x86/cpu: Drop cpu_devs[] and $VENDOR_init_cpu() hooks

These helpers each fill in a single cpu_devs[] pointer, and since c/s
00b4f4d0f "x86/cpuid: Drop get_cpu_vendor() completely", this array is read
exactly once on boot.

Delete the hooks and cpu_devs[], and have early_cpu_detect() pick the
appropriate cpu_dev structure directly.

As early_cpu_init() is empty now other than a call to early_cpu_detect(), and
this isn't expected to change moving forwards, rename the latter and delete
the former.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/cpu/amd.c

@@ -792,14 +792,8 @@ static void init_amd(struct cpuinfo_x86 *c)
 	check_syscfg_dram_mod_en();
 }
 
-static const struct cpu_dev amd_cpu_dev = {
+const struct cpu_dev amd_cpu_dev = {
 	.c_vendor	= "AMD",
 	.c_early_init	= early_init_amd,
 	.c_init		= init_amd,
 };
-
-int __init amd_init_cpu(void)
-{
-	cpu_devs[X86_VENDOR_AMD] = &amd_cpu_dev;
-	return 0;
-}

xen/arch/x86/cpu/centaur.c

@@ -54,13 +54,7 @@ static void init_centaur(struct cpuinfo_x86 *c)
 		init_c3(c);
 }
 
-static const struct cpu_dev centaur_cpu_dev = {
+const struct cpu_dev centaur_cpu_dev = {
 	.c_vendor	= "Centaur",
 	.c_init		= init_centaur,
 };
-
-int __init centaur_init_cpu(void)
-{
-	cpu_devs[X86_VENDOR_CENTAUR] = &centaur_cpu_dev;
-	return 0;
-}

xen/arch/x86/cpu/common.c

@@ -42,8 +42,6 @@ unsigned int __read_mostly levelling_caps;
 DEFINE_PER_CPU(struct cpuidmasks, cpuidmasks);
 struct cpuidmasks __read_mostly cpuidmask_defaults;
 
-const struct cpu_dev *__read_mostly cpu_devs[X86_VENDOR_NUM] = {};
-
 unsigned int paddr_bits __read_mostly = 36;
 unsigned int hap_paddr_bits __read_mostly = 36;
 unsigned int vaddr_bits __read_mostly = VADDR_BITS;
@@ -270,7 +268,7 @@ static inline u32 phys_pkg_id(u32 cpuid_apic, int index_msb)
 
    WARNING: this function is only called on the BP.  Don't add code here
    that is supposed to run on all CPUs. */
-static void __init early_cpu_detect(void)
+void __init early_cpu_init(void)
 {
 	struct cpuinfo_x86 *c = &boot_cpu_data;
 	u32 eax, ebx, ecx, edx;
@@ -284,12 +282,16 @@ static void __init early_cpu_detect(void)
 	*(u32 *)&c->x86_vendor_id[4] = edx;
 
 	c->x86_vendor = x86_cpuid_lookup_vendor(ebx, ecx, edx);
-	if (c->x86_vendor < ARRAY_SIZE(cpu_devs) && cpu_devs[c->x86_vendor])
-		this_cpu = cpu_devs[c->x86_vendor];
-	else
+	switch (c->x86_vendor) {
+	case X86_VENDOR_INTEL:	  this_cpu = &intel_cpu_dev;    break;
+	case X86_VENDOR_AMD:	  this_cpu = &amd_cpu_dev;      break;
+	case X86_VENDOR_CENTAUR:  this_cpu = &centaur_cpu_dev;  break;
+	case X86_VENDOR_SHANGHAI: this_cpu = &shanghai_cpu_dev; break;
+	default:
 		printk(XENLOG_ERR
 		       "Unrecognised or unsupported CPU vendor '%.12s'\n",
 		       c->x86_vendor_id);
+	}
 
 	cpuid(0x00000001, &eax, &ebx, &ecx, &edx);
 	c->x86 = get_cpu_family(eax, &c->x86_model, &c->x86_mask);
@@ -677,23 +679,6 @@ void print_cpu_info(unsigned int cpu)
 
 static cpumask_t cpu_initialized;
 
-/* This is hacky. :)
- * We're emulating future behavior.
- * In the future, the cpu-specific init functions will be called implicitly
- * via the magic of initcalls.
- * They will insert themselves into the cpu_devs structure.
- * Then, when cpu_init() is called, we can just iterate over that array.
- */
-
-void __init early_cpu_init(void)
-{
-	intel_cpu_init();
-	amd_init_cpu();
-	centaur_init_cpu();
-	shanghai_init_cpu();
-	early_cpu_detect();
-}
-
 /*
  * Sets up system tables and descriptors.
  *

xen/arch/x86/cpu/cpu.h

@@ -6,7 +6,8 @@ struct cpu_dev {
 	void		(*c_init)(struct cpuinfo_x86 * c);
 };
 
-extern const struct cpu_dev *cpu_devs[X86_VENDOR_NUM];
+extern const struct cpu_dev intel_cpu_dev, amd_cpu_dev, centaur_cpu_dev,
+    shanghai_cpu_dev;
 
 extern bool_t opt_arat;
 extern unsigned int opt_cpuid_mask_ecx, opt_cpuid_mask_edx;
@@ -15,8 +16,3 @@ extern unsigned int opt_cpuid_mask_ext_ecx, opt_cpuid_mask_ext_edx;
 
 extern int get_model_name(struct cpuinfo_x86 *c);
 extern void display_cacheinfo(struct cpuinfo_x86 *c);
-
-int intel_cpu_init(void);
-int amd_init_cpu(void);
-int centaur_init_cpu(void);
-int shanghai_init_cpu(void);

xen/arch/x86/cpu/intel.c

@@ -348,17 +348,8 @@ static void init_intel(struct cpuinfo_x86 *c)
 		__set_bit(X86_FEATURE_ARAT, c->x86_capability);
 }
 
-static const struct cpu_dev intel_cpu_dev = {
+const struct cpu_dev intel_cpu_dev = {
 	.c_vendor	= "Intel",
 	.c_early_init	= early_init_intel,
 	.c_init		= init_intel,
 };
-
-int __init intel_cpu_init(void)
-{
-	cpu_devs[X86_VENDOR_INTEL] = &intel_cpu_dev;
-	return 0;
-}
-
-// arch_initcall(intel_cpu_init);
-

xen/arch/x86/cpu/shanghai.c

@@ -15,13 +15,7 @@ static void init_shanghai(struct cpuinfo_x86 *c)
     init_intel_cacheinfo(c);
 }
 
-static const struct cpu_dev shanghai_cpu_dev = {
+const struct cpu_dev shanghai_cpu_dev = {
     .c_vendor   = "  Shang",
     .c_init     = init_shanghai,
 };
-
-int __init shanghai_init_cpu(void)
-{
-    cpu_devs[X86_VENDOR_SHANGHAI] = &shanghai_cpu_dev;
-    return 0;
-}