[U-Boot] [PATCH v8 4/8] efi_loader: AArch64: Run EFI payloads in EL2 if U-Boot runs in EL3

[Alexander Graf]

Some boards decided not to run ATF or other secure firmware in EL3, so
they instead run U-Boot there. The uEFI spec doesn't know what EL3 is
though - it only knows about EL2 and EL1. So if we see that we're running
in EL3, let's get into EL2 to make payloads happy.

Signed-off-by: Alexander Graf <agraf at suse.de>
Reviewed-by: York Sun <york.sun at nxp.com>

---

v4 -> v5:

  - Remove manual ttbr / tcr copy
  - Regenerate page tables in EL2, getting us non-secured page tables
---
 cmd/bootefi.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/cmd/bootefi.c b/cmd/bootefi.c
index ae1b713..ca41170 100644
--- a/cmd/bootefi.c
+++ b/cmd/bootefi.c
@@ -226,6 +226,17 @@ static unsigned long do_bootefi_exec(void *efi, void *fdt)
 		return status == EFI_SUCCESS ? 0 : -EINVAL;
 	}
 
+#ifdef CONFIG_ARM64
+	/* On AArch64 we need to make sure we call our payload in < EL3 */
+	if (current_el() == 3) {
+		smp_kick_all_cpus();
+		dcache_disable();	/* flush cache before switch to EL2 */
+		armv8_switch_to_el2();
+		/* Enable caches again */
+		dcache_enable();
+	}
+#endif
+
 	return entry(&loaded_image_info, &systab);
 }
 
-- 
1.8.5.6