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x86/intel_rdt: Show bitmask of shareable resource with other executing units

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CPUID.(EAX=0x10, ECX=res#):EBX[31:0] reports a bit mask for a resource.
Each set bit within the length of the CBM indicates the corresponding
unit of the resource allocation may be used by other entities in the
platform (e.g. an integrated graphics engine or hardware units outside
the processor core and have direct access to the resource). Each
cleared bit within the length of the CBM indicates the corresponding
allocation unit can be configured to implement a priority-based
allocation scheme without interference with other hardware agents in
the system. Bits outside the length of the CBM are reserved.

More details on the bit mask are described in x86 Software Developer's
Manual.

The bitmask is shown in "info" directory for each resource. It's
up to user to decide how to use the bitmask within a CBM in a partition
to share or isolate a resource with other executing units.

Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: ak@linux.intel.com
Cc: davidcc@google.com
Cc: vikas.shivappa@linux.intel.com
Link: http://lkml.kernel.org/r/20170725223904.12996-1-tony.luck@intel.com
This commit is contained in:
Fenghua Yu 2017-07-25 15:39:04 -07:00 committed by Thomas Gleixner
parent e33026831b
commit 0dd2d7494c
4 changed files with 28 additions and 0 deletions
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7
Documentation/x86/intel_rdt_ui.txt
View file

@ -48,6 +48,13 @@ related to allocation:
"min_cbm_bits": The minimum number of consecutive bits which
must be set when writing a mask.
"shareable_bits": Bitmask of shareable resource with other executing
entities (e.g. I/O). User can use this when
setting up exclusive cache partitions. Note that
some platforms support devices that have their
own settings for cache use which can over-ride
these bits.
Memory bandwitdh(MB) subdirectory contains the following files
with respect to allocation:

2
arch/x86/kernel/cpu/intel_rdt.c
View file

@ -193,6 +193,7 @@ static inline bool cache_alloc_hsw_probe(void)
r->num_closid = 4;
r->default_ctrl = max_cbm;
r->cache.cbm_len = 20;
r->cache.shareable_bits = 0xc0000;
r->cache.min_cbm_bits = 2;
r->alloc_capable = true;
r->alloc_enabled = true;
@ -260,6 +261,7 @@ static void rdt_get_cache_alloc_cfg(int idx, struct rdt_resource *r)
r->num_closid = edx.split.cos_max + 1;
r->cache.cbm_len = eax.split.cbm_len + 1;
r->default_ctrl = BIT_MASK(eax.split.cbm_len + 1) - 1;
r->cache.shareable_bits = ebx & r->default_ctrl;
r->data_width = (r->cache.cbm_len + 3) / 4;
r->alloc_capable = true;
r->alloc_enabled = true;

3
arch/x86/kernel/cpu/intel_rdt.h
View file

@ -227,12 +227,15 @@ struct msr_param {
* @cbm_idx_offset: Offset of CBM index. CBM index is computed by:
* closid * cbm_idx_multi + cbm_idx_offset
* in a cache bit mask
* @shareable_bits: Bitmask of shareable resource with other
* executing entities
*/
struct rdt_cache {
unsigned int cbm_len;
unsigned int min_cbm_bits;
unsigned int cbm_idx_mult;
unsigned int cbm_idx_offset;
unsigned int shareable_bits;
};
/**

16
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
View file

@ -596,6 +596,15 @@ static int rdt_min_cbm_bits_show(struct kernfs_open_file *of,
return 0;
}
static int rdt_shareable_bits_show(struct kernfs_open_file *of,
struct seq_file *seq, void *v)
{
struct rdt_resource *r = of->kn->parent->priv;
seq_printf(seq, "%x\n", r->cache.shareable_bits);
return 0;
}
static int rdt_min_bw_show(struct kernfs_open_file *of,
struct seq_file *seq, void *v)
{
@ -711,6 +720,13 @@ static struct rftype res_common_files[] = {
.seq_show = rdt_min_cbm_bits_show,
.fflags = RF_CTRL_INFO | RFTYPE_RES_CACHE,
},
{
.name = "shareable_bits",
.mode = 0444,
.kf_ops = &rdtgroup_kf_single_ops,
.seq_show = rdt_shareable_bits_show,
.fflags = RF_CTRL_INFO | RFTYPE_RES_CACHE,
},
{
.name = "min_bandwidth",
.mode = 0444,