On Fri, Apr 26, 2024 at 04:17:52PM +0100, Conor Dooley wrote:
On Sat, Apr 20, 2024 at 06:04:36PM -0700, Charlie Jenkins wrote:
If vlenb is provided in the device tree, prefer that over reading the vlenb csr.
Signed-off-by: Charlie Jenkins charlie@rivosinc.com
arch/riscv/include/asm/cpufeature.h | 2 ++ arch/riscv/kernel/cpufeature.c | 26 ++++++++++++++++++++++++++ arch/riscv/kernel/vector.c | 13 +++++++++---- 3 files changed, 37 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h index 347805446151..809f61ffb667 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 riscv_vlenb_dt[NR_CPUS];
void riscv_user_isa_enable(void); #if defined(CONFIG_RISCV_MISALIGNED) diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index c6e27b45e192..48874aac4871 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -35,6 +35,8 @@ static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly; /* Per-cpu ISA extensions. */ struct riscv_isainfo hart_isa[NR_CPUS]; +u32 riscv_vlenb_dt[NR_CPUS];
/**
- riscv_isa_extension_base() - Get base extension word
@@ -656,6 +658,28 @@ static int __init riscv_isa_fallback_setup(char *__unused) early_param("riscv_isa_fallback", riscv_isa_fallback_setup); #endif +static void riscv_set_vlenb_from_dt(void)
I'd expect to see a name here that had "of" in it, not "dt".
Also, "set" - I think "get" is more suitable here given that this doesn't actually set the vlen, we only do any setting later on in riscv_v_set_vsize().
+{
- int cpu;
- 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");continue;}if (!of_property_read_u32(cpu_node, "riscv,vlenb", &riscv_vlenb_dt[cpu])) {of_node_put(cpu_node);continue;}of_node_put(cpu_node);- }
+}
void __init riscv_fill_hwcap(void) { char print_str[NUM_ALPHA_EXTS + 1]; @@ -675,6 +699,8 @@ void __init riscv_fill_hwcap(void) } else { int ret = riscv_fill_hwcap_from_ext_list(isa2hwcap);
riscv_set_vlenb_from_dt();Hmm, I think we can go a step further here. We know all of the CPUs widths by the time we get to the first call to riscv_v_setup_vsize(), can we examine the whole list and decide not to enable vector if they do not match, rather than continuing and failing to online CPUs that having the mismatched size?
I guess that can go into the `if (elf_hwcap & COMPAT_HWCAP_ISA_V)` condition we already have, and would require clearing the bit from the mask we have at the moment.
Cheers, Conor.
- if (ret && riscv_isa_fallback) { pr_info("Falling back to deprecated "riscv,isa"\n"); riscv_fill_hwcap_from_isa_string(isa2hwcap);
diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c index 6727d1d3b8f2..fb7f3ca80d9e 100644 --- a/arch/riscv/kernel/vector.c +++ b/arch/riscv/kernel/vector.c @@ -32,11 +32,16 @@ EXPORT_SYMBOL_GPL(riscv_v_vsize); int riscv_v_setup_vsize(void) { unsigned long this_vsize;
- int cpu = smp_processor_id();
- /* There are 32 vector registers with vlenb length. */
- riscv_v_enable();
- this_vsize = csr_read(CSR_VLENB) * 32;
- riscv_v_disable();
- if (riscv_vlenb_dt[cpu]) {
this_vsize = riscv_vlenb_dt[cpu];
- } else {
/* There are 32 vector registers with vlenb length. */riscv_v_enable();this_vsize = csr_read(CSR_VLENB) * 32;riscv_v_disable();- }
if (!riscv_v_vsize) { riscv_v_vsize = this_vsize;
-- 2.44.0