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authorMarc Zyngier <maz@kernel.org>2019-08-18 14:09:47 +0100
committerMarc Zyngier <maz@kernel.org>2019-09-09 12:29:09 +0100
commit92f35b751c71d14250a401246f2c792e3aa5b386 (patch)
treea1a662935b14d6f2922517e1a45a708c182eb6c8 /virt
parente8688ba3874915b7d1661a57adf15a9c9e877df7 (diff)
KVM: arm/arm64: vgic: Allow more than 256 vcpus for KVM_IRQ_LINE
While parts of the VGIC support a large number of vcpus (we bravely allow up to 512), other parts are more limited. One of these limits is visible in the KVM_IRQ_LINE ioctl, which only allows 256 vcpus to be signalled when using the CPU or PPI types. Unfortunately, we've cornered ourselves badly by allocating all the bits in the irq field. Since the irq_type subfield (8 bit wide) is currently only taking the values 0, 1 and 2 (and we have been careful not to allow anything else), let's reduce this field to only 4 bits, and allocate the remaining 4 bits to a vcpu2_index, which acts as a multiplier: vcpu_id = 256 * vcpu2_index + vcpu_index With that, and a new capability (KVM_CAP_ARM_IRQ_LINE_LAYOUT_2) allowing this to be discovered, it becomes possible to inject PPIs to up to 4096 vcpus. But please just don't. Whilst we're there, add a clarification about the use of KVM_IRQ_LINE on arm, which is not completely conditionned by KVM_CAP_IRQCHIP. Reported-by: Zenghui Yu <yuzenghui@huawei.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Zenghui Yu <yuzenghui@huawei.com> Signed-off-by: Marc Zyngier <maz@kernel.org>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/arm/arm.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 35a069815baf..86c6aa1cb58e 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -196,6 +196,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_MP_STATE:
case KVM_CAP_IMMEDIATE_EXIT:
case KVM_CAP_VCPU_EVENTS:
+ case KVM_CAP_ARM_IRQ_LINE_LAYOUT_2:
r = 1;
break;
case KVM_CAP_ARM_SET_DEVICE_ADDR:
@@ -888,6 +889,7 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
irq_type = (irq >> KVM_ARM_IRQ_TYPE_SHIFT) & KVM_ARM_IRQ_TYPE_MASK;
vcpu_idx = (irq >> KVM_ARM_IRQ_VCPU_SHIFT) & KVM_ARM_IRQ_VCPU_MASK;
+ vcpu_idx += ((irq >> KVM_ARM_IRQ_VCPU2_SHIFT) & KVM_ARM_IRQ_VCPU2_MASK) * (KVM_ARM_IRQ_VCPU_MASK + 1);
irq_num = (irq >> KVM_ARM_IRQ_NUM_SHIFT) & KVM_ARM_IRQ_NUM_MASK;
trace_kvm_irq_line(irq_type, vcpu_idx, irq_num, irq_level->level);

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