From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Wu, Feng" <feng.wu@intel.com>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"joro@8bytes.org" <joro@8bytes.org>,
"mtosatti@redhat.com" <mtosatti@redhat.com>,
"eric.auger@linaro.org" <eric.auger@linaro.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu()
Date: Thu, 17 Sep 2015 17:58:21 +0200 [thread overview]
Message-ID: <20150917155821.GB2573@potion.brq.redhat.com> (raw)
In-Reply-To: <55FACD35.1030602@redhat.com>
2015-09-17 16:24+0200, Paolo Bonzini:
> 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).
KVM handles that case, it's just convoluted.
(I wish we scrapped the IR-less x2APIC mode.)
For interrupts from MSI and IOxAPIC:
- Flat logical interrupts are delivered as if we had natural
(CPU0<->bit0, CPU1<->bit1, ...) flat logical xAPIC for first 8 VCPUs.
- Cluster logical doesn't work much, it's interpreted like flat logical.
I didn't care about xAPIC cluster because Linux, the sole user of our
paravirtualized x2APIC, doesn't configure it.
I'll paste kvm_apic_mda() source for better explanation:
static u32 kvm_apic_mda(unsigned int dest_id, struct kvm_lapic *source,
struct kvm_lapic *target)
{
bool ipi = source != NULL;
bool x2apic_mda = apic_x2apic_mode(ipi ? source : target);
if (!ipi && dest_id == APIC_BROADCAST && x2apic_mda)
return X2APIC_BROADCAST;
return x2apic_mda ? dest_id : SET_APIC_DEST_FIELD(dest_id);
}
MSI/IOxAPIC interrupt means that source is NULL and if the target is in
x2APIC mode, the original 'dest_id' is returned as mda => a flat logical
xAPIC to 0x0f will get interpreted as (cluster) logical x2APIC 0xf in
kvm_apic_match_logical_addr().
xAPIC address are only 8 bit long so they always get delivered to x2APIC
cluster 0, where first 16 bits work like xAPIC flat logical mode.
next prev parent reply other threads:[~2015-09-17 15:58 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-16 8:49 [PATCH v8 00/13] Add VT-d Posted-Interrupts support Feng Wu
2015-09-16 8:49 ` [PATCH v8 01/13] KVM: Extend struct pi_desc for VT-d Posted-Interrupts Feng Wu
2015-09-16 8:49 ` [PATCH v8 02/13] KVM: Add some helper functions for Posted-Interrupts Feng Wu
2015-09-16 8:49 ` [PATCH v8 03/13] KVM: Define a new interface kvm_intr_is_single_vcpu() Feng Wu
2015-09-16 9:23 ` Paolo Bonzini
2015-09-17 3:17 ` Wu, Feng
2015-09-17 9:42 ` Paolo Bonzini
2015-09-17 13:36 ` Wu, Feng
2015-09-17 14:24 ` Paolo Bonzini
2015-09-17 15:58 ` Radim Krčmář [this message]
2015-09-17 16:00 ` Paolo Bonzini
2015-09-17 23:18 ` Wu, Feng
2015-09-18 16:16 ` Radim Krčmář
2015-09-18 16:17 ` Paolo Bonzini
2015-09-17 23:15 ` Wu, Feng
2015-09-16 8:50 ` [PATCH v8 04/13] KVM: Make struct kvm_irq_routing_table accessible Feng Wu
2015-09-16 8:50 ` [PATCH v8 05/13] KVM: make kvm_set_msi_irq() public Feng Wu
2015-09-16 8:50 ` [PATCH v8 06/13] vfio: Register/unregister irq_bypass_producer Feng Wu
2015-09-16 8:50 ` [PATCH v8 07/13] KVM: x86: Update IRTE for posted-interrupts Feng Wu
2015-09-16 8:50 ` [PATCH v8 08/13] KVM: Implement IRQ bypass consumer callbacks for x86 Feng Wu
2015-09-16 8:50 ` [PATCH v8 09/13] KVM: Add an arch specific hooks in 'struct kvm_kernel_irqfd' Feng Wu
2015-09-16 9:27 ` Paolo Bonzini
2015-09-17 1:51 ` Wu, Feng
2015-09-17 9:38 ` Paolo Bonzini
2015-09-16 8:50 ` [PATCH v8 10/13] KVM: Update Posted-Interrupts Descriptor when vCPU is preempted Feng Wu
2015-09-16 9:29 ` Paolo Bonzini
2015-09-16 8:50 ` [PATCH v8 11/13] KVM: Update Posted-Interrupts Descriptor when vCPU is blocked Feng Wu
2015-09-16 9:32 ` Paolo Bonzini
2015-09-16 8:50 ` [PATCH v8 12/13] KVM: Warn if 'SN' is set during posting interrupts by software Feng Wu
2015-09-16 9:32 ` Paolo Bonzini
2015-09-16 8:50 ` [PATCH v8 13/13] iommu/vt-d: Add a command line parameter for VT-d posted-interrupts Feng Wu
2015-09-16 9:34 ` [PATCH v8 00/13] Add VT-d Posted-Interrupts support Paolo Bonzini
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