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KVM: x86: Rework INIT and SIPI handling

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A VCPU sending INIT or SIPI to some other VCPU races for setting the
remote VCPU's mp_state. When we were unlucky, KVM_MP_STATE_INIT_RECEIVED
was overwritten by kvm_emulate_halt and, thus, got lost.

This introduces APIC events for those two signals, keeping them in
kvm_apic until kvm_apic_accept_events is run over the target vcpu
context. kvm_apic_has_events reports to kvm_arch_vcpu_runnable if there
are pending events, thus if vcpu blocking should end.

The patch comes with the side effect of effectively obsoleting
KVM_MP_STATE_SIPI_RECEIVED. We still accept it from user space, but
immediately translate it to KVM_MP_STATE_INIT_RECEIVED + KVM_APIC_SIPI.
The vcpu itself will no longer enter the KVM_MP_STATE_SIPI_RECEIVED
state. That also means we no longer exit to user space after receiving a
SIPI event.

Furthermore, we already reset the VCPU on INIT, only fixing up the code
segment later on when SIPI arrives. Moreover, we fix INIT handling for
the BSP: it never enter wait-for-SIPI but directly starts over on INIT.

Tested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
This commit is contained in:
Jan Kiszka
2013-03-13 12:42:34 +01:00
committed by Gleb Natapov
parent 5d21881432
commit 66450a21f9
6 changed files with 93 additions and 45 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
arch/x86/kvm/lapic.c
View File

@@ -731,7 +731,11 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
case APIC_DM_INIT:
if (!trig_mode || level) {
result = 1;
vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
/* assumes that there are only KVM_APIC_INIT/SIPI */
apic->pending_events = (1UL << KVM_APIC_INIT);
/* make sure pending_events is visible before sending
* the request */
smp_wmb();
kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_vcpu_kick(vcpu);
} else {
@@ -743,13 +747,13 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
case APIC_DM_STARTUP:
apic_debug("SIPI to vcpu %d vector 0x%02x\n",
vcpu->vcpu_id, vector);
if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
result = 1;
vcpu->arch.sipi_vector = vector;
vcpu->arch.mp_state = KVM_MP_STATE_SIPI_RECEIVED;
kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_vcpu_kick(vcpu);
}
result = 1;
apic->sipi_vector = vector;
/* make sure sipi_vector is visible for the receiver */
smp_wmb();
set_bit(KVM_APIC_SIPI, &apic->pending_events);
kvm_make_request(KVM_REQ_EVENT, vcpu);
kvm_vcpu_kick(vcpu);
break;
case APIC_DM_EXTINT:
@@ -1860,6 +1864,34 @@ int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data)
addr);
}
void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
{
struct kvm_lapic *apic = vcpu->arch.apic;
unsigned int sipi_vector;
if (!kvm_vcpu_has_lapic(vcpu))
return;
if (test_and_clear_bit(KVM_APIC_INIT, &apic->pending_events)) {
kvm_lapic_reset(vcpu);
kvm_vcpu_reset(vcpu);
if (kvm_vcpu_is_bsp(apic->vcpu))
vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
else
vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
}
if (test_and_clear_bit(KVM_APIC_SIPI, &apic->pending_events) &&
vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
/* evaluate pending_events before reading the vector */
smp_rmb();
sipi_vector = apic->sipi_vector;
pr_debug("vcpu %d received sipi with vector # %x\n",
vcpu->vcpu_id, sipi_vector);
kvm_vcpu_deliver_sipi_vector(vcpu, sipi_vector);
vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
}
}
void kvm_lapic_init(void)
{
/* do not patch jump label more than once per second */