[PATCH] x86/topology: Fix Hygon logical_die_id by mapping from amd_node_id

[Aichun Shi]

On Hygon CPUs, for some cases such as EDAC error decoding, contiguous die
IDs are required. cpuinfo_topology.amd_node_id cannot be used directly as
it may be non-contiguous, thus cpuinfo_topology.logical_die_id can be used
in such cases.

When CPUID leaf 0x80000026 is not available on Hygon CPUs, die (or node)
topology is not encoded in APIC ID space. logical_die_id obtained from
topology_get_logical_id(apicid, TOPO_DIE_DOMAIN) therefore does not align
with die (or node) topology and is incorrect.

Fix this by adding a Hygon-only fixup in a new topology_hygon.c: Build a
bijective mapping from (logical_pkg_id, amd_node_id) to a contiguous
logical_die_id. Leave the original APIC-based path unchanged when CPUID
leaf 0x80000026 is available.

Signed-off-by: Aichun Shi <shiaichun@xxxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/Makefile          |  2 +-
 arch/x86/kernel/cpu/topology.h        |  5 ++
 arch/x86/kernel/cpu/topology_common.c |  3 +
 arch/x86/kernel/cpu/topology_hygon.c  | 86 +++++++++++++++++++++++++++
 4 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/kernel/cpu/topology_hygon.c

diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 2f8a58ef690e..4e80d0a5d0c9 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -38,10 +38,10 @@ obj-y					+= intel.o tsx.o
 obj-$(CONFIG_PM)			+= intel_epb.o
 endif
 obj-$(CONFIG_CPU_SUP_AMD)		+= amd.o
+obj-$(CONFIG_CPU_SUP_HYGON)		+= hygon.o topology_hygon.o
 ifeq ($(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
 obj-$(CONFIG_CPU_SUP_TRANSMETA_32)	+= transmeta.o
diff --git a/arch/x86/kernel/cpu/topology.h b/arch/x86/kernel/cpu/topology.h
index 37326297f80c..7203ff0457a4 100644
--- a/arch/x86/kernel/cpu/topology.h
+++ b/arch/x86/kernel/cpu/topology.h
@@ -22,6 +22,11 @@ void topology_set_dom(struct topo_scan *tscan, enum x86_topology_domains dom,
 bool cpu_parse_topology_ext(struct topo_scan *tscan);
 void cpu_parse_topology_amd(struct topo_scan *tscan);
 void cpu_topology_fixup_amd(struct topo_scan *tscan);
+#ifdef CONFIG_CPU_SUP_HYGON
+void cpu_topology_fixup_hygon(struct topo_scan *tscan);
+#else
+static inline void cpu_topology_fixup_hygon(struct topo_scan *tscan) { }
+#endif
 
 static inline u32 topo_shift_apicid(u32 apicid, enum x86_topology_domains dom)
 {
diff --git a/arch/x86/kernel/cpu/topology_common.c b/arch/x86/kernel/cpu/topology_common.c
index 71625795d711..82803744bd0e 100644
--- a/arch/x86/kernel/cpu/topology_common.c
+++ b/arch/x86/kernel/cpu/topology_common.c
@@ -199,6 +199,9 @@ static void topo_set_ids(struct topo_scan *tscan, bool early)
 
 	if (c->x86_vendor == X86_VENDOR_AMD)
 		cpu_topology_fixup_amd(tscan);
+
+	if (c->x86_vendor == X86_VENDOR_HYGON && !early)
+		cpu_topology_fixup_hygon(tscan);
 }
 
 void cpu_parse_topology(struct cpuinfo_x86 *c)
diff --git a/arch/x86/kernel/cpu/topology_hygon.c b/arch/x86/kernel/cpu/topology_hygon.c
new file mode 100644
index 000000000000..645c30524da6
--- /dev/null
+++ b/arch/x86/kernel/cpu/topology_hygon.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/cpu.h>
+#include <linux/printk.h>
+#include <linux/spinlock.h>
+
+#include <asm/processor.h>
+
+#include "topology.h"
+
+/* (logical_pkg_id, amd_node_id) -> logical_die_id mapping. */
+struct hygon_die_map_entry {
+	u32 logical_pkg_id;
+	u32 amd_node_id;
+	u32 logical_die_id;
+};
+
+static DEFINE_SPINLOCK(hygon_die_map_lock);
+static struct hygon_die_map_entry hygon_die_map[NR_CPUS];
+static u32 hygon_next_logical_die_id;
+static unsigned int hygon_die_map_nr;
+
+/*
+ * Build a bijective mapping from (logical_pkg_id, amd_node_id) to a contiguous
+ * logical_die_id for Hygon CPUs.
+ *
+ * Returns logical_die_id (>= 0) on success, or -EINVAL on error.
+ */
+static int hygon_get_logical_die_id(struct topo_scan *tscan)
+{
+	struct cpuinfo_x86 *c = tscan->c;
+	unsigned long flags;
+	int logical_die_id;
+	unsigned int i;
+	int logical_pkg_id = c->topo.logical_pkg_id;
+
+	if (c->x86_vendor != X86_VENDOR_HYGON)
+		return -EINVAL;
+
+	if (logical_pkg_id < 0)
+		return -EINVAL;
+
+	spin_lock_irqsave(&hygon_die_map_lock, flags);
+
+	/* Look up existing (logical_pkg_id, amd_node_id) -> logical_die_id. */
+	for (i = 0; i < hygon_die_map_nr; i++) {
+		if (hygon_die_map[i].logical_pkg_id == logical_pkg_id &&
+		    hygon_die_map[i].amd_node_id == tscan->amd_node_id) {
+			logical_die_id = hygon_die_map[i].logical_die_id;
+			goto out_unlock;
+		}
+	}
+
+	if (hygon_die_map_nr >= ARRAY_SIZE(hygon_die_map)) {
+		pr_warn_once("CPU topo: Hygon die map exhausted\n");
+		logical_die_id = -EINVAL;
+		goto out_unlock;
+	}
+
+	/* Allocate new contiguous logical_die_id. */
+	logical_die_id = hygon_next_logical_die_id++;
+	hygon_die_map[hygon_die_map_nr++] = (struct hygon_die_map_entry) {
+		.logical_pkg_id = logical_pkg_id,
+		.amd_node_id = tscan->amd_node_id,
+		.logical_die_id = logical_die_id,
+	};
+
+out_unlock:
+	spin_unlock_irqrestore(&hygon_die_map_lock, flags);
+	return logical_die_id;
+}
+
+void cpu_topology_fixup_hygon(struct topo_scan *tscan)
+{
+	/* Skip the fixup if CPUID leaf 0x80000026 is available. */
+	if (tscan->c->extended_cpuid_level >= 0x80000026)
+		return;
+
+	/* When CPUID leaf 0x80000026 is not available, die (node) topology is
+	 * not encoded in APIC ID space. logical_die_id from the DIE domain is
+	 * incorrect, so fix it up.
+	 */
+	int logical_die_id = hygon_get_logical_die_id(tscan);
+
+	if (logical_die_id >= 0)
+		tscan->c->topo.logical_die_id = logical_die_id;
+}
-- 
2.47.3