Commit 5797d10e authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'cxl-for-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl 

Pull compute express link (CXL) updates from Dave Jiang:
 "The additions of note are adding CXL region remove support for locked
  CXL decoders, adding unit testing support for XOR address translation,
  and adding unit testing support for extended linear cache.

  Misc:
   - Remove incorrect page-allocator quirk section in documentation
   - Remove unused devm_cxl_port_enumerate_dports() function
   - Fix typo in cdat.c code comment
   - Replace use of system_wq with system_percpu_wq
   - Add locked CXL decoder support for region removal
   - Return when generic target updated
   - Rename region_res_match_cxl_range() to spa_maps_hpa()
   - Clarify comment in spa_maps_hpa()

  Enable unit testing for XOR address translation of SPA to DPA and vice versa:
   - Refactor address translation funcs for testing in cxl_region
   - Make the XOR calculations available for testing
   - Add cxl_translate module for address translation testing in
     cxl_test

  Extended Linear Cache changes:
   - Add extended linear cache size sysfs attribute
   - Adjust failure emission of extended linear cache detection in
     cxl_acpi
   - Added extended linear cache unit testing support in cxl_test

  Preparation refactor patches for PRM translation support:
   - Simplify cxl_rd_ops allocation and handling
   - Group xor arithmetric setup code in a single block
   - Remove local variable @inc in cxl_port_setup_targets()"

* tag 'cxl-for-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl: (22 commits)
  cxl/test: Assign overflow_err_count from log->nr_overflow
  cxl/test: Remove ret_limit race condition in mock_get_event()
  cxl/test: remove unused mock function for cxl_rcd_component_reg_phys()
  cxl/test: Add support for acpi extended linear cache
  cxl/test: Add cxl_test CFMWS support for extended linear cache
  cxl/test: Standardize CXL auto region size
  cxl/region: Remove local variable @inc in cxl_port_setup_targets()
  cxl/acpi: Group xor arithmetric setup code in a single block
  cxl: Simplify cxl_rd_ops allocation and handling
  cxl: Clarify comment in spa_maps_hpa()
  cxl: Rename region_res_match_cxl_range() to spa_maps_hpa()
  acpi/hmat: Return when generic target is updated
  cxl: Add handling of locked CXL decoder
  cxl/region: Add support to indicate region has extended linear cache
  cxl: Adjust extended linear cache failure emission in cxl_acpi
  cxl/test: Add cxl_translate module for address translation testing
  cxl/acpi: Make the XOR calculations available for testing
  cxl/region: Refactor address translation funcs for testing
  cxl/pci: replace use of system_wq with system_percpu_wq
  cxl: fix typos in cdat.c comments
  ...
parents 43dfc13c ea5514e3

Documentation/ABI/testing/sysfs-bus-cxl

+10 −1
Original line number Diff line number Diff line
@@ -496,8 +496,17 @@ Description: 
		changed, only freed by writing 0. The kernel makes no guarantees

		that data is maintained over an address space freeing event, and

		there is no guarantee that a free followed by an allocate

		results in the same address being allocated.

		results in the same address being allocated. If extended linear

		cache is present, the size indicates extended linear cache size

		plus the CXL region size.



What:		/sys/bus/cxl/devices/regionZ/extended_linear_cache_size

Date:		October, 2025

KernelVersion:	v6.19

Contact:	linux-cxl@vger.kernel.org

Description:

		(RO) The size of extended linear cache, if there is an extended

		linear cache. Otherwise the attribute will not be visible.



What:		/sys/bus/cxl/devices/regionZ/mode

Date:		January, 2023

Documentation/driver-api/cxl/allocation/page-allocator.rst

+0 −31
Original line number Diff line number Diff line
@@ -41,37 +41,6 @@ To simplify this, the page allocator will prefer :code:`ZONE_MOVABLE` over 
will fallback to allocate from :code:`ZONE_NORMAL`.





Zone and Node Quirks

====================

Let's consider a configuration where the local DRAM capacity is largely onlined

into :code:`ZONE_NORMAL`, with no :code:`ZONE_MOVABLE` capacity present. The

CXL capacity has the opposite configuration - all onlined in

:code:`ZONE_MOVABLE`.



Under the default allocation policy, the page allocator will completely skip

:code:`ZONE_MOVABLE` as a valid allocation target.  This is because, as of

Linux v6.15, the page allocator does (approximately) the following: ::



  for (each zone in local_node):



    for (each node in fallback_order):



      attempt_allocation(gfp_flags);



Because the local node does not have :code:`ZONE_MOVABLE`, the CXL node is

functionally unreachable for direct allocation.  As a result, the only way

for CXL capacity to be used is via `demotion` in the reclaim path.



This configuration also means that if the DRAM ndoe has :code:`ZONE_MOVABLE`

capacity - when that capacity is depleted, the page allocator will actually

prefer CXL :code:`ZONE_MOVABLE` pages over DRAM :code:`ZONE_NORMAL` pages.



We may wish to invert this priority in future Linux versions.



If `demotion` and `swap` are disabled, Linux will begin to cause OOM crashes

when the DRAM nodes are depleted. See the reclaim section for more details.





CGroups and CPUSets

===================

Finally, assuming CXL memory is reachable via the page allocation (i.e. onlined

drivers/acpi/numa/hmat.c

+6 −5
Original line number Diff line number Diff line
@@ -910,12 +910,13 @@ static void hmat_register_target(struct memory_target *target) 
	 * Register generic port perf numbers. The nid may not be

	 * initialized and is still NUMA_NO_NODE.

	 */

	mutex_lock(&target_lock);

	scoped_guard(mutex, &target_lock) {

		if (*(u16 *)target->gen_port_device_handle) {

			hmat_update_generic_target(target);

			target->registered = true;

			return;

		}

	}

	mutex_unlock(&target_lock);



	hmat_hotplug_target(target);

}

drivers/cxl/acpi.c

+41 −32
Original line number Diff line number Diff line
@@ -11,25 +11,36 @@ 
#include "cxlpci.h"

#include "cxl.h"



struct cxl_cxims_data {

	int nr_maps;

	u64 xormaps[] __counted_by(nr_maps);

};



static const guid_t acpi_cxl_qtg_id_guid =

	GUID_INIT(0xF365F9A6, 0xA7DE, 0x4071,

		  0xA6, 0x6A, 0xB4, 0x0C, 0x0B, 0x4F, 0x8E, 0x52);



static u64 cxl_apply_xor_maps(struct cxl_root_decoder *cxlrd, u64 addr)

#define HBIW_TO_NR_MAPS_SIZE (CXL_DECODER_MAX_INTERLEAVE + 1)

static const int hbiw_to_nr_maps[HBIW_TO_NR_MAPS_SIZE] = {

	[1] = 0, [2] = 1, [3] = 0, [4] = 2, [6] = 1, [8] = 3, [12] = 2, [16] = 4

};



static const int valid_hbiw[] = { 1, 2, 3, 4, 6, 8, 12, 16 };



u64 cxl_do_xormap_calc(struct cxl_cxims_data *cximsd, u64 addr, int hbiw)

{

	struct cxl_cxims_data *cximsd = cxlrd->platform_data;

	int hbiw = cxlrd->cxlsd.nr_targets;

	int nr_maps_to_apply = -1;

	u64 val;

	int pos;



	/* No xormaps for host bridge interleave ways of 1 or 3 */

	if (hbiw == 1 || hbiw == 3)

		return addr;

	/*

	 * Strictly validate hbiw since this function is used for testing and

	 * that nullifies any expectation of trusted parameters from the CXL

	 * Region Driver.

	 */

	for (int i = 0; i < ARRAY_SIZE(valid_hbiw); i++) {

		if (valid_hbiw[i] == hbiw) {

			nr_maps_to_apply = hbiw_to_nr_maps[hbiw];

			break;

		}

	}

	if (nr_maps_to_apply == -1 || nr_maps_to_apply > cximsd->nr_maps)

		return ULLONG_MAX;



	/*

	 * In regions using XOR interleave arithmetic the CXL HPA may not
@@ -60,6 +71,14 @@ static u64 cxl_apply_xor_maps(struct cxl_root_decoder *cxlrd, u64 addr) 


	return addr;

}

EXPORT_SYMBOL_FOR_MODULES(cxl_do_xormap_calc, "cxl_translate");



static u64 cxl_apply_xor_maps(struct cxl_root_decoder *cxlrd, u64 addr)

{

	struct cxl_cxims_data *cximsd = cxlrd->platform_data;



	return cxl_do_xormap_calc(cximsd, addr, cxlrd->cxlsd.nr_targets);

}



struct cxl_cxims_context {

	struct device *dev;
@@ -353,7 +372,7 @@ static int cxl_acpi_set_cache_size(struct cxl_root_decoder *cxlrd) 


	rc = hmat_get_extended_linear_cache_size(&res, nid, &cache_size);

	if (rc)

		return rc;

		return 0;



	/*

	 * The cache range is expected to be within the CFMWS.
@@ -378,22 +397,19 @@ static void cxl_setup_extended_linear_cache(struct cxl_root_decoder *cxlrd) 
	int rc;



	rc = cxl_acpi_set_cache_size(cxlrd);

	if (!rc)

		return;



	if (rc != -EOPNOTSUPP) {

	if (rc) {

		/*

		 * Failing to support extended linear cache region resize does not

		 * Failing to retrieve extended linear cache region resize does not

		 * prevent the region from functioning. Only causes cxl list showing

		 * incorrect region size.

		 */

		dev_warn(cxlrd->cxlsd.cxld.dev.parent,

			 "Extended linear cache calculation failed rc:%d\n", rc);

	}

			 "Extended linear cache retrieval failed rc:%d\n", rc);



		/* Ignoring return code */

		cxlrd->cache_size = 0;

	}

}



DEFINE_FREE(put_cxlrd, struct cxl_root_decoder *,

	    if (!IS_ERR_OR_NULL(_T)) put_device(&_T->cxlsd.cxld.dev))
@@ -453,8 +469,6 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws, 
		ig = CXL_DECODER_MIN_GRANULARITY;

	cxld->interleave_granularity = ig;



	cxl_setup_extended_linear_cache(cxlrd);



	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_XOR) {

		if (ways != 1 && ways != 3) {

			cxims_ctx = (struct cxl_cxims_context) {
@@ -470,18 +484,13 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws, 
				return -EINVAL;

			}

		}

		cxlrd->ops.hpa_to_spa = cxl_apply_xor_maps;

		cxlrd->ops.spa_to_hpa = cxl_apply_xor_maps;

	}



	cxlrd->qos_class = cfmws->qtg_id;



	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_XOR) {

		cxlrd->ops = kzalloc(sizeof(*cxlrd->ops), GFP_KERNEL);

		if (!cxlrd->ops)

			return -ENOMEM;

	cxl_setup_extended_linear_cache(cxlrd);



		cxlrd->ops->hpa_to_spa = cxl_apply_xor_maps;

		cxlrd->ops->spa_to_hpa = cxl_apply_xor_maps;

	}

	cxlrd->qos_class = cfmws->qtg_id;



	rc = cxl_decoder_add(cxld);

	if (rc)

drivers/cxl/core/cdat.c

+2 −2
Original line number Diff line number Diff line
@@ -826,7 +826,7 @@ static struct xarray *cxl_switch_gather_bandwidth(struct cxl_region *cxlr, 
		cxl_coordinates_combine(coords, coords, ctx->coord);



		/*

		 * Take the min of the calculated bandwdith and the upstream

		 * Take the min of the calculated bandwidth and the upstream

		 * switch SSLBIS bandwidth if there's a parent switch

		 */

		if (!is_root)
@@ -949,7 +949,7 @@ static struct xarray *cxl_hb_gather_bandwidth(struct xarray *xa) 
/**

 * cxl_region_update_bandwidth - Update the bandwidth access coordinates of a region

 * @cxlr: The region being operated on

 * @input_xa: xarray holds cxl_perf_ctx wht calculated bandwidth per ACPI0017 instance

 * @input_xa: xarray holds cxl_perf_ctx with calculated bandwidth per ACPI0017 instance

 */

static void cxl_region_update_bandwidth(struct cxl_region *cxlr,

					struct xarray *input_xa)