x86/resctrl: Fix min_cbm_bits for AMD

AMD systems support zero CBM (capacity bit mask) for cache allocation.
That is reflected in rdt_init_res_defs_amd() by:

  r->cache.arch_has_empty_bitmaps = true;

However given the unified code in cbm_validate(), checking for:

  val == 0 && !arch_has_empty_bitmaps

is not enough because of another check in cbm_validate():

  if ((zero_bit - first_bit) < r->cache.min_cbm_bits)

The default value of r->cache.min_cbm_bits = 1.

Leading to:

  $ cd /sys/fs/resctrl
  $ mkdir foo
  $ cd foo
  $ echo L3:0=0 > schemata
    -bash: echo: write error: Invalid argument
  $ cat /sys/fs/resctrl/info/last_cmd_status
    Need at least 1 bits in the mask

Initialize the min_cbm_bits to 0 for AMD. Also, remove the default
setting of min_cbm_bits and initialize it separately.

After the fix:

  $ cd /sys/fs/resctrl
  $ mkdir foo
  $ cd foo
  $ echo L3:0=0 > schemata
  $ cat /sys/fs/resctrl/info/last_cmd_status
    ok

Fixes: 316e7f901f5a ("x86/resctrl: Add struct rdt_cache::arch_has_{sparse, empty}_bitmaps")
Co-developed-by: Stephane Eranian <[email protected]>
Signed-off-by: Stephane Eranian <[email protected]>
Signed-off-by: Babu Moger <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Ingo Molnar <[email protected]>
Reviewed-by: James Morse <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Reviewed-by: Fenghua Yu <[email protected]>
Cc: <[email protected]>
Link: https://lore.kernel.org/lkml/[email protected]

0 files changed, 0 insertions, 0 deletions