Re: [PATCH] powerpc/64s: Allow control of RFI flush via debugfs
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2018-01-16 14:41:35
On Tue, 16 Jan 2018 22:24:31 +1100 Michael Ellerman [off-list ref] wrote:
Expose the state of the RFI flush (enabled/disabled) via debugfs, and
allow it to be enabled/disabled at runtime.
eg: $ cat /sys/kernel/debug/powerpc/rfi_flush
1
$ echo 0 > /sys/kernel/debug/powerpc/rfi_flush
$ cat /sys/kernel/debug/powerpc/rfi_flush
0
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
quoted hunk ↗ jump to hunk
--- arch/powerpc/kernel/setup_64.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+)diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index 624d2a62d05d..e67413f4a8f0 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c@@ -38,6 +38,7 @@ #include <linux/memory.h> #include <linux/nmi.h> +#include <asm/debugfs.h> #include <asm/io.h> #include <asm/kdump.h> #include <asm/prom.h>@@ -902,6 +903,35 @@ void __init setup_rfi_flush(enum l1d_flush_type types, bool enable) rfi_flush_enable(enable); } +#ifdef CONFIG_DEBUG_FS +static int rfi_flush_set(void *data, u64 val) +{ + if (val == 1) + rfi_flush_enable(true); + else if (val == 0) + rfi_flush_enable(false); + else + return -EINVAL; + + return 0; +} + +static int rfi_flush_get(void *data, u64 *val) +{ + *val = rfi_flush ? 1 : 0; + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(fops_rfi_flush, rfi_flush_get, rfi_flush_set, "%llu\n"); + +static __init int rfi_flush_debugfs_init(void) +{ + debugfs_create_file("rfi_flush", 0600, powerpc_debugfs_root, NULL, &fops_rfi_flush); + return 0; +} +device_initcall(rfi_flush_debugfs_init); +#endif + ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf) { if (rfi_flush)