Hi Shameer,
On 10/2/25 2:08 PM, Shameer Kolothum wrote:
>
>> -----Original Message-----
>> From: Eric Auger <[email protected]>
>> Sent: 02 October 2025 11:05
>> To: Shameer Kolothum <[email protected]>; qemu-
>> [email protected]; [email protected]
>> Cc: [email protected]; Jason Gunthorpe <[email protected]>; Nicolin
>> Chen <[email protected]>; [email protected]; [email protected];
>> Nathan Chen <[email protected]>; Matt Ochs <[email protected]>;
>> [email protected]; [email protected];
>> [email protected]; [email protected];
>> [email protected]; [email protected]; [email protected];
>> [email protected]
>> Subject: Re: [PATCH v4 09/27] hw/arm/smmuv3-accel: Support nested STE
>> install/uninstall support
>>
>> External email: Use caution opening links or attachments
>>
>>
>> Hi Shameer,
>>
>> On 9/29/25 3:36 PM, Shameer Kolothum wrote:
>>> From: Nicolin Chen <[email protected]>
>>>
>>> Allocates a s1 HWPT for the Guest s1 stage and attaches that to the
>>> pass-through vfio device. This will be invoked when Guest issues
>>> SMMU_CMD_CFGI_STE/STE_RANGE.
>> ON set both alloc + attachment are done. On unset you shall explain the
>> gym related to config/abort hwpt. Those are S1 hwpt, right? I think this
>> shall be reflected in the name to make it clearer? In the previous patch
>> I didn't really understand that.
> Ok. There are three HWPTs in play here.
>
> BYPASS HWPT
> ABORT HWPT
> S1 HWPT --> This is when Guest has a valid S1 (STE_VALID &&
> STE_CFG_S1_ENABLED)
>
> In previous patch we allocate a common BYPASS and ABORT HWPT for all devices
> in a vIOMMU. We reuse that here in this patch and attach if Guest request a S1
> bypass or abort case.
>
> The S1 HWPT is allocated as and when the Guest has a valid STE with context
> descriptor and use that for attachment.
>
> Whether we can call them S1 HWPT only, I am not sure. Because, I think,
> during alloc() call the kernel allocates a Nested HWPT(IOMMU_DOMAIN_NESTED)
> which uses a Guest S1 nested on a S2 HWPT.
the role of BYPASS HWPT and ABORT_HWPT must be better explained I think.
Same in previous patch. I understand they abstract stage 1 in abort or
bypass. I think we shall better explain what HWPT hierarchy we are
putting in place refering to the kernel uapi (and not kernel internal
implementation). Thanks Eric
>
> Anyway, I will rephrase the comments and variable names to make it clear.
>
> Thanks,
> Shameer
