hvf: add breakpoint handlers

Required for guest debugging. The code has been structured like the KVM
counterpart.

Signed-off-by: Francesco Cagnin <fcagnin@quarkslab.com>
Message-id: 20230601153107.81955-4-fcagnin@quarkslab.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 126 insertions, 0 deletions

diff --git a/accel/hvf/hvf-accel-ops.c b/accel/hvf/hvf-accel-ops.c
index 24913ca..92601b1 100644
--- a/accel/hvf/hvf-accel-ops.c
+++ b/accel/hvf/hvf-accel-ops.c
@@ -52,6 +52,7 @@
 #include "qemu/main-loop.h"
 #include "exec/address-spaces.h"
 #include "exec/exec-all.h"
+#include "exec/gdbstub.h"
 #include "sysemu/cpus.h"
 #include "sysemu/hvf.h"
 #include "sysemu/hvf_int.h"
@@ -334,6 +335,8 @@ static int hvf_accel_init(MachineState *ms)
         s->slots[x].slot_id = x;
     }
 
+    QTAILQ_INIT(&s->hvf_sw_breakpoints);
+
     hvf_state = s;
     memory_listener_register(&hvf_memory_listener, &address_space_memory);
 
@@ -462,6 +465,108 @@ static void hvf_start_vcpu_thread(CPUState *cpu)
                        cpu, QEMU_THREAD_JOINABLE);
 }
 
+static int hvf_insert_breakpoint(CPUState *cpu, int type, hwaddr addr, hwaddr len)
+{
+    struct hvf_sw_breakpoint *bp;
+    int err;
+
+    if (type == GDB_BREAKPOINT_SW) {
+        bp = hvf_find_sw_breakpoint(cpu, addr);
+        if (bp) {
+            bp->use_count++;
+            return 0;
+        }
+
+        bp = g_new(struct hvf_sw_breakpoint, 1);
+        bp->pc = addr;
+        bp->use_count = 1;
+        err = hvf_arch_insert_sw_breakpoint(cpu, bp);
+        if (err) {
+            g_free(bp);
+            return err;
+        }
+
+        QTAILQ_INSERT_HEAD(&hvf_state->hvf_sw_breakpoints, bp, entry);
+    } else {
+        err = hvf_arch_insert_hw_breakpoint(addr, len, type);
+        if (err) {
+            return err;
+        }
+    }
+
+    CPU_FOREACH(cpu) {
+        err = hvf_update_guest_debug(cpu);
+        if (err) {
+            return err;
+        }
+    }
+    return 0;
+}
+
+static int hvf_remove_breakpoint(CPUState *cpu, int type, hwaddr addr, hwaddr len)
+{
+    struct hvf_sw_breakpoint *bp;
+    int err;
+
+    if (type == GDB_BREAKPOINT_SW) {
+        bp = hvf_find_sw_breakpoint(cpu, addr);
+        if (!bp) {
+            return -ENOENT;
+        }
+
+        if (bp->use_count > 1) {
+            bp->use_count--;
+            return 0;
+        }
+
+        err = hvf_arch_remove_sw_breakpoint(cpu, bp);
+        if (err) {
+            return err;
+        }
+
+        QTAILQ_REMOVE(&hvf_state->hvf_sw_breakpoints, bp, entry);
+        g_free(bp);
+    } else {
+        err = hvf_arch_remove_hw_breakpoint(addr, len, type);
+        if (err) {
+            return err;
+        }
+    }
+
+    CPU_FOREACH(cpu) {
+        err = hvf_update_guest_debug(cpu);
+        if (err) {
+            return err;
+        }
+    }
+    return 0;
+}
+
+static void hvf_remove_all_breakpoints(CPUState *cpu)
+{
+    struct hvf_sw_breakpoint *bp, *next;
+    CPUState *tmpcpu;
+
+    QTAILQ_FOREACH_SAFE(bp, &hvf_state->hvf_sw_breakpoints, entry, next) {
+        if (hvf_arch_remove_sw_breakpoint(cpu, bp) != 0) {
+            /* Try harder to find a CPU that currently sees the breakpoint. */
+            CPU_FOREACH(tmpcpu)
+            {
+                if (hvf_arch_remove_sw_breakpoint(tmpcpu, bp) == 0) {
+                    break;
+                }
+            }
+        }
+        QTAILQ_REMOVE(&hvf_state->hvf_sw_breakpoints, bp, entry);
+        g_free(bp);
+    }
+    hvf_arch_remove_all_hw_breakpoints();
+
+    CPU_FOREACH(cpu) {
+        hvf_update_guest_debug(cpu);
+    }
+}
+
 static void hvf_accel_ops_class_init(ObjectClass *oc, void *data)
 {
     AccelOpsClass *ops = ACCEL_OPS_CLASS(oc);
@@ -473,6 +578,10 @@ static void hvf_accel_ops_class_init(ObjectClass *oc, void *data)
     ops->synchronize_post_init = hvf_cpu_synchronize_post_init;
     ops->synchronize_state = hvf_cpu_synchronize_state;
     ops->synchronize_pre_loadvm = hvf_cpu_synchronize_pre_loadvm;
+
+    ops->insert_breakpoint = hvf_insert_breakpoint;
+    ops->remove_breakpoint = hvf_remove_breakpoint;
+    ops->remove_all_breakpoints = hvf_remove_all_breakpoints;
 };
 static const TypeInfo hvf_accel_ops_type = {
     .name = ACCEL_OPS_NAME("hvf"),
diff --git a/accel/hvf/hvf-all.c b/accel/hvf/hvf-all.c
index 0043f4d..e983c23 100644
--- a/accel/hvf/hvf-all.c
+++ b/accel/hvf/hvf-all.c
@@ -44,3 +44,20 @@ void assert_hvf_ok(hv_return_t ret)
 
     abort();
 }
+
+struct hvf_sw_breakpoint *hvf_find_sw_breakpoint(CPUState *cpu, target_ulong pc)
+{
+    struct hvf_sw_breakpoint *bp;
+
+    QTAILQ_FOREACH(bp, &hvf_state->hvf_sw_breakpoints, entry) {
+        if (bp->pc == pc) {
+            return bp;
+        }
+    }
+    return NULL;
+}
+
+int hvf_sw_breakpoints_active(CPUState *cpu)
+{
+    return !QTAILQ_EMPTY(&hvf_state->hvf_sw_breakpoints);
+}