From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 5 Jun 2018 22:57:38 +0000 (+0200)
Subject: x86/cpu/AMD: Evaluate smp_num_siblings early
X-Git-Tag: v4.1.12-124.31.3~651
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a4813e96d68c4617601be2f4eadfaea9b9ebbe30;p=users%2Fjedix%2Flinux-maple.git

x86/cpu/AMD: Evaluate smp_num_siblings early

To support force disabling of SMT it's required to know the number of
thread siblings early. amd_get_topology() cannot be called before the APIC
driver is selected, so split out the part which initializes
smp_num_siblings and invoke it from amd_early_init().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>

Orabug: 28220674
CVE: CVE-2018-3620

(cherry picked from commit 1e1d7e25fd759eddf96d8ab39d0a90a1979b2d8c)

Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Conflicts:
	arch/x86/kernel/cpu/amd.c
Contextual
---

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index eaa846fa2733..199809d443a8 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -283,6 +283,16 @@ static int nearby_node(int apicid)
 }
 #endif
 
+static void amd_get_topology_early(struct cpuinfo_x86 *c)
+{
+	if (boot_cpu_has(X86_FEATURE_TOPOEXT)) {
+		u32 eax, ebx, ecx, edx;
+
+		cpuid(0x8000001e, &eax, &ebx, &ecx, &edx);
+		smp_num_siblings = ((ebx >> 8) & 0xff) + 1;
+	}
+}
+
 /*
  * Fixup core topology information for
  * (1) AMD multi-node processors
@@ -560,6 +570,8 @@ static void early_init_amd(struct cpuinfo_x86 *c)
 	/* F16h erratum 793, CVE-2013-6885 */
 	if (c->x86 == 0x16 && c->x86_model <= 0xf)
 		msr_set_bit(MSR_AMD64_LS_CFG, 15);
+
+	amd_get_topology_early(c);
 }
 
 static const int amd_erratum_383[];