From 0c60c531f53544117f96d508fd9918f78ecf0df5 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Lo=C3=AFc=20Lefort?= Date: Thu, 13 Mar 2025 20:30:10 +0100 Subject: [PATCH] target/riscv: pmp: exit csr writes early if value was not changed MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Signed-off-by: Loïc Lefort Reviewed-by: Daniel Henrique Barboza Reviewed-by: Alistair Francis Reviewed-by: LIU Zhiwei Message-ID: <20250313193011.720075-5-loic@rivosinc.com> Signed-off-by: Alistair Francis --- target/riscv/pmp.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c index 8fc313990a..4070e21ea3 100644 --- a/target/riscv/pmp.c +++ b/target/riscv/pmp.c @@ -142,6 +142,11 @@ static inline uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t pmp_index) static bool pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val) { if (pmp_index < MAX_RISCV_PMPS) { + if (env->pmp_state.pmp[pmp_index].cfg_reg == val) { + /* no change */ + return false; + } + if (pmp_is_readonly(env, pmp_index)) { qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpcfg write - read only\n"); @@ -529,6 +534,11 @@ void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index, bool is_next_cfg_tor = false; if (addr_index < MAX_RISCV_PMPS) { + if (env->pmp_state.pmp[addr_index].addr_reg == val) { + /* no change */ + return; + } + /* * In TOR mode, need to check the lock bit of the next pmp * (if there is a next). @@ -545,14 +555,12 @@ void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index, } if (!pmp_is_readonly(env, addr_index)) { - if (env->pmp_state.pmp[addr_index].addr_reg != val) { - env->pmp_state.pmp[addr_index].addr_reg = val; - pmp_update_rule_addr(env, addr_index); - if (is_next_cfg_tor) { - pmp_update_rule_addr(env, addr_index + 1); - } - tlb_flush(env_cpu(env)); + env->pmp_state.pmp[addr_index].addr_reg = val; + pmp_update_rule_addr(env, addr_index); + if (is_next_cfg_tor) { + pmp_update_rule_addr(env, addr_index + 1); } + tlb_flush(env_cpu(env)); } else { qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpaddr write - read only\n"); -- 2.39.5