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    Leaf 0xb will be superseded by leaf 0x80000026 soon, which is just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, 6 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/topology.h b/arch/x86/kernel/cpu/topology.h
index 2b100cd11f17..7eead546c20e 100644
--- a/arch/x86/kernel/cpu/topology.h
+++ b/arch/x86/kernel/cpu/topology.h
@@ -9,6 +9,10 @@ struct topo_scan {
 
 	/* Legacy CPUID[1]:EBX[23:16] number of logical processors */
 	unsigned int		ebx1_nproc_shift;
+
+	/* AMD specific node ID which cannot be mapped into APIC space. */
+	u16			amd_nodes_per_pkg;
+	u16			amd_node_id;
 };
 
 bool topo_is_converted(struct cpuinfo_x86 *c);
@@ -17,6 +21,8 @@ void cpu_parse_topology(struct cpuinfo_x86 *c);
 void topology_set_dom(struct topo_scan *tscan, enum x86_topology_domains dom,
 		      unsigned int shift, unsigned int ncpus);
 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);
 
 static inline u32 topo_shift_apicid(u32 apicid, enum x86_topology_domains dom)
 {