[PATCH v3 2/5] x86/microcode: Create per-vendor microcode_ops builders

[Alejandro Vallejo <alejandro.vallejo@cloud.com>]

Replace the ucode_ops assignments in core.c for per-vendor calls.
This is in preparation for another patch that adds Intel-specific
conditions.

While moving the code around, also remove the family check on Intel, as
microcode loading is present on every Intel 64 machine.

Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
---
v3:
  * Subsumes v2/patch1
  * Removes previous long comment on rationale for skipping family checks (Jan/Andrew)
  * Isolates vendor-specific code in ${VENDOR}.c (Jan, from v2/patch4)
---
 xen/arch/x86/cpu/microcode/amd.c     | 16 ++++++++++------
 xen/arch/x86/cpu/microcode/core.c    | 10 +++-------
 xen/arch/x86/cpu/microcode/intel.c   | 13 +++++++------
 xen/arch/x86/cpu/microcode/private.h | 19 ++++++++++++++++++-
 4 files changed, 38 insertions(+), 20 deletions(-)

diff --git a/xen/arch/x86/cpu/microcode/amd.c b/xen/arch/x86/cpu/microcode/amd.c
index a9a5557835..7c9f311454 100644
--- a/xen/arch/x86/cpu/microcode/amd.c
+++ b/xen/arch/x86/cpu/microcode/amd.c
@@ -432,9 +432,13 @@ static struct microcode_patch *cf_check cpu_request_microcode(
     return patch;
 }
 
-const struct microcode_ops __initconst_cf_clobber amd_ucode_ops = {
-    .cpu_request_microcode            = cpu_request_microcode,
-    .collect_cpu_info                 = collect_cpu_info,
-    .apply_microcode                  = apply_microcode,
-    .compare_patch                    = compare_patch,
-};
+void __init amd_get_ucode_ops(struct microcode_ops *ops)
+{
+    if ( boot_cpu_data.x86 < 0x10 )
+        return;
+
+    ops->cpu_request_microcode = cpu_request_microcode;
+    ops->collect_cpu_info      = collect_cpu_info;
+    ops->apply_microcode       = apply_microcode;
+    ops->compare_patch         = compare_patch;
+}
diff --git a/xen/arch/x86/cpu/microcode/core.c b/xen/arch/x86/cpu/microcode/core.c
index df7e1df870..530e3e8267 100644
--- a/xen/arch/x86/cpu/microcode/core.c
+++ b/xen/arch/x86/cpu/microcode/core.c
@@ -845,19 +845,15 @@ static int __init early_microcode_update_cpu(void)
 int __init early_microcode_init(unsigned long *module_map,
                                 const struct multiboot_info *mbi)
 {
-    const struct cpuinfo_x86 *c = &boot_cpu_data;
     int rc = 0;
 
-    switch ( c->x86_vendor )
+    switch ( boot_cpu_data.x86_vendor )
     {
     case X86_VENDOR_AMD:
-        if ( c->x86 >= 0x10 )
-            ucode_ops = amd_ucode_ops;
+        amd_get_ucode_ops(&ucode_ops);
         break;
-
     case X86_VENDOR_INTEL:
-        if ( c->x86 >= 6 )
-            ucode_ops = intel_ucode_ops;
+        intel_get_ucode_ops(&ucode_ops);
         break;
     }
 
diff --git a/xen/arch/x86/cpu/microcode/intel.c b/xen/arch/x86/cpu/microcode/intel.c
index 8d4d6574aa..a99e402b98 100644
--- a/xen/arch/x86/cpu/microcode/intel.c
+++ b/xen/arch/x86/cpu/microcode/intel.c
@@ -385,9 +385,10 @@ static struct microcode_patch *cf_check cpu_request_microcode(
     return patch;
 }
 
-const struct microcode_ops __initconst_cf_clobber intel_ucode_ops = {
-    .cpu_request_microcode            = cpu_request_microcode,
-    .collect_cpu_info                 = collect_cpu_info,
-    .apply_microcode                  = apply_microcode,
-    .compare_patch                    = compare_patch,
-};
+void __init intel_get_ucode_ops(struct microcode_ops *ops)
+{
+    ops->cpu_request_microcode = cpu_request_microcode;
+    ops->collect_cpu_info      = collect_cpu_info;
+    ops->apply_microcode       = apply_microcode;
+    ops->compare_patch         = compare_patch;
+}
diff --git a/xen/arch/x86/cpu/microcode/private.h b/xen/arch/x86/cpu/microcode/private.h
index 626aeb4d08..13f0c7fb8e 100644
--- a/xen/arch/x86/cpu/microcode/private.h
+++ b/xen/arch/x86/cpu/microcode/private.h
@@ -60,6 +60,23 @@ struct microcode_ops {
         const struct microcode_patch *new, const struct microcode_patch *old);
 };
 
-extern const struct microcode_ops amd_ucode_ops, intel_ucode_ops;
+/**
+ * Retrieve the vendor-specific microcode management handlers
+ *
+ * Note that this is not an static set of handlers and may change from
+ * system to system depending on the presence of certain runtime features.
+ * even for the same 
+ *
+ *   - If the system has no microcode facilities, no handler is set.
+ *   - If the system has unrestricted microcode facilities, all handlers
+ *     are set
+ *   - If the system has microcode facilities, but they can't be used to
+ *     update the revision, then all handlers except for apply_microcode()
+ *     are set
+ *
+ * @param[out] ops Set of vendor-specific microcode handlers to overwrite
+ */
+void intel_get_ucode_ops(struct microcode_ops *ops);
+void amd_get_ucode_ops(struct microcode_ops *ops);
 
 #endif /* ASM_X86_MICROCODE_PRIVATE_H */
-- 
2.34.1