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Groups > linux.kernel > #1227078
| From | Paolo Bonzini <pbonzini@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() |
| Date | 2015-09-17 16:30 +0200 |
| Message-ID | <q9Imf-6cb-45@gated-at.bofh.it> (permalink) |
| References | (1 earlier) <q9h2H-7W-37@gated-at.bofh.it> <q9hcn-ja-37@gated-at.bofh.it> <q9xTP-7ER-11@gated-at.bofh.it> <q9DZg-89b-15@gated-at.bofh.it> <q9HzQ-50m-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
>> 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.
>
> Yes, irq->dest_id is defined as u32, but by looking the current KVM
> code, seems desst_id is used as an u8 variable, even in x2apic mode
> the dest_id will not beyond 255 (except for broadcast dest in in x2apic
> mode). Correct me if I am wrong. Thanks a lot!
Actually you're right, the MSI destination is only 8 bits. I was
confused because of
#define MSI_ADDR_DEST_ID_MASK 0x00ffff0
in arch/x86/include/asm/msidef.h. But there may be a bug, see below...
>>> + if (cid >= ARRAY_SIZE(map->logical_map)) {
>>> + WARN_ON_ONCE(1);
>>
>> In x2apic mode irq->dest_id could have bits 12..15 set.
>
> cid is gotten from bit 16 ..31 of the ldr (in apic_logical_id()), and
> in x2apic mode, ldr is constructed in kvm_apic_set_x2apic_id() as
> below:
>
> u32 ldr = ((id >> 4) << 16) | (1 << (id & 0xf));
>
> So in fact, cid is (id >> 4), I cannot think of why cid can beyond 15.
I think kvm_apic_match_logical_addr for MSI and IOAPIC interrupts is
buggy in x2apic mode.
It does:
if (apic_x2apic_mode(apic))
return ((logical_id >> 16) == (mda >> 16))
&& (logical_id & mda & 0xffff) != 0;
But mda is only 8-bits for MSI and IOAPIC interrupts.
Radim, should kvm_apic_mda also handle the !ipi && x2apic_mda && dest_id
!= APIC_BROADCAST case? It never triggers with Linux because it uses
only the physical mode (that's not super-easy to see;
ioapic_set_affinity looks for the RTEs in irq_data->chip_data and that
is allocated with kzalloc).
> Do I miss something here? Thanks!
No, you were right.
But still I think the WARNs are unnecessary; it is conceivable that some
future chipset adds support for more than 8-bits in the dest_id.
Paolo
> Thanks,
> Feng
>
>>
>> Paolo
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[PATCH v8 00/13] Add VT-d Posted-Interrupts support Feng Wu <feng.wu@intel.com> - 2015-09-16 11:10 +0200
[PATCH v8 10/13] KVM: Update Posted-Interrupts Descriptor when vCPU is preempted Feng Wu <feng.wu@intel.com> - 2015-09-16 11:10 +0200
Re: [PATCH v8 10/13] KVM: Update Posted-Interrupts Descriptor when vCPU is preempted Paolo Bonzini <pbonzini@redhat.com> - 2015-09-16 11:30 +0200
[PATCH v8 11/13] KVM: Update Posted-Interrupts Descriptor when vCPU is blocked Feng Wu <feng.wu@intel.com> - 2015-09-16 11:10 +0200
Re: [PATCH v8 11/13] KVM: Update Posted-Interrupts Descriptor when vCPU is blocked Paolo Bonzini <pbonzini@redhat.com> - 2015-09-16 11:40 +0200
[PATCH v8 13/13] iommu/vt-d: Add a command line parameter for VT-d posted-interrupts Feng Wu <feng.wu@intel.com> - 2015-09-16 11:10 +0200
[PATCH v8 02/13] KVM: Add some helper functions for Posted-Interrupts Feng Wu <feng.wu@intel.com> - 2015-09-16 11:10 +0200
[PATCH v8 04/13] KVM: Make struct kvm_irq_routing_table accessible Feng Wu <feng.wu@intel.com> - 2015-09-16 11:10 +0200
[PATCH v8 12/13] KVM: Warn if 'SN' is set during posting interrupts by software Feng Wu <feng.wu@intel.com> - 2015-09-16 11:10 +0200
Re: [PATCH v8 12/13] KVM: Warn if 'SN' is set during posting interrupts by software Paolo Bonzini <pbonzini@redhat.com> - 2015-09-16 11:40 +0200
[PATCH v8 06/13] vfio: Register/unregister irq_bypass_producer Feng Wu <feng.wu@intel.com> - 2015-09-16 11:10 +0200
[PATCH v8 09/13] KVM: Add an arch specific hooks in 'struct kvm_kernel_irqfd' Feng Wu <feng.wu@intel.com> - 2015-09-16 11:10 +0200
Re: [PATCH v8 09/13] KVM: Add an arch specific hooks in 'struct kvm_kernel_irqfd' Paolo Bonzini <pbonzini@redhat.com> - 2015-09-16 11:30 +0200
RE: [PATCH v8 09/13] KVM: Add an arch specific hooks in 'struct kvm_kernel_irqfd' "Wu, Feng" <feng.wu@intel.com> - 2015-09-17 04:00 +0200
Re: [PATCH v8 09/13] KVM: Add an arch specific hooks in 'struct kvm_kernel_irqfd' Paolo Bonzini <pbonzini@redhat.com> - 2015-09-17 11:40 +0200
[PATCH v8 07/13] KVM: x86: Update IRTE for posted-interrupts Feng Wu <feng.wu@intel.com> - 2015-09-16 11:10 +0200
[PATCH v8 01/13] KVM: Extend struct pi_desc for VT-d Posted-Interrupts Feng Wu <feng.wu@intel.com> - 2015-09-16 11:20 +0200
[PATCH v8 05/13] KVM: make kvm_set_msi_irq() public Feng Wu <feng.wu@intel.com> - 2015-09-16 11:20 +0200
[PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() Feng Wu <feng.wu@intel.com> - 2015-09-16 11:20 +0200
Re: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() Paolo Bonzini <pbonzini@redhat.com> - 2015-09-16 11:30 +0200
RE: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() "Wu, Feng" <feng.wu@intel.com> - 2015-09-17 05:20 +0200
Re: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() Paolo Bonzini <pbonzini@redhat.com> - 2015-09-17 11:50 +0200
RE: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() "Wu, Feng" <feng.wu@intel.com> - 2015-09-17 15:40 +0200
Re: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() Paolo Bonzini <pbonzini@redhat.com> - 2015-09-17 16:30 +0200
Re: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() Radim Krčmář <rkrcmar@redhat.com> - 2015-09-17 18:00 +0200
Re: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() Paolo Bonzini <pbonzini@redhat.com> - 2015-09-17 18:10 +0200
RE: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() "Wu, Feng" <feng.wu@intel.com> - 2015-09-18 01:20 +0200
Re: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() Paolo Bonzini <pbonzini@redhat.com> - 2015-09-18 18:20 +0200
Re: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() Radim Krčmář <rkrcmar@redhat.com> - 2015-09-18 18:20 +0200
RE: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() "Wu, Feng" <feng.wu@intel.com> - 2015-09-18 01:20 +0200
Re: [PATCH v8 00/13] Add VT-d Posted-Interrupts support Paolo Bonzini <pbonzini@redhat.com> - 2015-09-16 11:40 +0200
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