gdbstub: move sstep flags probing into AccelClass

The support of single-stepping is very much dependent on support from
the accelerator we are using. To avoid special casing in gdbstub move
the probing out to an AccelClass function so future accelerators can
put their code there.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Mads Ynddal <mads@ynddal.dk>
Message-Id: <20220929114231.583801-44-alex.bennee@linaro.org>

diff --git a/accel/accel-common.c b/accel/accel-common.c
index 50035bda55d0f85d0dcde52fbfc673b4656a87ad..df72cc989a9b02c15914a252abaf15f1904fb5c6 100644 (file)
--- a/accel/accel-common.c
+++ b/accel/accel-common.c
@@ -129,6 +129,16 @@ bool accel_cpu_realizefn(CPUState *cpu, Error **errp)
     return true;
 }
 
+int accel_supported_gdbstub_sstep_flags(void)
+{
+    AccelState *accel = current_accel();
+    AccelClass *acc = ACCEL_GET_CLASS(accel);
+    if (acc->gdbstub_supported_sstep_flags) {
+        return acc->gdbstub_supported_sstep_flags();
+    }
+    return 0;
+}
+
 static const TypeInfo accel_cpu_type = {
     .name = TYPE_ACCEL_CPU,
     .parent = TYPE_OBJECT,

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 5acab1767fe1abc3f291a5ecf3b1d09ea5f5d907..c55938453a1e5fcecd3d12e95f2923782ef365c2 100644 (file)
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -175,7 +175,7 @@ bool kvm_direct_msi_allowed;
 bool kvm_ioeventfd_any_length_allowed;
 bool kvm_msi_use_devid;
 bool kvm_has_guest_debug;
-int kvm_sstep_flags;
+static int kvm_sstep_flags;
 static bool kvm_immediate_exit;
 static hwaddr kvm_max_slot_size = ~0;
 
@@ -3712,6 +3712,17 @@ static void kvm_accel_instance_init(Object *obj)
     s->kvm_dirty_ring_size = 0;
 }
 
+/**
+ * kvm_gdbstub_sstep_flags():
+ *
+ * Returns: SSTEP_* flags that KVM supports for guest debug. The
+ * support is probed during kvm_init()
+ */
+static int kvm_gdbstub_sstep_flags(void)
+{
+    return kvm_sstep_flags;
+}
+
 static void kvm_accel_class_init(ObjectClass *oc, void *data)
 {
     AccelClass *ac = ACCEL_CLASS(oc);
@@ -3719,6 +3730,7 @@ static void kvm_accel_class_init(ObjectClass *oc, void *data)
     ac->init_machine = kvm_init;
     ac->has_memory = kvm_accel_has_memory;
     ac->allowed = &kvm_allowed;
+    ac->gdbstub_supported_sstep_flags = kvm_gdbstub_sstep_flags;
 
     object_class_property_add(oc, "kernel-irqchip", "on|off|split",
         NULL, kvm_set_kernel_irqchip,

diff --git a/accel/tcg/tcg-all.c b/accel/tcg/tcg-all.c
index 47952eecd77910072b3751e6fdebf944922ec21a..30b503fb22fcbe09b39ad7e55e113eac01352ddf 100644 (file)
--- a/accel/tcg/tcg-all.c
+++ b/accel/tcg/tcg-all.c
@@ -25,6 +25,7 @@
 
 #include "qemu/osdep.h"
 #include "sysemu/tcg.h"
+#include "sysemu/replay.h"
 #include "sysemu/cpu-timers.h"
 #include "tcg/tcg.h"
 #include "qapi/error.h"
@@ -207,12 +208,28 @@ static void tcg_set_splitwx(Object *obj, bool value, Error **errp)
     s->splitwx_enabled = value;
 }
 
+static int tcg_gdbstub_supported_sstep_flags(void)
+{
+    /*
+     * In replay mode all events will come from the log and can't be
+     * suppressed otherwise we would break determinism. However as those
+     * events are tied to the number of executed instructions we won't see
+     * them occurring every time we single step.
+     */
+    if (replay_mode != REPLAY_MODE_NONE) {
+        return SSTEP_ENABLE;
+    } else {
+        return SSTEP_ENABLE | SSTEP_NOIRQ | SSTEP_NOTIMER;
+    }
+}
+
 static void tcg_accel_class_init(ObjectClass *oc, void *data)
 {
     AccelClass *ac = ACCEL_CLASS(oc);
     ac->name = "tcg";
     ac->init_machine = tcg_init_machine;
     ac->allowed = &tcg_allowed;
+    ac->gdbstub_supported_sstep_flags = tcg_gdbstub_supported_sstep_flags;
 
     object_class_property_add_str(oc, "thread",
                                   tcg_get_thread,

diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index 7d8fe475b389478ec95d5f7557d49e13c1768e74..a0755e6505e9997ac49b399c78a78094cbf1e7bf 100644 (file)
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -383,27 +383,13 @@ static void init_gdbserver_state(void)
     gdbserver_state.last_packet = g_byte_array_sized_new(MAX_PACKET_LENGTH + 4);
 
     /*
-     * In replay mode all events will come from the log and can't be
-     * suppressed otherwise we would break determinism. However as those
-     * events are tied to the number of executed instructions we won't see
-     * them occurring every time we single step.
-     */
-    if (replay_mode != REPLAY_MODE_NONE) {
-        gdbserver_state.supported_sstep_flags = SSTEP_ENABLE;
-    } else if (kvm_enabled()) {
-        gdbserver_state.supported_sstep_flags = kvm_get_supported_sstep_flags();
-    } else {
-        gdbserver_state.supported_sstep_flags =
-            SSTEP_ENABLE | SSTEP_NOIRQ | SSTEP_NOTIMER;
-    }
-
-    /*
-     * By default use no IRQs and no timers while single stepping so as to
-     * make single stepping like an ICE HW step.
+     * What single-step modes are supported is accelerator dependent.
+     * By default try to use no IRQs and no timers while single
+     * stepping so as to make single stepping like a typical ICE HW step.
      */
+    gdbserver_state.supported_sstep_flags = accel_supported_gdbstub_sstep_flags();
     gdbserver_state.sstep_flags = SSTEP_ENABLE | SSTEP_NOIRQ | SSTEP_NOTIMER;
     gdbserver_state.sstep_flags &= gdbserver_state.supported_sstep_flags;
-
 }
 
 #ifndef CONFIG_USER_ONLY

diff --git a/include/qemu/accel.h b/include/qemu/accel.h
index be56da1b999d1a28902ab22c7cb72e021b879711..ce4747634a7c08ced9f8d7a250d48a3b9d5f26e6 100644 (file)
--- a/include/qemu/accel.h
+++ b/include/qemu/accel.h
@@ -43,6 +43,10 @@ typedef struct AccelClass {
     bool (*has_memory)(MachineState *ms, AddressSpace *as,
                        hwaddr start_addr, hwaddr size);
 #endif
+
+    /* gdbstub related hooks */
+    int (*gdbstub_supported_sstep_flags)(void);
+
     bool *allowed;
     /*
      * Array of global properties that would be applied when specific
@@ -92,4 +96,12 @@ void accel_cpu_instance_init(CPUState *cpu);
  */
 bool accel_cpu_realizefn(CPUState *cpu, Error **errp);
 
+/**
+ * accel_supported_gdbstub_sstep_flags:
+ *
+ * Returns the supported single step modes for the configured
+ * accelerator.
+ */
+int accel_supported_gdbstub_sstep_flags(void);
+
 #endif /* QEMU_ACCEL_H */

diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index efd6dee818f28174e80e0d4676876c2f22a01031..a20ad51aadf3fcd43825380165d355af1e11f91f 100644 (file)
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -47,7 +47,6 @@ extern bool kvm_direct_msi_allowed;
 extern bool kvm_ioeventfd_any_length_allowed;
 extern bool kvm_msi_use_devid;
 extern bool kvm_has_guest_debug;
-extern int kvm_sstep_flags;
 
 #define kvm_enabled()           (kvm_allowed)
 /**
@@ -174,12 +173,6 @@ extern int kvm_sstep_flags;
  */
 #define kvm_supports_guest_debug() (kvm_has_guest_debug)
 
-/*
- * kvm_supported_sstep_flags
- * Returns: SSTEP_* flags that KVM supports for guest debug
- */
-#define kvm_get_supported_sstep_flags() (kvm_sstep_flags)
-
 #else
 
 #define kvm_enabled()           (0)
@@ -198,7 +191,6 @@ extern int kvm_sstep_flags;
 #define kvm_ioeventfd_any_length_enabled() (false)
 #define kvm_msi_devid_required() (false)
 #define kvm_supports_guest_debug() (false)
-#define kvm_get_supported_sstep_flags() (0)
 
 #endif  /* CONFIG_KVM_IS_POSSIBLE */