• Christoffer Dall's avatar
    KVM: arm/arm64: Fix bug when registering redist iodevs · 552c9f47
    Christoffer Dall authored
    If userspace creates the VCPUs after initializing the VGIC, then we end
    up in a situation where we trigger a bug in kvm_vcpu_get_idx(), because
    it is called prior to adding the VCPU into the vcpus array on the VM.
    
    There is no tight coupling between the VCPU index and the area of the
    redistributor region used for the VCPU, so we can simply ensure that all
    creations of redistributors are serialized per VM, and increment an
    offset when we successfully add a redistributor.
    
    The vgic_register_redist_iodev() function can be called from two paths:
    vgic_redister_all_redist_iodev() which is called via the kvm_vgic_addr()
    device attribute handler.  This patch already holds the kvm->lock mutex.
    
    The other path is via kvm_vgic_vcpu_init, which is called through a
    longer chain from kvm_vm_ioctl_create_vcpu(), which releases the
    kvm->lock mutex just before calling kvm_arch_vcpu_create(), so we can
    simply take this mutex again later for our purposes.
    
    Fixes: ab6f468c10 ("KVM: arm/arm64: Register iodevs when setting redist base and creating VCPUs")
    Signed-off-by: default avatarChristoffer Dall <cdall@linaro.org>
    Tested-by: default avatarJean-Philippe Brucker <jean-philippe.brucker@arm.com>
    Reviewed-by: default avatarEric Auger <eric.auger@redhat.com>
    552c9f47
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