[openwrt/openwrt] bcm4908: add HVC workaround for booting kernel 5.15

[LEDE Commits]

rmilecki pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/86cf0f93f1ce603771ea06e581c8937ba1ad8918

commit 86cf0f93f1ce603771ea06e581c8937ba1ad8918
Author: Rafał Miłecki <rafal at milecki.pl>
AuthorDate: Thu Mar 16 23:34:37 2023 +0100

    bcm4908: add HVC workaround for booting kernel 5.15
    
    Signed-off-by: Rafał Miłecki <rafal at milecki.pl>
---
 .../301-arm64-don-t-issue-HVC-on-boot.patch        | 30 ++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/target/linux/bcm4908/patches-5.15/301-arm64-don-t-issue-HVC-on-boot.patch b/target/linux/bcm4908/patches-5.15/301-arm64-don-t-issue-HVC-on-boot.patch
new file mode 100644
index 0000000000..d167c2ed00
--- /dev/null
+++ b/target/linux/bcm4908/patches-5.15/301-arm64-don-t-issue-HVC-on-boot.patch
@@ -0,0 +1,30 @@
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal at milecki.pl>
+Date: Thu, 12 Aug 2021 11:52:42 +0200
+Subject: [PATCH] arm64: don't issue HVC on boot
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Broadcom's CFE loader seems to miss setting SCR_EL3.HCE which results in
+generating an UNDEF and kernel panic on the first HVC.
+
+HVC gets issued by kernels 5.12+ while booting, by kexec and KVM. Until
+someone finds a workaround we have to avoid all above.
+
+Workarounds: 0c93df9622d4 ("arm64: Initialise as nVHE before switching to VHE")
+Signed-off-by: Rafał Miłecki <rafal at milecki.pl>
+---
+ arch/arm64/kernel/hyp-stub.S | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/arch/arm64/kernel/hyp-stub.S
++++ b/arch/arm64/kernel/hyp-stub.S
+@@ -238,7 +238,7 @@ SYM_FUNC_START(switch_to_vhe)
+ 
+ 	// Turn the world upside down
+ 	mov	x0, #HVC_VHE_RESTART
+-	hvc	#0
++//	hvc	#0
+ 1:
+ 	ret
+ SYM_FUNC_END(switch_to_vhe)