[PATCH v10 05/14] riscv: vector: Use vlenb from DT for thead
Andy Chiu
andybnac at gmail.com
Wed Oct 2 09:34:22 PDT 2024
Charlie Jenkins <charlie at rivosinc.com> 於 2024年9月12日 週四 下午1:57寫道：
>
> If thead,vlenb is provided in the device tree, prefer that over reading
> the vlenb csr.
>
> Signed-off-by: Charlie Jenkins <charlie at rivosinc.com>
> Acked-by: Conor Dooley <conor.dooley at microchip.com>
> ---
> arch/riscv/Kconfig.vendor | 13 +++++++
> arch/riscv/include/asm/cpufeature.h | 2 +
> arch/riscv/include/asm/vendor_extensions/thead.h | 6 +++
> arch/riscv/kernel/cpufeature.c | 48 ++++++++++++++++++++++++
> arch/riscv/kernel/vector.c | 12 +++++-
> arch/riscv/kernel/vendor_extensions/thead.c | 11 ++++++
> 6 files changed, 91 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/Kconfig.vendor b/arch/riscv/Kconfig.vendor
> index 9897442bd44f..b096548fe0ff 100644
> --- a/arch/riscv/Kconfig.vendor
> +++ b/arch/riscv/Kconfig.vendor
> @@ -26,6 +26,19 @@ config RISCV_ISA_VENDOR_EXT_THEAD
> extensions. Without this option enabled, T-Head vendor extensions will
> not be detected at boot and their presence not reported to userspace.
>
> + If you don't know what to do here, say Y.
> +
> +config RISCV_ISA_XTHEADVECTOR
> + bool "xtheadvector extension support"
> + depends on RISCV_ISA_VENDOR_EXT_THEAD
> + depends on RISCV_ISA_V
> + depends on FPU
> + default y
> + help
> + Say N here if you want to disable all xtheadvector related procedures
> + in the kernel. This will disable vector for any T-Head board that
> + contains xtheadvector rather than the standard vector.
> +
> If you don't know what to do here, say Y.
> endmenu
>
> diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h
> index 45f9c1171a48..28bdeb1005e0 100644
> --- a/arch/riscv/include/asm/cpufeature.h
> +++ b/arch/riscv/include/asm/cpufeature.h
> @@ -31,6 +31,8 @@ DECLARE_PER_CPU(struct riscv_cpuinfo, riscv_cpuinfo);
> /* Per-cpu ISA extensions. */
> extern struct riscv_isainfo hart_isa[NR_CPUS];
>
> +extern u32 thead_vlenb_of;
> +
> void riscv_user_isa_enable(void);
>
> #define _RISCV_ISA_EXT_DATA(_name, _id, _subset_exts, _subset_exts_size, _validate) { \
> diff --git a/arch/riscv/include/asm/vendor_extensions/thead.h b/arch/riscv/include/asm/vendor_extensions/thead.h
> index 48421d1553ad..190c91e37e95 100644
> --- a/arch/riscv/include/asm/vendor_extensions/thead.h
> +++ b/arch/riscv/include/asm/vendor_extensions/thead.h
> @@ -13,4 +13,10 @@
>
> extern struct riscv_isa_vendor_ext_data_list riscv_isa_vendor_ext_list_thead;
>
> +#ifdef CONFIG_RISCV_ISA_VENDOR_EXT_THEAD
> +void disable_xtheadvector(void);
> +#else
> +void disable_xtheadvector(void) { }
> +#endif
> +
> #endif
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 46e69b9d66a7..9340efd79af9 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -37,6 +37,8 @@ static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
> /* Per-cpu ISA extensions. */
> struct riscv_isainfo hart_isa[NR_CPUS];
>
> +u32 thead_vlenb_of;
> +
> /**
> * riscv_isa_extension_base() - Get base extension word
> *
> @@ -772,6 +774,46 @@ static void __init riscv_fill_vendor_ext_list(int cpu)
> }
> }
>
> +static int has_thead_homogeneous_vlenb(void)
> +{
> + int cpu;
> + u32 prev_vlenb = 0;
> + u32 vlenb;
> +
> + /* Ignore thead,vlenb property if xtheavector is not enabled in the kernel */
> + if (!IS_ENABLED(CONFIG_RISCV_ISA_XTHEADVECTOR))
> + return 0;
> +
> + for_each_possible_cpu(cpu) {
> + struct device_node *cpu_node;
> +
> + cpu_node = of_cpu_device_node_get(cpu);
> + if (!cpu_node) {
> + pr_warn("Unable to find cpu node\n");
> + return -ENOENT;
> + }
> +
> + if (of_property_read_u32(cpu_node, "thead,vlenb", &vlenb)) {
> + of_node_put(cpu_node);
> +
> + if (prev_vlenb)
> + return -ENOENT;
> + continue;
> + }
> +
> + if (prev_vlenb && vlenb != prev_vlenb) {
> + of_node_put(cpu_node);
> + return -ENOENT;
> + }
> +
> + prev_vlenb = vlenb;
> + of_node_put(cpu_node);
> + }
> +
> + thead_vlenb_of = vlenb;
> + return 0;
> +}
> +
> static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
> {
> unsigned int cpu;
> @@ -825,6 +867,12 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
> riscv_fill_vendor_ext_list(cpu);
> }
>
> + if (riscv_isa_vendor_extension_available(THEAD_VENDOR_ID, XTHEADVECTOR) &&
> + has_thead_homogeneous_vlenb() < 0) {
> + pr_warn("Unsupported heterogeneous vlenb detected, vector extension disabled.\n");
> + disable_xtheadvector();
> + }
> +
> if (bitmap_empty(riscv_isa, RISCV_ISA_EXT_MAX))
> return -ENOENT;
>
> diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c
> index 682b3feee451..9775d6a9c8ee 100644
> --- a/arch/riscv/kernel/vector.c
> +++ b/arch/riscv/kernel/vector.c
> @@ -33,7 +33,17 @@ int riscv_v_setup_vsize(void)
> {
> unsigned long this_vsize;
>
> - /* There are 32 vector registers with vlenb length. */
> + /*
> + * There are 32 vector registers with vlenb length.
> + *
> + * If the thead,vlenb property was provided by the firmware, use that
> + * instead of probing the CSRs.
> + */
> + if (thead_vlenb_of) {
> + this_vsize = thead_vlenb_of * 32;
> + return 0;
> + }
> +
> riscv_v_enable();
> this_vsize = csr_read(CSR_VLENB) * 32;
> riscv_v_disable();
> diff --git a/arch/riscv/kernel/vendor_extensions/thead.c b/arch/riscv/kernel/vendor_extensions/thead.c
> index 0f27baf8d245..519dbf70710a 100644
> --- a/arch/riscv/kernel/vendor_extensions/thead.c
> +++ b/arch/riscv/kernel/vendor_extensions/thead.c
> @@ -5,6 +5,7 @@
> #include <asm/vendor_extensions/thead.h>
>
> #include <linux/array_size.h>
> +#include <linux/cpumask.h>
> #include <linux/types.h>
>
> /* All T-Head vendor extensions supported in Linux */
> @@ -16,3 +17,13 @@ struct riscv_isa_vendor_ext_data_list riscv_isa_vendor_ext_list_thead = {
> .ext_data_count = ARRAY_SIZE(riscv_isa_vendor_ext_thead),
> .ext_data = riscv_isa_vendor_ext_thead,
> };
> +
> +void disable_xtheadvector(void)
> +{
> + int cpu;
> +
> + for_each_possible_cpu(cpu)
> + clear_bit(RISCV_ISA_VENDOR_EXT_XTHEADVECTOR, riscv_isa_vendor_ext_list_thead.per_hart_isa_bitmap[cpu].isa);
> +
> + clear_bit(RISCV_ISA_VENDOR_EXT_XTHEADVECTOR, riscv_isa_vendor_ext_list_thead.all_harts_isa_bitmap.isa);
> +}
Given that we already have an infra to resolve and validate isa, with
riscv_resolve_isa(), shouldn't we reuse that part of the code and
assign "has_thead_homogeneous_vlenb()" as a validate function? I know
it would need some modifications because it seems like
riscv_resolve_isa is not there for vendor extensions yet.
Sorry I am late on reviewing this series. I think we can refactor it
as follow up patches if we want to keep up development.
Thanks,
Andy
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