[PATCH v2 3/4] KVM: x86: make interrupt delivery fast and slow path behave the same

Radim Krčmář
2016-12-13T16:31:07Z

Slow path tried to prevent IPIs from x2APIC VCPUs from being delivered
to xAPIC VCPUs and vice-versa. Make slow path behave like fast path,
which never distinguished that.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
arch/x86/kvm/lapic.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index e645b4bc6437..bc8df7ce2766 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -612,7 +612,7 @@ static bool kvm_apic_match_physical_addr(struct kvm_lapic *apic, u32 mda)
if (apic_x2apic_mode(apic))
return mda == kvm_x2apic_id(apic);

- return mda == SET_APIC_DEST_FIELD(kvm_xapic_id(apic));
+ return mda == kvm_xapic_id(apic);
}

static bool kvm_apic_match_logical_addr(struct kvm_lapic *apic, u32 mda)
@@ -629,7 +629,6 @@ static bool kvm_apic_match_logical_addr(struct kvm_lapic *apic, u32 mda)
&& (logical_id & mda & 0xffff) != 0;

logical_id = GET_APIC_LOGICAL_ID(logical_id);
- mda = GET_APIC_DEST_FIELD(mda);

switch (kvm_lapic_get_reg(apic, APIC_DFR)) {
case APIC_DFR_FLAT:
@@ -646,9 +645,9 @@ static bool kvm_apic_match_logical_addr(struct kvm_lapic *apic, u32 mda)

/* The KVM local APIC implementation has two quirks:
*
- * - the xAPIC MDA stores the destination at bits 24-31, while this
- * is not true of struct kvm_lapic_irq's dest_id field. This is
- * just a quirk in the API and is not problematic.
+ * - Real hardware delivers interrupts destined to x2APIC ID > 0xff to LAPICs
+ * in xAPIC mode if the "destination & 0xff" matches its xAPIC ID.
+ * KVM doesn't do that aliasing.
*
* - in-kernel IOAPIC messages have to be delivered directly to
* x2APIC, because the kernel does not support interrupt remapping.
@@ -664,13 +663,12 @@ static u32 kvm_apic_mda(struct kvm_vcpu *vcpu, unsigned int dest_id,
struct kvm_lapic *source, struct kvm_lapic *target)
{
bool ipi = source != NULL;
- bool x2apic_mda = apic_x2apic_mode(ipi ? source : target);

if (!vcpu->kvm->arch.x2apic_broadcast_quirk_disabled &&
- !ipi && dest_id == APIC_BROADCAST && x2apic_mda)
+ !ipi && dest_id == APIC_BROADCAST && apic_x2apic_mode(target))
return X2APIC_BROADCAST;

- return x2apic_mda ? dest_id : SET_APIC_DEST_FIELD(dest_id);
+ return dest_id;
}

bool kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source,
--
2.11.0