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Message-ID: <b1f44974-0609-4697-bada-9bcf27f7df43@intel.com>
Date: Mon, 14 Jul 2025 16:51:40 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Robert Richter <rrichter@....com>, Davidlohr Bueso <dave@...olabs.net>,
Jonathan Cameron <jonathan.cameron@...wei.com>,
Alison Schofield <alison.schofield@...el.com>,
Vishal Verma <vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>,
Dan Williams <dan.j.williams@...el.com>
Cc: linux-kernel@...r.kernel.org, linux-cxl@...r.kernel.org
Subject: Re: [PATCH] cxl: Remove core/acpi.c and cxl core dependency on ACPI
On 7/14/25 2:36 PM, Dave Jiang wrote:
>
>
> On 7/11/25 8:15 AM, Robert Richter wrote:
>> From Dave [1]:
>>
>> """
>> It was a mistake to introduce core/acpi.c and putting ACPI dependency on
>> cxl_core when adding the extended linear cache support.
>> """
>>
>> Current implementation calls hmat_get_extended_linear_cache_size() of
>> the ACPI subsystem. That external reference causes issue running
>> cxl_test as there is no way to "mock" that function and ignore it when
>> using cxl test.
>>
>> Instead of working around that using cxlrd ops and extensively
>> expanding cxl_test code [1], just move HMAT calls out of the core
>> module to cxl_acpi. Implement this by adding a @cache_size member to
>> struct cxl_root_decoder. During initialization the cache size is
>> determined and added to the root decoder object in cxl_acpi. Later on
>> in cxl_core the cache_size parameter is used to setup extended linear
>> caching.
>>
>> [1] https://patch.msgid.link/20250610172938.139428-1-dave.jiang@intel.com
>>
>> Cc: Dave Jiang <dave.jiang@...el.com>
>> Signed-off-by: Robert Richter <rrichter@....com>
>
> Applied to cxl/next
> 4211a8a86304a53719931e7d19efc102eb8ede24
Actually 8d41af0d378dc0832d64b71bb0f71098c23dd1c4
Had to add the removal of core/acpi.o entry from tools/testing/cxl/Kbuild
>
>> ---
>> drivers/cxl/acpi.c | 59 +++++++++++++++++++++++++++++++++++++++
>> drivers/cxl/core/Makefile | 1 -
>> drivers/cxl/core/acpi.c | 11 --------
>> drivers/cxl/core/core.h | 2 --
>> drivers/cxl/core/region.c | 7 +----
>> drivers/cxl/cxl.h | 1 +
>> 6 files changed, 61 insertions(+), 20 deletions(-)
>> delete mode 100644 drivers/cxl/core/acpi.c
>>
>> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
>> index a1a99ec3f12c..712624cba2b6 100644
>> --- a/drivers/cxl/acpi.c
>> +++ b/drivers/cxl/acpi.c
>> @@ -335,6 +335,63 @@ static int add_or_reset_cxl_resource(struct resource *parent, struct resource *r
>> return rc;
>> }
>>
>> +static int cxl_acpi_set_cache_size(struct cxl_root_decoder *cxlrd)
>> +{
>> + struct cxl_decoder *cxld = &cxlrd->cxlsd.cxld;
>> + struct range *hpa = &cxld->hpa_range;
>> + resource_size_t size = range_len(hpa);
>> + resource_size_t start = hpa->start;
>> + resource_size_t cache_size;
>> + struct resource res;
>> + int nid, rc;
>> +
>> + res = DEFINE_RES(start, size, 0);
>> + nid = phys_to_target_node(start);
>> +
>> + rc = hmat_get_extended_linear_cache_size(&res, nid, &cache_size);
>> + if (rc)
>> + return rc;
>> +
>> + /*
>> + * The cache range is expected to be within the CFMWS.
>> + * Currently there is only support cache_size == cxl_size. CXL
>> + * size is then half of the total CFMWS window size.
>> + */
>> + size = size >> 1;
>> + if (cache_size && size != cache_size) {
>> + dev_warn(&cxld->dev,
>> + "Extended Linear Cache size %pa != CXL size %pa. No Support!",
>> + &cache_size, &size);
>> + return -ENXIO;
>> + }
>> +
>> + cxlrd->cache_size = cache_size;
>> +
>> + return 0;
>> +}
>> +
>> +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) {
>> + /*
>> + * Failing to support 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);
>> + }
>> +
>> + /* 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))
>> DEFINE_FREE(del_cxl_resource, struct resource *, if (_T) del_cxl_resource(_T))
>> @@ -394,6 +451,8 @@ 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) {
>> diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
>> index 79e2ef81fde8..5ad8fef210b5 100644
>> --- a/drivers/cxl/core/Makefile
>> +++ b/drivers/cxl/core/Makefile
>> @@ -15,7 +15,6 @@ cxl_core-y += hdm.o
>> cxl_core-y += pmu.o
>> cxl_core-y += cdat.o
>> cxl_core-y += ras.o
>> -cxl_core-y += acpi.o
>> cxl_core-$(CONFIG_TRACING) += trace.o
>> cxl_core-$(CONFIG_CXL_REGION) += region.o
>> cxl_core-$(CONFIG_CXL_MCE) += mce.o
>> diff --git a/drivers/cxl/core/acpi.c b/drivers/cxl/core/acpi.c
>> deleted file mode 100644
>> index f13b4dae6ac5..000000000000
>> --- a/drivers/cxl/core/acpi.c
>> +++ /dev/null
>> @@ -1,11 +0,0 @@
>> -// SPDX-License-Identifier: GPL-2.0-only
>> -/* Copyright(c) 2024 Intel Corporation. All rights reserved. */
>> -#include <linux/acpi.h>
>> -#include "cxl.h"
>> -#include "core.h"
>> -
>> -int cxl_acpi_get_extended_linear_cache_size(struct resource *backing_res,
>> - int nid, resource_size_t *size)
>> -{
>> - return hmat_get_extended_linear_cache_size(backing_res, nid, size);
>> -}
>> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
>> index 29b61828a847..9462aea9ce9d 100644
>> --- a/drivers/cxl/core/core.h
>> +++ b/drivers/cxl/core/core.h
>> @@ -120,8 +120,6 @@ int cxl_port_get_switch_dport_bandwidth(struct cxl_port *port,
>> int cxl_ras_init(void);
>> void cxl_ras_exit(void);
>> int cxl_gpf_port_setup(struct cxl_dport *dport);
>> -int cxl_acpi_get_extended_linear_cache_size(struct resource *backing_res,
>> - int nid, resource_size_t *size);
>>
>> #ifdef CONFIG_CXL_FEATURES
>> struct cxl_feat_entry *
>> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
>> index 6e5e1460068d..bc542a7142c0 100644
>> --- a/drivers/cxl/core/region.c
>> +++ b/drivers/cxl/core/region.c
>> @@ -3282,15 +3282,10 @@ static int cxl_extended_linear_cache_resize(struct cxl_region *cxlr,
>> {
>> struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
>> struct cxl_region_params *p = &cxlr->params;
>> - int nid = phys_to_target_node(res->start);
>> resource_size_t size = resource_size(res);
>> resource_size_t cache_size, start;
>> - int rc;
>> -
>> - rc = cxl_acpi_get_extended_linear_cache_size(res, nid, &cache_size);
>> - if (rc)
>> - return rc;
>>
>> + cache_size = cxlrd->cache_size;
>> if (!cache_size)
>> return 0;
>>
>> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
>> index e7b66ca1d423..4643a95ca111 100644
>> --- a/drivers/cxl/cxl.h
>> +++ b/drivers/cxl/cxl.h
>> @@ -432,6 +432,7 @@ typedef u64 (*cxl_hpa_to_spa_fn)(struct cxl_root_decoder *cxlrd, u64 hpa);
>> */
>> struct cxl_root_decoder {
>> struct resource *res;
>> + resource_size_t cache_size;
>> atomic_t region_id;
>> cxl_hpa_to_spa_fn hpa_to_spa;
>> void *platform_data;
>
>
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