imsm: use efivarfs interface for reading UEFI variables

Read UEFI variables using the new efivarfs interface, fallback to
sysfs-efivars if that fails.

Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/platform-intel.c b/platform-intel.c
index 54ef37f247fdddf17813a86776ae44a6f5dcfed4..37274da96c141debdc1d3ef0d60230ca9604262c 100644 (file)
--- a/platform-intel.c
+++ b/platform-intel.c
@@ -416,6 +416,7 @@ static const struct imsm_orom *find_imsm_hba_orom(struct sys_dev *hba)
   (d0), (d1), (d2), (d3), (d4), (d5), (d6), (d7) }})
 
 #define SYS_EFI_VAR_PATH "/sys/firmware/efi/vars"
+#define SYS_EFIVARS_PATH "/sys/firmware/efi/efivars"
 #define SCU_PROP "RstScuV"
 #define AHCI_PROP "RstSataV"
 #define AHCI_SSATA_PROP "RstsSatV"
@@ -426,13 +427,47 @@ static const struct imsm_orom *find_imsm_hba_orom(struct sys_dev *hba)
 
 #define PCI_CLASS_RAID_CNTRL 0x010400
 
-int read_efi_variable(void *buffer, ssize_t buf_size, char *variable_name, struct efi_guid guid)
+static int read_efi_var(void *buffer, ssize_t buf_size, char *variable_name, struct efi_guid guid)
+{
+       char path[PATH_MAX];
+       char buf[GUID_STR_MAX];
+       int fd;
+       ssize_t n;
+
+       snprintf(path, PATH_MAX, "%s/%s-%s", SYS_EFIVARS_PATH, variable_name, guid_str(buf, guid));
+
+       fd = open(path, O_RDONLY);
+       if (fd < 0)
+               return 1;
+
+       /* read the variable attributes and ignore it */
+       n = read(fd, buf, sizeof(__u32));
+       if (n < 0) {
+               close(fd);
+               return 1;
+       }
+
+       /* read the variable data */
+       n = read(fd, buffer, buf_size);
+       close(fd);
+       if (n < buf_size)
+               return 1;
+
+       return 0;
+}
+
+static int read_efi_variable(void *buffer, ssize_t buf_size, char *variable_name, struct efi_guid guid)
 {
        char path[PATH_MAX];
        char buf[GUID_STR_MAX];
        int dfd;
        ssize_t n, var_data_len;
 
+       /* Try to read the variable using the new efivarfs interface first.
+        * If that fails, fall back to the old sysfs-efivars interface. */
+       if (!read_efi_var(buffer, buf_size, variable_name, guid))
+               return 0;
+
        snprintf(path, PATH_MAX, "%s/%s-%s/size", SYS_EFI_VAR_PATH, variable_name, guid_str(buf, guid));
 
        dprintf("EFI VAR: path=%s\n", path);