[PATCH v1 23/40] x86/cacheinfo: Move AMD cache_disable_0/1 handling to separate file

Ahmed S. Darwish
2025-03-04T08:53:24Z

Parent commit decoupled amd_northbridge out of _cpuid4_info_regs, where
it was merely "parked" there until ci_info_init() can store it in the
priv pointer of the linux/cacheinfo.h API.

Given that decoupling, move the AMD-specific L3 cache_disable_0/1 sysfs
code from the generic (and already extremely convoluted) x86/cacheinfo
code into its own file.

Compile the file only if CONFIG_AMD_NB and CONFIG_SYSFS are both
enabled, which mirrors the existing logic.

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
---
arch/x86/kernel/cpu/Makefile | 3 +
arch/x86/kernel/cpu/amd_cache_disable.c | 301 ++++++++++++++++++++++++
arch/x86/kernel/cpu/cacheinfo.c | 298 -----------------------
arch/x86/kernel/cpu/cpu.h | 9 +
4 files changed, 313 insertions(+), 298 deletions(-)
create mode 100644 arch/x86/kernel/cpu/amd_cache_disable.c

diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 4efdf5c2efc8..3a39396d422d 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -38,6 +38,9 @@ obj-y += intel.o tsx.o
obj-$(CONFIG_PM) += intel_epb.o
endif
obj-$(CONFIG_CPU_SUP_AMD) += amd.o
+ifeq ($(CONFIG_AMD_NB)$(CONFIG_SYSFS),yy)
+obj-y += amd_cache_disable.o
+endif
obj-$(CONFIG_CPU_SUP_HYGON) += hygon.o
obj-$(CONFIG_CPU_SUP_CYRIX_32) += cyrix.o
obj-$(CONFIG_CPU_SUP_CENTAUR) += centaur.o
diff --git a/arch/x86/kernel/cpu/amd_cache_disable.c b/arch/x86/kernel/cpu/amd_cache_disable.c
new file mode 100644
index 000000000000..6d53aee0d869
--- /dev/null
+++ b/arch/x86/kernel/cpu/amd_cache_disable.c
@@ -0,0 +1,301 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AMD L3 cache_disable_{0,1} sysfs handling
+ * Documentation/ABI/testing/sysfs-devices-system-cpu
+ */
+
+#include <linux/cacheinfo.h>
+#include <linux/capability.h>
+#include <linux/pci.h>
+#include <linux/sysfs.h>
+
+#include <asm/amd_nb.h>
+
+#include "cpu.h"
+
+/*
+ * L3 cache descriptors
+ */
+static void amd_calc_l3_indices(struct amd_northbridge *nb)
+{
+ struct amd_l3_cache *l3 = &nb->l3_cache;
+ unsigned int sc0, sc1, sc2, sc3;
+ u32 val = 0;
+
+ pci_read_config_dword(nb->misc, 0x1C4, &val);
+
+ /* calculate subcache sizes */
+ l3->subcaches[0] = sc0 = !(val & BIT(0));
+ l3->subcaches[1] = sc1 = !(val & BIT(4));
+
+ if (boot_cpu_data.x86 == 0x15) {
+ l3->subcaches[0] = sc0 += !(val & BIT(1));
+ l3->subcaches[1] = sc1 += !(val & BIT(5));
+ }
+
+ l3->subcaches[2] = sc2 = !(val & BIT(8)) + !(val & BIT(9));
+ l3->subcaches[3] = sc3 = !(val & BIT(12)) + !(val & BIT(13));
+
+ l3->indices = (max(max3(sc0, sc1, sc2), sc3) << 10) - 1;
+}
+
+/*
+ * check whether a slot used for disabling an L3 index is occupied.
+ * @l3: L3 cache descriptor
+ * @slot: slot number (0..1)
+ *
+ * @returns: the disabled index if used or negative value if slot free.
+ */
+static int amd_get_l3_disable_slot(struct amd_northbridge *nb, unsigned int slot)
+{
+ unsigned int reg = 0;
+
+ pci_read_config_dword(nb->misc, 0x1BC + slot * 4, &reg);
+
+ /* check whether this slot is activated already */
+ if (reg & (3UL << 30))
+ return reg & 0xfff;
+
+ return -1;
+}
+
+static ssize_t show_cache_disable(struct cacheinfo *ci, char *buf, unsigned int slot)
+{
+ int index;
+ struct amd_northbridge *nb = ci->priv;
+
+ index = amd_get_l3_disable_slot(nb, slot);
+ if (index >= 0)
+ return sprintf(buf, "%d\n", index);
+
+ return sprintf(buf, "FREE\n");
+}
+
+#define SHOW_CACHE_DISABLE(slot) \
+static ssize_t \
+cache_disable_##slot##_show(struct device *dev, \
+ struct device_attribute *attr, char *buf) \
+{ \
+ struct cacheinfo *ci = dev_get_drvdata(dev); \
+ return show_cache_disable(ci, buf, slot); \
+}
+
+SHOW_CACHE_DISABLE(0)
+SHOW_CACHE_DISABLE(1)
+
+static void amd_l3_disable_index(struct amd_northbridge *nb, int cpu,
+ unsigned int slot, unsigned long idx)
+{
+ int i;
+
+ idx |= BIT(30);
+
+ /*
+ * disable index in all 4 subcaches
+ */
+ for (i = 0; i < 4; i++) {
+ u32 reg = idx | (i << 20);
+
+ if (!nb->l3_cache.subcaches[i])
+ continue;
+
+ pci_write_config_dword(nb->misc, 0x1BC + slot * 4, reg);
+
+ /*
+ * We need to WBINVD on a core on the node containing the L3
+ * cache which indices we disable therefore a simple wbinvd()
+ * is not sufficient.
+ */
+ wbinvd_on_cpu(cpu);
+
+ reg |= BIT(31);
+ pci_write_config_dword(nb->misc, 0x1BC + slot * 4, reg);
+ }
+}
+
+/*
+ * disable a L3 cache index by using a disable-slot
+ *
+ * @l3: L3 cache descriptor
+ * @cpu: A CPU on the node containing the L3 cache
+ * @slot: slot number (0..1)
+ * @index: index to disable
+ *
+ * @return: 0 on success, error status on failure
+ */
+static int amd_set_l3_disable_slot(struct amd_northbridge *nb, int cpu,
+ unsigned int slot, unsigned long index)
+{
+ int ret = 0;
+
+ /* check if @slot is already used or the index is already disabled */
+ ret = amd_get_l3_disable_slot(nb, slot);
+ if (ret >= 0)
+ return -EEXIST;
+
+ if (index > nb->l3_cache.indices)
+ return -EINVAL;
+
+ /* check whether the other slot has disabled the same index already */
+ if (index == amd_get_l3_disable_slot(nb, !slot))
+ return -EEXIST;
+
+ amd_l3_disable_index(nb, cpu, slot, index);
+
+ return 0;
+}
+
+static ssize_t store_cache_disable(struct cacheinfo *ci, const char *buf,
+ size_t count, unsigned int slot)
+{
+ struct amd_northbridge *nb = ci->priv;
+ unsigned long val = 0;
+ int cpu, err = 0;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ cpu = cpumask_first(&ci->shared_cpu_map);
+
+ if (kstrtoul(buf, 10, &val) < 0)
+ return -EINVAL;
+
+ err = amd_set_l3_disable_slot(nb, cpu, slot, val);
+ if (err) {
+ if (err == -EEXIST)
+ pr_warn("L3 slot %d in use/index already disabled!\n",
+ slot);
+ return err;
+ }
+ return count;
+}
+
+#define STORE_CACHE_DISABLE(slot) \
+static ssize_t \
+cache_disable_##slot##_store(struct device *dev, \
+ struct device_attribute *attr, \
+ const char *buf, size_t count) \
+{ \
+ struct cacheinfo *ci = dev_get_drvdata(dev); \
+ return store_cache_disable(ci, buf, count, slot); \
+}
+
+STORE_CACHE_DISABLE(0)
+STORE_CACHE_DISABLE(1)
+
+static ssize_t subcaches_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct cacheinfo *ci = dev_get_drvdata(dev);
+ int cpu = cpumask_first(&ci->shared_cpu_map);
+
+ return sprintf(buf, "%x\n", amd_get_subcaches(cpu));
+}
+
+static ssize_t subcaches_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct cacheinfo *ci = dev_get_drvdata(dev);
+ int cpu = cpumask_first(&ci->shared_cpu_map);
+ unsigned long val;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (kstrtoul(buf, 16, &val) < 0)
+ return -EINVAL;
+
+ if (amd_set_subcaches(cpu, val))
+ return -EINVAL;
+
+ return count;
+}
+
+static DEVICE_ATTR_RW(cache_disable_0);
+static DEVICE_ATTR_RW(cache_disable_1);
+static DEVICE_ATTR_RW(subcaches);
+
+static umode_t cache_private_attrs_is_visible(struct kobject *kobj,
+ struct attribute *attr, int unused)
+{
+ struct device *dev = kobj_to_dev(kobj);
+ struct cacheinfo *ci = dev_get_drvdata(dev);
+ umode_t mode = attr->mode;
+
+ if (!ci->priv)
+ return 0;
+
+ if ((attr == &dev_attr_subcaches.attr) &&
+ amd_nb_has_feature(AMD_NB_L3_PARTITIONING))
+ return mode;
+
+ if ((attr == &dev_attr_cache_disable_0.attr ||
+ attr == &dev_attr_cache_disable_1.attr) &&
+ amd_nb_has_feature(AMD_NB_L3_INDEX_DISABLE))
+ return mode;
+
+ return 0;
+}
+
+static struct attribute_group cache_private_group = {
+ .is_visible = cache_private_attrs_is_visible,
+};
+
+static void init_amd_l3_attrs(void)
+{
+ static struct attribute **amd_l3_attrs;
+ int n = 1;
+
+ if (amd_l3_attrs) /* already initialized */
+ return;
+
+ if (amd_nb_has_feature(AMD_NB_L3_INDEX_DISABLE))
+ n += 2;
+ if (amd_nb_has_feature(AMD_NB_L3_PARTITIONING))
+ n += 1;
+
+ amd_l3_attrs = kcalloc(n, sizeof(*amd_l3_attrs), GFP_KERNEL);
+ if (!amd_l3_attrs)
+ return;
+
+ n = 0;
+ if (amd_nb_has_feature(AMD_NB_L3_INDEX_DISABLE)) {
+ amd_l3_attrs[n++] = &dev_attr_cache_disable_0.attr;
+ amd_l3_attrs[n++] = &dev_attr_cache_disable_1.attr;
+ }
+ if (amd_nb_has_feature(AMD_NB_L3_PARTITIONING))
+ amd_l3_attrs[n++] = &dev_attr_subcaches.attr;
+
+ cache_private_group.attrs = amd_l3_attrs;
+}
+
+const struct attribute_group *cache_get_priv_group(struct cacheinfo *ci)
+{
+ struct amd_northbridge *nb = ci->priv;
+
+ if (ci->level < 3 || !nb)
+ return NULL;
+
+ if (nb && nb->l3_cache.indices)
+ init_amd_l3_attrs();
+
+ return &cache_private_group;
+}
+
+struct amd_northbridge *amd_init_l3_cache(int index)
+{
+ struct amd_northbridge *nb;
+ int node;
+
+ /* only for L3, and not in virtualized environments */
+ if (index < 3)
+ return NULL;
+
+ node = topology_amd_node_id(smp_processor_id());
+ nb = node_to_amd_nb(node);
+ if (nb && !nb->l3_cache.indices)
+ amd_calc_l3_indices(nb);
+
+ return nb;
+}
diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index 2a56c7cc3c2d..eadd117c05e1 100644
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -9,12 +9,9 @@
*/

#include <linux/cacheinfo.h>
-#include <linux/capability.h>
#include <linux/cpu.h>
#include <linux/cpuhotplug.h>
-#include <linux/pci.h>
#include <linux/stop_machine.h>
-#include <linux/sysfs.h>

#include <asm/amd_nb.h>
#include <asm/cacheinfo.h>
@@ -300,301 +297,6 @@ amd_cpuid4(int index, union _cpuid4_leaf_eax *eax,
(ebx->split.ways_of_associativity + 1) - 1;
}

-#if defined(CONFIG_AMD_NB) && defined(CONFIG_SYSFS)
-
-/*
- * L3 cache descriptors
- */
-static void amd_calc_l3_indices(struct amd_northbridge *nb)
-{
- struct amd_l3_cache *l3 = &nb->l3_cache;
- unsigned int sc0, sc1, sc2, sc3;
- u32 val = 0;
-
- pci_read_config_dword(nb->misc, 0x1C4, &val);
-
- /* calculate subcache sizes */
- l3->subcaches[0] = sc0 = !(val & BIT(0));
- l3->subcaches[1] = sc1 = !(val & BIT(4));
-
- if (boot_cpu_data.x86 == 0x15) {
- l3->subcaches[0] = sc0 += !(val & BIT(1));
- l3->subcaches[1] = sc1 += !(val & BIT(5));
- }
-
- l3->subcaches[2] = sc2 = !(val & BIT(8)) + !(val & BIT(9));
- l3->subcaches[3] = sc3 = !(val & BIT(12)) + !(val & BIT(13));
-
- l3->indices = (max(max3(sc0, sc1, sc2), sc3) << 10) - 1;
-}
-
-/*
- * check whether a slot used for disabling an L3 index is occupied.
- * @l3: L3 cache descriptor
- * @slot: slot number (0..1)
- *
- * @returns: the disabled index if used or negative value if slot free.
- */
-static int amd_get_l3_disable_slot(struct amd_northbridge *nb, unsigned slot)
-{
- unsigned int reg = 0;
-
- pci_read_config_dword(nb->misc, 0x1BC + slot * 4, &reg);
-
- /* check whether this slot is activated already */
- if (reg & (3UL << 30))
- return reg & 0xfff;
-
- return -1;
-}
-
-static ssize_t show_cache_disable(struct cacheinfo *ci, char *buf, unsigned int slot)
-{
- int index;
- struct amd_northbridge *nb = ci->priv;
-
- index = amd_get_l3_disable_slot(nb, slot);
- if (index >= 0)
- return sprintf(buf, "%d\n", index);
-
- return sprintf(buf, "FREE\n");
-}
-
-#define SHOW_CACHE_DISABLE(slot) \
-static ssize_t \
-cache_disable_##slot##_show(struct device *dev, \
- struct device_attribute *attr, char *buf) \
-{ \
- struct cacheinfo *ci = dev_get_drvdata(dev); \
- return show_cache_disable(ci, buf, slot); \
-}
-SHOW_CACHE_DISABLE(0)
-SHOW_CACHE_DISABLE(1)
-
-static void amd_l3_disable_index(struct amd_northbridge *nb, int cpu,
- unsigned slot, unsigned long idx)
-{
- int i;
-
- idx |= BIT(30);
-
- /*
- * disable index in all 4 subcaches
- */
- for (i = 0; i < 4; i++) {
- u32 reg = idx | (i << 20);
-
- if (!nb->l3_cache.subcaches[i])
- continue;
-
- pci_write_config_dword(nb->misc, 0x1BC + slot * 4, reg);
-
- /*
- * We need to WBINVD on a core on the node containing the L3
- * cache which indices we disable therefore a simple wbinvd()
- * is not sufficient.
- */
- wbinvd_on_cpu(cpu);
-
- reg |= BIT(31);
- pci_write_config_dword(nb->misc, 0x1BC + slot * 4, reg);
- }
-}
-
-/*
- * disable a L3 cache index by using a disable-slot
- *
- * @l3: L3 cache descriptor
- * @cpu: A CPU on the node containing the L3 cache
- * @slot: slot number (0..1)
- * @index: index to disable
- *
- * @return: 0 on success, error status on failure
- */
-static int amd_set_l3_disable_slot(struct amd_northbridge *nb, int cpu,
- unsigned slot, unsigned long index)
-{
- int ret = 0;
-
- /* check if @slot is already used or the index is already disabled */
- ret = amd_get_l3_disable_slot(nb, slot);
- if (ret >= 0)
- return -EEXIST;
-
- if (index > nb->l3_cache.indices)
- return -EINVAL;
-
- /* check whether the other slot has disabled the same index already */
- if (index == amd_get_l3_disable_slot(nb, !slot))
- return -EEXIST;
-
- amd_l3_disable_index(nb, cpu, slot, index);
-
- return 0;
-}
-
-static ssize_t store_cache_disable(struct cacheinfo *ci, const char *buf,
- size_t count, unsigned int slot)
-{
- unsigned long val = 0;
- int cpu, err = 0;
- struct amd_northbridge *nb = ci->priv;
-
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
-
- cpu = cpumask_first(&ci->shared_cpu_map);
-
- if (kstrtoul(buf, 10, &val) < 0)
- return -EINVAL;
-
- err = amd_set_l3_disable_slot(nb, cpu, slot, val);
- if (err) {
- if (err == -EEXIST)
- pr_warn("L3 slot %d in use/index already disabled!\n",
- slot);
- return err;
- }
- return count;
-}
-
-#define STORE_CACHE_DISABLE(slot) \
-static ssize_t \
-cache_disable_##slot##_store(struct device *dev, \
- struct device_attribute *attr, \
- const char *buf, size_t count) \
-{ \
- struct cacheinfo *ci = dev_get_drvdata(dev); \
- return store_cache_disable(ci, buf, count, slot); \
-}
-STORE_CACHE_DISABLE(0)
-STORE_CACHE_DISABLE(1)
-
-static ssize_t subcaches_show(struct device *dev,
- struct device_attribute *attr, char *buf)
-{
- struct cacheinfo *ci = dev_get_drvdata(dev);
- int cpu = cpumask_first(&ci->shared_cpu_map);
-
- return sprintf(buf, "%x\n", amd_get_subcaches(cpu));
-}
-
-static ssize_t subcaches_store(struct device *dev,
- struct device_attribute *attr,
- const char *buf, size_t count)
-{
- struct cacheinfo *ci = dev_get_drvdata(dev);
- int cpu = cpumask_first(&ci->shared_cpu_map);
- unsigned long val;
-
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
-
- if (kstrtoul(buf, 16, &val) < 0)
- return -EINVAL;
-
- if (amd_set_subcaches(cpu, val))
- return -EINVAL;
-
- return count;
-}
-
-static DEVICE_ATTR_RW(cache_disable_0);
-static DEVICE_ATTR_RW(cache_disable_1);
-static DEVICE_ATTR_RW(subcaches);
-
-static umode_t
-cache_private_attrs_is_visible(struct kobject *kobj,
- struct attribute *attr, int unused)
-{
- struct device *dev = kobj_to_dev(kobj);
- struct cacheinfo *ci = dev_get_drvdata(dev);
- umode_t mode = attr->mode;
-
- if (!ci->priv)
- return 0;
-
- if ((attr == &dev_attr_subcaches.attr) &&
- amd_nb_has_feature(AMD_NB_L3_PARTITIONING))
- return mode;
-
- if ((attr == &dev_attr_cache_disable_0.attr ||
- attr == &dev_attr_cache_disable_1.attr) &&
- amd_nb_has_feature(AMD_NB_L3_INDEX_DISABLE))
- return mode;
-
- return 0;
-}
-
-static struct attribute_group cache_private_group = {
- .is_visible = cache_private_attrs_is_visible,
-};
-
-static void init_amd_l3_attrs(void)
-{
- int n = 1;
- static struct attribute **amd_l3_attrs;
-
- if (amd_l3_attrs) /* already initialized */
- return;
-
- if (amd_nb_has_feature(AMD_NB_L3_INDEX_DISABLE))
- n += 2;
- if (amd_nb_has_feature(AMD_NB_L3_PARTITIONING))
- n += 1;
-
- amd_l3_attrs = kcalloc(n, sizeof(*amd_l3_attrs), GFP_KERNEL);
- if (!amd_l3_attrs)
- return;
-
- n = 0;
- if (amd_nb_has_feature(AMD_NB_L3_INDEX_DISABLE)) {
- amd_l3_attrs[n++] = &dev_attr_cache_disable_0.attr;
- amd_l3_attrs[n++] = &dev_attr_cache_disable_1.attr;
- }
- if (amd_nb_has_feature(AMD_NB_L3_PARTITIONING))
- amd_l3_attrs[n++] = &dev_attr_subcaches.attr;
-
- cache_private_group.attrs = amd_l3_attrs;
-}
-
-const struct attribute_group *
-cache_get_priv_group(struct cacheinfo *ci)
-{
- struct amd_northbridge *nb = ci->priv;
-
- if (ci->level < 3 || !nb)
- return NULL;
-
- if (nb && nb->l3_cache.indices)
- init_amd_l3_attrs();
-
- return &cache_private_group;
-}
-
-static struct amd_northbridge *amd_init_l3_cache(int index)
-{
- struct amd_northbridge *nb;
- int node;
-
- /* only for L3, and not in virtualized environments */
- if (index < 3)
- return NULL;
-
- node = topology_amd_node_id(smp_processor_id());
- nb = node_to_amd_nb(node);
- if (nb && !nb->l3_cache.indices)
- amd_calc_l3_indices(nb);
-
- return nb;
-}
-#else
-static struct amd_northbridge *amd_init_l3_cache(int index)
-{
- return NULL;
-}
-#endif /* CONFIG_AMD_NB && CONFIG_SYSFS */
-
/*
* Fill passed _cpuid4_info_regs structure.
* Intel-only code paths should pass NULL for the amd_northbridge
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index 51deb60a9d26..bc38b2d56f26 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -75,6 +75,15 @@ extern void check_null_seg_clears_base(struct cpuinfo_x86 *c);
void cacheinfo_amd_init_llc_id(struct cpuinfo_x86 *c, u16 die_id);
void cacheinfo_hygon_init_llc_id(struct cpuinfo_x86 *c);

+#if defined(CONFIG_AMD_NB) && defined(CONFIG_SYSFS)
+struct amd_northbridge *amd_init_l3_cache(int index);
+#else
+static inline struct amd_northbridge *amd_init_l3_cache(int index)
+{
+ return NULL;
+}
+#endif
+
unsigned int aperfmperf_get_khz(int cpu);
void cpu_select_mitigations(void);

--
2.48.1