Patel <apatel@ventanamicro.com> wrote:
>>
>> This series aims to improve IPI support in Linux RISC-V in following ways:
>>  1) Treat IPIs as normal per-CPU interrupts instead of having custom RISC-V
>>     specific hooks. This also makes Linux RISC-V IPI support aligned with
>>     other architectures.
>>  2) Remote TLB flushes and icache flushes should prefer local IPIs instead
>>     of SBI calls whenever we have specialized hardware (such as RISC-V AIA
>>     IMSIC and RISC-V SWI) which allows S-mode software to directly inject
>>     IPIs without any assistance from M-mode runtime firmware.
>
> [...]
>
> I'm queuing patches 3 and 9 via the irqchip tree as they are
> standalone.
>
> For the rest, I need an Ack from the riscv maintainers as they change
> a large amount of arch-specific code, and the couple of irqchip
> patches depend on these changes.
>
> Palmer, Paul?

I haven't gotten time to give this a proper review, but I think we've 
got enough of a mess with our interrupt handling that it doesn't really 
matter so

Acked-by: Palmer Dabbelt <palmer@rivosinc.com>

if you want to take it for this cycle that's fine with me, but I'm also 
fine holding off so it can have a while to bake in linux-next -- there's 
no real rush for any of this, as there's no hardware yet.

>
> Thanks,
>
> 	M.

Re: [PATCH v16 0/9] RISC-V IPI Improvements

[Marc Zyngier]

On 2023-02-15 03:17, Palmer Dabbelt wrote:
> On Sun, 05 Feb 2023 03:04:14 PST (-0800), Marc Zyngier wrote:
>> On Tue, 03 Jan 2023 14:12:12 +0000,
>> Anup Patel <apatel@ventanamicro.com> wrote:
>>> 
>>> This series aims to improve IPI support in Linux RISC-V in following 
>>> ways:
>>>  1) Treat IPIs as normal per-CPU interrupts instead of having custom 
>>> RISC-V
>>>     specific hooks. This also makes Linux RISC-V IPI support aligned 
>>> with
>>>     other architectures.
>>>  2) Remote TLB flushes and icache flushes should prefer local IPIs 
>>> instead
>>>     of SBI calls whenever we have specialized hardware (such as 
>>> RISC-V AIA
>>>     IMSIC and RISC-V SWI) which allows S-mode software to directly 
>>> inject
>>>     IPIs without any assistance from M-mode runtime firmware.
>> 
>> [...]
>> 
>> I'm queuing patches 3 and 9 via the irqchip tree as they are
>> standalone.
>> 
>> For the rest, I need an Ack from the riscv maintainers as they change
>> a large amount of arch-specific code, and the couple of irqchip
>> patches depend on these changes.
>> 
>> Palmer, Paul?
> 
> I haven't gotten time to give this a proper review, but I think we've
> got enough of a mess with our interrupt handling that it doesn't
> really matter so
> 
> Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
> 
> if you want to take it for this cycle that's fine with me, but I'm
> also fine holding off so it can have a while to bake in linux-next --
> there's no real rush for any of this, as there's no hardware yet.

Letting this sort of things simmering in -next is the way.

Now that the basic dependencies are on their way, I'd expect this to be
rebased on 6.3-rc1, and we can then put the whole thing in -next.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

Re: [PATCH v16 0/9] RISC-V IPI Improvements

[Anup Patel]

On Mon, Feb 20, 2023 at 2:05 PM Marc Zyngier <maz@kernel.org> wrote:
>
> On 2023-02-15 03:17, Palmer Dabbelt wrote:
> > On Sun, 05 Feb 2023 03:04:14 PST (-0800), Marc Zyngier wrote:
> >> On Tue, 03 Jan 2023 14:12:12 +0000,
> >> Anup Patel <apatel@ventanamicro.com> wrote:
> >>>
> >>> This series aims to improve IPI support in Linux RISC-V in following
> >>> ways:
> >>>  1) Treat IPIs as normal per-CPU interrupts instead of having custom
> >>> RISC-V
> >>>     specific hooks. This also makes Linux RISC-V IPI support aligned
> >>> with
> >>>     other architectures.
> >>>  2) Remote TLB flushes and icache flushes should prefer local IPIs
> >>> instead
> >>>     of SBI calls whenever we have specialized hardware (such as
> >>> RISC-V AIA
> >>>     IMSIC and RISC-V SWI) which allows S-mode software to directly
> >>> inject
> >>>     IPIs without any assistance from M-mode runtime firmware.
> >>
> >> [...]
> >>
> >> I'm queuing patches 3 and 9 via the irqchip tree as they are
> >> standalone.
> >>
> >> For the rest, I need an Ack from the riscv maintainers as they change
> >> a large amount of arch-specific code, and the couple of irqchip
> >> patches depend on these changes.
> >>
> >> Palmer, Paul?
> >
> > I haven't gotten time to give this a proper review, but I think we've
> > got enough of a mess with our interrupt handling that it doesn't
> > really matter so
> >
> > Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
> >
> > if you want to take it for this cycle that's fine with me, but I'm
> > also fine holding off so it can have a while to bake in linux-next --
> > there's no real rush for any of this, as there's no hardware yet.
>
> Letting this sort of things simmering in -next is the way.
>
> Now that the basic dependencies are on their way, I'd expect this to be
> rebased on 6.3-rc1, and we can then put the whole thing in -next.

Okay, I will rebase on 6.3-rc1 whenever it is available.

Thanks,
Anup

>
> Thanks,
>
>          M.
> --
> Jazz is not dead. It just smells funny...