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efi_loader: Add OS notifications for SetVariable at runtime

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Previous patches enable SetVariable at runtime using a volatile storage
backend using EFI_RUNTIME_SERVICES_DATA allocared memory. Since there's
no recommendation from the spec on how to notify the OS, add a volatile
EFI variable that contains the filename relative to the ESP. OS'es
can use that file and update it at runtime

$~ efivar -p -n b2ac5fc9-92b7-4acd-aeac-11e818c3130c-RTStorageVolatile
GUID: b2ac5fc9-92b7-4acd-aeac-11e818c3130c
Name: "RTStorageVolatile"
Attributes:
	Boot Service Access
	Runtime Service Access
Value:
00000000  75 62 6f 6f 74 65 66 69  2e 76 61 72 00           |ubootefi.var.   |

Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
This commit is contained in:
Ilias Apalodimas
2024-04-18 15:54:51 +03:00
committed by Heinrich Schuchardt
parent c28d32f946
commit bc3dd2493e
2 changed files with 20 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
include/efi_loader.h
View File

@@ -159,6 +159,10 @@ static inline void efi_set_bootdev(const char *dev, const char *devnr,
#define EFICONFIG_AUTO_GENERATED_ENTRY_GUID \
EFI_GUID(0x8108ac4e, 0x9f11, 0x4d59, \
0x85, 0x0e, 0xe2, 0x1a, 0x52, 0x2c, 0x59, 0xb2)
#define U_BOOT_EFI_RT_VAR_FILE_GUID \
EFI_GUID(0xb2ac5fc9, 0x92b7, 0x4acd, \
0xae, 0xac, 0x11, 0xe8, 0x18, 0xc3, 0x13, 0x0c)
/* Use internal device tree when starting UEFI application */
#define EFI_FDT_USE_INTERNAL NULL

19
lib/efi_loader/efi_runtime.c
View File

@@ -10,6 +10,7 @@
#include <dm.h>
#include <elf.h>
#include <efi_loader.h>
#include <efi_variable.h>
#include <log.h>
#include <malloc.h>
#include <rtc.h>
@@ -110,6 +111,7 @@ static __efi_runtime_data efi_uintn_t efi_descriptor_size;
*/
efi_status_t efi_init_runtime_supported(void)
{
const efi_guid_t efi_guid_efi_rt_var_file = U_BOOT_EFI_RT_VAR_FILE_GUID;
efi_status_t ret;
struct efi_rt_properties_table *rt_table;
@@ -127,9 +129,20 @@ efi_status_t efi_init_runtime_supported(void)
EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP |
EFI_RT_SUPPORTED_CONVERT_POINTER;
if (IS_ENABLED(CONFIG_EFI_RT_VOLATILE_STORE))
rt_table->runtime_services_supported |=
EFI_RT_SUPPORTED_SET_VARIABLE;
if (IS_ENABLED(CONFIG_EFI_RT_VOLATILE_STORE)) {
ret = efi_set_variable_int(u"RTStorageVolatile",
&efi_guid_efi_rt_var_file,
EFI_VARIABLE_BOOTSERVICE_ACCESS |
EFI_VARIABLE_RUNTIME_ACCESS |
EFI_VARIABLE_READ_ONLY,
sizeof(EFI_VAR_FILE_NAME),
EFI_VAR_FILE_NAME, false);
if (ret != EFI_SUCCESS) {
log_err("Failed to set RTStorageVolatile\n");
return ret;
}
rt_table->runtime_services_supported |= EFI_RT_SUPPORTED_SET_VARIABLE;
}
/*
* This value must be synced with efi_runtime_detach_list