[Qemu-devel] [PATCH 12/21] build list of available accelerators

[Glauber Costa <glommer@redhat.com>]

From: Glauber Costa <gcosta@redhat.com>

instead of hardcoding kqemu_start() in exec.c, which would require
such a hack for all available accelerators, semantics of register_qemu_accel()
is changed a little bit. It only builds a list of available accelerators.
The last one registered is the first tried.

This is a temporary solution, since we don't control exactly the order in which
things are loaded by the constructor attributes. The final goal is to have command
line switches and priority lists to determine that.

"info accelerator" is changed to accomodate it. It now prints a list of available
accelerators, and only if one of them is active, a detailed description of it is printed.

Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
---
 accel.c   |    3 ++
 accel.h   |   63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 exec.c    |    3 --
 kqemu.c   |    5 +--
 monitor.c |   12 +++++++++-
 vl.c      |    7 ++++++
 6 files changed, 83 insertions(+), 10 deletions(-)

diff --git a/accel.c b/accel.c
index 45ad1ee..3186d46 100644
--- a/accel.c
+++ b/accel.c
@@ -2,6 +2,7 @@
 #include "accel.h"
 
 QEMUAccel *current_accel;
+QEMUCont *head = NULL;
 
 int _accel_nop(void)
 {
@@ -17,8 +18,10 @@ int noaccel_info(CPUState *env, char *buf)
 
 /* Accelerator wrapper for the no-accel (raw qemu) case */
 QEMUAccel noaccel = {
+    .name = "none",
     .cpu_interrupt = accel_nop,
     .init_env = accel_nop,
+    .start = accel_nop,
     .flush_cache = accel_nop,
     .flush_page = accel_nop,
     .info = noaccel_info,
diff --git a/accel.h b/accel.h
index c305e8c..c6f0ff3 100644
--- a/accel.h
+++ b/accel.h
@@ -2,8 +2,10 @@
 #define _ACCEL_H_
 
 typedef struct QEMUAccel {
+    char *name;
     void (*cpu_interrupt)(CPUState *env);
     void (*init_env)(CPUState *env);
+    int (*start)(void);
     void (*flush_cache)(CPUState *env, int global);
     void (*flush_page)(CPUState *env, target_ulong addr);
     int (*info)(CPUState *env, char *buf);
@@ -15,12 +17,51 @@ typedef struct QEMUAccel {
 #endif
 } QEMUAccel;
 
+typedef struct QEMUCont {
+    QEMUAccel *acc;
+    int active;
+    struct QEMUCont *next;
+} QEMUCont;
+
 extern QEMUAccel *current_accel;
 extern QEMUAccel noaccel;
+#ifdef USE_KQEMU
+extern QEMUAccel kqemu_accel;
+#endif
 
-static inline void register_qemu_accel(QEMUAccel *accel)
+extern QEMUCont *head;
+void *qemu_mallocz(size_t size);
+
+static inline int register_qemu_accel(QEMUAccel *accel)
 {
-    current_accel = accel;
+    QEMUCont *new, *tmp, *last = NULL;
+
+    for (tmp = head, last; tmp; tmp = tmp->next) {
+        /* we disallow registering the same accelerator twice */
+        if (tmp->acc ==  accel)
+            return -1;
+
+        if (!tmp->next)
+            last = tmp;
+    }
+
+    new = qemu_mallocz(sizeof(*head));
+
+    new->acc = accel;
+    new->active = 0;
+    new->next = NULL;
+
+    if (!head)
+        head = new;
+    else
+        last->next = new;
+
+    return 0;
+}
+
+static inline QEMUCont *get_accel_head(void)
+{
+    return head;
 }
 
 static inline void accel_cpu_interrupt(CPUState *env)
@@ -28,6 +69,24 @@ static inline void accel_cpu_interrupt(CPUState *env)
     current_accel->cpu_interrupt(env);
 }
 
+static inline int accel_start(void)
+{
+    int status = -1;
+    /* The top accelerator in the list gets tried first, but if it fails,
+     * keep trying until one of them succeeds or we exhaust the list */
+    QEMUCont *tmp = head;
+    while (tmp) {
+        if (tmp->acc && tmp->acc->start && (!(tmp->acc->start())) ) {
+            tmp->active = 1;
+            current_accel = tmp->acc;
+            status = 0;
+            break;
+        }
+        tmp = tmp->next;
+    }
+    return status;
+}
+
 static inline void accel_init_env(CPUState *env)
 {
     current_accel->init_env(env);
diff --git a/exec.c b/exec.c
index b6f54c2..ac378a5 100644
--- a/exec.c
+++ b/exec.c
@@ -497,9 +497,6 @@ void cpu_exec_init_all(unsigned long tb_size)
 #if !defined(CONFIG_USER_ONLY)
     io_mem_init();
 #endif
-#ifdef USE_KQEMU
-    kqemu_start();
-#endif
 }
 
 #if defined(CPU_SAVE_VERSION) && !defined(CONFIG_USER_ONLY)
diff --git a/kqemu.c b/kqemu.c
index e1c2dc3..9b4263d 100644
--- a/kqemu.c
+++ b/kqemu.c
@@ -155,7 +155,6 @@ static void kqemu_update_cpuid(CPUState *env)
        accelerated code */
 }
 
-QEMUAccel kqemu_accel;
 extern int smp_cpus;
 
 int kqemu_start(void)
@@ -240,7 +239,6 @@ int kqemu_start(void)
     }
     nb_pages_to_flush = 0;
     nb_ram_pages_to_update = 0;
-    register_qemu_accel(&kqemu_accel);
 
     qpi_init();
     return 0;
@@ -436,8 +434,10 @@ void kqemu_set_phys_mem(uint64_t start_addr, ram_addr_t size,
 }
 
 QEMUAccel kqemu_accel = {
+    .name = "KQEMU",
     .cpu_interrupt = kqemu_cpu_interrupt,
     .init_env = kqemu_init_env,
+    .start = kqemu_start,
     .flush_cache = kqemu_flush,
     .flush_page = kqemu_flush_page,
     .info = kqemu_info,
@@ -452,7 +452,6 @@ QEMUAccel kqemu_accel = {
 #endif
 };
 
-
 struct fpstate {
     uint16_t fpuc;
     uint16_t dummy1;
diff --git a/monitor.c b/monitor.c
index 2f92bcc..06bd806 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1234,6 +1234,15 @@ static void mem_info(void)
 }
 #endif
 
+static int do_accel_do_list(void)
+{
+    QEMUCont *tmp;
+    for (tmp= get_accel_head(); tmp != NULL; tmp = tmp->next)
+    {
+        term_printf("%c %s\n", tmp->active ? '*' : ' ', tmp->acc->name);
+    }
+}
+
 #define MAX_BUF 1024
 static void do_info_accelerator(void)
 {
@@ -1247,10 +1256,9 @@ static void do_info_accelerator(void)
         return;
     }
 
+    do_accel_do_list();
     if (accel_info(env, buf))
         term_printf(buf);
-    else
-        term_printf("No accelerator present\n");
 }
 
 #ifdef CONFIG_PROFILER
diff --git a/vl.c b/vl.c
index 55a0c08..c5fb2dc 100644
--- a/vl.c
+++ b/vl.c
@@ -140,6 +140,7 @@
 #include "disas.h"
 
 #include "exec-all.h"
+#include "accel.h"
 
 #define DEFAULT_NETWORK_SCRIPT "/etc/qemu-ifup"
 #define DEFAULT_NETWORK_DOWN_SCRIPT "/etc/qemu-ifdown"
@@ -8809,6 +8810,7 @@ int main(int argc, char **argv)
     }
 #endif
 
+    register_qemu_accel(&kqemu_accel);
     register_qemu_accel(&noaccel);
 
     register_machines();
@@ -9583,6 +9585,11 @@ int main(int argc, char **argv)
     /* init the dynamic translator */
     cpu_exec_init_all(tb_size * 1024 * 1024);
 
+    if (accel_start()) {
+	    fprintf(stderr, "qemu: error, no suitable accelerator found\n");
+	    exit(1);
+    }
+
     bdrv_init();
 
     /* we always create the cdrom drive, even if no disk is there */
-- 
1.5.5.1