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Commit 0dd2d749 authored by Fenghua Yu's avatar Fenghua Yu Committed by Thomas Gleixner
Browse files

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



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: default avatarReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: default avatarFenghua Yu <fenghua.yu@intel.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
Signed-off-by: default avatarThomas 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
parent e3302683

Documentation/x86/intel_rdt_ui.txt

+7 −0
Original line number Diff line number Diff line
@@ -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:

arch/x86/kernel/cpu/intel_rdt.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/kernel/cpu/intel_rdt.h

+3 −0
Original line number Diff line number Diff line
@@ -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;

};



/**

arch/x86/kernel/cpu/intel_rdt_rdtgroup.c

+16 −0
Original line number Diff line number Diff line
@@ -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,