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[2001:1ae9:1c2:4c00:20f:c6b4:1e57:7965]) by smtp.gmail.com with ESMTPSA id t15-20020a1709066bcf00b0096f7500502csm6851471ejs.199.2023.06.07.04.48.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Jun 2023 04:48:38 -0700 (PDT) Date: Wed, 7 Jun 2023 13:48:37 +0200 From: Andrew Jones To: Daniel Henrique Barboza 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 Subject: Re: [PATCH 13/16] target/riscv/kvm.c: add multi-letter extension KVM properties Message-ID: <20230607-9a499522ac7de9ebcf0c8699@orel> References: <20230530194623.272652-1-dbarboza@ventanamicro.com> <20230530194623.272652-14-dbarboza@ventanamicro.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230530194623.272652-14-dbarboza@ventanamicro.com> Received-SPF: pass client-ip=2a00:1450:4864:20::632; envelope-from=ajones@ventanamicro.com; helo=mail-ej1-x632.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, 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 On Tue, May 30, 2023 at 04:46:20PM -0300, Daniel Henrique Barboza wrote: > Let's add KVM user properties for the multi-letter extensions that KVM > currently supports: zicbom, zicboz, zihintpause, zbb, ssaia, sstc, > svinval and svpbmt. > > As with the recently added MISA properties we're also going to add a > 'user_set' flag in each of them. The flag will be set only if the user > chose an option that's different from the host and will require extra > handling from the KVM driver. > > However, multi-letter CPUs have more cases to cover than MISA > extensions, so we're adding an extra 'supported' flag as well. This flag > will reflect if a given extension is supported by KVM, i.e. KVM knows > how to handle it. This is determined during KVM extension discovery in > kvm_riscv_init_multiext_cfg(), where we test for EINVAL errors. Any > other error different from EINVAL will cause an abort. I wish that was ENOENT, but I suppose that ship sailed. > > The 'supported' flag will then be used later on to give an exception for > users that are disabling multi-letter extensions that are unknown to > KVM. > > Signed-off-by: Daniel Henrique Barboza > --- > target/riscv/kvm.c | 136 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 136 insertions(+) > > diff --git a/target/riscv/kvm.c b/target/riscv/kvm.c > index bb1dafe263..b4193a10d8 100644 > --- a/target/riscv/kvm.c > +++ b/target/riscv/kvm.c > @@ -202,6 +202,99 @@ static void kvm_riscv_update_cpu_misa_ext(RISCVCPU *cpu, CPUState *cs) > } > } > > +typedef struct RISCVCPUMultiExtConfig { > + const char *name; No description? I'd prefer we use the same cfg struct for single-letter and multi-letter extensions. We can use a union to overlap cpu_cfg_offset and misa_bit. > + int kvm_reg_id; > + int cpu_cfg_offset; > + bool supported; > + bool user_set; > +} RISCVCPUMultiExtConfig; > + > +#define CPUCFG(_prop) offsetof(struct RISCVCPUConfig, _prop) > + > +/* > + * KVM ISA Multi-letter extensions. We care about the order > + * since it'll be used to create the ISA string later on. > + * We follow the same ordering rules of isa_edata_arr[] > + * from target/riscv/cpu.c. > + */ > +static RISCVCPUMultiExtConfig kvm_multi_ext_cfgs[] = { > + {.name = "zicbom", .kvm_reg_id = KVM_RISCV_ISA_EXT_ZICBOM, > + .cpu_cfg_offset = CPUCFG(ext_icbom)}, > + {.name = "zicboz", .kvm_reg_id = KVM_RISCV_ISA_EXT_ZICBOZ, > + .cpu_cfg_offset = CPUCFG(ext_icboz)}, > + {.name = "zihintpause", .kvm_reg_id = KVM_RISCV_ISA_EXT_ZIHINTPAUSE, > + .cpu_cfg_offset = CPUCFG(ext_zihintpause)}, > + {.name = "zbb", .kvm_reg_id = KVM_RISCV_ISA_EXT_ZBB, > + .cpu_cfg_offset = CPUCFG(ext_zbb)}, > + {.name = "ssaia", .kvm_reg_id = KVM_RISCV_ISA_EXT_SSAIA, > + .cpu_cfg_offset = CPUCFG(ext_ssaia)}, > + {.name = "sstc", .kvm_reg_id = KVM_RISCV_ISA_EXT_SSTC, > + .cpu_cfg_offset = CPUCFG(ext_sstc)}, > + {.name = "svinval", .kvm_reg_id = KVM_RISCV_ISA_EXT_SVINVAL, > + .cpu_cfg_offset = CPUCFG(ext_svinval)}, > + {.name = "svpbmt", .kvm_reg_id = KVM_RISCV_ISA_EXT_SVPBMT, > + .cpu_cfg_offset = CPUCFG(ext_svpbmt)}, As pointed out in the last patch, it'd be nice to share names (and descriptions) with TCG. > +}; > + > +static void kvm_cpu_cfg_set(RISCVCPU *cpu, RISCVCPUMultiExtConfig *multi_ext, > + uint32_t val) > +{ > + int cpu_cfg_offset = multi_ext->cpu_cfg_offset; > + bool *ext_enabled = (void *)&cpu->cfg + cpu_cfg_offset; > + > + *ext_enabled = val; > +} > + > +static uint32_t kvm_cpu_cfg_get(RISCVCPU *cpu, > + RISCVCPUMultiExtConfig *multi_ext) > +{ > + int cpu_cfg_offset = multi_ext->cpu_cfg_offset; > + bool *ext_enabled = (void *)&cpu->cfg + cpu_cfg_offset; > + > + return *ext_enabled; > +} > + > +static void kvm_cpu_set_multi_ext_cfg(Object *obj, Visitor *v, > + const char *name, > + void *opaque, Error **errp) > +{ > + RISCVCPUMultiExtConfig *multi_ext_cfg = opaque; > + RISCVCPU *cpu = RISCV_CPU(obj); > + bool value, host_val; > + > + if (!visit_type_bool(v, name, &value, errp)) { > + return; > + } > + > + host_val = kvm_cpu_cfg_get(cpu, multi_ext_cfg); > + > + /* > + * Ignore if the user is setting the same value > + * as the host. > + */ > + if (value == host_val) { > + return; > + } > + > + if (!multi_ext_cfg->supported) { > + /* > + * Error out if the user is trying to enable an > + * extension that KVM doesn't support. Ignore > + * option otherwise. > + */ > + if (value) { > + error_setg(errp, "KVM does not support disabling extension %s", > + multi_ext_cfg->name); > + } > + > + return; > + } > + > + multi_ext_cfg->user_set = true; > + kvm_cpu_cfg_set(cpu, multi_ext_cfg, value); > +} > + > static void kvm_riscv_add_cpu_user_properties(Object *cpu_obj) > { > int i; > @@ -216,6 +309,15 @@ static void kvm_riscv_add_cpu_user_properties(Object *cpu_obj) > object_property_set_description(cpu_obj, misa_cfg->name, > misa_cfg->description); > } > + > + for (i = 0; i < ARRAY_SIZE(kvm_multi_ext_cfgs); i++) { > + RISCVCPUMultiExtConfig *multi_cfg = &kvm_multi_ext_cfgs[i]; > + > + object_property_add(cpu_obj, multi_cfg->name, "bool", > + NULL, You have a getter function, so we might as well set it here, no? > + kvm_cpu_set_multi_ext_cfg, > + NULL, multi_cfg); > + } > } > > static int kvm_riscv_get_regs_core(CPUState *cs) > @@ -531,6 +633,39 @@ static void kvm_riscv_init_misa_ext_mask(RISCVCPU *cpu, > env->misa_ext = env->misa_ext_mask; > } > > +static void kvm_riscv_init_multiext_cfg(RISCVCPU *cpu, KVMScratchCPU *kvmcpu) > +{ > + CPURISCVState *env = &cpu->env; > + uint64_t val; > + int i, ret; > + > + for (i = 0; i < ARRAY_SIZE(kvm_multi_ext_cfgs); i++) { > + RISCVCPUMultiExtConfig *multi_ext_cfg = &kvm_multi_ext_cfgs[i]; > + struct kvm_one_reg reg; > + > + reg.id = kvm_riscv_reg_id(env, KVM_REG_RISCV_ISA_EXT, > + multi_ext_cfg->kvm_reg_id); > + reg.addr = (uint64_t)&val; > + ret = ioctl(kvmcpu->cpufd, KVM_GET_ONE_REG, ®); > + if (ret != 0) { > + if (ret == -EINVAL) { > + /* Silently default to 'false' if KVM does not support it. */ > + multi_ext_cfg->supported = false; > + val = false; > + } else { > + error_report("Unable to read ISA_EXT KVM register %s, " > + "error %d", multi_ext_cfg->name, ret); > + kvm_riscv_destroy_scratch_vcpu(kvmcpu); I don't think we usually bother cleaning up when exiting, we just let exit do it, but OK. > + exit(EXIT_FAILURE); > + } > + } else { > + multi_ext_cfg->supported = true; > + } > + > + kvm_cpu_cfg_set(cpu, multi_ext_cfg, val); > + } > +} > + > void kvm_riscv_init_user_properties(Object *cpu_obj) > { > RISCVCPU *cpu = RISCV_CPU(cpu_obj); > @@ -543,6 +678,7 @@ void kvm_riscv_init_user_properties(Object *cpu_obj) > kvm_riscv_add_cpu_user_properties(cpu_obj); > kvm_riscv_init_machine_ids(cpu, &kvmcpu); > kvm_riscv_init_misa_ext_mask(cpu, &kvmcpu); > + kvm_riscv_init_multiext_cfg(cpu, &kvmcpu); > > kvm_riscv_destroy_scratch_vcpu(&kvmcpu); > } > -- > 2.40.1 > > Thanks, drew