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hw/i386/amd_iommu: Fix xtsup when vcpus < 255

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If vCPUs > 255 then x86 common code (x86_cpus_init()) call kvm_enable_x2apic().
But if vCPUs <= 255 then the common code won't calls kvm_enable_x2apic().

This is because commit 8c6619f3e6 ("hw/i386/amd_iommu: Simplify non-KVM
checks on XTSup feature") removed the call to kvm_enable_x2apic when xtsup
is "on", which break things when guest is booted with x2apic mode and
there are <= 255 vCPUs.

Fix this by adding back kvm_enable_x2apic() call when xtsup=on.

Fixes: 8c6619f3e6 ("hw/i386/amd_iommu: Simplify non-KVM checks on XTSup feature")
Reported-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Tested-by: Tested-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Cc: Philippe Mathieu-Daudé <philmd@linaro.org>
Cc: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Sairaj Kodilkar <sarunkod@amd.com>
Message-Id: <20250516100535.4980-3-sarunkod@amd.com>
Fixes: 8c6619f3e6 ("hw/i386/amd_iommu: Simplify non-KVM checks on XTSup feature")
Reported-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Tested-by: Tested-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Cc: Philippe Mathieu-Daudé <philmd@linaro.org>
Cc: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Sairaj Kodilkar <sarunkod@amd.com>
This commit is contained in:
Vasant Hegde 2025-05-16 15:35:35 +05:30 • committed by Michael S. Tsirkin
parent 31753d5a33
commit 0f178860df
1 changed files with 8 additions and 0 deletions
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8
hw/i386/amd_iommu.c
View file

@ -1715,6 +1715,14 @@ static void amdvi_sysbus_realize(DeviceState *dev, Error **errp)
exit(EXIT_FAILURE);
}
if (s->xtsup) {
if (kvm_irqchip_is_split() && !kvm_enable_x2apic()) {
error_report("AMD IOMMU xtsup=on requires x2APIC support on "
"the KVM side");
exit(EXIT_FAILURE);
}
}
pci_setup_iommu(bus, &amdvi_iommu_ops, s);
amdvi_init(s);
}