x86/efi: Dump the EFI page table

This is very useful for debugging issues with the recently added
pagetable switching code for EFI virtual mode.

Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

arch/x86/platform/efi/efi.c

@@ -1021,6 +1021,7 @@ void __init efi_enter_virtual_mode(void)
 
 	efi_setup_page_tables();
 	efi_sync_low_kernel_mappings();
+	efi_dump_pagetable();
 
 	if (!efi_setup) {
 		status = phys_efi_set_virtual_address_map(

arch/x86/platform/efi/efi_32.c

@@ -41,6 +41,7 @@ static unsigned long efi_rt_eflags;
 
 void efi_sync_low_kernel_mappings(void) {}
 void efi_setup_page_tables(void) {}
+void __init efi_dump_pagetable(void) {}
 
 void __init efi_map_region(efi_memory_desc_t *md)
 {

arch/x86/platform/efi/efi_64.c

@@ -242,3 +242,12 @@ void __init efi_runtime_mkexec(void)
 	if (__supported_pte_mask & _PAGE_NX)
 		runtime_code_page_mkexec();
 }
+
+void __init efi_dump_pagetable(void)
+{
+#ifdef CONFIG_EFI_PGT_DUMP
+	pgd_t *pgd = (pgd_t *)__va(real_mode_header->trampoline_pgd);
+
+	ptdump_walk_pgd_level(NULL, pgd);
+#endif
+}