linux-kernel - Re: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single

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Date:	Thu, 17 Sep 2015 11:42:05 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	"Wu, Feng" <feng.wu@...el.com>,
	"alex.williamson@...hat.com" <alex.williamson@...hat.com>,
	"joro@...tes.org" <joro@...tes.org>,
	"mtosatti@...hat.com" <mtosatti@...hat.com>
Cc:	"eric.auger@...aro.org" <eric.auger@...aro.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 03/13] KVM: Define a new interface
 kvm_intr_is_single_vcpu()



On 17/09/2015 05:17, Wu, Feng wrote:
>>> > > +	if (irq->dest_mode == APIC_DEST_PHYSICAL) {
>>> > > +		if (irq->dest_id == 0xFF)
>>> > > +			goto out;
>>> > > +
>>> > > +		if (irq->dest_id >= ARRAY_SIZE(map->phys_map)) {
>> > 
>> > Warning here is wrong, the guest can trigger it.
> Could you please share more information about how the guest
> triggers these conditions (including the following two), Thanks
> a lot!

irq->dest_id is a 16-bit value, so it can be > 255.

> +		if (!kvm_apic_logical_map_valid(map)) {
> +			WARN_ON_ONCE(1);

Here, the guest can trigger it by setting a few APICs in flat mode and
others in cluster mode, for example.

> +		if (cid >= ARRAY_SIZE(map->logical_map)) {
> +			WARN_ON_ONCE(1);

In x2apic mode irq->dest_id could have bits 12..15 set.

Paolo
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