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Commit 6228a0da authored by Feng Wu's avatar Feng Wu Committed by Paolo Bonzini
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KVM: x86: Add lowest-priority support for vt-d posted-interrupts 



Use vector-hashing to deliver lowest-priority interrupts for
VT-d posted-interrupts. This patch extends kvm_intr_is_single_vcpu()
to support lowest-priority handling.

Signed-off-by: default avatarFeng Wu <feng.wu@intel.com>
Reviewed-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 52004014

arch/x86/kvm/lapic.c

+49 −7
Original line number Diff line number Diff line
@@ -798,6 +798,20 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src, 
	return ret;

}



/*

 * This routine tries to handler interrupts in posted mode, here is how

 * it deals with different cases:

 * - For single-destination interrupts, handle it in posted mode

 * - Else if vector hashing is enabled and it is a lowest-priority

 *   interrupt, handle it in posted mode and use the following mechanism

 *   to find the destinaiton vCPU.

 *	1. For lowest-priority interrupts, store all the possible

 *	   destination vCPUs in an array.

 *	2. Use "guest vector % max number of destination vCPUs" to find

 *	   the right destination vCPU in the array for the lowest-priority

 *	   interrupt.

 * - Otherwise, use remapped mode to inject the interrupt.

 */

bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq,

			struct kvm_vcpu **dest_vcpu)

{
@@ -839,6 +853,33 @@ bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq, 
		if (cid >= ARRAY_SIZE(map->logical_map))

			goto out;



		if (kvm_vector_hashing_enabled() &&

				kvm_lowest_prio_delivery(irq)) {

			int idx;

			unsigned int dest_vcpus;



			dest_vcpus = hweight16(bitmap);

			if (dest_vcpus == 0)

				goto out;



			idx = kvm_vector_to_index(irq->vector, dest_vcpus,

						  &bitmap, 16);



			/*

			 * We may find a hardware disabled LAPIC here, if that

			 * is the case, print out a error message once for each

			 * guest and return

			 */

			dst = map->logical_map[cid][idx];

			if (!dst && !kvm->arch.disabled_lapic_found) {

				kvm->arch.disabled_lapic_found = true;

				printk(KERN_INFO

					"Disabled LAPIC found during irq injection\n");

				goto out;

			}



			*dest_vcpu = dst->vcpu;

		} else {

			for_each_set_bit(i, &bitmap, 16) {

				dst = map->logical_map[cid][i];

				if (++r == 2)
@@ -850,6 +891,7 @@ bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq, 
			else

				goto out;

		}

	}



	ret = true;

out: