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[2403:580b:97e8:0:82ce:f179:8a79:69f4]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1f6323e18c7sm62375435ad.177.2024.06.03.04.17.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Jun 2024 04:17:44 -0700 (PDT) From: Alistair Francis X-Google-Original-From: Alistair Francis To: qemu-devel@nongnu.org Cc: alistair23@gmail.com, =?utf-8?q?Christoph_M=C3=BCllner?= , LIU Zhiwei , Alistair Francis Subject: [PULL v2 16/27] riscv: thead: Add th.sxstatus CSR emulation Date: Mon, 3 Jun 2024 21:16:32 +1000 Message-ID: <20240603111643.258712-17-alistair.francis@wdc.com> X-Mailer: git-send-email 2.45.1 In-Reply-To: <20240603111643.258712-1-alistair.francis@wdc.com> References: <20240603111643.258712-1-alistair.francis@wdc.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::631; envelope-from=alistair23@gmail.com; helo=mail-pl1-x631.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, 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, 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 From: Christoph Müllner The th.sxstatus CSR can be used to identify available custom extension on T-Head CPUs. The CSR is documented here: https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadsxstatus.adoc An important property of this patch is, that the th.sxstatus MAEE field is not set (indicating that XTheadMae is not available). XTheadMae is a memory attribute extension (similar to Svpbmt) which is implemented in many T-Head CPUs (C906, C910, etc.) and utilizes bits in PTEs that are marked as reserved. QEMU maintainers prefer to not implement XTheadMae, so we need give kernels a mechanism to identify if XTheadMae is available in a system or not. And this patch introduces this mechanism in QEMU in a way that's compatible with real HW (i.e., probing the th.sxstatus.MAEE bit). Further context can be found on the list: https://lists.gnu.org/archive/html/qemu-devel/2024-02/msg00775.html Reviewed-by: LIU Zhiwei Reviewed-by: Alistair Francis Signed-off-by: Christoph Müllner Message-ID: <20240429073656.2486732-1-christoph.muellner@vrull.eu> Signed-off-by: Alistair Francis --- MAINTAINERS | 1 + target/riscv/cpu.h | 3 ++ target/riscv/cpu.c | 1 + target/riscv/th_csr.c | 79 ++++++++++++++++++++++++++++++++++++++++ target/riscv/meson.build | 1 + 5 files changed, 85 insertions(+) create mode 100644 target/riscv/th_csr.c diff --git a/MAINTAINERS b/MAINTAINERS index 448dc951c5..e9d861e8ef 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -343,6 +343,7 @@ L: qemu-riscv@nongnu.org S: Supported F: target/riscv/insn_trans/trans_xthead.c.inc F: target/riscv/xthead*.decode +F: target/riscv/th_* F: disas/riscv-xthead* RISC-V XVentanaCondOps extension diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h index 04ab0f153a..12d8b5344a 100644 --- a/target/riscv/cpu.h +++ b/target/riscv/cpu.h @@ -826,4 +826,7 @@ target_ulong riscv_new_csr_seed(target_ulong new_value, uint8_t satp_mode_max_from_map(uint32_t map); const char *satp_mode_str(uint8_t satp_mode, bool is_32_bit); +/* Implemented in th_csr.c */ +void th_register_custom_csrs(RISCVCPU *cpu); + #endif /* RISCV_CPU_H */ diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c index abeb50369c..2946ac298a 100644 --- a/target/riscv/cpu.c +++ b/target/riscv/cpu.c @@ -547,6 +547,7 @@ static void rv64_thead_c906_cpu_init(Object *obj) cpu->cfg.mvendorid = THEAD_VENDOR_ID; #ifndef CONFIG_USER_ONLY set_satp_mode_max_supported(cpu, VM_1_10_SV39); + th_register_custom_csrs(cpu); #endif /* inherited from parent obj via riscv_cpu_init() */ diff --git a/target/riscv/th_csr.c b/target/riscv/th_csr.c new file mode 100644 index 0000000000..6c970d4e81 --- /dev/null +++ b/target/riscv/th_csr.c @@ -0,0 +1,79 @@ +/* + * T-Head-specific CSRs. + * + * Copyright (c) 2024 VRULL GmbH + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2 or later, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program. If not, see . + */ + +#include "qemu/osdep.h" +#include "cpu.h" +#include "cpu_vendorid.h" + +#define CSR_TH_SXSTATUS 0x5c0 + +/* TH_SXSTATUS bits */ +#define TH_SXSTATUS_UCME BIT(16) +#define TH_SXSTATUS_MAEE BIT(21) +#define TH_SXSTATUS_THEADISAEE BIT(22) + +typedef struct { + int csrno; + int (*insertion_test)(RISCVCPU *cpu); + riscv_csr_operations csr_ops; +} riscv_csr; + +static RISCVException smode(CPURISCVState *env, int csrno) +{ + if (riscv_has_ext(env, RVS)) { + return RISCV_EXCP_NONE; + } + + return RISCV_EXCP_ILLEGAL_INST; +} + +static int test_thead_mvendorid(RISCVCPU *cpu) +{ + if (cpu->cfg.mvendorid != THEAD_VENDOR_ID) { + return -1; + } + + return 0; +} + +static RISCVException read_th_sxstatus(CPURISCVState *env, int csrno, + target_ulong *val) +{ + /* We don't set MAEE here, because QEMU does not implement MAEE. */ + *val = TH_SXSTATUS_UCME | TH_SXSTATUS_THEADISAEE; + return RISCV_EXCP_NONE; +} + +static riscv_csr th_csr_list[] = { + { + .csrno = CSR_TH_SXSTATUS, + .insertion_test = test_thead_mvendorid, + .csr_ops = { "th.sxstatus", smode, read_th_sxstatus } + } +}; + +void th_register_custom_csrs(RISCVCPU *cpu) +{ + for (size_t i = 0; i < ARRAY_SIZE(th_csr_list); i++) { + int csrno = th_csr_list[i].csrno; + riscv_csr_operations *csr_ops = &th_csr_list[i].csr_ops; + if (!th_csr_list[i].insertion_test(cpu)) { + riscv_set_csr_ops(csrno, csr_ops); + } + } +} diff --git a/target/riscv/meson.build b/target/riscv/meson.build index a5e0734e7f..a4bd61e52a 100644 --- a/target/riscv/meson.build +++ b/target/riscv/meson.build @@ -33,6 +33,7 @@ riscv_system_ss.add(files( 'monitor.c', 'machine.c', 'pmu.c', + 'th_csr.c', 'time_helper.c', 'riscv-qmp-cmds.c', ))