x86/apic: Sanitize num_processors handling

num_processors is 0 by default and only gets incremented when local APICs
are registered.

Make init_apic_mappings(), which tries to enable the local APIC in the case
that no SMP configuration was found set num_processors to 1.

This allows to remove yet another check for the local APIC and yet another
place which registers the boot CPUs local APIC ID.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Juergen Gross <jgross@suse.com> # Xen PV (dom0 and unpriv. guest)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 84ff5b27590bb3a192e7e696f310729463b098b8..564d584c8b99814f418979b70af6a8fb65f336f9 100644 (file)
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2130,9 +2130,12 @@ void __init init_apic_mappings(void)
        if (x2apic_mode)
                return;
 
-       if (!smp_found_config && !detect_init_APIC()) {
-               pr_info("APIC: disable apic facility\n");
-               apic_disable();
+       if (!smp_found_config) {
+               if (!detect_init_APIC()) {
+                       pr_info("APIC: disable apic facility\n");
+                       apic_disable();
+               }
+               num_processors = 1;
        }
 }
 

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 5467c58827f59cecb6ed48b4bec32fa65a98f0d4..fc2173b7dc89345231f0fe977bf2ec5b9a2e6eaa 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1397,24 +1397,6 @@ __init void prefill_possible_map(void)
 {
        int i, possible;
 
-       /* No processor was found in mptable or ACPI MADT */
-       if (!num_processors) {
-               if (boot_cpu_has(X86_FEATURE_APIC)) {
-                       int apicid = boot_cpu_physical_apicid;
-                       int cpu = read_apic_id();
-
-                       pr_warn("Boot CPU (id %d) not listed by BIOS\n", cpu);
-
-                       /* Make sure boot cpu is enumerated */
-                       if (apic->cpu_present_to_apicid(0) == BAD_APICID &&
-                           apic->apic_id_valid(apicid))
-                               generic_processor_info(apicid);
-               }
-
-               if (!num_processors)
-                       num_processors = 1;
-       }
-
        i = setup_max_cpus ?: 1;
        if (setup_possible_cpus == -1) {
                possible = num_processors;