Determining flat mode according to cid_mask is wrong, since currently KVM
supports zero clusters in x2apic mode. Use ldr_bits instead.
Since we recalculate the apic map whenever the DFR is changed, the bug appears
to have no effect, and perhaps the entire check can be removed.
Signed-off-by: Nadav Amit <namit@xxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/lapic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index b8345dd..cfce429 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -171,7 +171,7 @@ static void recalculate_apic_map(struct kvm *kvm)
new->cid_mask = (1 << KVM_X2APIC_CID_BITS) - 1;
new->lid_mask = 0xffff;
} else if (kvm_apic_sw_enabled(apic) &&
- !new->cid_mask /* flat mode */ &&
+ new->ldr_bits == 8 /* flat mode */ &&
kvm_apic_get_reg(apic, APIC_DFR) == APIC_DFR_CLUSTER) {
new->cid_shift = 4;
new->cid_mask = 0xf;
--
1.9.1
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