linux-kernel - Re: [RFC PATCH v6 2/4] iommu/vt-d: don's issue devTLB flush request when device is disconnected

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Date: Mon, 25 Dec 2023 09:56:18 +0800
From: Ethan Zhao <haifeng.zhao@...ux.intel.com>
To: Lukas Wunner <lukas@...ner.de>
Cc: bhelgaas@...gle.com, baolu.lu@...ux.intel.com, dwmw2@...radead.org,
 will@...nel.org, robin.murphy@....com, linux-pci@...r.kernel.org,
 iommu@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v6 2/4] iommu/vt-d: don's issue devTLB flush request
 when device is disconnected


On 12/24/2023 6:32 PM, Lukas Wunner wrote:
> On Sun, Dec 24, 2023 at 12:06:55AM -0500, Ethan Zhao wrote:
>> --- a/drivers/iommu/intel/pasid.c
>> +++ b/drivers/iommu/intel/pasid.c
>> @@ -481,6 +481,9 @@ devtlb_invalidation_with_pasid(struct intel_iommu *iommu,
>>   	if (!info || !info->ats_enabled)
>>   		return;
>>   
>> +	if (pci_dev_is_disconnected(to_pci_dev(dev)))
>> +		return;
>> +
>>   	sid = info->bus << 8 | info->devfn;
>>   	qdep = info->ats_qdep;
>>   	pfsid = info->pfsid;
> Do you even need this or is patch [4/4] sufficient?
> Is there a benefit to the hunk above on top of patch [4/4]?

this is enough for purely surprise_removal or safe_removal,

it is better to not send "ATS invalidation request" than sent,

then check device state later.


Thanks,

Ethan

> Thanks,
>
> Lukas
>