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Date: Mon, 20 May 2024 09:33:41 +0800
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Cc: baolu.lu@linux.intel.com, "iommu@lists.linux.dev"
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Subject: Re: [PATCH v5 5/9] iommufd: Add iommufd fault object
To: "Tian, Kevin" <kevin.tian@intel.com>, Jason Gunthorpe <jgg@ziepe.ca>,
 Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
 Robin Murphy <robin.murphy@arm.com>,
 Jean-Philippe Brucker <jean-philippe@linaro.org>,
 Nicolin Chen <nicolinc@nvidia.com>, "Liu, Yi L" <yi.l.liu@intel.com>,
 Jacob Pan <jacob.jun.pan@linux.intel.com>,
 Joel Granados <j.granados@samsung.com>
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 <20240430145710.68112-6-baolu.lu@linux.intel.com>
 <BN9PR11MB52769AC595B6BDA8FB4639258CEC2@BN9PR11MB5276.namprd11.prod.outlook.com>
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From: Baolu Lu <baolu.lu@linux.intel.com>
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On 5/15/24 4:37 PM, Tian, Kevin wrote:
>> +
>> +		iopf_group_response(group, response.code);
> PCIe spec states that a response failure disables the PRI interface. For SR-IOV
> it'd be dangerous allowing user to trigger such code to VF to close the entire
> shared PRI interface.
> 
> Just another example lacking of coordination for shared capabilities between
> PF/VF. But exposing such gap to userspace makes it worse.

Yes. You are right.

> 
> I guess we don't want to make this work depending on that cleanup. The
> minimal correct thing is to disallow attaching VF to a fault-capable hwpt
> with a note here that once we turn on support for VF the response failure
> code should not be forwarded to the hardware. Instead it's an indication
> that the user cannot serve more requests and such situation waits for
> a vPRI reset to recover.

Is it the same thing to disallow PRI for VF in IOMMUFD?

Best regards,
baolu