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KVM: Add "exiting guest mode" state

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Currently we keep track of only two states: guest mode and host
mode.  This patch adds an "exiting guest mode" state that tells
us that an IPI will happen soon, so unless we need to wait for the
IPI, we can avoid it completely.

Also
1: No need atomically to read/write ->mode in vcpu's thread

2: reorganize struct kvm_vcpu to make ->mode and ->requests
   in the same cache line explicitly

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Xiao Guangrong
2011-01-12 15:40:31 +08:00
committed by Marcelo Tosatti
parent d48ead8b0b
commit 6b7e2d0991
4 changed files with 35 additions and 12 deletions
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16
arch/x86/kvm/x86.c
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@@ -5210,14 +5210,18 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
kvm_load_guest_fpu(vcpu);
kvm_load_guest_xcr0(vcpu);
atomic_set(&vcpu->guest_mode, 1);
smp_wmb();
vcpu->mode = IN_GUEST_MODE;
/* We should set ->mode before check ->requests,
* see the comment in make_all_cpus_request.
*/
smp_mb();
local_irq_disable();
if (!atomic_read(&vcpu->guest_mode) || vcpu->requests
if (vcpu->mode == EXITING_GUEST_MODE || vcpu->requests
|| need_resched() || signal_pending(current)) {
atomic_set(&vcpu->guest_mode, 0);
vcpu->mode = OUTSIDE_GUEST_MODE;
smp_wmb();
local_irq_enable();
preempt_enable();
@@ -5253,7 +5257,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
kvm_get_msr(vcpu, MSR_IA32_TSC, &vcpu->arch.last_guest_tsc);
atomic_set(&vcpu->guest_mode, 0);
vcpu->mode = OUTSIDE_GUEST_MODE;
smp_wmb();
local_irq_enable();
@@ -6157,7 +6161,7 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
me = get_cpu();
if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu))
if (atomic_xchg(&vcpu->guest_mode, 0))
if (kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE)
smp_send_reschedule(cpu);
put_cpu();
}