efi: Export EFI runtime memory mapping to sysfs

kexec kernel will need exactly same mapping for EFI runtime memory
ranges. Thus here export the runtime ranges mapping to sysfs,
kexec-tools will assemble them and pass to 2nd kernel via setup_data.

Introducing a new directory /sys/firmware/efi/runtime-map just like
/sys/firmware/memmap. Containing below attribute in each file of that
directory:

attribute  num_pages  phys_addr  type  virt_addr

Signed-off-by: Dave Young <dyoung@redhat.com>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

1 files changed, 43 insertions, 3 deletions

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 28591072fbb7..74fe7a719508 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -76,6 +76,9 @@ static __initdata efi_config_table_type_t arch_tables[] = {
         {NULL_GUID, NULL, NULL},
 };
 
+static void *efi_runtime_map;
+static int nr_efi_runtime_map;
+
 /*
  * Returns 1 if 'facility' is enabled, 0 otherwise.
  */
@@ -824,6 +827,39 @@ static void __init get_systab_virt_addr(efi_memory_desc_t *md)
         }
 }
 
+static int __init save_runtime_map(void)
+{
+        efi_memory_desc_t *md;
+        void *tmp, *p, *q = NULL;
+        int count = 0;
+
+        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
+                md = p;
+
+                if (!(md->attribute & EFI_MEMORY_RUNTIME) ||
+                    (md->type == EFI_BOOT_SERVICES_CODE) ||
+                    (md->type == EFI_BOOT_SERVICES_DATA))
+                        continue;
+                tmp = krealloc(q, (count + 1) * memmap.desc_size, GFP_KERNEL);
+                if (!tmp)
+                        goto out;
+                q = tmp;
+
+                memcpy(q + count * memmap.desc_size, md, memmap.desc_size);
+                count++;
+        }
+
+        efi_runtime_map = q;
+        nr_efi_runtime_map = count;
+        efi_runtime_map_setup(efi_runtime_map, nr_efi_runtime_map,
+                              boot_params.efi_info.efi_memdesc_size);
+
+        return 0;
+out:
+        kfree(q);
+        return -ENOMEM;
+}
+
 /*
  * Map efi memory ranges for runtime serivce and update new_memmap with virtual
  * addresses.
@@ -849,7 +885,7 @@ static void * __init efi_map_regions(int *count)
                 tmp = krealloc(new_memmap, (*count + 1) * memmap.desc_size,
                                GFP_KERNEL);
                 if (!tmp)
-                        goto out_krealloc;
+                        goto out;
                 new_memmap = tmp;
                 memcpy(new_memmap + (*count * memmap.desc_size), md,
                        memmap.desc_size);
@@ -857,7 +893,7 @@ static void * __init efi_map_regions(int *count)
         }
 
         return new_memmap;
-out_krealloc:
+out:
         kfree(new_memmap);
         return NULL;
 }
@@ -883,7 +919,7 @@ void __init efi_enter_virtual_mode(void)
 {
         efi_status_t status;
         void *new_memmap = NULL;
-        int count = 0;
+        int err, count = 0;
 
         efi.systab = NULL;
 
@@ -904,6 +940,10 @@ void __init efi_enter_virtual_mode(void)
                 return;
         }
 
+        err = save_runtime_map();
+        if (err)
+                pr_err("Error saving runtime map, efi runtime on kexec non-functional!!\n");
+
         BUG_ON(!efi.systab);
 
         efi_setup_page_tables();