Re: [PATCH v2 1/4] LoongArch: Probe more CPU features from CPUCFG

From: Huacai Chen
Date: Fri Sep 13 2024 - 04:48:25 EST

Hi, Jiaxun,

On Fri, Sep 13, 2024 at 4:56 AM Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx> wrote:
>
> Probe ISA level, TLB, IOCSR information from CPUCFG to
> improve kernel resilience to different core implementations.
>
> Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
> ---
> arch/loongarch/include/asm/cpu.h | 4 +++
> arch/loongarch/include/asm/loongarch.h | 3 +-
> arch/loongarch/kernel/cpu-probe.c | 54 ++++++++++++++++++++++++----------
> 3 files changed, 44 insertions(+), 17 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/cpu.h b/arch/loongarch/include/asm/cpu.h
> index 843f9c4ec980..251a15439cff 100644
> --- a/arch/loongarch/include/asm/cpu.h
> +++ b/arch/loongarch/include/asm/cpu.h
> @@ -100,6 +100,8 @@ enum cpu_type_enum {
> #define CPU_FEATURE_HYPERVISOR 25 /* CPU has hypervisor (running in VM) */
> #define CPU_FEATURE_PTW 26 /* CPU has hardware page table walker */
> #define CPU_FEATURE_AVECINT 27 /* CPU has avec interrupt */
> +#define CPU_FEATURE_IOCSR 28 /* CPU has IOCSR */
> +#define CPU_FEATURE_LSPW 29 /* CPU has LSPW */
I don't see LSPW being used, so just remove it now?

>
> #define LOONGARCH_CPU_CPUCFG BIT_ULL(CPU_FEATURE_CPUCFG)
> #define LOONGARCH_CPU_LAM BIT_ULL(CPU_FEATURE_LAM)
> @@ -129,5 +131,7 @@ enum cpu_type_enum {
> #define LOONGARCH_CPU_HYPERVISOR BIT_ULL(CPU_FEATURE_HYPERVISOR)
> #define LOONGARCH_CPU_PTW BIT_ULL(CPU_FEATURE_PTW)
> #define LOONGARCH_CPU_AVECINT BIT_ULL(CPU_FEATURE_AVECINT)
> +#define LOONGARCH_CPU_IOCSR BIT_ULL(CPU_FEATURE_IOCSR)
> +#define LOONGARCH_CPU_LSPW BIT_ULL(CPU_FEATURE_LSPW)
>
> #endif /* _ASM_CPU_H */
> diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
> index 631d249b3ef2..23af28f00c3c 100644
> --- a/arch/loongarch/include/asm/loongarch.h
> +++ b/arch/loongarch/include/asm/loongarch.h
> @@ -60,8 +60,7 @@
> #define CPUCFG0_PRID GENMASK(31, 0)
>
> #define LOONGARCH_CPUCFG1 0x1
> -#define CPUCFG1_ISGR32 BIT(0)
> -#define CPUCFG1_ISGR64 BIT(1)
> +#define CPUCFG1_ISA GENMASK(1, 0)
> #define CPUCFG1_PAGING BIT(2)
> #define CPUCFG1_IOCSR BIT(3)
> #define CPUCFG1_PABITS GENMASK(11, 4)
> diff --git a/arch/loongarch/kernel/cpu-probe.c b/arch/loongarch/kernel/cpu-probe.c
> index 14f0449f5452..5dc8ca3c4387 100644
> --- a/arch/loongarch/kernel/cpu-probe.c
> +++ b/arch/loongarch/kernel/cpu-probe.c
> @@ -92,11 +92,29 @@ static void cpu_probe_common(struct cpuinfo_loongarch *c)
> unsigned long asid_mask;
>
> c->options = LOONGARCH_CPU_CPUCFG | LOONGARCH_CPU_CSR |
> - LOONGARCH_CPU_TLB | LOONGARCH_CPU_VINT | LOONGARCH_CPU_WATCH;
> + LOONGARCH_CPU_VINT | LOONGARCH_CPU_WATCH;
>
> elf_hwcap = HWCAP_LOONGARCH_CPUCFG;
>
> config = read_cpucfg(LOONGARCH_CPUCFG1);
> +
> + switch (config & CPUCFG1_ISA) {
> + case 0:
> + set_isa(c, LOONGARCH_CPU_ISA_LA32R);
> + break;
> + case 1:
> + set_isa(c, LOONGARCH_CPU_ISA_LA32S);
> + break;
> + case 2:
> + set_isa(c, LOONGARCH_CPU_ISA_LA64);
> + break;
> + default:
> + pr_warn("Warning: unknown ISA level\n");
> + }
> + if (config & CPUCFG1_PAGING)
> + c->options |= LOONGARCH_CPU_TLB;
> + if (config & CPUCFG1_IOCSR)
> + c->options |= LOONGARCH_CPU_IOCSR;
> if (config & CPUCFG1_UAL) {
> c->options |= LOONGARCH_CPU_UAL;
> elf_hwcap |= HWCAP_LOONGARCH_UAL;
> @@ -157,6 +175,8 @@ static void cpu_probe_common(struct cpuinfo_loongarch *c)
> elf_hwcap |= HWCAP_LOONGARCH_LBT_MIPS;
> }
> #endif
> + if (config & CPUCFG2_LSPW)
> + c->options |= LOONGARCH_CPU_LSPW;
>
> config = read_cpucfg(LOONGARCH_CPUCFG6);
> if (config & CPUCFG6_PMP)
> @@ -222,6 +242,7 @@ static inline void cpu_probe_loongson(struct cpuinfo_loongarch *c, unsigned int
> {
> uint64_t *vendor = (void *)(&cpu_full_name[VENDOR_OFFSET]);
> uint64_t *cpuname = (void *)(&cpu_full_name[CPUNAME_OFFSET]);
> + const char *core_name = "Unknown";
>
> if (!__cpu_full_name[cpu])
> __cpu_full_name[cpu] = cpu_full_name;
> @@ -232,40 +253,43 @@ static inline void cpu_probe_loongson(struct cpuinfo_loongarch *c, unsigned int
> switch (c->processor_id & PRID_SERIES_MASK) {
> case PRID_SERIES_LA132:
> c->cputype = CPU_LOONGSON32;
> - set_isa(c, LOONGARCH_CPU_ISA_LA32S);
> __cpu_family[cpu] = "Loongson-32bit";
> - pr_info("32-bit Loongson Processor probed (LA132 Core)\n");
> + core_name = "LA132";
> break;
> case PRID_SERIES_LA264:
> c->cputype = CPU_LOONGSON64;
> - set_isa(c, LOONGARCH_CPU_ISA_LA64);
> __cpu_family[cpu] = "Loongson-64bit";
> - pr_info("64-bit Loongson Processor probed (LA264 Core)\n");
> + core_name = "LA264";
> break;
> case PRID_SERIES_LA364:
> c->cputype = CPU_LOONGSON64;
> - set_isa(c, LOONGARCH_CPU_ISA_LA64);
> __cpu_family[cpu] = "Loongson-64bit";
> - pr_info("64-bit Loongson Processor probed (LA364 Core)\n");
> + core_name = "LA364";
> break;
> case PRID_SERIES_LA464:
> c->cputype = CPU_LOONGSON64;
> - set_isa(c, LOONGARCH_CPU_ISA_LA64);
> __cpu_family[cpu] = "Loongson-64bit";
> - pr_info("64-bit Loongson Processor probed (LA464 Core)\n");
> + core_name = "LA464";
> break;
> case PRID_SERIES_LA664:
> c->cputype = CPU_LOONGSON64;
> - set_isa(c, LOONGARCH_CPU_ISA_LA64);
> __cpu_family[cpu] = "Loongson-64bit";
> - pr_info("64-bit Loongson Processor probed (LA664 Core)\n");
> + core_name = "LA664";
> break;
> default: /* Default to 64 bit */
> - c->cputype = CPU_LOONGSON64;
> - set_isa(c, LOONGARCH_CPU_ISA_LA64);
> - __cpu_family[cpu] = "Loongson-64bit";
> - pr_info("64-bit Loongson Processor probed (Unknown Core)\n");
> + if (c->isa_level & LOONGARCH_CPU_ISA_LA64) {
> + c->cputype = CPU_LOONGSON64;
> + __cpu_family[cpu] = "Loongson-64bit";
> + } else if (c->isa_level & LOONGARCH_CPU_ISA_LA32S) {
> + c->cputype = CPU_LOONGSON32;
> + __cpu_family[cpu] = "Loongson-32bit";
> + } else if (c->isa_level & LOONGARCH_CPU_ISA_LA32R) {
> + c->cputype = CPU_LOONGSON32;
> + __cpu_family[cpu] = "Loongson-32bit Reduced";
> + }
I prefer to move this part before the switch-case of PRID (and it is
better to convert to a switch-case too), then the switch-case of PRID
can be only used for probing core-name.

Huacai

> }
> +
> + pr_info("%s Processor probed (%s Core)\n", __cpu_family[cpu], core_name);
> }
>
> #ifdef CONFIG_64BIT
>
> --
> 2.46.0
>