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- // SPDX-License-Identifier: GPL-2.0
- #include <linux/io.h>
- #include <linux/slab.h>
- #include <linux/memblock.h>
- #include <linux/cc_platform.h>
- #include <linux/pgtable.h>
- #include <asm/set_memory.h>
- #include <asm/realmode.h>
- #include <asm/tlbflush.h>
- #include <asm/crash.h>
- #include <asm/sev.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 load_trampoline_pgtable(void)
- {
- #ifdef CONFIG_X86_32
- load_cr3(initial_page_table);
- #else
- /*
- * This function is called before exiting to real-mode and that will
- * fail with CR4.PCIDE still set.
- */
- if (boot_cpu_has(X86_FEATURE_PCID))
- cr4_clear_bits(X86_CR4_PCIDE);
- write_cr3(real_mode_header->trampoline_pgd);
- #endif
- /*
- * The CR3 write above will not flush global TLB entries.
- * Stale, global entries from previous page tables may still be
- * present. Flush those stale entries.
- *
- * This ensures that memory accessed while running with
- * trampoline_pgd is *actually* mapped into trampoline_pgd.
- */
- __flush_tlb_all();
- }
- 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_phys_alloc_range(size, PAGE_SIZE, 0, 1<<20);
- if (!mem)
- pr_info("No sub-1M memory is available for the trampoline\n");
- else
- set_real_mode_mem(mem);
- /*
- * Unconditionally reserve the entire fisrt 1M, see comment in
- * setup_arch().
- */
- memblock_reserve(0, SZ_1M);
- }
- static void __init sme_sev_setup_real_mode(struct trampoline_header *th)
- {
- #ifdef CONFIG_AMD_MEM_ENCRYPT
- if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
- th->flags |= TH_FLAGS_SME_ACTIVE;
- if (cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) {
- /*
- * Skip the call to verify_cpu() in secondary_startup_64 as it
- * will cause #VC exceptions when the AP can't handle them yet.
- */
- th->start = (u64) secondary_startup_64_no_verify;
- if (sev_es_setup_ap_jump_table(real_mode_header))
- panic("Failed to get/update SEV-ES AP Jump Table");
- }
- #endif
- }
- 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;
- int i;
- #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 (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
- 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 performed *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;
- trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
- /* Map the real mode stub as virtual == physical */
- trampoline_pgd[0] = trampoline_pgd_entry.pgd;
- /*
- * Include the entirety of the kernel mapping into the trampoline
- * PGD. This way, all mappings present in the normal kernel page
- * tables are usable while running on trampoline_pgd.
- */
- for (i = pgd_index(__PAGE_OFFSET); i < PTRS_PER_PGD; i++)
- trampoline_pgd[i] = init_top_pgt[i].pgd;
- #endif
- sme_sev_setup_real_mode(trampoline_header);
- }
- /*
- * 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);
- }
- void __init init_real_mode(void)
- {
- if (!real_mode_header)
- panic("Real mode trampoline was not allocated");
- setup_real_mode();
- set_real_mode_permissions();
- }
- static int __init do_init_real_mode(void)
- {
- x86_platform.realmode_init();
- return 0;
- }
- early_initcall(do_init_real_mode);
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