Re: [PATCH 4/4] test/avocado: test Linux boot up in x2APIC with userspace local APIC

[David Woodhouse]

On Tue, 2023-02-21 at 23:05 +0700, Bui Quang Minh wrote:
> 
> +    def test_physical_x2apic(self):
> +        """
> +        :avocado: tags=physical_x2apic
> +        """
> +
> +        self.common_vm_setup(True)
> +
> +        self.kernel_params = (self.distro.default_kernel_params +
> +                              ' quiet intel_iommu=on x2apic_phys')
> +        self.run_and_check()
> +        self.ssh_command('dmesg | grep "Switched APIC routing to physical 
> x2apic"')
> +
> +    def test_cluster_x2apic(self):
> +        """
> +        :avocado: tags=cluster_x2apic
> +        """
> +
> +        self.common_vm_setup(True)
> +        self.kernel_params = (self.distro.default_kernel_params +
> +                              ' quiet intel_iommu=on')
> +        self.run_and_check()
> +        self.ssh_command('dmesg | grep "Switched APIC routing to cluster 
> x2apic"')

Shouldn't Linux also enable X2APIC in physical mode if it doesn't have
an IOMMU? It'll just refuse to online any CPUs with APIC ID > 255.

For bonus points, make the Linux guest realise that we can do those
extra 7 bits of Extended Destinatation ID, which it normally detects
from the KVM_FEATURE_MSI_EXT_DEST_ID bit under KVM.

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