x86/intel_rdt: Export the minimum number of set mask bits in sysfs

The minimum number of bits set for a cache mask is checked by the kernel
when writing a mask, but there is no way for the user to retrieve this
information.

Add a new file 'min_cbm_bits' to the info directory and export the
information to user space.

[ tglx: Massaged changelog ]
Signed-off-by: Shaohua Li <shli@fb.com>
Cc: fenghua.yu@intel.com
Cc: tony.luck@intel.com
Link: http://lkml.kernel.org/r/e69b1ffa206d0353eea58101e1bf9b677d9732f7.1478207143.git.shli@fb.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index e66c7a58505e20f189ddaaa11c5e197c26e314a6..4795880274f96fdfe255817a94b127937ba601f6 100644 (file)
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -472,6 +472,16 @@ static int rdt_cbm_mask_show(struct kernfs_open_file *of,
        return 0;
 }
 
+static int rdt_min_cbm_bits_show(struct kernfs_open_file *of,
+                            struct seq_file *seq, void *v)
+{
+       struct rdt_resource *r = of->kn->parent->priv;
+
+       seq_printf(seq, "%d\n", r->min_cbm_bits);
+
+       return 0;
+}
+
 /* rdtgroup information files for one cache resource. */
 static struct rftype res_info_files[] = {
        {
@@ -486,6 +496,12 @@ static struct rftype res_info_files[] = {
                .kf_ops         = &rdtgroup_kf_single_ops,
                .seq_show       = rdt_cbm_mask_show,
        },
+       {
+               .name           = "min_cbm_bits",
+               .mode           = 0444,
+               .kf_ops         = &rdtgroup_kf_single_ops,
+               .seq_show       = rdt_min_cbm_bits_show,
+       },
 };
 
 static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)