[Qemu-devel] [PATCH 02/20] 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.
---
 accel.h           |   16 ++++++++++++++++
 block-raw-posix.c |    5 -----
 exec.c            |    3 +++
 kqemu.c           |    9 +++++++++
 vl.c              |    8 +++-----
 5 files changed, 31 insertions(+), 10 deletions(-)
 create mode 100644 accel.h

diff --git a/accel.h b/accel.h
new file mode 100644
index 0000000..e16ca69
--- /dev/null
+++ b/accel.h
@@ -0,0 +1,16 @@
+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);
+}
diff --git a/block-raw-posix.c b/block-raw-posix.c
index fd40dda..0e6c781 100644
--- a/block-raw-posix.c
+++ b/block-raw-posix.c
@@ -439,11 +439,6 @@ 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.c b/exec.c
index f459abe..b3d1133 100644
--- a/exec.c
+++ b/exec.c
@@ -41,6 +41,8 @@
 #include <qemu.h>
 #endif
 
+#include "accel.h"
+
 //#define DEBUG_TB_INVALIDATE
 //#define DEBUG_FLUSH
 //#define DEBUG_TLB
@@ -1391,6 +1393,7 @@ void cpu_interrupt(CPUState *env, int mask)
         resetlock(&interrupt_lock);
     }
 #endif
+    accel_cpu_interrupt(env);
 }
 
 void cpu_reset_interrupt(CPUState *env, int mask)
diff --git a/kqemu.c b/kqemu.c
index 9b52237..87c06cd 100644
--- a/kqemu.c
+++ b/kqemu.c
@@ -50,6 +50,7 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include "kqemu.h"
+#include "accel.h"
 
 #ifdef _WIN32
 #define KQEMU_DEVICE "\\\\.\\kqemu"
@@ -150,6 +151,8 @@ static void kqemu_update_cpuid(CPUState *env)
        accelerated code */
 }
 
+QEMUAccel kqemu_accel;
+
 int kqemu_start(void)
 {
     struct kqemu_init kinit;
@@ -232,6 +235,7 @@ int kqemu_start(void)
     }
     nb_pages_to_flush = 0;
     nb_ram_pages_to_update = 0;
+    register_qemu_accel(&kqemu_accel);
 
     qpi_init();
     return 0;
@@ -243,6 +247,11 @@ void kqemu_init_env(CPUState *env)
     env->kqemu_enabled = kqemu_allowed;
 }
 
+QEMUAccel kqemu_accel = {
+    .cpu_interrupt = kqemu_cpu_interrupt,
+};
+
+
 void kqemu_flush_page(CPUState *env, target_ulong addr)
 {
 #if defined(DEBUG)
diff --git a/vl.c b/vl.c
index 908aa39..4fb88fc 100644
--- a/vl.c
+++ b/vl.c
@@ -131,6 +131,8 @@ int inet_aton(const char *cp, struct in_addr *ia);
 
 #include "exec-all.h"
 
+#include "accel.h"
+
 #define DEFAULT_NETWORK_SCRIPT "/etc/qemu-ifup"
 #define DEFAULT_NETWORK_DOWN_SCRIPT "/etc/qemu-ifdown"
 #ifdef __sun__
@@ -239,6 +241,7 @@ 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)
 
@@ -1199,11 +1202,6 @@ 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;
     }
-- 
1.5.5.1