Commit d94e1dc9 authored by Avi Kivity's avatar Avi Kivity

KVM: Get rid of KVM_REQ_KICK

KVM_REQ_KICK poisons vcpu->requests by having a bit set during normal
operation.  This causes the fast path check for a clear vcpu->requests
to fail all the time, triggering tons of atomic operations.

Fix by replacing KVM_REQ_KICK with a vcpu->guest_mode atomic.
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 54b8486f
......@@ -4604,13 +4604,15 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (vcpu->fpu_active)
kvm_load_guest_fpu(vcpu);
local_irq_disable();
atomic_set(&vcpu->guest_mode, 1);
smp_wmb();
clear_bit(KVM_REQ_KICK, &vcpu->requests);
smp_mb__after_clear_bit();
local_irq_disable();
if (vcpu->requests || need_resched() || signal_pending(current)) {
set_bit(KVM_REQ_KICK, &vcpu->requests);
if (!atomic_read(&vcpu->guest_mode) || vcpu->requests
|| need_resched() || signal_pending(current)) {
atomic_set(&vcpu->guest_mode, 0);
smp_wmb();
local_irq_enable();
preempt_enable();
r = 1;
......@@ -4655,7 +4657,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
if (hw_breakpoint_active())
hw_breakpoint_restore();
set_bit(KVM_REQ_KICK, &vcpu->requests);
atomic_set(&vcpu->guest_mode, 0);
smp_wmb();
local_irq_enable();
++vcpu->stat.exits;
......@@ -5580,7 +5583,7 @@ void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
me = get_cpu();
if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu))
if (!test_and_set_bit(KVM_REQ_KICK, &vcpu->requests))
if (atomic_xchg(&vcpu->guest_mode, 0))
smp_send_reschedule(cpu);
put_cpu();
}
......
......@@ -81,6 +81,7 @@ struct kvm_vcpu {
int vcpu_id;
struct mutex mutex;
int cpu;
atomic_t guest_mode;
struct kvm_run *run;
unsigned long requests;
unsigned long guest_debug;
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment