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

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:

quoted

The pci_ats_supported() function checks if a device supports ATS and is
allowed to use it.

Signed-off-by: Jean-Philippe Brucker <redacted>
---
  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.

Thanks,
Jean

Best regards,
baolu

quoted

-		    ecap_dev_iotlb_support(iommu->ecap) &&
-		    pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_ATS) &&
+		if (ecap_dev_iotlb_support(iommu->ecap) &&
+		    pci_ats_supported(pdev) &&
  		    dmar_find_matched_atsr_unit(pdev))
  			info->ats_supported = 1;

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