From d379c748a30dce4bc6114111a5d6c0acec9c05a7 Mon Sep 17 00:00:00 2001 From: Daniel Henrique Barboza Date: Mon, 18 Dec 2023 09:53:12 -0300 Subject: [PATCH] target/riscv: add rv64i CPU We don't have any form of a 'bare bones' CPU. rv64, our default CPUs, comes with a lot of defaults. This is fine for most regular uses but it's not suitable when more control of what is actually loaded in the CPU is required. A bare-bones CPU would be annoying to deal with if not by profile support, a way to load a multitude of extensions with a single flag. Profile support is going to be implemented shortly, so let's add a CPU for it. The new 'rv64i' CPU will have only RVI loaded. It is inspired in the profile specification that dictates, for RVA22U64 [1]: "RVA22U64 Mandatory Base RV64I is the mandatory base ISA for RVA22U64" And so it seems that RV64I is the mandatory base ISA for all profiles listed in [1], making it an ideal CPU to use with profile support. rv64i is a CPU of type TYPE_RISCV_BARE_CPU. It has a mix of features from pre-existent CPUs: - it allows extensions to be enabled, like generic CPUs; - it will not inherit extension defaults, like vendor CPUs. This is the minimum extension set to boot OpenSBI and buildroot using rv64i: ./build/qemu-system-riscv64 -nographic -M virt \ -cpu rv64i,sv39=true,g=true,c=true,s=true,u=true Our minimal riscv,isa in this case will be: # cat /proc/device-tree/cpus/cpu@0/riscv,isa rv64imafdc_zicntr_zicsr_zifencei_zihpm_zca_zcd# [1] https://github.com/riscv/riscv-profiles/blob/main/profiles.adoc Signed-off-by: Daniel Henrique Barboza Reviewed-by: Andrew Jones Reviewed-by: Alistair Francis Message-ID: <20231218125334.37184-5-dbarboza@ventanamicro.com> Signed-off-by: Alistair Francis --- target/riscv/cpu-qom.h | 2 ++ target/riscv/cpu.c | 46 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 48 insertions(+) diff --git a/target/riscv/cpu-qom.h b/target/riscv/cpu-qom.h index ca7dd509e3..4d1aa54311 100644 --- a/target/riscv/cpu-qom.h +++ b/target/riscv/cpu-qom.h @@ -24,6 +24,7 @@ #define TYPE_RISCV_CPU "riscv-cpu" #define TYPE_RISCV_DYNAMIC_CPU "riscv-dynamic-cpu" #define TYPE_RISCV_VENDOR_CPU "riscv-vendor-cpu" +#define TYPE_RISCV_BARE_CPU "riscv-bare-cpu" #define RISCV_CPU_TYPE_SUFFIX "-" TYPE_RISCV_CPU #define RISCV_CPU_TYPE_NAME(name) (name RISCV_CPU_TYPE_SUFFIX) @@ -33,6 +34,7 @@ #define TYPE_RISCV_CPU_BASE32 RISCV_CPU_TYPE_NAME("rv32") #define TYPE_RISCV_CPU_BASE64 RISCV_CPU_TYPE_NAME("rv64") #define TYPE_RISCV_CPU_BASE128 RISCV_CPU_TYPE_NAME("x-rv128") +#define TYPE_RISCV_CPU_RV64I RISCV_CPU_TYPE_NAME("rv64i") #define TYPE_RISCV_CPU_IBEX RISCV_CPU_TYPE_NAME("lowrisc-ibex") #define TYPE_RISCV_CPU_SHAKTI_C RISCV_CPU_TYPE_NAME("shakti-c") #define TYPE_RISCV_CPU_SIFIVE_E31 RISCV_CPU_TYPE_NAME("sifive-e31") diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c index bf0235305e..33d25d12a6 100644 --- a/target/riscv/cpu.c +++ b/target/riscv/cpu.c @@ -371,6 +371,17 @@ static void set_satp_mode_max_supported(RISCVCPU *cpu, /* Set the satp mode to the max supported */ static void set_satp_mode_default_map(RISCVCPU *cpu) { + /* + * Bare CPUs do not default to the max available. + * Users must set a valid satp_mode in the command + * line. + */ + if (object_dynamic_cast(OBJECT(cpu), TYPE_RISCV_BARE_CPU) != NULL) { + warn_report("No satp mode set. Defaulting to 'bare'"); + cpu->cfg.satp_mode.map = (1 << VM_1_10_MBARE); + return; + } + cpu->cfg.satp_mode.map = cpu->cfg.satp_mode.supported; } #endif @@ -553,6 +564,28 @@ static void rv128_base_cpu_init(Object *obj) set_satp_mode_max_supported(RISCV_CPU(obj), VM_1_10_SV57); #endif } + +static void rv64i_bare_cpu_init(Object *obj) +{ + CPURISCVState *env = &RISCV_CPU(obj)->env; + riscv_cpu_set_misa(env, MXL_RV64, RVI); + + /* Remove the defaults from the parent class */ + RISCV_CPU(obj)->cfg.ext_zicntr = false; + RISCV_CPU(obj)->cfg.ext_zihpm = false; + + /* Set to QEMU's first supported priv version */ + env->priv_ver = PRIV_VERSION_1_10_0; + + /* + * Support all available satp_mode settings. The default + * value will be set to MBARE if the user doesn't set + * satp_mode manually (see set_satp_mode_default()). + */ +#ifndef CONFIG_USER_ONLY + set_satp_mode_max_supported(RISCV_CPU(obj), VM_1_10_SV64); +#endif +} #else static void rv32_base_cpu_init(Object *obj) { @@ -1755,6 +1788,13 @@ char *riscv_isa_string(RISCVCPU *cpu) .instance_init = initfn \ } +#define DEFINE_BARE_CPU(type_name, initfn) \ + { \ + .name = type_name, \ + .parent = TYPE_RISCV_BARE_CPU, \ + .instance_init = initfn \ + } + static const TypeInfo riscv_cpu_type_infos[] = { { .name = TYPE_RISCV_CPU, @@ -1777,6 +1817,11 @@ static const TypeInfo riscv_cpu_type_infos[] = { .parent = TYPE_RISCV_CPU, .abstract = true, }, + { + .name = TYPE_RISCV_BARE_CPU, + .parent = TYPE_RISCV_CPU, + .abstract = true, + }, DEFINE_DYNAMIC_CPU(TYPE_RISCV_CPU_ANY, riscv_any_cpu_init), DEFINE_DYNAMIC_CPU(TYPE_RISCV_CPU_MAX, riscv_max_cpu_init), #if defined(TARGET_RISCV32) @@ -1793,6 +1838,7 @@ static const TypeInfo riscv_cpu_type_infos[] = { DEFINE_VENDOR_CPU(TYPE_RISCV_CPU_THEAD_C906, rv64_thead_c906_cpu_init), DEFINE_VENDOR_CPU(TYPE_RISCV_CPU_VEYRON_V1, rv64_veyron_v1_cpu_init), DEFINE_DYNAMIC_CPU(TYPE_RISCV_CPU_BASE128, rv128_base_cpu_init), + DEFINE_BARE_CPU(TYPE_RISCV_CPU_RV64I, rv64i_bare_cpu_init), #endif }; -- 2.30.2