Re: [RFC PATCH v2 17/20] hw/arm/smmuv3: Check idr registers for STE_S1CDMAX and STE_S1STALLD

[Eric Auger <eric.auger@redhat.com>]

Hi,

On 3/27/25 8:54 AM, Shameerali Kolothum Thodi wrote:
>
>> -----Original Message-----
>> From: Nicolin Chen <nicolinc@nvidia.com>
>> Sent: Wednesday, March 26, 2025 7:47 PM
>> To: Eric Auger <eric.auger@redhat.com>
>> Cc: Shameerali Kolothum Thodi
>> <shameerali.kolothum.thodi@huawei.com>; qemu-arm@nongnu.org;
>> qemu-devel@nongnu.org; peter.maydell@linaro.org; jgg@nvidia.com;
>> ddutile@redhat.com; berrange@redhat.com; nathanc@nvidia.com;
>> mochs@nvidia.com; smostafa@google.com; Linuxarm
>> <linuxarm@huawei.com>; Wangzhou (B) <wangzhou1@hisilicon.com>;
>> jiangkunkun <jiangkunkun@huawei.com>; Jonathan Cameron
>> <jonathan.cameron@huawei.com>; zhangfei.gao@linaro.org
>> Subject: Re: [RFC PATCH v2 17/20] hw/arm/smmuv3: Check idr registers for
>> STE_S1CDMAX and STE_S1STALLD
>>
>>> Again I think we need to understand the consequence of having a more
>>> comprehensive support of SSID. This also holds with old the IDR fields
>>> that may be inherited from the HW and we don't support yet in the
>>> emulation code
>> To support guest-level SVA, it must support SSID. We can keep the
>> SSIDSIZE=0 in an emulated SMMU. Would you elaborate the concern of
>> doing so?
I just want to make sure we dissociate both accel and emulated paths and
we do not advertise SSID in one mode while we do not fully support it.
>>
> Regarding adding support for SSID/SVA in emulation code, the support also depends on
> device PRI/IOPF feature as well. Do we have any emulated devices that can make use
> this? I would say we can add that support later if there is any real use cases for that.

x86 may be ahead of us in this area. Maybe this was tested by Zhenzhong
when contributing emulation for S1 support in intel_iommu?

Eric
>
> Thanks,
> Shameer