If the guest takes advantage of the directed EOI feature by setting
APIC_SPIV_DIRECTED_EOI, it is expected to signal EOI by writing to
the EOI register of the respective IOAPIC.
>From Intel's x2APIC Specification:
"following the EOI to the local x2APIC unit for a level triggered
interrupt, perform a directed EOI to the IOxAPIC generating the
interrupt by writing to its EOI register."
Commit fc61b800f950 ("KVM: Add Directed EOI support to APIC emulation")
inhibited EOI on LAPIC EOI register write but didn't add the IOAPIC
part. IOAPIC_REG_EOI writes were handled only on IA64 and the code
was later removed with the rest of IA64 support.
The bug has gone undetected for a long time because Linux writes to
IOAPIC_REG_EOI only if the IOAPIC version is >=0x20. Windows doesn't
seem to perform such a check.
This commit re-adds IOAPIC_REG_EOI and implements it in terms of
__kvm_ioapic_update_eoi.
Fixes: fc61b800f950 ("KVM: Add Directed EOI support to APIC emulation")
Signed-off-by: Ladi Prosek <lprosek@xxxxxxxxxx>
---
arch/x86/kvm/ioapic.c | 46 ++++++++++++++++++++++++++++------------------
arch/x86/kvm/ioapic.h | 1 +
2 files changed, 29 insertions(+), 18 deletions(-)
diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
index 289270a..8df1c6c 100644
--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c
@@ -415,14 +415,15 @@ static void kvm_ioapic_eoi_inject_work(struct work_struct *work)
#define IOAPIC_SUCCESSIVE_IRQ_MAX_COUNT 10000
static void __kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu,
- struct kvm_ioapic *ioapic, int vector, int trigger_mode)
+ struct kvm_ioapic *ioapic, int vector, int trigger_mode,
+ bool directed)
{
struct dest_map *dest_map = &ioapic->rtc_status.dest_map;
struct kvm_lapic *apic = vcpu->arch.apic;
int i;
/* RTC special handling */
- if (test_bit(vcpu->vcpu_id, dest_map->map) &&
+ if (!directed && test_bit(vcpu->vcpu_id, dest_map->map) &&
vector == dest_map->vectors[vcpu->vcpu_id])
rtc_irq_eoi(ioapic, vcpu);
@@ -432,21 +433,23 @@ static void __kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu,
if (ent->fields.vector != vector)
continue;
- /*
- * We are dropping lock while calling ack notifiers because ack
- * notifier callbacks for assigned devices call into IOAPIC
- * recursively. Since remote_irr is cleared only after call
- * to notifiers if the same vector will be delivered while lock
- * is dropped it will be put into irr and will be delivered
- * after ack notifier returns.
- */
- spin_unlock(&ioapic->lock);
- kvm_notify_acked_irq(ioapic->kvm, KVM_IRQCHIP_IOAPIC, i);
- spin_lock(&ioapic->lock);
-
- if (trigger_mode != IOAPIC_LEVEL_TRIG ||
- kvm_lapic_get_reg(apic, APIC_SPIV) & APIC_SPIV_DIRECTED_EOI)
- continue;
+ if (!directed) {
+ /*
+ * We are dropping lock while calling ack notifiers because ack
+ * notifier callbacks for assigned devices call into IOAPIC
+ * recursively. Since remote_irr is cleared only after call
+ * to notifiers if the same vector will be delivered while lock
+ * is dropped it will be put into irr and will be delivered
+ * after ack notifier returns.
+ */
+ spin_unlock(&ioapic->lock);
+ kvm_notify_acked_irq(ioapic->kvm, KVM_IRQCHIP_IOAPIC, i);
+ spin_lock(&ioapic->lock);
+
+ if (trigger_mode != IOAPIC_LEVEL_TRIG ||
+ kvm_lapic_get_reg(apic, APIC_SPIV) & APIC_SPIV_DIRECTED_EOI)
+ continue;
+ }
ASSERT(ent->fields.trig_mode == IOAPIC_LEVEL_TRIG);
ent->fields.remote_irr = 0;
@@ -478,7 +481,7 @@ void kvm_ioapic_update_eoi(struct kvm_vcpu *vcpu, int vector, int trigger_mode)
struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
spin_lock(&ioapic->lock);
- __kvm_ioapic_update_eoi(vcpu, ioapic, vector, trigger_mode);
+ __kvm_ioapic_update_eoi(vcpu, ioapic, vector, trigger_mode, false);
spin_unlock(&ioapic->lock);
}
@@ -540,6 +543,7 @@ static int ioapic_mmio_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this,
gpa_t addr, int len, const void *val)
{
struct kvm_ioapic *ioapic = to_ioapic(this);
+ struct kvm_lapic *apic = vcpu->arch.apic;
u32 data;
if (!ioapic_in_range(ioapic, addr))
return -EOPNOTSUPP;
@@ -575,6 +579,12 @@ static int ioapic_mmio_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this,
ioapic_write_indirect(ioapic, data);
break;
+ case IOAPIC_REG_EOI:
+ if (kvm_lapic_get_reg(apic, APIC_SPIV) & APIC_SPIV_DIRECTED_EOI)
+ __kvm_ioapic_update_eoi(vcpu, ioapic, data,
+ IOAPIC_LEVEL_TRIG, true);
+ break;
+
default:
break;
}
diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
index 1cc6e54..251b61b 100644
--- a/arch/x86/kvm/ioapic.h
+++ b/arch/x86/kvm/ioapic.h
@@ -20,6 +20,7 @@ struct kvm_vcpu;
/* Direct registers. */
#define IOAPIC_REG_SELECT 0x00
#define IOAPIC_REG_WINDOW 0x10
+#define IOAPIC_REG_EOI 0x40
/* Indirect registers. */
#define IOAPIC_REG_APIC_ID 0x00 /* x86 IOAPIC only */
--
2.9.3
