Re: [PATCH v3 26/26] tests/functional: Expand Aarch64 SMMU tests to run on HVF accelerator

["Alex Bennée" <alex.bennee@linaro.org>]

Philippe Mathieu-Daudé <philmd@linaro.org> writes:

> On 23/6/25 17:04, Alex Bennée wrote:
>> Philippe Mathieu-Daudé <philmd@linaro.org> writes:
>> 
>>> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>>> ---
>>>   tests/functional/test_aarch64_smmu.py | 12 +++++++++---
>>>   1 file changed, 9 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/tests/functional/test_aarch64_smmu.py b/tests/functional/test_aarch64_smmu.py
>>> index c65d0f28178..e0f4a922176 100755
>>> --- a/tests/functional/test_aarch64_smmu.py
>>> +++ b/tests/functional/test_aarch64_smmu.py
>>> @@ -17,7 +17,7 @@
>>>     from qemu_test import LinuxKernelTest, Asset,
>>> exec_command_and_wait_for_pattern
>>>   from qemu_test import BUILD_DIR
>>> -from qemu.utils import kvm_available
>>> +from qemu.utils import kvm_available, hvf_available
>>>       class SMMU(LinuxKernelTest):
>>> @@ -45,11 +45,17 @@ def set_up_boot(self, path):
>>>           self.vm.add_args('-device', 'virtio-net,netdev=n1' + self.IOMMU_ADDON)
>>>         def common_vm_setup(self, kernel, initrd, disk):
>>> -        self.require_accelerator("kvm")
>>> +        if hvf_available(self.qemu_bin):
>>> +            accel = "hvf"
>>> +        elif kvm_available(self.qemu_bin):
>>> +            accel = "kvm"
>>> +        else:
>>> +            self.skipTest("Neither HVF nor KVM accelerator is available")
>>> +        self.require_accelerator(accel)
>> I think this is fine so:
>> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
>
> Thanks.
>
>> However I wonder if something like:
>>          hwaccel = self.require_hw_accelerator()
>> Could fetch the appropriate platform accelerator for use in -accel
>> bellow?
>
> Then we'd need to make it per-host arch, and I'm pretty sure hw
> accelerators don't support the same features. So I'd expect a
> rather painful experience. WDYT?

Aren't the features a function of the machine type rather than the host?
Shouldn't an -M virt machine look the same on TCG, KVM and HVF
regardless of the underlying accelerator?

I guess there are cases like split-irqchip which affect the
implementation but hopefully not the guest view of things.

Do you have an example?

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro