Comment 2 for bug 1084373

All the required 13 patches were merged in kernel v3.9:

0d91ea8 x86, doc: Documentation for early microcode loading
9cd4d78 x86/microcode_intel.h: Define functions and macros for early loading ucode
d288e1c x86/common.c: Make have_cpuid_p() a global function
e6ebf5d x86/common.c: load ucode in 64 bit or show loading ucode info in 32 bit on AP
a8ebf6d x86/microcode_core_early.c: Define interfaces for early loading ucode
e666dfa x86/microcode_intel_lib.c: Early update ucode on Intel's CPU
086fc8f x86/tlbflush.h: Define __native_flush_tlb_global_irq_disabled()
ec400dd x86/microcode_intel_early.c: Early update ucode on Intel's CPU
63b553c x86/head_32.S: Early update ucode in 32-bit
feddc9d x86/head64.c: Early update ucode in 64-bit
cd745be x86/mm/init.c: Copy ucode from initrd image to kernel memory
da76f64 x86/Kconfig: Make early microcode loading a configuration feature

The above 12 patches for early load microcode also depends on one early page fault handler patch:
8170e6b x86, 64bit: Use a #PF handler to materialize early mappings on demand