Subject: Re: [PATCH v2 08/11] iommu/vt-d: Use pci_ats_supported()

From: Lu Baolu <[email-masked]>
Date: Thu, 12 Mar 2020 16:18:46 +0800

On 2020/3/12 15:54, Jean-Philippe Brucker wrote:
> Hi Baolu,
> 
> On Thu, Mar 12, 2020 at 09:44:16AM +0800, Lu Baolu wrote:
>> Hi Jean,
>>
>> On 2020/3/11 20:45, Jean-Philippe Brucker wrote:
>>> The pci_ats_supported() function checks if a device supports ATS and is
>>> allowed to use it.
>>>
>>> Signed-off-by: Jean-Philippe Brucker <[email-masked]>
>>> ---
>>>    drivers/iommu/intel-iommu.c | 9 +++------
>>>    1 file changed, 3 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>>> index 6fa6de2b6ad5..17208280ef5c 100644
>>> --- a/drivers/iommu/intel-iommu.c
>>> +++ b/drivers/iommu/intel-iommu.c
>>> @@ -1454,8 +1454,7 @@ static void iommu_enable_dev_iotlb(struct device_domain_info *info)
>>>    	    !pci_reset_pri(pdev) && !pci_enable_pri(pdev, 32))
>>>    		info->pri_enabled = 1;
>>>    #endif
>>> -	if (!pdev->untrusted && info->ats_supported &&
>>> -	    pci_ats_page_aligned(pdev) &&
>>> +	if (info->ats_supported && pci_ats_page_aligned(pdev) &&
>>>    	    !pci_enable_ats(pdev, VTD_PAGE_SHIFT)) {
>>>    		info->ats_enabled = 1;
>>>    		domain_update_iotlb(info->domain);
>>> @@ -2611,10 +2610,8 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
>>>    	if (dev && dev_is_pci(dev)) {
>>>    		struct pci_dev *pdev = to_pci_dev(info->dev);
>>> -		if (!pdev->untrusted &&
>>> -		    !pci_ats_disabled() &&
>>
>> The pci_ats_disabled() couldn't be replaced by pci_ats_supported(). Even
>> pci_ats_supported() returns true, user still can disable it. Or move
>> ats_disabled into pci_ats_supported()?
> 
> It is already there, but hidden behind the "if (!dev->ats_cap)":
> pci_ats_init() only sets dev->ats_cap after checking that
> pci_ats_disabled() returns false.
>

Ah! Yes.

Acked-by: Lu Baolu <[email-masked]>

> Thanks,
> Jean

Best regards,
baolu

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