WARN if KVM emulates an IPI without clearing the BUSY flag, failure to do
so could hang the guest if it waits for the IPI be sent.
Opportunistically use APIC_ICR_BUSY macro instead of open coding the
magic number, and add a comment to clarify why kvm_recalculate_apic_map()
is unconditionally invoked (it's really, really confusing for IPIs due to
the existence of fast paths that don't trigger a potential recalc).
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 10 +++++++++-
arch/x86/kvm/x86.c | 9 ++++-----
2 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 6e1f9e83eb68..4f57b6f5ebd4 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1282,6 +1282,9 @@ void kvm_apic_send_ipi(struct kvm_lapic *apic, u32 icr_low, u32 icr_high)
{
struct kvm_lapic_irq irq;
+ /* KVM has no delay and should always clear the BUSY/PENDING flag. */
+ WARN_ON_ONCE(icr_low & APIC_ICR_BUSY);
+
irq.vector = icr_low & APIC_VECTOR_MASK;
irq.delivery_mode = icr_low & APIC_MODE_MASK;
irq.dest_mode = icr_low & APIC_DEST_MASK;
@@ -2060,7 +2063,7 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
}
case APIC_ICR:
/* No delay here, so we always clear the pending bit */
- val &= ~(1 << 12);
+ val &= ~APIC_ICR_BUSY;
kvm_apic_send_ipi(apic, val, kvm_lapic_get_reg(apic, APIC_ICR2));
kvm_lapic_set_reg(apic, APIC_ICR, val);
break;
@@ -2139,6 +2142,11 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
break;
}
+ /*
+ * Recalculate APIC maps if necessary, e.g. if the software enable bit
+ * was toggled, the APIC ID changed, etc... The maps are marked dirty
+ * on relevant changes, i.e. this is a nop for most writes.
+ */
kvm_recalculate_apic_map(apic->vcpu->kvm);
return ret;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c25a6ef0ff06..9024e33c2add 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2012,11 +2012,10 @@ static int handle_fastpath_set_x2apic_icr_irqoff(struct kvm_vcpu *vcpu, u64 data
return 1;
if (((data & APIC_SHORT_MASK) == APIC_DEST_NOSHORT) &&
- ((data & APIC_DEST_MASK) == APIC_DEST_PHYSICAL) &&
- ((data & APIC_MODE_MASK) == APIC_DM_FIXED) &&
- ((u32)(data >> 32) != X2APIC_BROADCAST)) {
-
- data &= ~(1 << 12);
+ ((data & APIC_DEST_MASK) == APIC_DEST_PHYSICAL) &&
+ ((data & APIC_MODE_MASK) == APIC_DM_FIXED) &&
+ ((u32)(data >> 32) != X2APIC_BROADCAST)) {
+ data &= ~APIC_ICR_BUSY;
kvm_apic_send_ipi(vcpu->arch.apic, (u32)data, (u32)(data >> 32));
kvm_lapic_set_reg(vcpu->arch.apic, APIC_ICR2, (u32)(data >> 32));
kvm_lapic_set_reg(vcpu->arch.apic, APIC_ICR, (u32)data);
--
2.35.0.263.gb82422642f-goog
