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powerpc/64s: Allow control of RFI flush via debugfs

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commit 236003e6b5443c45c18e613d2b0d776a9f87540e upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Ellerman 2018-01-16 22:17:18 +11:00 committed by Greg Kroah-Hartman
parent 517bdccc3a
commit d6eded6c94
1 changed files with 30 additions and 0 deletions
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30
arch/powerpc/kernel/setup_64.c
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@ -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>
@ -885,6 +886,35 @@ 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)