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| -rw-r--r-- | Documentation/virt/kvm/api.rst | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 14121315d4a5..62afc031897c 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -863,6 +863,14 @@ KVM_CREATE_DEVICE, which also supports creating a GICv2. Using KVM_CREATE_DEVICE is preferred over KVM_CREATE_IRQCHIP for GICv2. On s390, a dummy irq routing table is created. +On x86, subsequent vcpu creation may install a private 4 KiB memory slot at the +default APIC base address (0xfee00000). User memory regions must not overlap +this address; doing so will cause vcpu creation to fail with ``EEXIST``, or the +memory region to be rejected if created after the vcpu. This occurs when +APIC access acceleration is enabled (APICv on Intel, AVIC on AMD), which is +the default on supported hardware. The same constraint applies when using +``KVM_CAP_SPLIT_IRQCHIP``. + Note that on s390 the KVM_CAP_S390_IRQCHIP vm capability needs to be enabled before KVM_CREATE_IRQCHIP can be used. @@ -7934,6 +7942,10 @@ used in the IRQ routing table. The first args[0] MSI routes are reserved for the IOAPIC pins. Whenever the LAPIC receives an EOI for these routes, a KVM_EXIT_IOAPIC_EOI vmexit will be reported to userspace. +As with ``KVM_CREATE_IRQCHIP``, subsequent vcpu creation may install a private +memory slot at the APIC base address (0xfee00000) that must not overlap user +memory regions. See ``KVM_CREATE_IRQCHIP`` for details. + Fails if VCPU has already been created, or if the irqchip is already in the kernel (i.e. KVM_CREATE_IRQCHIP has already been called). |