If thead,vlenb is provided in the device tree, prefer that over reading the vlenb csr.
Signed-off-by: Charlie Jenkins charlie@rivosinc.com --- arch/riscv/Kconfig.vendor | 13 ++++++++++ arch/riscv/include/asm/cpufeature.h | 2 ++ arch/riscv/kernel/cpufeature.c | 48 +++++++++++++++++++++++++++++++++++++ arch/riscv/kernel/vector.c | 12 +++++++++- 4 files changed, 74 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 b029ca72cebc..e0a3164c7a06 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) { \ diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index 2107c59575dd..077be4ab1f9a 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 * @@ -625,6 +627,46 @@ 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; @@ -689,6 +731,12 @@ 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"); + elf_hwcap &= ~COMPAT_HWCAP_ISA_V; + } + 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 6727d1d3b8f2..3ba2f2432483 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();