x86/vdso: Initialize the CPU/node NR segment descriptor earlier

Currently the CPU/node NR segment descriptor (GDT_ENTRY_CPU_NUMBER) is
initialized relatively late during CPU init, from the vCPU code, which
has a number of disadvantages, such as hotplug CPU notifiers and SMP
cross-calls.

Instead just initialize it much earlier, directly in cpu_init().

This reduces complexity and increases robustness.

[ mingo: Wrote new changelog. ]

Suggested-by: H. Peter Anvin <hpa@zytor.com>
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Markus T Metzger <markus.t.metzger@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1537312139-5580-9-git-send-email-chang.seok.bae@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 39b5584c5808ec7169009ffb590a2e362a7c733e..3f9d43f26f630b29ef9cb53f39d9f2079df84a06 100644 (file)
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -332,35 +332,6 @@ static __init int vdso_setup(char *s)
        return 0;
 }
 __setup("vdso=", vdso_setup);
-#endif
-
-#ifdef CONFIG_X86_64
-static void vgetcpu_cpu_init(void *arg)
-{
-       int cpu = smp_processor_id();
-       struct desc_struct d = { };
-       unsigned long cpudata = vdso_encode_cpu_node(cpu, cpu_to_node(cpu));
-
-       if (static_cpu_has(X86_FEATURE_RDTSCP))
-               write_rdtscp_aux(cpudata);
-
-       /* Store CPU and node number in limit */
-       d.limit0 = cpudata;
-       d.limit1 = cpudata >> 16;
-
-       d.type = 5;             /* RO data, expand down, accessed */
-       d.dpl = 3;              /* Visible to user code */
-       d.s = 1;                /* Not a system segment */
-       d.p = 1;                /* Present */
-       d.d = 1;                /* 32-bit */
-
-       write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_CPU_NUMBER, &d, DESCTYPE_S);
-}
-
-static int vgetcpu_online(unsigned int cpu)
-{
-       return smp_call_function_single(cpu, vgetcpu_cpu_init, NULL, 1);
-}
 
 static int __init init_vdso(void)
 {
@@ -370,9 +341,7 @@ static int __init init_vdso(void)
        init_vdso_image(&vdso_image_x32);
 #endif
 
-       /* notifier priority > KVM */
-       return cpuhp_setup_state(CPUHP_AP_X86_VDSO_VMA_ONLINE,
-                                "x86/vdso/vma:online", vgetcpu_online, NULL);
+       return 0;
 }
 subsys_initcall(init_vdso);
 #endif /* CONFIG_X86_64 */

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 44c4ef3d989b59b7bd98ebf617f8e5ee1d2a9548..a148d18a1ef027305b1ae08b49ab7dc2a7ed5b64 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1669,6 +1669,29 @@ static void wait_for_master_cpu(int cpu)
 #endif
 }
 
+#ifdef CONFIG_X86_64
+static void setup_getcpu(int cpu)
+{
+       unsigned long cpudata = vdso_encode_cpu_node(cpu, early_cpu_to_node(cpu));
+       struct desc_struct d = { };
+
+       if (static_cpu_has(X86_FEATURE_RDTSCP))
+               write_rdtscp_aux(cpudata);
+
+       /* Store CPU and node number in limit. */
+       d.limit0 = cpudata;
+       d.limit1 = cpudata >> 16;
+
+       d.type = 5;             /* RO data, expand down, accessed */
+       d.dpl = 3;              /* Visible to user code */
+       d.s = 1;                /* Not a system segment */
+       d.p = 1;                /* Present */
+       d.d = 1;                /* 32-bit */
+
+       write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_CPU_NUMBER, &d, DESCTYPE_S);
+}
+#endif
+
 /*
  * cpu_init() initializes state that is per-CPU. Some data is already
  * initialized (naturally) in the bootstrap process, such as the GDT
@@ -1706,6 +1729,7 @@ void cpu_init(void)
            early_cpu_to_node(cpu) != NUMA_NO_NODE)
                set_numa_node(early_cpu_to_node(cpu));
 #endif
+       setup_getcpu(cpu);
 
        me = current;