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[201.69.66.110]) by smtp.gmail.com with ESMTPSA id j15-20020a9d7f0f000000b006b5887ba78fsm6002203otq.81.2023.06.29.15.04.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 29 Jun 2023 15:04:33 -0700 (PDT) Message-ID: <8d54c842-fd7a-0e9d-3835-10599d7de5c2@ventanamicro.com> Date: Thu, 29 Jun 2023 19:04:28 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v6 11/20] target/riscv/cpu: add misa_ext_info_arr[] Content-Language: en-US To: Andrew Jones Cc: qemu-devel@nongnu.org, qemu-riscv@nongnu.org, alistair.francis@wdc.com, bmeng@tinylab.org, liweiwei@iscas.ac.cn, zhiwei_liu@linux.alibaba.com, palmer@rivosinc.com, philmd@linaro.org References: <20230628213033.170315-1-dbarboza@ventanamicro.com> <20230628213033.170315-12-dbarboza@ventanamicro.com> <20230629-6a932f8d5f71fefc9afbd974@orel> From: Daniel Henrique Barboza In-Reply-To: <20230629-6a932f8d5f71fefc9afbd974@orel> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::32a; envelope-from=dbarboza@ventanamicro.com; helo=mail-ot1-x32a.google.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 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, NICE_REPLY_A=-0.093, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-riscv@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-riscv-bounces+qemu-riscv=archiver.kernel.org@nongnu.org Sender: qemu-riscv-bounces+qemu-riscv=archiver.kernel.org@nongnu.org Drew, On 6/29/23 05:59, Andrew Jones wrote: > On Wed, Jun 28, 2023 at 06:30:24PM -0300, Daniel Henrique Barboza wrote: >> Next patch will add KVM specific user properties for both MISA and >> multi-letter extensions. For MISA extensions we want to make use of what >> is already available in misa_ext_cfgs[] to avoid code repetition. >> >> misa_ext_info_arr[] array will hold name and description for each MISA >> extension that misa_ext_cfgs[] is declaring. We'll then use this new >> array in KVM code to avoid duplicating strings. >> >> There's nothing holding us back from doing the same with multi-letter >> extensions. For now doing just with MISA extensions is enough. >> >> Suggested-by: Andrew Jones >> Signed-off-by: Daniel Henrique Barboza >> --- >> target/riscv/cpu.c | 83 ++++++++++++++++++++++++++++++---------------- >> target/riscv/cpu.h | 7 +++- >> 2 files changed, 61 insertions(+), 29 deletions(-) >> >> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c >> index 2485e820f8..90dd2078ae 100644 >> --- a/target/riscv/cpu.c >> +++ b/target/riscv/cpu.c >> @@ -1558,33 +1558,57 @@ static void cpu_get_misa_ext_cfg(Object *obj, Visitor *v, const char *name, >> visit_type_bool(v, name, &value, errp); >> } >> >> -static const RISCVCPUMisaExtConfig misa_ext_cfgs[] = { >> - {.name = "a", .description = "Atomic instructions", >> - .misa_bit = RVA, .enabled = true}, >> - {.name = "c", .description = "Compressed instructions", >> - .misa_bit = RVC, .enabled = true}, >> - {.name = "d", .description = "Double-precision float point", >> - .misa_bit = RVD, .enabled = true}, >> - {.name = "f", .description = "Single-precision float point", >> - .misa_bit = RVF, .enabled = true}, >> - {.name = "i", .description = "Base integer instruction set", >> - .misa_bit = RVI, .enabled = true}, >> - {.name = "e", .description = "Base integer instruction set (embedded)", >> - .misa_bit = RVE, .enabled = false}, >> - {.name = "m", .description = "Integer multiplication and division", >> - .misa_bit = RVM, .enabled = true}, >> - {.name = "s", .description = "Supervisor-level instructions", >> - .misa_bit = RVS, .enabled = true}, >> - {.name = "u", .description = "User-level instructions", >> - .misa_bit = RVU, .enabled = true}, >> - {.name = "h", .description = "Hypervisor", >> - .misa_bit = RVH, .enabled = true}, >> - {.name = "x-j", .description = "Dynamic translated languages", >> - .misa_bit = RVJ, .enabled = false}, >> - {.name = "v", .description = "Vector operations", >> - .misa_bit = RVV, .enabled = false}, >> - {.name = "g", .description = "General purpose (IMAFD_Zicsr_Zifencei)", >> - .misa_bit = RVG, .enabled = false}, >> +typedef struct misa_ext_info { >> + const char *name; >> + const char *description; >> +} MISAExtInfo; >> + >> +#define MISA_EXT_INFO(_idx, _propname, _descr) \ >> + [(_idx - 'A')] = {.name = _propname, .description = _descr} > > We don't have to give up on passing RV* to this macro. Directly > using __builtin_ctz() with a constant should work, i.e. > > #define MISA_EXT_INFO(_bit, _propname, _descr) \ > [__builtin_ctz(_bit)] = {.name = _propname, .description = _descr} > > and then > > MISA_EXT_INFO(RVA, "a", "Atomic instructions"), > MISA_EXT_INFO(RVD, "d", "Double-precision float point"), > ... > > (We don't need the ctz32() wrapper since we know we'll never input zero to > __builtin_ctz().) I run the series through gitlab because I got worried about this change in different compilers and so on. And in fact I fear that we break 'clang-user' with it: https://gitlab.com/danielhb/qemu/-/jobs/4569265199 u.c.o -c ../target/riscv/cpu.c ../target/riscv/cpu.c:1624:5: error: initializer element is not a compile-time constant MISA_CFG(RVA, true), ^~~~~~~~~~~~~~~~~~~ ../target/riscv/cpu.c:1619:53: note: expanded from macro 'MISA_CFG' {.name = misa_ext_info_arr[MISA_INFO_IDX(_bit)].name, \ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~ 1 error generated. [1503/2619] Compiling C object libqemu-ppc64le-linux-user.fa.p/linux-user_syscall.c.o Which is a shame because gcc and everyone else is okay with it, but 'clang-user' and 'tsan-build' runners are complaining about it. Unless there's a directive to make clang accept this code (I didn't find any) we'll need to keep updating name and description during runtime, and we'll have to keep removing 'const' from misa_ext_cfgs[]. Thanks, Daniel > >> + >> +static const MISAExtInfo misa_ext_info_arr[] = { >> + MISA_EXT_INFO('A', "a", "Atomic instructions"), >> + MISA_EXT_INFO('C', "c", "Compressed instructions"), >> + MISA_EXT_INFO('D', "d", "Double-precision float point"), >> + MISA_EXT_INFO('F', "f", "Single-precision float point"), >> + MISA_EXT_INFO('I', "i", "Base integer instruction set"), >> + MISA_EXT_INFO('E', "e", "Base integer instruction set (embedded)"), >> + MISA_EXT_INFO('M', "m", "Integer multiplication and division"), >> + MISA_EXT_INFO('S', "s", "Supervisor-level instructions"), >> + MISA_EXT_INFO('U', "u", "User-level instructions"), >> + MISA_EXT_INFO('H', "h", "Hypervisor"), >> + MISA_EXT_INFO('J', "x-j", "Dynamic translated languages"), >> + MISA_EXT_INFO('V', "v", "Vector operations"), >> + MISA_EXT_INFO('G', "g", "General purpose (IMAFD_Zicsr_Zifencei)"), >> +}; >> + >> +const char *riscv_get_misa_ext_name(uint32_t bit) >> +{ >> + return misa_ext_info_arr[ctz32(bit)].name; >> +} >> + >> +const char *riscv_get_misa_ext_descr(uint32_t bit) > > nit: I'd prefer riscv_get_misa_ext_description() for the name. > >> +{ >> + return misa_ext_info_arr[ctz32(bit)].description; >> +} >> + >> +#define MISA_CFG(_bit, _enabled) \ >> + {.misa_bit = _bit, .enabled = _enabled} >> + >> +static RISCVCPUMisaExtConfig misa_ext_cfgs[] = { >> + MISA_CFG(RVA, true), >> + MISA_CFG(RVC, true), >> + MISA_CFG(RVD, true), >> + MISA_CFG(RVF, true), >> + MISA_CFG(RVI, true), >> + MISA_CFG(RVE, false), >> + MISA_CFG(RVM, true), >> + MISA_CFG(RVS, true), >> + MISA_CFG(RVU, true), >> + MISA_CFG(RVH, true), >> + MISA_CFG(RVJ, false), >> + MISA_CFG(RVV, false), >> + MISA_CFG(RVG, false), >> }; >> >> static void riscv_cpu_add_misa_properties(Object *cpu_obj) >> @@ -1592,7 +1616,10 @@ static void riscv_cpu_add_misa_properties(Object *cpu_obj) >> int i; >> >> for (i = 0; i < ARRAY_SIZE(misa_ext_cfgs); i++) { >> - const RISCVCPUMisaExtConfig *misa_cfg = &misa_ext_cfgs[i]; >> + RISCVCPUMisaExtConfig *misa_cfg = &misa_ext_cfgs[i]; >> + >> + misa_cfg->name = riscv_get_misa_ext_name(misa_cfg->misa_bit); >> + misa_cfg->description = riscv_get_misa_ext_descr(misa_cfg->misa_bit); > > This might be necessary for the KVM side, but we should be able to avoid > this runtime setting here where the compiler can be certain everything is > a constant. We just need the old MISA_CFG() back, slightly tweaked to use > __builtin_ctz(). > >> >> object_property_add(cpu_obj, misa_cfg->name, "bool", >> cpu_get_misa_ext_cfg, >> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h >> index cc20ee25a7..acae118b9b 100644 >> --- a/target/riscv/cpu.h >> +++ b/target/riscv/cpu.h >> @@ -41,7 +41,10 @@ >> >> #define RV(x) ((target_ulong)1 << (x - 'A')) >> >> -/* Consider updating misa_ext_cfgs[] when adding new MISA bits here */ >> +/* >> + * Consider updating misa_ext_info_arr[] and misa_ext_cfgs[] >> + * when adding new MISA bits here. >> + */ >> #define RVI RV('I') >> #define RVE RV('E') /* E and I are mutually exclusive */ >> #define RVM RV('M') >> @@ -56,6 +59,8 @@ >> #define RVJ RV('J') >> #define RVG RV('G') >> >> +const char *riscv_get_misa_ext_name(uint32_t bit); >> +const char *riscv_get_misa_ext_descr(uint32_t bit); >> >> /* Privileged specification version */ >> enum { >> -- >> 2.41.0 >> > > Thanks, > drew