softmmu: Restore use of CPU watchpoint for all accelerators

CPU watchpoints can be use by non-TCG accelerators.

KVM uses them:

  $ git grep CPUWatchpoint|fgrep kvm
  target/arm/kvm64.c:1558:        CPUWatchpoint *wp = find_hw_watchpoint(cs, debug_exit->far);
  target/i386/kvm/kvm.c:5216:static CPUWatchpoint hw_watchpoint;
  target/ppc/kvm.c:443:static CPUWatchpoint hw_watchpoint;
  target/s390x/kvm/kvm.c:139:static CPUWatchpoint hw_watchpoint;

See for example commit e4482ab7e3 ("target-arm: kvm - add support
for HW assisted debug"):

     This adds basic support for HW assisted debug. The ioctl interface
     to KVM allows us to pass an implementation defined number of break
     and watch point registers. [...]

This partially reverts commit 2609ec2868e6c286e755a73b4504714a0296a.

Fixes: 2609ec2868 ("softmmu: Extract watchpoint API from physmem.c")
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230328173117.15226-4-philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

include/hw/core/cpu.h

@@ -949,7 +949,7 @@ static inline bool cpu_breakpoint_test(CPUState *cpu, vaddr pc, int mask)
     return false;
 }
 
-#if !defined(CONFIG_TCG) || defined(CONFIG_USER_ONLY)
+#if defined(CONFIG_USER_ONLY)
 static inline int cpu_watchpoint_insert(CPUState *cpu, vaddr addr, vaddr len,
                                         int flags, CPUWatchpoint **watchpoint)
 {

softmmu/meson.build

@@ -5,11 +5,11 @@ specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: [files(
   'physmem.c',
   'qtest.c',
   'dirtylimit.c',
+  'watchpoint.c',
 )])
 
 specific_ss.add(when: ['CONFIG_SOFTMMU', 'CONFIG_TCG'], if_true: [files(
   'icount.c',
-  'watchpoint.c',
 )])
 
 softmmu_ss.add(files(

softmmu/watchpoint.c

@@ -104,6 +104,8 @@ void cpu_watchpoint_remove_all(CPUState *cpu, int mask)
     }
 }
 
+#ifdef CONFIG_TCG
+
 /*
  * Return true if this watchpoint address matches the specified
  * access (ie the address range covered by the watchpoint overlaps
@@ -220,3 +222,5 @@ void cpu_check_watchpoint(CPUState *cpu, vaddr addr, vaddr len,
         }
     }
 }
+
+#endif /* CONFIG_TCG */