[Qemu-devel] [PATCH 07/15] kvm: Separate TCG from KVM cpu execution

[Jan Kiszka]

Mixing up TCG bits with KVM already led to problems around eflags
emulation on x86. Moreover, quite some code that TCG requires on cpu
enty/exit is useless for KVM. So dispatch between tcg_cpu_exec and
kvm_cpu_exec as early as possible.

The core logic of cpu_halted from cpu_exec is added to
kvm_arch_process_irqchip_events. Moving away from cpu_exec makes
exception_index meaningless for KVM, we can simply pass the exit reason
directly (only "EXCP_DEBUG vs. rest" is relevant).

Signed-off-by: Jan Kiszka <address@hidden>
---
 cpu-exec.c        |   19 ++++++-------------
 cpus.c            |   10 +++++-----
 kvm-all.c         |   19 +++++++++----------
 target-i386/kvm.c |    6 +++---
 4 files changed, 23 insertions(+), 31 deletions(-)

diff --git a/cpu-exec.c b/cpu-exec.c
index 9c0b10d..b03b3a7 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -226,13 +226,11 @@ int cpu_exec(CPUState *env1)
     }
 
 #if defined(TARGET_I386)
-    if (!kvm_enabled()) {
-        /* put eflags in CPU temporary format */
-        CC_SRC = env->eflags & (CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
-        DF = 1 - (2 * ((env->eflags >> 10) & 1));
-        CC_OP = CC_OP_EFLAGS;
-        env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
-    }
+    /* put eflags in CPU temporary format */
+    CC_SRC = env->eflags & (CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
+    DF = 1 - (2 * ((env->eflags >> 10) & 1));
+    CC_OP = CC_OP_EFLAGS;
+    env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);
 #elif defined(TARGET_SPARC)
 #elif defined(TARGET_M68K)
     env->cc_op = CC_OP_FLAGS;
@@ -257,7 +255,7 @@ int cpu_exec(CPUState *env1)
         if (setjmp(env->jmp_env) == 0) {
 #if defined(__sparc__) && !defined(CONFIG_SOLARIS)
 #undef env
-                    env = cpu_single_env;
+            env = cpu_single_env;
 #define env cpu_single_env
 #endif
             /* if an exception is pending, we execute it here */
@@ -316,11 +314,6 @@ int cpu_exec(CPUState *env1)
                 }
             }
 
-            if (kvm_enabled()) {
-                kvm_cpu_exec(env);
-                longjmp(env->jmp_env, 1);
-            }
-
             next_tb = 0; /* force lookup of first TB */
             for(;;) {
                 interrupt_request = env->interrupt_request;
diff --git a/cpus.c b/cpus.c
index d4b5e80..2414316 100644
--- a/cpus.c
+++ b/cpus.c
@@ -800,8 +800,6 @@ static void qemu_kvm_wait_io_event(CPUState *env)
     qemu_wait_io_event_common(env);
 }
 
-static int qemu_cpu_exec(CPUState *env);
-
 static void *qemu_kvm_cpu_thread_fn(void *arg)
 {
     CPUState *env = arg;
@@ -829,7 +827,7 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
 
     while (1) {
         if (cpu_can_run(env)) {
-            r = qemu_cpu_exec(env);
+            r = kvm_cpu_exec(env);
             if (r == EXCP_DEBUG) {
                 cpu_handle_debug_exception(env);
             }
@@ -1040,7 +1038,7 @@ void vm_stop(int reason)
 
 #endif
 
-static int qemu_cpu_exec(CPUState *env)
+static int tcg_cpu_exec(CPUState *env)
 {
     int ret;
 #ifdef CONFIG_PROFILER
@@ -1095,9 +1093,11 @@ bool cpu_exec_all(void)
             break;
         }
         if (cpu_can_run(env)) {
-            r = qemu_cpu_exec(env);
             if (kvm_enabled()) {
+                r = kvm_cpu_exec(env);
                 qemu_kvm_eat_signals(env);
+            } else {
+                r = tcg_cpu_exec(env);
             }
             if (r == EXCP_DEBUG) {
                 cpu_handle_debug_exception(env);
diff --git a/kvm-all.c b/kvm-all.c
index 19cf188..802c6b8 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -895,10 +895,11 @@ int kvm_cpu_exec(CPUState *env)
 
     if (kvm_arch_process_irqchip_events(env)) {
         env->exit_request = 0;
-        env->exception_index = EXCP_HLT;
-        return 0;
+        return EXCP_HLT;
     }
 
+    cpu_single_env = env;
+
     do {
         if (env->kvm_vcpu_dirty) {
             kvm_arch_put_registers(env, KVM_PUT_RUNTIME_STATE);
@@ -927,7 +928,6 @@ int kvm_cpu_exec(CPUState *env)
         kvm_flush_coalesced_mmio_buffer();
 
         if (ret == -EINTR || ret == -EAGAIN) {
-            cpu_exit(env);
             DPRINTF("io window exit\n");
             ret = 0;
             break;
@@ -978,8 +978,8 @@ int kvm_cpu_exec(CPUState *env)
             DPRINTF("kvm_exit_debug\n");
 #ifdef KVM_CAP_SET_GUEST_DEBUG
             if (kvm_arch_debug(&run->debug.arch)) {
-                env->exception_index = EXCP_DEBUG;
-                return 0;
+                ret = EXCP_DEBUG;
+                goto out;
             }
             /* re-enter, this exception was guest-internal */
             ret = 1;
@@ -995,13 +995,12 @@ int kvm_cpu_exec(CPUState *env)
     if (ret < 0) {
         cpu_dump_state(env, stderr, fprintf, CPU_DUMP_CODE);
         vm_stop(VMSTOP_PANIC);
-        env->exit_request = 1;
-    }
-    if (env->exit_request) {
-        env->exit_request = 0;
-        env->exception_index = EXCP_INTERRUPT;
     }
+    ret = EXCP_INTERRUPT;
 
+out:
+    env->exit_request = 0;
+    cpu_single_env = NULL;
     return ret;
 }
 
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index ba183c4..377a0a3 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -1502,12 +1502,13 @@ int kvm_arch_post_run(CPUState *env, struct kvm_run 
*run)
 
 int kvm_arch_process_irqchip_events(CPUState *env)
 {
+    if (env->interrupt_request & (CPU_INTERRUPT_HARD | CPU_INTERRUPT_NMI)) {
+        env->halted = 0;
+    }
     if (env->interrupt_request & CPU_INTERRUPT_INIT) {
         kvm_cpu_synchronize_state(env);
         do_cpu_init(env);
-        env->exception_index = EXCP_HALTED;
     }
-
     if (env->interrupt_request & CPU_INTERRUPT_SIPI) {
         kvm_cpu_synchronize_state(env);
         do_cpu_sipi(env);
@@ -1522,7 +1523,6 @@ static int kvm_handle_halt(CPUState *env)
           (env->eflags & IF_MASK)) &&
         !(env->interrupt_request & CPU_INTERRUPT_NMI)) {
         env->halted = 1;
-        env->exception_index = EXCP_HLT;
         return 0;
     }
 
-- 
1.7.1