From b62e0ce76098d53c875f0aff70776f08418ccb58 Mon Sep 17 00:00:00 2001 From: Andrew Jones Date: Wed, 24 Apr 2024 16:28:09 +0200 Subject: [PATCH] target/riscv: Raise exceptions on wrs.nto MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Implementing wrs.nto to always just return is consistent with the specification, as the instruction is permitted to terminate the stall for any reason, but it's not useful for virtualization, where we'd like the guest to trap to the hypervisor in order to allow scheduling of the lock holding VCPU. Change to always immediately raise exceptions when the appropriate conditions are present, otherwise continue to just return. Note, immediately raising exceptions is also consistent with the specification since the time limit that should expire prior to the exception is implementation-specific. Signed-off-by: Andrew Jones Reviewed-by: Christoph Müllner Reviewed-by: Daniel Henrique Barboza Reviewed-by: Alistair Francis Message-ID: <20240424142808.62936-2-ajones@ventanamicro.com> Signed-off-by: Alistair Francis --- target/riscv/helper.h | 1 + target/riscv/insn_trans/trans_rvzawrs.c.inc | 29 ++++++++++++++------- target/riscv/op_helper.c | 11 ++++++++ 3 files changed, 32 insertions(+), 9 deletions(-) diff --git a/target/riscv/helper.h b/target/riscv/helper.h index 8a63523851..451261ce5a 100644 --- a/target/riscv/helper.h +++ b/target/riscv/helper.h @@ -132,6 +132,7 @@ DEF_HELPER_6(csrrw_i128, tl, env, int, tl, tl, tl, tl) DEF_HELPER_1(sret, tl, env) DEF_HELPER_1(mret, tl, env) DEF_HELPER_1(wfi, void, env) +DEF_HELPER_1(wrs_nto, void, env) DEF_HELPER_1(tlb_flush, void, env) DEF_HELPER_1(tlb_flush_all, void, env) /* Native Debug */ diff --git a/target/riscv/insn_trans/trans_rvzawrs.c.inc b/target/riscv/insn_trans/trans_rvzawrs.c.inc index 32efbff4d5..0eef033838 100644 --- a/target/riscv/insn_trans/trans_rvzawrs.c.inc +++ b/target/riscv/insn_trans/trans_rvzawrs.c.inc @@ -16,7 +16,7 @@ * this program. If not, see . */ -static bool trans_wrs(DisasContext *ctx) +static bool trans_wrs_sto(DisasContext *ctx, arg_wrs_sto *a) { if (!ctx->cfg_ptr->ext_zawrs) { return false; @@ -40,12 +40,23 @@ static bool trans_wrs(DisasContext *ctx) return true; } -#define GEN_TRANS_WRS(insn) \ -static bool trans_ ## insn(DisasContext *ctx, arg_ ## insn *a) \ -{ \ - (void)a; \ - return trans_wrs(ctx); \ -} +static bool trans_wrs_nto(DisasContext *ctx, arg_wrs_nto *a) +{ + if (!ctx->cfg_ptr->ext_zawrs) { + return false; + } -GEN_TRANS_WRS(wrs_nto) -GEN_TRANS_WRS(wrs_sto) + /* + * Depending on the mode of execution, mstatus.TW and hstatus.VTW, wrs.nto + * should raise an exception when the implementation-specific bounded time + * limit has expired. Our time limit is zero, so we either return + * immediately, as does our implementation of wrs.sto, or raise an + * exception, as handled by the wrs.nto helper. + */ +#ifndef CONFIG_USER_ONLY + gen_helper_wrs_nto(tcg_env); +#endif + + /* We only get here when helper_wrs_nto() doesn't raise an exception. */ + return trans_wrs_sto(ctx, NULL); +} diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c index f414aaebdb..2baf5bc3ca 100644 --- a/target/riscv/op_helper.c +++ b/target/riscv/op_helper.c @@ -380,6 +380,17 @@ void helper_wfi(CPURISCVState *env) } } +void helper_wrs_nto(CPURISCVState *env) +{ + if (env->virt_enabled && (env->priv == PRV_S || env->priv == PRV_U) && + get_field(env->hstatus, HSTATUS_VTW) && + !get_field(env->mstatus, MSTATUS_TW)) { + riscv_raise_exception(env, RISCV_EXCP_VIRT_INSTRUCTION_FAULT, GETPC()); + } else if (env->priv != PRV_M && get_field(env->mstatus, MSTATUS_TW)) { + riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC()); + } +} + void helper_tlb_flush(CPURISCVState *env) { CPUState *cs = env_cpu(env);