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

[David Woodhouse <dwmw2@infradead.org>]

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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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