Comment 6 for bug 1879587

Unfortunately, I won't be able to send the code or binary for the hypervisor as of now (it will become available at some point in the future though). I've done a bit of debugging on the QEMU code and it seems like the approach you are taking works fine in general but the register mapping code doesn't seem quite right. Applying this patch (on top of yours):

From e2182581dcdeedc2cb88cd21b88b4db744677737 Mon Sep 17 00:00:00 2001
From: Julien Freche <email address hidden>
Date: Tue, 4 Aug 2020 11:54:49 -0700
Subject: [PATCH] Possible fix

---
 target/arm/helper.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 60b80228fd..455c92b891 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -9619,17 +9619,16 @@ static int aarch64_regnum(CPUARMState *env, int aarch32_reg)
         switch (mode) {
         case ARM_CPU_MODE_USR:
         case ARM_CPU_MODE_SYS:
- return 14;
         case ARM_CPU_MODE_HYP:
- return 16;
+ return 14;
         case ARM_CPU_MODE_IRQ:
- return 18;
+ return 16;
         case ARM_CPU_MODE_SVC:
- return 20;
+ return 18;
         case ARM_CPU_MODE_ABT:
- return 22;
+ return 20;
         case ARM_CPU_MODE_UND:
- return 24;
+ return 22;
         case ARM_CPU_MODE_FIQ:
             return 30;
         default:
--
2.28.0

Based on the ARM documentation, I would think that LR_svc maps to X18, not X20. I fixed the ones that seemed wrong but I haven't check every possible case so you may want to double check this. With the patch I was able to boot Linux correctly.

Let me know if that makes sense