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Sun, 11 Apr 2021 16:04:25 -0700 (PDT) MIME-Version: 1.0 References: <3d2dbabe5d5e25c1c88b9fda0bbdd5f154b2993e.1617367533.git.alistair.francis@wdc.com> In-Reply-To: From: Alistair Francis Date: Mon, 12 Apr 2021 09:03:58 +1000 Message-ID: Subject: Re: [PATCH v1 5/8] target/riscv: Implementation of enhanced PMP (ePMP) To: Bin Meng Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2607:f8b0:4864:20::d29; envelope-from=alistair23@gmail.com; helo=mail-io1-xd29.google.com X-Spam_score_int: -17 X-Spam_score: -1.8 X-Spam_bar: - X-Spam_report: (-1.8 / 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_ENVFROM_END_DIGIT=0.25, 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: Hou Weiying , "open list:RISC-V" , "qemu-devel@nongnu.org Developers" , Hongzheng-Li , Palmer Dabbelt , Alistair Francis , Myriad-Dreamin Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Apr 9, 2021 at 2:24 PM Bin Meng wrote: > > 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. Yep, so if MML and MMWP aren't set then we just fall back to the standard PMP checks which are below. So M-mode accesses will be allowed and other privs won't be. > > > + } > > + > > 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. Thanks, I have fixed this and all the other comments. Alistair > > > + return; > > + } > > } > > > > for (i = 0; i < sizeof(target_ulong); i++) { > > -- > > Regards, > Bin