Merge tag 'efi-urgent' into x86/urgent

 * More tweaking to the EFI variable anti-bricking algorithm. Quite a
   few users were reporting boot regressions in v3.9. This has now been
   fixed with a more accurate "minimum storage requirement to avoid
   bricking" value from Samsung (5K instead of 50%) and code to trigger
   garbage collection when we near our limit - Matthew Garrett.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

4 files changed, 65 insertions, 178 deletions

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 35ee62fccf98..c205035a6b96 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -251,51 +251,6 @@ static void find_bits(unsigned long mask, u8 *pos, u8 *size)
         *size = len;
 }
 
-static efi_status_t setup_efi_vars(struct boot_params *params)
-{
-        struct setup_data *data;
-        struct efi_var_bootdata *efidata;
-        u64 store_size, remaining_size, var_size;
-        efi_status_t status;
-
-        if (sys_table->runtime->hdr.revision < EFI_2_00_SYSTEM_TABLE_REVISION)
-                return EFI_UNSUPPORTED;
-
-        data = (struct setup_data *)(unsigned long)params->hdr.setup_data;
-
-        while (data && data->next)
-                data = (struct setup_data *)(unsigned long)data->next;
-
-        status = efi_call_phys4((void *)sys_table->runtime->query_variable_info,
-                                EFI_VARIABLE_NON_VOLATILE |
-                                EFI_VARIABLE_BOOTSERVICE_ACCESS |
-                                EFI_VARIABLE_RUNTIME_ACCESS, &store_size,
-                                &remaining_size, &var_size);
-
-        if (status != EFI_SUCCESS)
-                return status;
-
-        status = efi_call_phys3(sys_table->boottime->allocate_pool,
-                                EFI_LOADER_DATA, sizeof(*efidata), &efidata);
-
-        if (status != EFI_SUCCESS)
-                return status;
-
-        efidata->data.type = SETUP_EFI_VARS;
-        efidata->data.len = sizeof(struct efi_var_bootdata) -
-                sizeof(struct setup_data);
-        efidata->data.next = 0;
-        efidata->store_size = store_size;
-        efidata->remaining_size = remaining_size;
-        efidata->max_var_size = var_size;
-
-        if (data)
-                data->next = (unsigned long)efidata;
-        else
-                params->hdr.setup_data = (unsigned long)efidata;
-
-}
-
 static efi_status_t setup_efi_pci(struct boot_params *params)
 {
         efi_pci_io_protocol *pci;
@@ -1202,8 +1157,6 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table,
 
         setup_graphics(boot_params);
 
-        setup_efi_vars(boot_params);
-
         setup_efi_pci(boot_params);
 
         status = efi_call_phys3(sys_table->boottime->allocate_pool,
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 2fb5d5884e23..60c89f30c727 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -102,13 +102,6 @@ extern void efi_call_phys_epilog(void);
 extern void efi_unmap_memmap(void);
 extern void efi_memory_uc(u64 addr, unsigned long size);
 
-struct efi_var_bootdata {
-        struct setup_data data;
-        u64 store_size;
-        u64 remaining_size;
-        u64 max_var_size;
-};
-
 #ifdef CONFIG_EFI
 
 static inline bool efi_is_native(void)
diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
index 08744242b8d2..c15ddaf90710 100644
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/arch/x86/include/uapi/asm/bootparam.h
@@ -6,7 +6,6 @@
 #define SETUP_E820_EXT                  1
 #define SETUP_DTB                       2
 #define SETUP_PCI                       3
-#define SETUP_EFI_VARS                  4
 
 /* ram_size flags */
 #define RAMDISK_IMAGE_START_MASK        0x07FF
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 82089d8b1954..5ae2eb09419e 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -42,7 +42,6 @@
 #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>
@@ -54,12 +53,12 @@
 
 #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
+#define EFI_MIN_RESERVE 5120
+
+#define EFI_DUMMY_GUID \
+        EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e, 0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92, 0xa9)
+
+static efi_char16_t efi_dummy_name[6] = { 'D', 'U', 'M', 'M', 'Y', 0 };
 
 struct efi __read_mostly efi = {
         .mps        = EFI_INVALID_TABLE_ADDR,
@@ -79,13 +78,6 @@ struct efi_memory_map memmap;
 static struct efi efi_phys __initdata;
 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;
 
 /*
@@ -188,53 +180,8 @@ static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
                                                efi_char16_t *name,
                                                efi_guid_t *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 = 0;
-                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;
+        return efi_call_virt3(get_next_variable,
+                              name_size, name, vendor);
 }
 
 static efi_status_t virt_efi_set_variable(efi_char16_t *name,
@@ -243,34 +190,9 @@ static efi_status_t virt_efi_set_variable(efi_char16_t *name,
                                           unsigned long data_size,
                                           void *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;
+        return efi_call_virt5(set_variable,
+                              name, vendor, attr,
+                              data_size, data);
 }
 
 static efi_status_t virt_efi_query_variable_info(u32 attr,
@@ -786,9 +708,6 @@ void __init efi_init(void)
         char vendor[100] = "unknown";
         int i = 0;
         void *tmp;
-        struct setup_data *data;
-        struct efi_var_bootdata *efi_var_data;
-        u64 pa_data;
 
 #ifdef CONFIG_X86_32
         if (boot_params.efi_info.efi_systab_hi ||
@@ -806,22 +725,6 @@ void __init efi_init(void)
         if (efi_systab_init(efi_phys.systab))
                 return;
 
-        pa_data = boot_params.hdr.setup_data;
-        while (pa_data) {
-                data = early_ioremap(pa_data, sizeof(*efi_var_data));
-                if (data->type == SETUP_EFI_VARS) {
-                        efi_var_data = (struct efi_var_bootdata *)data;
-
-                        efi_var_store_size = efi_var_data->store_size;
-                        efi_var_remaining_size = efi_var_data->remaining_size;
-                        efi_var_max_var_size = efi_var_data->max_var_size;
-                }
-                pa_data = data->next;
-                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);
 
         /*
@@ -1085,6 +988,13 @@ void __init efi_enter_virtual_mode(void)
                 runtime_code_page_mkexec();
 
         kfree(new_memmap);
+
+        /* clean DUMMY object */
+        efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
+                         EFI_VARIABLE_NON_VOLATILE |
+                         EFI_VARIABLE_BOOTSERVICE_ACCESS |
+                         EFI_VARIABLE_RUNTIME_ACCESS,
+                         0, NULL);
 }
 
 /*
@@ -1136,33 +1046,65 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
         efi_status_t status;
         u64 storage_size, remaining_size, max_size;
 
+        if (!(attributes & EFI_VARIABLE_NON_VOLATILE))
+                return 0;
+
         status = efi.query_variable_info(attributes, &storage_size,
                                          &remaining_size, &max_size);
         if (status != EFI_SUCCESS)
                 return status;
 
-        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.
+         * 5KB. This figure was provided by Samsung, so should be safe.
          */
+        if ((remaining_size - size < EFI_MIN_RESERVE) &&
+                !efi_no_storage_paranoia) {
+
+                /*
+                 * Triggering garbage collection may require that the firmware
+                 * generate a real EFI_OUT_OF_RESOURCES error. We can force
+                 * that by attempting to use more space than is available.
+                 */
+                unsigned long dummy_size = remaining_size + 1024;
+                void *dummy = kmalloc(dummy_size, GFP_ATOMIC);
+
+                status = efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
+                                          EFI_VARIABLE_NON_VOLATILE |
+                                          EFI_VARIABLE_BOOTSERVICE_ACCESS |
+                                          EFI_VARIABLE_RUNTIME_ACCESS,
+                                          dummy_size, dummy);
+
+                if (status == EFI_SUCCESS) {
+                        /*
+                         * This should have failed, so if it didn't make sure
+                         * that we delete it...
+                         */
+                        efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
+                                         EFI_VARIABLE_NON_VOLATILE |
+                                         EFI_VARIABLE_BOOTSERVICE_ACCESS |
+                                         EFI_VARIABLE_RUNTIME_ACCESS,
+                                         0, dummy);
+                }
 
-        if (!storage_size || size > remaining_size ||
-            (max_size && size > max_size))
-                return EFI_OUT_OF_RESOURCES;
+                /*
+                 * The runtime code may now have triggered a garbage collection
+                 * run, so check the variable info again
+                 */
+                status = efi.query_variable_info(attributes, &storage_size,
+                                                 &remaining_size, &max_size);
 
-        if (!efi_no_storage_paranoia &&
-            ((active_size + size + VAR_METADATA_SIZE > storage_size / 2) &&
-             (remaining_size - size < storage_size / 2)))
-                return EFI_OUT_OF_RESOURCES;
+                if (status != EFI_SUCCESS)
+                        return status;
+
+                /*
+                 * There still isn't enough room, so return an error
+                 */
+                if (remaining_size - size < EFI_MIN_RESERVE)
+                        return EFI_OUT_OF_RESOURCES;
+        }
 
         return EFI_SUCCESS;
 }