powerpc/64s: Add dt_cpu_ftrs boot time setup option

Provide a dt_cpu_ftrs= cmdline option to disable the dt_cpu_ftrs CPU
feature discovery, and fall back to the "cputable" based version.

Also allow control of advertising unknown features to userspace and
with this parameter, and remove the clunky CONFIG option.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Add explicit early check of bootargs in dt_cpu_ftrs_init()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2017-05-11 21:24:41 +10:00 committed by Michael Ellerman
parent a4700a2610
commit a2b05b7aa6
3 changed files with 57 additions and 14 deletions

View file

@ -866,6 +866,15 @@
dscc4.setup= [NET]
dt_cpu_ftrs= [PPC]
Format: {"off" | "known"}
Control how the dt_cpu_ftrs device-tree binding is
used for CPU feature discovery and setup (if it
exists).
off: Do not use it, fall back to legacy cpu table.
known: Do not pass through unknown features to guests
or userspace, only those that the kernel is aware of.
dump_apple_properties [X86]
Dump name and content of EFI device properties on
x86 Macs. Useful for driver authors to determine

View file

@ -391,11 +391,6 @@ config PPC_DT_CPU_FTRS
firmware provides this binding.
If you're not sure say Y.
config PPC_CPUFEATURES_ENABLE_UNKNOWN
bool "cpufeatures pass through unknown features to guest/userspace"
depends on PPC_DT_CPU_FTRS
default y
config HIGHMEM
bool "High memory support"
depends on PPC32

View file

@ -8,6 +8,7 @@
#include <linux/export.h>
#include <linux/init.h>
#include <linux/jump_label.h>
#include <linux/libfdt.h>
#include <linux/memblock.h>
#include <linux/printk.h>
#include <linux/sched.h>
@ -671,12 +672,24 @@ static struct dt_cpu_feature_match __initdata
{"wait-v3", feat_enable, 0},
};
/* XXX: how to configure this? Default + boot time? */
#ifdef CONFIG_PPC_CPUFEATURES_ENABLE_UNKNOWN
#define CPU_FEATURE_ENABLE_UNKNOWN 1
#else
#define CPU_FEATURE_ENABLE_UNKNOWN 0
#endif
static bool __initdata using_dt_cpu_ftrs;
static bool __initdata enable_unknown = true;
static int __init dt_cpu_ftrs_parse(char *str)
{
if (!str)
return 0;
if (!strcmp(str, "off"))
using_dt_cpu_ftrs = false;
else if (!strcmp(str, "known"))
enable_unknown = false;
else
return 1;
return 0;
}
early_param("dt_cpu_ftrs", dt_cpu_ftrs_parse);
static void __init cpufeatures_setup_start(u32 isa)
{
@ -707,7 +720,7 @@ static bool __init cpufeatures_process_feature(struct dt_cpu_feature *f)
}
}
if (!known && CPU_FEATURE_ENABLE_UNKNOWN) {
if (!known && enable_unknown) {
if (!feat_try_enable_unknown(f)) {
pr_info("not enabling: %s (unknown and unsupported by kernel)\n",
f->name);
@ -756,6 +769,26 @@ static void __init cpufeatures_setup_finished(void)
cur_cpu_spec->cpu_features, cur_cpu_spec->mmu_features);
}
static int __init disabled_on_cmdline(void)
{
unsigned long root, chosen;
const char *p;
root = of_get_flat_dt_root();
chosen = of_get_flat_dt_subnode_by_name(root, "chosen");
if (chosen == -FDT_ERR_NOTFOUND)
return false;
p = of_get_flat_dt_prop(chosen, "bootargs", NULL);
if (!p)
return false;
if (strstr(p, "dt_cpu_ftrs=off"))
return true;
return false;
}
static int __init fdt_find_cpu_features(unsigned long node, const char *uname,
int depth, void *data)
{
@ -766,8 +799,6 @@ static int __init fdt_find_cpu_features(unsigned long node, const char *uname,
return 0;
}
static bool __initdata using_dt_cpu_ftrs = false;
bool __init dt_cpu_ftrs_in_use(void)
{
return using_dt_cpu_ftrs;
@ -775,6 +806,8 @@ bool __init dt_cpu_ftrs_in_use(void)
bool __init dt_cpu_ftrs_init(void *fdt)
{
using_dt_cpu_ftrs = false;
/* Setup and verify the FDT, if it fails we just bail */
if (!early_init_dt_verify(fdt))
return false;
@ -782,6 +815,9 @@ bool __init dt_cpu_ftrs_init(void *fdt)
if (!of_scan_flat_dt(fdt_find_cpu_features, NULL))
return false;
if (disabled_on_cmdline())
return false;
cpufeatures_setup_cpu();
using_dt_cpu_ftrs = true;
@ -1027,5 +1063,8 @@ static int __init dt_cpu_ftrs_scan_callback(unsigned long node, const char
void __init dt_cpu_ftrs_scan(void)
{
if (!using_dt_cpu_ftrs)
return;
of_scan_flat_dt(dt_cpu_ftrs_scan_callback, NULL);
}