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KVM: x86: Disable APIC logical map if vCPUs are aliased in logical mode

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Disable the optimized APIC logical map if multiple vCPUs are aliased to
the same logical ID.  Architecturally, all CPUs whose logical ID matches
the MDA are supposed to receive the interrupt; overwriting existing map
entries can result in missed IPIs.

Fixes: 1e08ec4a130e ("KVM: optimize apic interrupt delivery")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20230106011306.85230-22-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2023-01-06 01:12:54 +00:00 committed by Paolo Bonzini
parent 2bf934aadc
commit 2970052481
1 changed files with 3 additions and 2 deletions
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5
arch/x86/kvm/lapic.c
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@ -346,11 +346,12 @@ void kvm_recalculate_apic_map(struct kvm *kvm)
if (!mask)
continue;
if (!is_power_of_2(mask)) {
ldr = ffs(mask) - 1;
if (!is_power_of_2(mask) || cluster[ldr]) {
new->logical_mode = KVM_APIC_MODE_MAP_DISABLED;
continue;
}
cluster[ffs(mask) - 1] = apic;
cluster[ldr] = apic;
}
out:
old = rcu_dereference_protected(kvm->arch.apic_map,