Commit 057aa61b authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: VMX: Skip Posted Interrupt updates if APICv is hard disabled 



Explicitly skip posted interrupt updates if APICv is disabled in all of
KVM, or if the guest doesn't have an in-kernel APIC.  The PI descriptor
is kept up-to-date if APICv is inhibited, e.g. so that re-enabling APICv
doesn't require a bunch of updates, but neither the module param nor the
APIC type can be changed on-the-fly.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-21-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent d92a5d1c

arch/x86/kvm/vmx/posted_intr.c

+7 −4
Original line number Diff line number Diff line
@@ -29,11 +29,14 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu) 
	unsigned int dest;



	/*

	 * In case of hot-plug or hot-unplug, we may have to undo

	 * vmx_vcpu_pi_put even if there is no assigned device.  And we

	 * always keep PI.NDST up to date for simplicity: it makes the

	 * code easier, and CPU migration is not a fast path.

	 * To simplify hot-plug and dynamic toggling of APICv, keep PI.NDST and

	 * PI.SN up-to-date even if there is no assigned device or if APICv is

	 * deactivated due to a dynamic inhibit bit, e.g. for Hyper-V's SyncIC.

	 */

	if (!enable_apicv || !lapic_in_kernel(vcpu))

		return;



	/* Nothing to do if PI.SN and PI.NDST both have the desired value. */

	if (!pi_test_sn(pi_desc) && vcpu->cpu == cpu)

		return;