linux-kernel - [PATCH] x86/cpuid: Deal with broken firmware once more

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Message-ID: <alpine.DEB.2.20.1611091613540.3501@nanos>
Date:   Wed, 9 Nov 2016 16:35:51 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Charles (Chas) Williams" <ciwillia@...cade.com>
cc:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>, x86@...nel.org,
        LKML <linux-kernel@...r.kernel.org>,
        "M. Vefa Bicakci" <m.v.b@...box.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>
Subject: [PATCH] x86/cpuid: Deal with broken firmware once more

Both ACPI and MP specifications require that the APIC id in the respective
tables must be the same as the APIC id in CPUID. 

The kernel retrieves the physical package id from the APIC id during the
ACPI/MP table scan and builds the physical to logical package map.

There exist Virtualbox and Xen implementations which violate the spec. As a
result the physical to logical package map, which relies on the ACPI/MP
tables does not work on those systems, because the CPUID initialized
physical package id does not match the firmware id. This causes system
crashes and malfunction due to invalid package mappings.

The only way to cure this is to sanitize the physical package id after the
CPUID enumeration and yell when the APIC ids are different. If the physical
package IDs differ use the package information from the ACPI/MP tables so
the existing logical package map just works.

Reported-by: "Charles (Chas) Williams" <ciwillia@...cade.com>,
Reported-by: M. Vefa Bicakci <m.v.b@...box.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/kernel/cpu/common.c |   31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -979,6 +979,34 @@ static void x86_init_cache_qos(struct cp
 }
 
 /*
+ * The physical to logical package id mapping is initialized from the
+ * acpi/mptables information. Make sure that CPUID actually agrees with
+ * that.
+ */
+static void sanitize_package_id(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+	unsigned int pkg, apicid, cpu = smp_processor_id();
+
+	apicid = apic->cpu_present_to_apicid(cpu);
+	pkg = apicid >> boot_cpu_data.x86_coreid_bits;
+
+	if (apicid != c->initial_apicid) {
+		pr_err(FW_BUG "CPU%u: APIC id mismatch. Firmware: %x CPUID: %x\n",
+		       cpu, apicid, c->initial_apicid);
+	}
+	if (pkg != c->phys_proc_id) {
+		pr_err(FW_BUG "CPU%u: Using firmware package id %u instead of %u\n",
+		       cpu, pkg, c->phys_proc_id);
+		c->phys_proc_id = pkg;
+	}
+	c->logical_proc_id = topology_phys_to_logical_pkg(pkg);
+#else
+	c->locical_proc_id = 0;
+#endif
+}
+
+/*
  * This does the hard work of actually picking apart the CPU stuff...
  */
 static void identify_cpu(struct cpuinfo_x86 *c)
@@ -1103,8 +1131,7 @@ static void identify_cpu(struct cpuinfo_
 #ifdef CONFIG_NUMA
 	numa_add_cpu(smp_processor_id());
 #endif
-	/* The boot/hotplug time assigment got cleared, restore it */
-	c->logical_proc_id = topology_phys_to_logical_pkg(c->phys_proc_id);
+	sanitize_package_id(c);
 }
 
 /*