x86/cpu/intel: Evaluate smp_num_siblings early

Make use of the new early detection function to initialize smp_num_siblings
on the boot cpu before the MP-Table or ACPI/MADT scan happens. That's
required for force disabling SMT.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
CVE-2018-3620
CVE-2018-3646

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 6df33c2d6f014aeb5d0c9eef9717389c9de32641..9b9da099f2ef0434a00dfdaf8a6be217c18a1d62 100644 (file)
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -301,6 +301,13 @@ static void early_init_intel(struct cpuinfo_x86 *c)
        }
 
        check_mpx_erratum(c);
+
+       /*
+        * Get the number of SMT siblings early from the extended topology
+        * leaf, if available. Otherwise try the legacy SMT detection.
+        */
+       if (detect_extended_topology_early(c) < 0)
+               detect_ht_early(c);
 }
 
 #ifdef CONFIG_X86_32