x86/apic: Export x2apic_mode for use by KVM in "warm" path

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Export x2apic_mode so that KVM can query whether x2APIC is active
without having to incur the RDMSR in x2apic_enabled().  When Posted
Interrupts are in use for a guest with an assigned device, KVM ends up
checking for x2APIC at least once every time a vCPU halts.  KVM could
obviously snapshot x2apic_enabled() to avoid the RDMSR, but that's
rather silly given that x2apic_mode holds the exact info needed by KVM.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210115220354.434807-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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Sean Christopherson 2021-01-15 14:03:53 -08:00 • committed by Paolo Bonzini

parent c32b1b896d

commit db7d8e4768

1 changed files with 1 additions and 0 deletions

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arch/x86/kernel/apic/apic.c

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