riscv: Support irq_work via self IPIs

Support for arch_irq_work_raise() and arch_irq_work_has_interrupt() was
missing from riscv (a prerequisite for FULL_NOHZ).

Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

diff --git a/arch/riscv/include/asm/irq_work.h b/arch/riscv/include/asm/irq_work.h
new file mode 100644 (file)
index 0000000..d6c2779
--- /dev/null
+++ b/arch/riscv/include/asm/irq_work.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_IRQ_WORK_H
+#define _ASM_RISCV_IRQ_WORK_H
+
+static inline bool arch_irq_work_has_interrupt(void)
+{
+       return true;
+}
+extern void arch_irq_work_raise(void);
+#endif /* _ASM_RISCV_IRQ_WORK_H */

diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index b1d4f45..554b0fb 100644 (file)
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -16,6 +16,7 @@
 #include <linux/sched.h>
 #include <linux/seq_file.h>
 #include <linux/delay.h>
+#include <linux/irq_work.h>
 
 #include <asm/clint.h>
 #include <asm/sbi.h>
@@ -26,6 +27,7 @@ enum ipi_message_type {
        IPI_RESCHEDULE,
        IPI_CALL_FUNC,
        IPI_CPU_STOP,
+       IPI_IRQ_WORK,
        IPI_MAX
 };
 
@@ -123,6 +125,13 @@ static inline void clear_ipi(void)
                clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id()));
 }
 
+#ifdef CONFIG_IRQ_WORK
+void arch_irq_work_raise(void)
+{
+       send_ipi_single(smp_processor_id(), IPI_IRQ_WORK);
+}
+#endif
+
 void handle_IPI(struct pt_regs *regs)
 {
        struct pt_regs *old_regs = set_irq_regs(regs);
@@ -158,6 +167,11 @@ void handle_IPI(struct pt_regs *regs)
                        ipi_stop();
                }
 
+               if (ops & (1 << IPI_IRQ_WORK)) {
+                       stats[IPI_IRQ_WORK]++;
+                       irq_work_run();
+               }
+
                BUG_ON((ops >> IPI_MAX) != 0);
 
                /* Order data access and bit testing. */
@@ -173,6 +187,7 @@ static const char * const ipi_names[] = {
        [IPI_RESCHEDULE]        = "Rescheduling interrupts",
        [IPI_CALL_FUNC]         = "Function call interrupts",
        [IPI_CPU_STOP]          = "CPU stop interrupts",
+       [IPI_IRQ_WORK]          = "IRQ work interrupts",
 };
 
 void show_ipi_stats(struct seq_file *p, int prec)