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>

5 files changed, 21 insertions, 0 deletions

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 321a52ccf63a..61bd2ad94281 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -81,6 +81,15 @@ config X86_PTDUMP
           kernel.
           If in doubt, say "N"
 
+config EFI_PGT_DUMP
+        bool "Dump the EFI pagetable"
+        depends on EFI && X86_PTDUMP
+        ---help---
+          Enable this if you want to dump the EFI page table before
+          enabling virtual mode. This can be used to debug miscellaneous
+          issues with the mapping of the EFI runtime regions into that
+          table.
+
 config DEBUG_RODATA
         bool "Write protect kernel read-only data structures"
         default y
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index a7a8bd89024e..4afd3b3b658f 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -133,6 +133,7 @@ extern void efi_setup_page_tables(void);
 extern void __init old_map_region(efi_memory_desc_t *md);
 extern void __init runtime_code_page_mkexec(void);
 extern void __init efi_runtime_mkexec(void);
+extern void __init efi_dump_pagetable(void);
 
 struct efi_setup_data {
         u64 fw_vendor;
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 876dc5b9e4a3..37f20d71ec4b 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/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(
diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
index 0b74cdf7f816..39496ae3928a 100644
--- a/arch/x86/platform/efi/efi_32.c
+++ b/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)
 {
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 0c2a234fef1e..e05c69b46f05 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/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
+}