Unverified Commit 7977448b authored by Clément Léger's avatar Clément Léger Committed by Palmer Dabbelt
Browse files

riscv: misaligned: add a function to check misalign trap delegability 



Checking for the delegability of the misaligned access trap is needed
for the KVM FWFT extension implementation. Add a function to get the
delegability of the misaligned trap exception.

Signed-off-by: default avatarClément Léger <cleger@rivosinc.com>
Reviewed-by: default avatarAndrew Jones <ajones@ventanamicro.com>
Reviewed-by: default avatarCharlie Jenkins <charlie@rivosinc.com>
Tested-by: default avatarCharlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20250523101932.1594077-11-cleger@rivosinc.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@dabbelt.com>
parent 4eaaa65e

arch/riscv/include/asm/cpufeature.h

+6 −0
Original line number Diff line number Diff line
@@ -81,6 +81,12 @@ static inline bool unaligned_ctl_available(void) 


#if defined(CONFIG_RISCV_MISALIGNED)

DECLARE_PER_CPU(long, misaligned_access_speed);

bool misaligned_traps_can_delegate(void);

#else

static inline bool misaligned_traps_can_delegate(void)

{

	return false;

}

#endif



bool __init check_vector_unaligned_access_emulated_all_cpus(void);

arch/riscv/kernel/traps_misaligned.c

+15 −2
Original line number Diff line number Diff line
@@ -724,10 +724,10 @@ static int cpu_online_check_unaligned_access_emulated(unsigned int cpu) 
}

#endif



#ifdef CONFIG_RISCV_SBI



static bool misaligned_traps_delegated;



#ifdef CONFIG_RISCV_SBI



static int cpu_online_sbi_unaligned_setup(unsigned int cpu)

{

	if (sbi_fwft_set(SBI_FWFT_MISALIGNED_EXC_DELEG, 1, 0) &&
@@ -763,6 +763,7 @@ static int cpu_online_sbi_unaligned_setup(unsigned int cpu __always_unused) 
{

	return 0;

}



#endif



int cpu_online_unaligned_access_init(unsigned int cpu)
@@ -775,3 +776,15 @@ int cpu_online_unaligned_access_init(unsigned int cpu) 


	return cpu_online_check_unaligned_access_emulated(cpu);

}



bool misaligned_traps_can_delegate(void)

{

	/*

	 * Either we successfully requested misaligned traps delegation for all

	 * CPUs, or the SBI does not implement the FWFT extension but delegated

	 * the exception by default.

	 */

	return misaligned_traps_delegated ||

	       all_cpus_unaligned_scalar_access_emulated();

}

EXPORT_SYMBOL_GPL(misaligned_traps_can_delegate);