x86/cpu: Provide an AMD/HYGON specific topology parser

AMD/HYGON uses various methods for topology evaluation:

  - Leaf 0x80000008 and 0x8000001e based with an optional leaf 0xb,
    which is the preferred variant for modern CPUs.

    Leaf 0xb will be superseded by leaf 0x80000026 soon, which is just
    another variant of the Intel 0x1f leaf for whatever reasons.
    
  - Subleaf 0x80000008 and NODEID_MSR base

  - Legacy fallback

That code is following the principle of random bits and pieces all over the
place which results in multiple evaluations and impenetrable code flows in
the same way as the Intel parsing did.

Provide a sane implementation by clearly separating the three variants and
bringing them in the proper preference order in one place.

This provides the parsing for both AMD and HYGON because there is no point
in having a separate HYGON parser which only differs by 3 lines of
code. Any further divergence between AMD and HYGON can be handled in
different functions, while still sharing the existing parsers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Wang Wendy <wendy.wang@intel.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20240212153625.020038641@linutronix.de

1 files changed, 183 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/topology_amd.c b/arch/x86/kernel/cpu/topology_amd.c
new file mode 100644
index 000000000000..1a8b3ad493af
--- /dev/null
+++ b/arch/x86/kernel/cpu/topology_amd.c
@@ -0,0 +1,183 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/cpu.h>
+
+#include <asm/apic.h>
+#include <asm/memtype.h>
+#include <asm/processor.h>
+
+#include "cpu.h"
+
+static bool parse_8000_0008(struct topo_scan *tscan)
+{
+	struct {
+		// ecx
+		u32	cpu_nthreads		:  8, // Number of physical threads - 1
+						:  4, // Reserved
+			apicid_coreid_len	:  4, // Number of thread core ID bits (shift) in APIC ID
+			perf_tsc_len		:  2, // Performance time-stamp counter size
+						: 14; // Reserved
+	} ecx;
+	unsigned int sft;
+
+	if (tscan->c->extended_cpuid_level < 0x80000008)
+		return false;
+
+	cpuid_leaf_reg(0x80000008, CPUID_ECX, &ecx);
+
+	/* If the thread bits are 0, then get the shift value from ecx.cpu_nthreads */
+	sft = ecx.apicid_coreid_len;
+	if (!sft)
+		sft = get_count_order(ecx.cpu_nthreads + 1);
+
+	topology_set_dom(tscan, TOPO_SMT_DOMAIN, sft, ecx.cpu_nthreads + 1);
+	return true;
+}
+
+static void store_node(struct topo_scan *tscan, unsigned int nr_nodes, u16 node_id)
+{
+	/*
+	 * Starting with Fam 17h the DIE domain could probably be used to
+	 * retrieve the node info on AMD/HYGON. Analysis of CPUID dumps
+	 * suggests it's the topmost bit(s) of the CPU cores area, but
+	 * that's guess work and neither enumerated nor documented.
+	 *
+	 * Up to Fam 16h this does not work at all and the legacy node ID
+	 * has to be used.
+	 */
+	tscan->amd_nodes_per_pkg = nr_nodes;
+	tscan->amd_node_id = node_id;
+}
+
+static bool parse_8000_001e(struct topo_scan *tscan, bool has_0xb)
+{
+	struct {
+		// eax
+		u32	ext_apic_id		: 32; // Extended APIC ID
+		// ebx
+		u32	core_id			:  8, // Unique per-socket logical core unit ID
+			core_nthreads		:  8, // #Threads per core (zero-based)
+						: 16; // Reserved
+		// ecx
+		u32	node_id			:  8, // Node (die) ID of invoking logical CPU
+			nnodes_per_socket	:  3, // #nodes in invoking logical CPU's package/socket
+						: 21; // Reserved
+		// edx
+		u32				: 32; // Reserved
+	} leaf;
+
+	if (!boot_cpu_has(X86_FEATURE_TOPOEXT))
+		return false;
+
+	cpuid_leaf(0x8000001e, &leaf);
+
+	tscan->c->topo.initial_apicid = leaf.ext_apic_id;
+
+	/*
+	 * If leaf 0xb is available, then SMT shift is set already. If not
+	 * take it from ecx.threads_per_core and use topo_update_dom() -
+	 * topology_set_dom() would propagate and overwrite the already
+	 * propagated CORE level.
+	 */
+	if (!has_0xb) {
+		unsigned int nthreads = leaf.core_nthreads + 1;
+
+		topology_update_dom(tscan, TOPO_SMT_DOMAIN, get_count_order(nthreads), nthreads);
+	}
+
+	store_node(tscan, leaf.nnodes_per_socket + 1, leaf.node_id);
+
+	if (tscan->c->x86_vendor == X86_VENDOR_AMD) {
+		if (tscan->c->x86 == 0x15)
+			tscan->c->topo.cu_id = leaf.core_id;
+
+		cacheinfo_amd_init_llc_id(tscan->c, leaf.node_id);
+	} else {
+		/*
+		 * Package ID is ApicId[6..] on certain Hygon CPUs. See
+		 * commit e0ceeae708ce for explanation. The topology info
+		 * is screwed up: The package shift is always 6 and the
+		 * node ID is bit [4:5].
+		 */
+		if (!boot_cpu_has(X86_FEATURE_HYPERVISOR) && tscan->c->x86_model <= 0x3) {
+			topology_set_dom(tscan, TOPO_CORE_DOMAIN, 6,
+					 tscan->dom_ncpus[TOPO_CORE_DOMAIN]);
+		}
+		cacheinfo_hygon_init_llc_id(tscan->c);
+	}
+	return true;
+}
+
+static bool parse_fam10h_node_id(struct topo_scan *tscan)
+{
+	struct {
+		union {
+			u64	node_id		:  3,
+				nodes_per_pkg	:  3,
+				unused		: 58;
+			u64	msr;
+		};
+	} nid;
+
+	if (!boot_cpu_has(X86_FEATURE_NODEID_MSR))
+		return false;
+
+	rdmsrl(MSR_FAM10H_NODE_ID, nid.msr);
+	store_node(tscan, nid.nodes_per_pkg + 1, nid.node_id);
+	tscan->c->topo.llc_id = nid.node_id;
+	return true;
+}
+
+static void legacy_set_llc(struct topo_scan *tscan)
+{
+	unsigned int apicid = tscan->c->topo.initial_apicid;
+
+	/* parse_8000_0008() set everything up except llc_id */
+	tscan->c->topo.llc_id = apicid >> tscan->dom_shifts[TOPO_CORE_DOMAIN];
+}
+
+static void parse_topology_amd(struct topo_scan *tscan)
+{
+	bool has_0xb = false;
+
+	/*
+	 * If the extended topology leaf 0x8000_001e is available
+	 * try to get SMT and CORE shift from leaf 0xb first, then
+	 * try to get the CORE shift from leaf 0x8000_0008.
+	 */
+	if (cpu_feature_enabled(X86_FEATURE_TOPOEXT))
+		has_0xb = cpu_parse_topology_ext(tscan);
+
+	if (!has_0xb && !parse_8000_0008(tscan))
+		return;
+
+	/* Prefer leaf 0x8000001e if available */
+	if (parse_8000_001e(tscan, has_0xb))
+		return;
+
+	/* Try the NODEID MSR */
+	if (parse_fam10h_node_id(tscan))
+		return;
+
+	legacy_set_llc(tscan);
+}
+
+void cpu_parse_topology_amd(struct topo_scan *tscan)
+{
+	tscan->amd_nodes_per_pkg = 1;
+	parse_topology_amd(tscan);
+
+	if (tscan->amd_nodes_per_pkg > 1)
+		set_cpu_cap(tscan->c, X86_FEATURE_AMD_DCM);
+}
+
+void cpu_topology_fixup_amd(struct topo_scan *tscan)
+{
+	struct cpuinfo_x86 *c = tscan->c;
+
+	/*
+	 * Adjust the core_id relative to the node when there is more than
+	 * one node.
+	 */
+	if (tscan->c->x86 < 0x17 && tscan->amd_nodes_per_pkg > 1)
+		c->topo.core_id %= tscan->dom_ncpus[TOPO_CORE_DOMAIN] / tscan->amd_nodes_per_pkg;
+}