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KVM: ppc: Handle guest idle by emulating MSR[WE] writes 

This reduces host CPU usage when the guest is idle. However, the guest must
set MSR[WE] in its idle loop, which Linux did not do until 2.6.26.

Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Jerone Young <jyoung5@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Hollis Blanchard 2008-04-25 17:55:49 -05:00 committed by Avi Kivity
parent 3fe913e7c5
commit 45c5eb67da
4 changed files with 24 additions and 3 deletions
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1
arch/powerpc/kvm/booke_guest.c
View File

@ -49,6 +49,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
{ "inst_emu", VCPU_STAT(emulated_inst_exits) },
{ "dec", VCPU_STAT(dec_exits) },
{ "ext_intr", VCPU_STAT(ext_intr_exits) },
{ "halt_wakeup", VCPU_STAT(halt_wakeup) },
{ NULL }
};

20
arch/powerpc/kvm/powerpc.c
View File

@ -36,13 +36,12 @@ gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)
int kvm_cpu_has_interrupt(struct kvm_vcpu *v)
{
/* XXX implement me */
return 0;
return !!(v->arch.pending_exceptions);
}
int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
{
return 1;
return !(v->arch.msr & MSR_WE);
}
@ -214,6 +213,11 @@ static void kvmppc_decrementer_func(unsigned long data)
struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
kvmppc_queue_exception(vcpu, BOOKE_INTERRUPT_DECREMENTER);
if (waitqueue_active(&vcpu->wq)) {
wake_up_interruptible(&vcpu->wq);
vcpu->stat.halt_wakeup++;
}
}
int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
@ -339,6 +343,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
int r;
sigset_t sigsaved;
vcpu_load(vcpu);
if (vcpu->sigset_active)
sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);
@ -363,12 +369,20 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
if (vcpu->sigset_active)
sigprocmask(SIG_SETMASK, &sigsaved, NULL);
vcpu_put(vcpu);
return r;
}
int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu, struct kvm_interrupt *irq)
{
kvmppc_queue_exception(vcpu, BOOKE_INTERRUPT_EXTERNAL);
if (waitqueue_active(&vcpu->wq)) {
wake_up_interruptible(&vcpu->wq);
vcpu->stat.halt_wakeup++;
}
return 0;
}

1
include/asm-powerpc/kvm_host.h
View File

@ -59,6 +59,7 @@ struct kvm_vcpu_stat {
u32 emulated_inst_exits;
u32 dec_exits;
u32 ext_intr_exits;
u32 halt_wakeup;
};
struct tlbe {

5
include/asm-powerpc/kvm_ppc.h
View File

@ -77,12 +77,17 @@ static inline void kvmppc_clear_exception(struct kvm_vcpu *vcpu, int exception)
clear_bit(priority, &vcpu->arch.pending_exceptions);
}
/* Helper function for "full" MSR writes. No need to call this if only EE is
* changing. */
static inline void kvmppc_set_msr(struct kvm_vcpu *vcpu, u32 new_msr)
{
if ((new_msr & MSR_PR) != (vcpu->arch.msr & MSR_PR))
kvmppc_mmu_priv_switch(vcpu, new_msr & MSR_PR);
vcpu->arch.msr = new_msr;
if (vcpu->arch.msr & MSR_WE)
kvm_vcpu_block(vcpu);
}
#endif /* __POWERPC_KVM_PPC_H__ */