v4.19.13 snapshot.
diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
new file mode 100644
index 0000000..d101058
--- /dev/null
+++ b/arch/x86/realmode/init.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/memblock.h>
+#include <linux/mem_encrypt.h>
+
+#include <asm/set_memory.h>
+#include <asm/pgtable.h>
+#include <asm/realmode.h>
+#include <asm/tlbflush.h>
+
+struct real_mode_header *real_mode_header;
+u32 *trampoline_cr4_features;
+
+/* Hold the pgd entry used on booting additional CPUs */
+pgd_t trampoline_pgd_entry;
+
+void __init set_real_mode_mem(phys_addr_t mem, size_t size)
+{
+ void *base = __va(mem);
+
+ real_mode_header = (struct real_mode_header *) base;
+ printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
+ base, (unsigned long long)mem, size);
+}
+
+void __init reserve_real_mode(void)
+{
+ phys_addr_t mem;
+ size_t size = real_mode_size_needed();
+
+ if (!size)
+ return;
+
+ WARN_ON(slab_is_available());
+
+ /* Has to be under 1M so we can execute real-mode AP code. */
+ mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
+ if (!mem) {
+ pr_info("No sub-1M memory is available for the trampoline\n");
+ return;
+ }
+
+ memblock_reserve(mem, size);
+ set_real_mode_mem(mem, size);
+}
+
+static void __init setup_real_mode(void)
+{
+ u16 real_mode_seg;
+ const u32 *rel;
+ u32 count;
+ unsigned char *base;
+ unsigned long phys_base;
+ struct trampoline_header *trampoline_header;
+ size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
+#ifdef CONFIG_X86_64
+ u64 *trampoline_pgd;
+ u64 efer;
+#endif
+
+ base = (unsigned char *)real_mode_header;
+
+ /*
+ * If SME is active, the trampoline area will need to be in
+ * decrypted memory in order to bring up other processors
+ * successfully. This is not needed for SEV.
+ */
+ if (sme_active())
+ set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT);
+
+ memcpy(base, real_mode_blob, size);
+
+ phys_base = __pa(base);
+ real_mode_seg = phys_base >> 4;
+
+ rel = (u32 *) real_mode_relocs;
+
+ /* 16-bit segment relocations. */
+ count = *rel++;
+ while (count--) {
+ u16 *seg = (u16 *) (base + *rel++);
+ *seg = real_mode_seg;
+ }
+
+ /* 32-bit linear relocations. */
+ count = *rel++;
+ while (count--) {
+ u32 *ptr = (u32 *) (base + *rel++);
+ *ptr += phys_base;
+ }
+
+ /* Must be perfomed *after* relocation. */
+ trampoline_header = (struct trampoline_header *)
+ __va(real_mode_header->trampoline_header);
+
+#ifdef CONFIG_X86_32
+ trampoline_header->start = __pa_symbol(startup_32_smp);
+ trampoline_header->gdt_limit = __BOOT_DS + 7;
+ trampoline_header->gdt_base = __pa_symbol(boot_gdt);
+#else
+ /*
+ * Some AMD processors will #GP(0) if EFER.LMA is set in WRMSR
+ * so we need to mask it out.
+ */
+ rdmsrl(MSR_EFER, efer);
+ trampoline_header->efer = efer & ~EFER_LMA;
+
+ trampoline_header->start = (u64) secondary_startup_64;
+ trampoline_cr4_features = &trampoline_header->cr4;
+ *trampoline_cr4_features = mmu_cr4_features;
+
+ trampoline_header->flags = 0;
+ if (sme_active())
+ trampoline_header->flags |= TH_FLAGS_SME_ACTIVE;
+
+ trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
+ trampoline_pgd[0] = trampoline_pgd_entry.pgd;
+ trampoline_pgd[511] = init_top_pgt[511].pgd;
+#endif
+}
+
+/*
+ * reserve_real_mode() gets called very early, to guarantee the
+ * availability of low memory. This is before the proper kernel page
+ * tables are set up, so we cannot set page permissions in that
+ * function. Also trampoline code will be executed by APs so we
+ * need to mark it executable at do_pre_smp_initcalls() at least,
+ * thus run it as a early_initcall().
+ */
+static void __init set_real_mode_permissions(void)
+{
+ unsigned char *base = (unsigned char *) real_mode_header;
+ size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
+
+ size_t ro_size =
+ PAGE_ALIGN(real_mode_header->ro_end) -
+ __pa(base);
+
+ size_t text_size =
+ PAGE_ALIGN(real_mode_header->ro_end) -
+ real_mode_header->text_start;
+
+ unsigned long text_start =
+ (unsigned long) __va(real_mode_header->text_start);
+
+ set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
+ set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
+ set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
+}
+
+static int __init init_real_mode(void)
+{
+ if (!real_mode_header)
+ panic("Real mode trampoline was not allocated");
+
+ setup_real_mode();
+ set_real_mode_permissions();
+
+ return 0;
+}
+early_initcall(init_real_mode);