[Qemu-devel] [PATCH 1/4] [PATCH] introduce QEMUAccel and fill it with interrupt specific driver

[Glauber Costa <gcosta@redhat.com>]

This patch introduces QEMUAccel, a placeholder for function pointers
that aims at helping qemu to abstract accelerators such as kqemu and
kvm (actually, the 'accelerator' name was proposed by avi kivity, since
he loves referring to kvm that way).

To begin with, the accelerator is given the opportunity to register a
cpu_interrupt function, to be called after the raw cpu_interrupt.
This has the side effect of, for the kqemu accelerator, calling kqemu_cpu_interrupt
everytime, which didn't use to happen. But looking at the code, this seems safe to me.

This patch applies on raw qemu.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
---
 block-raw-posix.c |    5 -----
 exec-all.h        |   18 +++++++++++++++++-
 exec.c            |    2 ++
 kqemu.c           |   26 ++++++++++++++++----------
 vl.c              |    6 +-----
 5 files changed, 36 insertions(+), 21 deletions(-)

diff --git a/block-raw-posix.c b/block-raw-posix.c
index 6b0009e..61c23ba 100644
--- a/block-raw-posix.c
+++ b/block-raw-posix.c
@@ -250,11 +250,6 @@ static void aio_signal_handler(int signum)
     if (env) {
         /* stop the currently executing cpu because a timer occured */
         cpu_interrupt(env, CPU_INTERRUPT_EXIT);
-#ifdef USE_KQEMU
-        if (env->kqemu_enabled) {
-            kqemu_cpu_interrupt(env);
-        }
-#endif
     }
 #endif
 }
diff --git a/exec-all.h b/exec-all.h
index 3ce8242..5162307 100644
--- a/exec-all.h
+++ b/exec-all.h
@@ -574,6 +574,23 @@ static inline target_ulong get_phys_addr_code(CPUState *env, target_ulong addr)
 }
 #endif
 
+typedef struct QEMUAccel {
+    void (*cpu_interrupt)(CPUState *env);
+} QEMUAccel;
+
+extern QEMUAccel *current_accel;
+
+static inline void register_qemu_accel(QEMUAccel *accel)
+{
+    current_accel = accel;
+}
+
+static inline void accel_cpu_interrupt(CPUState *env)
+{
+    if (current_accel && current_accel->cpu_interrupt)
+        current_accel->cpu_interrupt(env);
+}
+
 #ifdef USE_KQEMU
 #define KQEMU_MODIFY_PAGE_MASK (0xff & ~(VGA_DIRTY_FLAG | CODE_DIRTY_FLAG))
 
@@ -583,7 +600,6 @@ void kqemu_flush_page(CPUState *env, target_ulong addr);
 void kqemu_flush(CPUState *env, int global);
 void kqemu_set_notdirty(CPUState *env, ram_addr_t ram_addr);
 void kqemu_modify_page(CPUState *env, ram_addr_t ram_addr);
-void kqemu_cpu_interrupt(CPUState *env);
 void kqemu_record_dump(void);
 
 static inline int kqemu_is_ok(CPUState *env)
diff --git a/exec.c b/exec.c
index 48dabd6..93d9b01 100644
--- a/exec.c
+++ b/exec.c
@@ -1226,6 +1226,8 @@ void cpu_interrupt(CPUState *env, int mask)
         tb_reset_jump_recursive(tb);
         resetlock(&interrupt_lock);
     }
+
+    accel_cpu_interrupt(env);
 }
 
 void cpu_reset_interrupt(CPUState *env, int mask)
diff --git a/kqemu.c b/kqemu.c
index 148a52f..c46698c 100644
--- a/kqemu.c
+++ b/kqemu.c
@@ -158,6 +158,19 @@ static void kqemu_update_cpuid(CPUState *env)
        accelerated code */
 }
 
+void kqemu_cpu_interrupt(CPUState *env)
+{
+#if defined(_WIN32) && KQEMU_VERSION >= 0x010101
+    /* cancelling the I/O request causes KQEMU to finish executing the
+       current block and successfully returning. */
+    CancelIo(kqemu_fd);
+#endif
+}
+
+QEMUAccel kqemu_accel = {
+    .cpu_interrupt = kqemu_cpu_interrupt,
+};
+
 int kqemu_init(CPUState *env)
 {
     struct kqemu_init init;
@@ -239,6 +252,9 @@ int kqemu_init(CPUState *env)
     }
     kqemu_update_cpuid(env);
     env->kqemu_enabled = kqemu_allowed;
+    if (env->kqemu_enabled)
+        register_qemu_accel(&kqemu_accel);
+
     nb_pages_to_flush = 0;
     nb_ram_pages_to_update = 0;
     return 0;
@@ -901,14 +917,4 @@ int kqemu_cpu_exec(CPUState *env)
     }
     return 0;
 }
-
-void kqemu_cpu_interrupt(CPUState *env)
-{
-#if defined(_WIN32) && KQEMU_VERSION >= 0x010101
-    /* cancelling the I/O request causes KQEMU to finish executing the
-       current block and successfully returning. */
-    CancelIo(kqemu_fd);
-#endif
-}
-
 #endif
diff --git a/vl.c b/vl.c
index 9289982..9272541 100644
--- a/vl.c
+++ b/vl.c
@@ -240,6 +240,7 @@ struct drive_opt {
 static CPUState *cur_cpu;
 static CPUState *next_cpu;
 static int event_pending = 1;
+QEMUAccel *current_accel;
 
 #define TFR(expr) do { if ((expr) != -1) break; } while (errno == EINTR)
 
@@ -1200,11 +1201,6 @@ static void host_alarm_handler(int host_signum)
         if (env) {
             /* stop the currently executing cpu because a timer occured */
             cpu_interrupt(env, CPU_INTERRUPT_EXIT);
-#ifdef USE_KQEMU
-            if (env->kqemu_enabled) {
-                kqemu_cpu_interrupt(env);
-            }
-#endif
         }
         event_pending = 1;
     }
-- 
1.5.0.6