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KVM: x86: add a flag to disable KVM x2apic broadcast quirk

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Add KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK as a feature flag to
KVM_CAP_X2APIC_API.

The quirk made KVM interpret 0xff as a broadcast even in x2APIC mode.
The enableable capability is needed in order to support standard x2APIC and
remain backward compatible.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[Expand kvm_apic_mda comment. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Radim Krčmář
2016-07-12 22:09:28 +02:00
committed by Paolo Bonzini
parent 3713131345
commit c519265f2a
5 changed files with 52 additions and 14 deletions
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6
Documentation/virtual/kvm/api.txt
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@@ -3844,12 +3844,18 @@ Returns: 0 on success, -EINVAL when args[0] contains invalid features
Valid feature flags in args[0] are
#define KVM_X2APIC_API_USE_32BIT_IDS (1ULL << 0)
#define KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK (1ULL << 1)
Enabling KVM_X2APIC_API_USE_32BIT_IDS changes the behavior of
KVM_SET_GSI_ROUTING, KVM_SIGNAL_MSI, KVM_SET_LAPIC, and KVM_GET_LAPIC,
allowing the use of 32-bit APIC IDs. See KVM_CAP_X2APIC_API in their
respective sections.
KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK must be enabled for x2APIC to work
in logical mode or with more than 255 VCPUs. Otherwise, KVM treats 0xff
as a broadcast even in x2APIC mode in order to support physical x2APIC
without interrupt remapping. This is undesirable in logical mode,
where 0xff represents CPUs 0-7 in cluster 0.
8. Other capabilities.