[PATCH] target/arm: Check if debug is already initialized

[Akihiko Odaki]

When virtualizing SMP system, kvm_arm_init_debug() will be called
multiple times. Check if the debug feature is already initialized when the
function is called; otherwise it will overwrite pointers to memory
allocated with the previous call and leak it.

Fixes: e4482ab7e3 ("target-arm: kvm - add support for HW assisted debug")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 target/arm/kvm64.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/target/arm/kvm64.c b/target/arm/kvm64.c
index 1197253d12..d2fce5e582 100644
--- a/target/arm/kvm64.c
+++ b/target/arm/kvm64.c
@@ -32,7 +32,11 @@
 #include "hw/acpi/ghes.h"
 #include "hw/arm/virt.h"
 
-static bool have_guest_debug;
+static enum {
+    GUEST_DEBUG_UNINITED,
+    GUEST_DEBUG_INITED,
+    GUEST_DEBUG_UNAVAILABLE,
+} guest_debug;
 
 /*
  * Although the ARM implementation of hardware assisted debugging
@@ -84,8 +88,14 @@ GArray *hw_breakpoints, *hw_watchpoints;
  */
 static void kvm_arm_init_debug(CPUState *cs)
 {
-    have_guest_debug = kvm_check_extension(cs->kvm_state,
-                                           KVM_CAP_SET_GUEST_DEBUG);
+    if (guest_debug) {
+        return;
+    }
+
+    if (!kvm_check_extension(cs->kvm_state, KVM_CAP_SET_GUEST_DEBUG)) {
+        guest_debug = GUEST_DEBUG_UNAVAILABLE;
+        return;
+    }
 
     max_hw_wps = kvm_check_extension(cs->kvm_state, 
KVM_CAP_GUEST_DEBUG_HW_WPS);
     hw_watchpoints = g_array_sized_new(true, true,
@@ -94,7 +104,8 @@ static void kvm_arm_init_debug(CPUState *cs)
     max_hw_bps = kvm_check_extension(cs->kvm_state, 
KVM_CAP_GUEST_DEBUG_HW_BPS);
     hw_breakpoints = g_array_sized_new(true, true,
                                        sizeof(HWBreakpoint), max_hw_bps);
-    return;
+
+    guest_debug = GUEST_DEBUG_INITED;
 }
 
 /**
@@ -1483,7 +1494,7 @@ static const uint32_t brk_insn = 0xd4200000;
 
 int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
 {
-    if (have_guest_debug) {
+    if (guest_debug == GUEST_DEBUG_INITED) {
         if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 0) 
||
             cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&brk_insn, 4, 1)) {
             return -EINVAL;
@@ -1499,7 +1510,7 @@ int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct 
kvm_sw_breakpoint *bp)
 {
     static uint32_t brk;
 
-    if (have_guest_debug) {
+    if (guest_debug == GUEST_DEBUG_INITED) {
         if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&brk, 4, 0) ||
             brk != brk_insn ||
             cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 1)) 
{
-- 
2.40.0