[kvm-unit-tests PATCH v2 02/17] x86 UEFI: Implement UEFI function calls

[Zixuan Wang <zixuanwang@google.com>]

From: Varad Gautam <varad.gautam@suse.com>

This commit implements helper functions that call UEFI services and
assist the boot up process.

Signed-off-by: Varad Gautam <varad.gautam@suse.com>
---
 lib/efi.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 lib/efi.c

diff --git a/lib/efi.c b/lib/efi.c
new file mode 100644
index 0000000..9711354
--- /dev/null
+++ b/lib/efi.c
@@ -0,0 +1,58 @@
+#include <linux/uefi.h>
+
+unsigned long __efiapi efi_main(efi_handle_t handle, efi_system_table_t *sys_tab);
+efi_system_table_t *efi_system_table = NULL;
+
+static void efi_free_pool(void *ptr)
+{
+	efi_bs_call(free_pool, ptr);
+}
+
+static efi_status_t efi_get_memory_map(struct efi_boot_memmap *map)
+{
+	efi_memory_desc_t *m = NULL;
+	efi_status_t status;
+	unsigned long key = 0, map_size = 0, desc_size = 0;
+
+	status = efi_bs_call(get_memory_map, &map_size,
+			     NULL, &key, &desc_size, NULL);
+	if (status != EFI_BUFFER_TOO_SMALL || map_size == 0)
+		goto out;
+
+	/* Pad map_size with additional descriptors so we don't need to
+	 * retry. */
+	map_size += 4 * desc_size;
+	*map->buff_size = map_size;
+	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
+			     map_size, (void **)&m);
+	if (status != EFI_SUCCESS)
+		goto out;
+
+	/* Get the map. */
+	status = efi_bs_call(get_memory_map, &map_size,
+			     m, &key, &desc_size, NULL);
+	if (status != EFI_SUCCESS) {
+		efi_free_pool(m);
+		goto out;
+	}
+
+	*map->desc_size = desc_size;
+	*map->map_size = map_size;
+	*map->key_ptr = key;
+out:
+	*map->map = m;
+	return status;
+}
+
+static efi_status_t efi_exit_boot_services(void *handle,
+					   struct efi_boot_memmap *map)
+{
+	return efi_bs_call(exit_boot_services, handle, *map->key_ptr);
+}
+
+unsigned long __efiapi efi_main(efi_handle_t handle, efi_system_table_t *sys_tab)
+{
+	efi_system_table = sys_tab;
+
+	return 0;
+}
-- 
2.33.0.259.gc128427fd7-goog