Patch "x86/CPU/AMD: Fix Bulldozer topology" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

x86/CPU/AMD: Fix Bulldozer topology

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-cpu-amd-fix-bulldozer-topology.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Borislav Petkov <[email protected]>
Date: Thu, 5 Jan 2017 10:26:38 +0100
Subject: x86/CPU/AMD: Fix Bulldozer topology

From: Borislav Petkov <[email protected]>

commit a33d331761bc5dd330499ca5ceceb67f0640a8e6 upstream.

The following commit:

8196dab4fc15 ("x86/cpu: Get rid of compute_unit_id")

... broke the initial strategy for Bulldozer-based cores' topology, where we consider each thread of a compute unit a standalone core and not a HT or SMT thread.

Revert to the firmware-supplied core_id numbering and do not make them thread siblings as we don't consider them for such even if they technically are, more or less.

---
 arch/x86/kernel/cpu/amd.c |    9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

@@ -309,15 +309,8 @@ static void amd_get_topology(struct cpui
 
 	/* get information required for multi-node processors */
 	if (boot_cpu_has(X86_FEATURE_TOPOEXT)) {
-		u32 eax, ebx, ecx, edx;
 
-		cpuid(0x8000001e, &eax, &ebx, &ecx, &edx);
-		node_id = ecx & 7;
-
-		/* get compute unit information */
-		smp_num_siblings = ((ebx >> 8) & 3) + 1;
-		c->x86_max_cores /= smp_num_siblings;
-		c->cpu_core_id = ebx & 0xff;
+		node_id = cpuid_ecx(0x8000001e) & 7;
 
 		/*
 		 * We may have multiple LLCs if L3 caches exist, so check if we

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/perf-x86-intel-uncore-fix-hardcoded-socket-0-assumption-in-the-haswell-init-code.patch queue-4.9/x86-cpu-amd-fix-bulldozer-topology.patch queue-4.9/x86-bugs-separate-amd-e400-erratum-and-c1e-bug.patch queue-4.9/x86-cpu-amd-clean-up-cpu_llc_id-assignment-per-topology-feature.patch