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kvm: Unconditionally reenter kernel after IO exits 

KVM requires to reenter the kernel after IO exits in order to complete
instruction emulation. Failing to do so will leave the kernel state
inconsistently behind. To ensure that we will get back ASAP, we issue a
self-signal that will cause KVM_RUN to return once the pending
operations are completed.

We can move kvm_arch_process_irqchip_events out of the inner VCPU loop.
The only state that mattered at its old place was a pending INIT
request. Catch it in kvm_arch_pre_run and also trigger a self-signal to
process the request on next kvm_cpu_exec.

This patch also fixes the missing exit_request check in kvm_cpu_exec in
the CONFIG_IOTHREAD case.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
CC: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Jan Kiszka 2011-02-01 22:16:00 +01:00 committed by Marcelo Tosatti
parent 46d62fac8a
commit 9ccfac9ea4
2 changed files with 22 additions and 14 deletions
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31
kvm-all.c
View File

@ -199,7 +199,6 @@ int kvm_pit_in_kernel(void)
return kvm_state->pit_in_kernel;
}
int kvm_init_vcpu(CPUState *env)
{
KVMState *s = kvm_state;
@ -896,29 +895,33 @@ int kvm_cpu_exec(CPUState *env)
DPRINTF("kvm_cpu_exec()\n");
if (kvm_arch_process_irqchip_events(env)) {
env->exit_request = 0;
env->exception_index = EXCP_HLT;
return 0;
}
do {
#ifndef CONFIG_IOTHREAD
if (env->exit_request) {
DPRINTF("interrupt exit requested\n");
ret = 0;
break;
}
#endif
if (kvm_arch_process_irqchip_events(env)) {
ret = 0;
break;
}
if (env->kvm_vcpu_dirty) {
kvm_arch_put_registers(env, KVM_PUT_RUNTIME_STATE);
env->kvm_vcpu_dirty = 0;
}
kvm_arch_pre_run(env, run);
if (env->exit_request) {
DPRINTF("interrupt exit requested\n");
/*
* KVM requires us to reenter the kernel after IO exits to complete
* instruction emulation. This self-signal will ensure that we
* leave ASAP again.
*/
qemu_cpu_kick_self();
}
cpu_single_env = NULL;
qemu_mutex_unlock_iothread();
ret = kvm_vcpu_ioctl(env, KVM_RUN, 0);
qemu_mutex_lock_iothread();
cpu_single_env = env;
kvm_arch_post_run(env, run);

5
target-i386/kvm.c
View File

@ -1426,6 +1426,11 @@ int kvm_arch_get_registers(CPUState *env)
int kvm_arch_pre_run(CPUState *env, struct kvm_run *run)
{
/* Force the VCPU out of its inner loop to process the INIT request */
if (env->interrupt_request & CPU_INTERRUPT_INIT) {
env->exit_request = 1;
}
/* Inject NMI */
if (env->interrupt_request & CPU_INTERRUPT_NMI) {
env->interrupt_request &= ~CPU_INTERRUPT_NMI;