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Thu, 08 Apr 2021 21:24:57 -0700 (PDT) MIME-Version: 1.0 References: <3d2dbabe5d5e25c1c88b9fda0bbdd5f154b2993e.1617367533.git.alistair.francis@wdc.com> In-Reply-To: <3d2dbabe5d5e25c1c88b9fda0bbdd5f154b2993e.1617367533.git.alistair.francis@wdc.com> From: Bin Meng Date: Fri, 9 Apr 2021 12:24:44 +0800 Message-ID: Subject: Re: [PATCH v1 5/8] target/riscv: Implementation of enhanced PMP (ePMP) To: Alistair Francis Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2607:f8b0:4864:20::b2a; envelope-from=bmeng.cn@gmail.com; helo=mail-yb1-xb2a.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: weiying_hou@outlook.com, "open list:RISC-V" , Ethan.Lee.QNL@gmail.com, "qemu-devel@nongnu.org Developers" , Palmer Dabbelt , Alistair Francis , camiyoru@gmail.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Apr 2, 2021 at 8:50 PM Alistair Francis wrote: > > From: Hou Weiying > > This commit adds support for ePMP v0.9.1. > > The ePMP spec can be found in: > https://docs.google.com/document/d/1Mh_aiHYxemL0umN3GTTw8vsbmzHZ_nxZXgjgOUzbvc8 > > Signed-off-by: Hongzheng-Li > Signed-off-by: Hou Weiying > Signed-off-by: Myriad-Dreamin > Message-Id: > [ Changes by AF: > - Rebase on master > - Update to latest spec > - Use a switch case to handle ePMP MML permissions > - Fix a few bugs > ] > Signed-off-by: Alistair Francis > --- > target/riscv/pmp.c | 165 +++++++++++++++++++++++++++++++++++++++++---- > 1 file changed, 153 insertions(+), 12 deletions(-) > > diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c > index 1d071b044b..3794c808e8 100644 > --- a/target/riscv/pmp.c > +++ b/target/riscv/pmp.c > @@ -90,11 +90,42 @@ static inline uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t pmp_index) > static void pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val) > { > if (pmp_index < MAX_RISCV_PMPS) { > - if (!pmp_is_locked(env, pmp_index)) { > - env->pmp_state.pmp[pmp_index].cfg_reg = val; > - pmp_update_rule(env, pmp_index); > + bool locked = true; > + > + if (riscv_feature(env, RISCV_FEATURE_EPMP)) { > + /* mseccfg.RLB is set */ > + if (MSECCFG_RLB_ISSET(env)) { > + locked = false; > + } > + > + /* mseccfg.MML is not set */ > + if (!MSECCFG_MML_ISSET(env) && !pmp_is_locked(env, pmp_index)) { > + locked = false; > + } > + > + /* mseccfg.MML is set */ > + if (MSECCFG_MML_ISSET(env)) { > + /* not adding execute bit */ > + if ((val & PMP_LOCK) != 0 && (val & PMP_EXEC) != PMP_EXEC) { > + locked = false; > + } > + /* shared region and not adding X bit*/ nits: /* is not aligned, and a space is needed before */ > + if ((val & PMP_LOCK) != PMP_LOCK && > + (val & 0x7) != (PMP_WRITE | PMP_EXEC)) { > + locked = false; > + } > + } > } else { > + if (!pmp_is_locked(env, pmp_index)) { > + locked = false; > + } > + } > + > + if (locked) { > qemu_log_mask(LOG_GUEST_ERROR, "ignoring pmpcfg write - locked\n"); > + } else { > + env->pmp_state.pmp[pmp_index].cfg_reg = val; > + pmp_update_rule(env, pmp_index); > } > } else { > qemu_log_mask(LOG_GUEST_ERROR, > @@ -217,6 +248,33 @@ static bool pmp_hart_has_privs_default(CPURISCVState *env, target_ulong addr, > { > bool ret; > > + if (riscv_feature(env, RISCV_FEATURE_EPMP)) { > + if (MSECCFG_MMWP_ISSET(env)) { > + /* > + * The Machine Mode Whitelist Policy (mseccfg.MMWP) is set > + * so we default to deny all, even for M mode. nits: M-mode > + */ > + *allowed_privs = 0; > + return false; > + } else if (MSECCFG_MML_ISSET(env)) { > + /* > + * The Machine Mode Lockdown (mseccfg.MML) bit is set > + * so we can only execute code in M mode with an applicable nits: M-mode > + * rule. > + * Other modes are disabled. nits: this line can be put in the same line of "rule." > + */ > + if (mode == PRV_M && !(privs & PMP_EXEC)) { > + ret = true; > + *allowed_privs = PMP_READ | PMP_WRITE; > + } else { > + ret = false; > + *allowed_privs = 0; > + } > + > + return ret; > + } If I understand the spec correctly, I think we are missing a branch to handle MML unset case, in which RWX is allowed in M-mode. > + } > + > if ((!riscv_feature(env, RISCV_FEATURE_PMP)) || (mode == PRV_M)) { > /* > * Privileged spec v1.10 states if HW doesn't implement any PMP entry > @@ -294,13 +352,94 @@ bool pmp_hart_has_privs(CPURISCVState *env, target_ulong addr, > pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg); > > /* > - * If the PMP entry is not off and the address is in range, do the priv > - * check > + * Convert the PMP permissions to match the truth table in the > + * ePMP spec. > */ > + const uint8_t epmp_operation = > + ((env->pmp_state.pmp[i].cfg_reg & PMP_LOCK) >> 4) | > + ((env->pmp_state.pmp[i].cfg_reg & PMP_READ) << 2) | > + (env->pmp_state.pmp[i].cfg_reg & PMP_WRITE) | > + ((env->pmp_state.pmp[i].cfg_reg & PMP_EXEC) >> 2); > + > if (((s + e) == 2) && (PMP_AMATCH_OFF != a_field)) { > - *allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC; > - if ((mode != PRV_M) || pmp_is_locked(env, i)) { > - *allowed_privs &= env->pmp_state.pmp[i].cfg_reg; > + /* > + * If the PMP entry is not off and the address is in range, > + * do the priv check > + */ > + if (!MSECCFG_MML_ISSET(env)) { > + /* > + * If mseccfg.MML Bit is not set, do pmp priv check > + * This will always apply to regular PMP. > + */ > + *allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC; > + if ((mode != PRV_M) || pmp_is_locked(env, i)) { > + *allowed_privs &= env->pmp_state.pmp[i].cfg_reg; > + } > + } else { > + /* > + * If mseccfg.MML Bit set, do the enhanced pmp priv check > + */ > + if (mode == PRV_M) { > + switch (epmp_operation) { > + case 0: > + case 1: > + case 4: > + case 5: > + case 6: > + case 7: > + case 8: > + *allowed_privs = 0; > + break; > + case 2: > + case 3: > + case 14: > + *allowed_privs = PMP_READ | PMP_WRITE; > + break; > + case 9: > + case 10: > + *allowed_privs = PMP_EXEC; > + break; > + case 11: > + case 13: > + *allowed_privs = PMP_READ | PMP_EXEC; > + break; > + case 12: > + case 15: > + *allowed_privs = PMP_READ; > + break; > + } > + } else { > + switch (epmp_operation) { > + case 0: > + case 8: > + case 9: > + case 12: > + case 13: > + case 14: > + *allowed_privs = 0; > + break; > + case 1: > + case 10: > + case 11: > + *allowed_privs = PMP_EXEC; > + break; > + case 2: > + case 4: > + case 15: > + *allowed_privs = PMP_READ; > + break; > + case 3: > + case 6: > + *allowed_privs = PMP_READ | PMP_WRITE; > + break; > + case 5: > + *allowed_privs = PMP_READ | PMP_EXEC; > + break; > + case 7: > + *allowed_privs = PMP_READ | PMP_WRITE | PMP_EXEC; > + break; > + } > + } > } > > ret = ((privs & *allowed_privs) == privs); > @@ -328,10 +467,12 @@ void pmpcfg_csr_write(CPURISCVState *env, uint32_t reg_index, > > trace_pmpcfg_csr_write(env->mhartid, reg_index, val); > > - if ((reg_index & 1) && (sizeof(target_ulong) == 8)) { > - qemu_log_mask(LOG_GUEST_ERROR, > - "ignoring pmpcfg write - incorrect address\n"); > - return; > + if (!riscv_feature(env, RISCV_FEATURE_EPMP) || !MSECCFG_RLB_ISSET(env)) { > + if ((reg_index & 1) && (sizeof(target_ulong) == 8)) { > + qemu_log_mask(LOG_GUEST_ERROR, > + "ignoring pmpcfg write - incorrect address\n"); If ePMP RLB is off, this log message is inaccurate and misleading. > + return; > + } > } > > for (i = 0; i < sizeof(target_ulong); i++) { > -- Regards, Bin