1 files changed, 100 insertions, 6 deletions

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 977d1ce7e173..4959e3f89d74 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -41,6 +41,7 @@
 #include <linux/io.h>
 #include <linux/reboot.h>
 #include <linux/bcd.h>
+#include <linux/ucs2_string.h>
 
 #include <asm/setup.h>
 #include <asm/efi.h>
@@ -51,6 +52,13 @@
 
 #define EFI_DEBUG       1
 
+/*
+ * There's some additional metadata associated with each
+ * variable. Intel's reference implementation is 60 bytes - bump that
+ * to account for potential alignment constraints
+ */
+#define VAR_METADATA_SIZE 64
+
 struct efi __read_mostly efi = {
         .mps        = EFI_INVALID_TABLE_ADDR,
         .acpi       = EFI_INVALID_TABLE_ADDR,
@@ -72,6 +80,9 @@ static efi_system_table_t efi_systab __initdata;
 static u64 efi_var_store_size;
 static u64 efi_var_remaining_size;
 static u64 efi_var_max_var_size;
+static u64 boot_used_size;
+static u64 boot_var_size;
+static u64 active_size;
 
 unsigned long x86_efi_facility;
 
@@ -166,8 +177,53 @@ static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
                                                efi_char16_t *name,
                                                efi_guid_t *vendor)
 {
-        return efi_call_virt3(get_next_variable,
-                              name_size, name, vendor);
+        efi_status_t status;
+        static bool finished = false;
+        static u64 var_size;
+
+        status = efi_call_virt3(get_next_variable,
+                                name_size, name, vendor);
+
+        if (status == EFI_NOT_FOUND) {
+                finished = true;
+                if (var_size < boot_used_size) {
+                        boot_var_size = boot_used_size - var_size;
+                        active_size += boot_var_size;
+                } else {
+                        printk(KERN_WARNING FW_BUG  "efi: Inconsistent initial sizes\n");
+                }
+        }
+
+        if (boot_used_size && !finished) {
+                unsigned long size;
+                u32 attr;
+                efi_status_t s;
+                void *tmp;
+
+                s = virt_efi_get_variable(name, vendor, &attr, &size, NULL);
+
+                if (s != EFI_BUFFER_TOO_SMALL || !size)
+                        return status;
+
+                tmp = kmalloc(size, GFP_ATOMIC);
+
+                if (!tmp)
+                        return status;
+
+                s = virt_efi_get_variable(name, vendor, &attr, &size, tmp);
+
+                if (s == EFI_SUCCESS && (attr & EFI_VARIABLE_NON_VOLATILE)) {
+                        var_size += size;
+                        var_size += ucs2_strsize(name, 1024);
+                        active_size += size;
+                        active_size += VAR_METADATA_SIZE;
+                        active_size += ucs2_strsize(name, 1024);
+                }
+
+                kfree(tmp);
+        }
+
+        return status;
 }
 
 static efi_status_t virt_efi_set_variable(efi_char16_t *name,
@@ -176,9 +232,34 @@ static efi_status_t virt_efi_set_variable(efi_char16_t *name,
                                           unsigned long data_size,
                                           void *data)
 {
-        return efi_call_virt5(set_variable,
-                              name, vendor, attr,
-                              data_size, data);
+        efi_status_t status;
+        u32 orig_attr = 0;
+        unsigned long orig_size = 0;
+
+        status = virt_efi_get_variable(name, vendor, &orig_attr, &orig_size,
+                                       NULL);
+
+        if (status != EFI_BUFFER_TOO_SMALL)
+                orig_size = 0;
+
+        status = efi_call_virt5(set_variable,
+                                name, vendor, attr,
+                                data_size, data);
+
+        if (status == EFI_SUCCESS) {
+                if (orig_size) {
+                        active_size -= orig_size;
+                        active_size -= ucs2_strsize(name, 1024);
+                        active_size -= VAR_METADATA_SIZE;
+                }
+                if (data_size) {
+                        active_size += data_size;
+                        active_size += ucs2_strsize(name, 1024);
+                        active_size += VAR_METADATA_SIZE;
+                }
+        }
+
+        return status;
 }
 
 static efi_status_t virt_efi_query_variable_info(u32 attr,
@@ -720,6 +801,8 @@ void __init efi_init(void)
                 early_iounmap(data, sizeof(*efi_var_data));
         }
 
+        boot_used_size = efi_var_store_size - efi_var_remaining_size;
+
         set_bit(EFI_SYSTEM_TABLES, &x86_efi_facility);
 
         /*
@@ -1042,10 +1125,21 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
         if (!max_size && remaining_size > size)
                 printk_once(KERN_ERR FW_BUG "Broken EFI implementation"
                             " is returning MaxVariableSize=0\n");
+        /*
+         * Some firmware implementations refuse to boot if there's insufficient
+         * space in the variable store. We account for that by refusing the
+         * write if permitting it would reduce the available space to under
+         * 50%. However, some firmware won't reclaim variable space until
+         * after the used (not merely the actively used) space drops below
+         * a threshold. We can approximate that case with the value calculated
+         * above. If both the firmware and our calculations indicate that the
+         * available space would drop below 50%, refuse the write.
+         */
 
         if (!storage_size || size > remaining_size ||
             (max_size && size > max_size) ||
-            (remaining_size - size) < (storage_size / 2))
+            ((active_size + size + VAR_METADATA_SIZE > storage_size / 2) &&
+             (remaining_size - size < storage_size / 2)))
                 return EFI_OUT_OF_RESOURCES;
 
         return EFI_SUCCESS;