From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 5 Jun 2018 22:55:39 +0000 (+0200)
Subject: x86/cpu/topology: Provide detect_extended_topology_early()
X-Git-Tag: v4.1.12-124.31.3~654
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=ce7f3678e9a01ef8af8b455d01dc6d3989f96a3b;p=users%2Fjedix%2Flinux-maple.git

x86/cpu/topology: Provide detect_extended_topology_early()

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

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>

Orabug: 28220674
CVE: CVE-2018-3620

(cherry picked from commit 95f3d39ccf7aaea79d1ffdac1c887c2e100ec1b6)

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

Conflicts:
	arch/x86/kernel/cpu/cpu.h
	arch/x86/kernel/cpu/topology.c
Contextual
---

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 5537d70cfdc6..621b9346032b 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -190,7 +190,7 @@ extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c,
 extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c);
 extern void init_amd_cacheinfo(struct cpuinfo_x86 *c);
 
-extern void detect_extended_topology(struct cpuinfo_x86 *c);
+extern int detect_extended_topology(struct cpuinfo_x86 *c);
 extern void detect_ht(struct cpuinfo_x86 *c);
 
 #ifdef CONFIG_X86_32
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index aff12c9cd277..ca5d33321e7c 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -46,6 +46,7 @@ extern const struct cpu_dev *const __x86_cpu_dev_start[],
 extern void get_cpu_cap(struct cpuinfo_x86 *c,
 			enum get_cpu_cap_behavior behavior);
 extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c);
+extern int detect_extended_topology_early(struct cpuinfo_x86 *c);
 extern int detect_ht_early(struct cpuinfo_x86 *c);
 extern void x86_spec_ctrl_setup_ap(void);
 
diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index 2c30e2cf1f1a..ad232ec8e61d 100644
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -21,20 +21,14 @@
 #define BITS_SHIFT_NEXT_LEVEL(eax)	((eax) & 0x1f)
 #define LEVEL_MAX_SIBLINGS(ebx)		((ebx) & 0xffff)
 
-/*
- * Check for extended topology enumeration cpuid leaf 0xb and if it
- * exists, use it for populating initial_apicid and cpu topology
- * detection.
- */
-void detect_extended_topology(struct cpuinfo_x86 *c)
+int detect_extended_topology_early(struct cpuinfo_x86 *c)
 {
 #ifdef CONFIG_SMP
-	unsigned int eax, ebx, ecx, edx, sub_index;
-	unsigned int ht_mask_width, core_plus_mask_width;
-	unsigned int core_select_mask, core_level_siblings;
+	unsigned int eax, ebx, ecx, edx;
+
 
 	if (c->cpuid_level < 0xb)
-		return;
+		return -1;
 
 	cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
 
@@ -42,7 +36,7 @@ void detect_extended_topology(struct cpuinfo_x86 *c)
 	 * check if the cpuid leaf 0xb is actually implemented.
 	 */
 	if (ebx == 0 || (LEAFB_SUBTYPE(ecx) != SMT_TYPE))
-		return;
+		return -1;
 
 	set_cpu_cap(c, X86_FEATURE_XTOPOLOGY);
 
@@ -50,10 +44,30 @@ void detect_extended_topology(struct cpuinfo_x86 *c)
 	 * initial apic id, which also represents 32-bit extended x2apic id.
 	 */
 	c->initial_apicid = edx;
+	smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
+#endif
+	return 0;
+}
+
+/*
+ * Check for extended topology enumeration cpuid leaf 0xb and if it
+ * exists, use it for populating initial_apicid and cpu topology
+ * detection.
+ */
+int detect_extended_topology(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+	unsigned int eax, ebx, ecx, edx, sub_index;
+	unsigned int ht_mask_width, core_plus_mask_width;
+	unsigned int core_select_mask, core_level_siblings;
+
+	if (detect_extended_topology_early(c) < 0)
+		return -1;
 
 	/*
 	 * Populate HT related information from sub-leaf level 0.
 	 */
+	cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
 	core_level_siblings = smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
 	core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
 
@@ -85,6 +99,6 @@ void detect_extended_topology(struct cpuinfo_x86 *c)
 
 	c->x86_max_cores = (core_level_siblings / smp_num_siblings);
 
-	return;
 #endif
+	return 0;
 }