From 7977448bf374f6e9592153838f072a89bd3b5c45 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Cl=C3=A9ment=20L=C3=A9ger?= Date: Fri, 23 May 2025 12:19:27 +0200 Subject: [PATCH] riscv: misaligned: add a function to check misalign trap delegability MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: Clément Léger Reviewed-by: Andrew Jones Reviewed-by: Charlie Jenkins Tested-by: Charlie Jenkins Link: https://lore.kernel.org/r/20250523101932.1594077-11-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/cpufeature.h | 6 ++++++ arch/riscv/kernel/traps_misaligned.c | 17 +++++++++++++++-- 2 files changed, 21 insertions(+), 2 deletions(-) diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h index 2bfa4ef383ed..fbd0e4306c93 100644 --- a/arch/riscv/include/asm/cpufeature.h +++ b/arch/riscv/include/asm/cpufeature.h @@ -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); diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c index 7ecaa8103fe7..93043924fe6c 100644 --- a/arch/riscv/kernel/traps_misaligned.c +++ b/arch/riscv/kernel/traps_misaligned.c @@ -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); -- 2.25.1