[RFC PATCH v4 03/10] RISC-V: Allow marking IPIs as suitable for remote FENCEs
From: Anup Patel <hidden>
Date: 2021-10-07 12:37:20
Also in:
linux-riscv, lkml
Subsystem:
risc-v architecture, the rest · Maintainers:
Paul Walmsley, Palmer Dabbelt, Albert Ou, Linus Torvalds
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 RISC-V kernel instead of using SBI calls. The upcoming ACLINT [M|S]SWI devices and AIA IMSIC devices allow direct IPI injection from the RISC-V kernel. To support this, we extend the riscv_ipi_set_virq_range() function so that irqchip drivers can mark IPIs as suitable for remote FENCEs. Signed-off-by: Anup Patel <redacted> --- arch/riscv/include/asm/smp.h | 18 ++++++++++++++++-- arch/riscv/kernel/sbi-ipi.c | 2 +- arch/riscv/kernel/smp.c | 11 ++++++++++- 3 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
index e5480d75b2d9..42569f1130f0 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. */
@@ -47,7 +50,12 @@ 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_irqs); +void riscv_ipi_set_virq_range(int virq, int nr_irqs, 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) /* Secondary hart entry */ asmlinkage void smp_callin(void);
@@ -103,10 +111,16 @@ 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 8d06b1e3d682..2728be0439a2 100644
--- a/arch/riscv/kernel/sbi-ipi.c
+++ b/arch/riscv/kernel/sbi-ipi.c@@ -149,7 +149,7 @@ static int __init sbi_ipi_set_virq(void) return -ENOMEM; } - riscv_ipi_set_virq_range(virq, BITS_PER_LONG); + riscv_ipi_set_virq_range(virq, BITS_PER_LONG, false); return 0; }
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index 53902cd1671f..b9ea5f88ca0e 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c@@ -159,7 +159,10 @@ 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;
@@ -182,6 +185,12 @@ 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); } EXPORT_SYMBOL_GPL(riscv_ipi_set_virq_range);
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2.25.1