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;