target/ppc: Clarify the meaning of return values in kvm_handle_debug

The kvm_handle_debug function can return 0 to go back into the guest
or return 1 to notify the gdbstub thread and pass control to GDB.

Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Message-Id: <20200110151344.278471-2-farosas@linux.ibm.com>
Tested-by: Leonardo Bras <leonardo@ibm.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 06fd0cc..c05dde5 100644 (file)
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -53,6 +53,9 @@
 
 #define PROC_DEVTREE_CPU      "/proc/device-tree/cpus/"
 
+#define DEBUG_RETURN_GUEST 0
+#define DEBUG_RETURN_GDB   1
+
 const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
     KVM_CAP_LAST_INFO
 };
@@ -1564,7 +1567,7 @@ void kvm_arch_update_guest_debug(CPUState *cs, struct kvm_guest_debug *dbg)
 static int kvm_handle_hw_breakpoint(CPUState *cs,
                                     struct kvm_debug_exit_arch *arch_info)
 {
-    int handle = 0;
+    int handle = DEBUG_RETURN_GUEST;
     int n;
     int flag = 0;
 
@@ -1572,13 +1575,13 @@ static int kvm_handle_hw_breakpoint(CPUState *cs,
         if (arch_info->status & KVMPPC_DEBUG_BREAKPOINT) {
             n = find_hw_breakpoint(arch_info->address, GDB_BREAKPOINT_HW);
             if (n >= 0) {
-                handle = 1;
+                handle = DEBUG_RETURN_GDB;
             }
         } else if (arch_info->status & (KVMPPC_DEBUG_WATCH_READ |
                                         KVMPPC_DEBUG_WATCH_WRITE)) {
             n = find_hw_watchpoint(arch_info->address,  &flag);
             if (n >= 0) {
-                handle = 1;
+                handle = DEBUG_RETURN_GDB;
                 cs->watchpoint_hit = &hw_watchpoint;
                 hw_watchpoint.vaddr = hw_debug_points[n].addr;
                 hw_watchpoint.flags = flag;
@@ -1590,12 +1593,12 @@ static int kvm_handle_hw_breakpoint(CPUState *cs,
 
 static int kvm_handle_singlestep(void)
 {
-    return 1;
+    return DEBUG_RETURN_GDB;
 }
 
 static int kvm_handle_sw_breakpoint(void)
 {
-    return 1;
+    return DEBUG_RETURN_GDB;
 }
 
 static int kvm_handle_debug(PowerPCCPU *cpu, struct kvm_run *run)
@@ -1647,7 +1650,7 @@ static int kvm_handle_debug(PowerPCCPU *cpu, struct kvm_run *run)
     env->error_code = POWERPC_EXCP_INVAL;
     ppc_cpu_do_interrupt(cs);
 
-    return 0;
+    return DEBUG_RETURN_GUEST;
 }
 
 int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)