From ed32cf6328c42c03098d40b725ed769adfe733e1 Mon Sep 17 00:00:00 2001
From: Hector Martin <marcan@marcan.st>
Date: Sun, 9 May 2021 03:15:25 +0900
Subject: [PATCH] hv_exc: Add a hacky STEP feature to interrupt guest after a
 while

This should eventually be a proper single step feature or something, but
for now...

Signed-off-by: Hector Martin <marcan@marcan.st>
---
 proxyclient/proxy.py | 1 +
 src/hv_exc.c         | 5 +++++
 src/uartproxy.h      | 1 +
 3 files changed, 7 insertions(+)

diff --git a/proxyclient/proxy.py b/proxyclient/proxy.py
index b2a35f5c..269b41ba 100755
--- a/proxyclient/proxy.py
+++ b/proxyclient/proxy.py
@@ -91,6 +91,7 @@ class EXC_RET(IntEnum):
     UNHANDLED = 1
     HANDLED = 2
     EXIT_GUEST = 3
+    STEP = 4
 
 ExcInfo = Struct(
     "spsr" / RegAdapter(SPSR),
diff --git a/src/hv_exc.c b/src/hv_exc.c
index ea4cf7b6..1bee983d 100644
--- a/src/hv_exc.c
+++ b/src/hv_exc.c
@@ -35,12 +35,17 @@ static void hv_exc_proxy(u64 *regs, uartproxy_exc_code_t type)
     int ret = uartproxy_run(&start);
 
     switch (ret) {
+        case EXC_RET_STEP:
         case EXC_RET_HANDLED:
             memcpy(regs, exc_info.regs, sizeof(exc_info.regs));
             msr(SPSR_EL2, exc_info.spsr);
             msr(ELR_EL2, exc_info.elr);
             msr(SP_EL0, exc_info.sp[0]);
             msr(SP_EL1, exc_info.sp[1]);
+            if (ret == EXC_RET_STEP) {
+                msr(CNTV_TVAL_EL0, 256);
+                msr(CNTV_CTL_EL0, 1);
+            }
             return;
         case EXC_EXIT_GUEST:
             hv_exit_guest();
diff --git a/src/uartproxy.h b/src/uartproxy.h
index 65121d25..f19ce4ef 100644
--- a/src/uartproxy.h
+++ b/src/uartproxy.h
@@ -24,6 +24,7 @@ typedef enum _uartproxy_exc_ret_t {
     EXC_RET_UNHANDLED = 1,
     EXC_RET_HANDLED = 2,
     EXC_EXIT_GUEST = 3,
+    EXC_RET_STEP = 4,
 } uartproxy_exc_ret_t;
 
 struct uartproxy_exc_info {