On Tue, 16 Jan 2018 22:24:31 +1100
Michael Ellerman <m...@ellerman.id.au> 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 <m...@ellerman.id.au>
Reviewed-by: Nicholas Piggin <npig...@gmail.com>
> ---
> 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)
