From c7301588a3aec9ebf36749da601d0d6e3d807bfc Mon Sep 17 00:00:00 2001
From: Peter Hoyes <Peter.Hoyes@arm.com>
Date: Thu, 19 May 2022 09:02:32 +0100
Subject: [PATCH] armv8: Enable icache when switching exception levels in
 bootefi

bootefi calls the function switch_to_non_secure_mode before calling the
UEFI payload to handle the case where U-Boot is running at EL3.

For AArch64, the UEFI specification states that:
   The core will be configured as follows:
     * MMU enabled
     * Instruction and data caches enabled

These requirements should be followed when switching exception levels
for EFI applications.

This function already disables and re-enables the data cache prior to
switching exception levels, but omits the instruction cache, meaning
the function returns with the instruction cache disabled at the new
exception level. Fix this by calling icache_disable prior to switching
exception levels and icache_enable afterwards.

Issue-Id: SCM-4641
Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com>
Upstream-Status: Inappropriate [other]
  Implementation pending further discussion
Change-Id: I678cd5ba39b56e124ab7854608289cd14651ce65

---
 arch/arm/cpu/armv8/exception_level.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm/cpu/armv8/exception_level.c b/arch/arm/cpu/armv8/exception_level.c
index 4aad1550f4..0a3e5428e7 100644
--- a/arch/arm/cpu/armv8/exception_level.c
+++ b/arch/arm/cpu/armv8/exception_level.c
@@ -27,6 +27,7 @@
 static void entry_non_secure(struct jmp_buf_data *non_secure_jmp)
 {
 	dcache_enable();
+	icache_enable();
 	debug("Reached non-secure mode\n");
 
 	/* Restore stack and registers saved in switch_to_non_secure_mode() */
@@ -61,6 +62,7 @@ void switch_to_non_secure_mode(void)
 		if (setjmp(&non_secure_jmp))
 			return;
 		dcache_disable();	/* flush cache before switch to EL2 */
+		icache_disable();
 		/* Move into EL2 and keep running there */
 		armv8_switch_to_el2((uintptr_t)&non_secure_jmp, 0, 0, 0,
 				    (uintptr_t)entry_non_secure, ES_TO_AARCH64);
@@ -68,6 +70,7 @@ void switch_to_non_secure_mode(void)
 		if (setjmp(&non_secure_jmp))
 			return;
 		dcache_disable();	/* flush cache before switch to EL1 */
+		icache_disable();
 		/* Move into EL1 and keep running there */
 		armv8_switch_to_el1((uintptr_t)&non_secure_jmp, 0, 0, 0,
 				    (uintptr_t)entry_non_secure, ES_TO_AARCH64);