Commit fb0f3d28 authored by Anup Patel's avatar Anup Patel Committed by Marc Zyngier
Browse files

RISC-V: Allow marking IPIs as suitable for remote FENCEs 



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: default avatarAnup Patel <apatel@ventanamicro.com>
Reviewed-by: default avatarAtish Patra <atishp@rivosinc.com>
Acked-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230328035223.1480939-5-apatel@ventanamicro.com
parent 832f15f4

arch/riscv/include/asm/smp.h

+16 −2
Original line number Diff line number Diff line
@@ -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)

arch/riscv/kernel/sbi-ipi.c

+1 −1
Original line number Diff line number Diff line
@@ -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");

}

arch/riscv/kernel/smp.c

+10 −1
Original line number Diff line number Diff line
@@ -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[] = {

drivers/clocksource/timer-clint.c

+1 −1
Original line number Diff line number Diff line
@@ -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