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Wed, 28 Aug 2024 10:47:50 -0700 (PDT) From: Deepak Gupta To: qemu-riscv@nongnu.org, qemu-devel@nongnu.org Cc: palmer@dabbelt.com, Alistair.Francis@wdc.com, laurent@vivier.eu, bmeng.cn@gmail.com, liwei1518@gmail.com, dbarboza@ventanamicro.com, zhiwei_liu@linux.alibaba.com, jim.shu@sifive.com, andy.chiu@sifive.com, kito.cheng@sifive.com, Deepak Gupta , Richard Henderson Subject: [PATCH v11 04/20] target/riscv: save and restore elp state on priv transitions Date: Wed, 28 Aug 2024 10:47:22 -0700 Message-ID: <20240828174739.714313-5-debug@rivosinc.com> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20240828174739.714313-1-debug@rivosinc.com> References: <20240828174739.714313-1-debug@rivosinc.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::52e; envelope-from=debug@rivosinc.com; helo=mail-pg1-x52e.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org elp state is recorded in *status on trap entry (less privilege to higher privilege) and restored in elp from *status on trap exit (higher to less privilege). Additionally this patch introduces a forward cfi helper function to determine if current privilege has forward cfi is enabled or not based on *envcfg (for U, VU, S, VU, HS) or mseccfg csr (for M). For qemu-user, a new field `ufcfien` is introduced which is by default set to false and helper function returns value deposited in `ufcfien` for qemu-user. Signed-off-by: Deepak Gupta Co-developed-by: Jim Shu Co-developed-by: Andy Chiu Reviewed-by: Richard Henderson --- target/riscv/cpu.h | 1 + target/riscv/cpu_helper.c | 54 +++++++++++++++++++++++++++++++++++++++ target/riscv/op_helper.c | 18 +++++++++++++ 3 files changed, 73 insertions(+) diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h index b2dc419ad0..a7c970e70c 100644 --- a/target/riscv/cpu.h +++ b/target/riscv/cpu.h @@ -531,6 +531,7 @@ void riscv_cpu_set_geilen(CPURISCVState *env, target_ulong geilen); bool riscv_cpu_vector_enabled(CPURISCVState *env); void riscv_cpu_set_virt_enabled(CPURISCVState *env, bool enable); int riscv_env_mmu_index(CPURISCVState *env, bool ifetch); +bool cpu_get_fcfien(CPURISCVState *env); G_NORETURN void riscv_cpu_do_unaligned_access(CPUState *cs, vaddr addr, MMUAccessType access_type, int mmu_idx, uintptr_t retaddr); diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c index 6709622dd3..5f38969aa6 100644 --- a/target/riscv/cpu_helper.c +++ b/target/riscv/cpu_helper.c @@ -33,6 +33,7 @@ #include "cpu_bits.h" #include "debug.h" #include "tcg/oversized-guest.h" +#include "pmp.h" int riscv_env_mmu_index(CPURISCVState *env, bool ifetch) { @@ -63,6 +64,33 @@ int riscv_env_mmu_index(CPURISCVState *env, bool ifetch) #endif } +bool cpu_get_fcfien(CPURISCVState *env) +{ + /* no cfi extension, return false */ + if (!env_archcpu(env)->cfg.ext_zicfilp) { + return false; + } + + switch (env->priv) { + case PRV_U: + if (riscv_has_ext(env, RVS)) { + return env->senvcfg & SENVCFG_LPE; + } + return env->menvcfg & MENVCFG_LPE; +#ifndef CONFIG_USER_ONLY + case PRV_S: + if (env->virt_enabled) { + return env->henvcfg & HENVCFG_LPE; + } + return env->menvcfg & MENVCFG_LPE; + case PRV_M: + return env->mseccfg & MSECCFG_MLPE; +#endif + default: + g_assert_not_reached(); + } +} + void cpu_get_tb_cpu_state(CPURISCVState *env, vaddr *pc, uint64_t *cs_base, uint32_t *pflags) { @@ -546,6 +574,15 @@ void riscv_cpu_swap_hypervisor_regs(CPURISCVState *env) } bool current_virt = env->virt_enabled; + /* + * If zicfilp extension available and henvcfg.LPE = 1, + * then apply SPELP mask on mstatus + */ + if (env_archcpu(env)->cfg.ext_zicfilp && + get_field(env->henvcfg, HENVCFG_LPE)) { + mstatus_mask |= SSTATUS_SPELP; + } + g_assert(riscv_has_ext(env, RVH)); if (current_virt) { @@ -1754,6 +1791,11 @@ void riscv_cpu_do_interrupt(CPUState *cs) if (env->priv <= PRV_S && cause < 64 && (((deleg >> cause) & 1) || s_injected || vs_injected)) { /* handle the trap in S-mode */ + /* save elp status */ + if (cpu_get_fcfien(env)) { + env->mstatus = set_field(env->mstatus, MSTATUS_SPELP, env->elp); + } + if (riscv_has_ext(env, RVH)) { uint64_t hdeleg = async ? env->hideleg : env->hedeleg; @@ -1802,6 +1844,11 @@ void riscv_cpu_do_interrupt(CPUState *cs) riscv_cpu_set_mode(env, PRV_S); } else { /* handle the trap in M-mode */ + /* save elp status */ + if (cpu_get_fcfien(env)) { + env->mstatus = set_field(env->mstatus, MSTATUS_MPELP, env->elp); + } + if (riscv_has_ext(env, RVH)) { if (env->virt_enabled) { riscv_cpu_swap_hypervisor_regs(env); @@ -1833,6 +1880,13 @@ void riscv_cpu_do_interrupt(CPUState *cs) riscv_cpu_set_mode(env, PRV_M); } + /* + * Interrupt/exception/trap delivery is asynchronous event and as per + * zicfilp spec CPU should clear up the ELP state. No harm in clearing + * unconditionally. + */ + env->elp = false; + /* * NOTE: it is not necessary to yield load reservations here. It is only * necessary for an SC from "another hart" to cause a load reservation diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c index 2baf5bc3ca..5848aaf437 100644 --- a/target/riscv/op_helper.c +++ b/target/riscv/op_helper.c @@ -313,6 +313,15 @@ target_ulong helper_sret(CPURISCVState *env) riscv_cpu_set_mode(env, prev_priv); + /* + * If forward cfi enabled for new priv, restore elp status + * and clear spelp in mstatus + */ + if (cpu_get_fcfien(env)) { + env->elp = get_field(env->mstatus, MSTATUS_SPELP); + } + env->mstatus = set_field(env->mstatus, MSTATUS_SPELP, 0); + return retpc; } @@ -357,6 +366,15 @@ target_ulong helper_mret(CPURISCVState *env) riscv_cpu_set_virt_enabled(env, prev_virt); } + /* + * If forward cfi enabled for new priv, restore elp status + * and clear mpelp in mstatus + */ + if (cpu_get_fcfien(env)) { + env->elp = get_field(env->mstatus, MSTATUS_MPELP); + } + env->mstatus = set_field(env->mstatus, MSTATUS_MPELP, 0); + return retpc; }