linux-kernel - [PATCH] PCI/ATS: PASID and PRI are only enumerated in PF devices.

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Date:   Tue, 21 Jul 2020 12:44:20 -0700
From:   Ashok Raj <ashok.raj@...el.com>
To:     linux-pci@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Cc:     Ashok Raj <ashok.raj@...el.com>, stable@...r.kernel.org,
        linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org
Subject: [PATCH] PCI/ATS: PASID and PRI are only enumerated in PF devices.

PASID and PRI capabilities are only enumerated in PF devices. VF devices
do not enumerate these capabilites. IOMMU drivers also need to enumerate
them before enabling features in the IOMMU. Extending the same support as
PASID feature discovery (pci_pasid_features) for PRI.

Signed-off-by: Ashok Raj <ashok.raj@...el.com>

v2: Fixed build failure from lkp when CONFIG_PRI=n
    Almost all the PRI functions were called only when CONFIG_PASID is
    set. Except the new pci_pri_supported().

To: Bjorn Helgaas <bhelgaas@...gle.com>
To: Joerg Roedel <joro@...tes.com>
To: Lu Baolu <baolu.lu@...el.com>
Cc: stable@...r.kernel.org
Cc: linux-pci@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Cc: Ashok Raj <ashok.raj@...el.com>
Cc: iommu@...ts.linux-foundation.org
---
 drivers/iommu/intel/iommu.c |  2 +-
 drivers/pci/ats.c           | 14 ++++++++++++++
 include/linux/pci-ats.h     |  4 ++++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index d759e7234e98..276452f5e6a7 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2560,7 +2560,7 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
 			}
 
 			if (info->ats_supported && ecap_prs(iommu->ecap) &&
-			    pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI))
+			    pci_pri_supported(pdev))
 				info->pri_supported = 1;
 		}
 	}
diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index b761c1f72f67..ffb4de8c5a77 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -461,6 +461,20 @@ int pci_pasid_features(struct pci_dev *pdev)
 }
 EXPORT_SYMBOL_GPL(pci_pasid_features);
 
+/**
+ * pci_pri_supported - Check if PRI is supported.
+ * @pdev: PCI device structure
+ *
+ * Returns false when no PRI capability is present.
+ * Returns true if PRI feature is supported and enabled
+ */
+bool pci_pri_supported(struct pci_dev *pdev)
+{
+	/* VFs share the PF PRI configuration */
+	return !!(pci_physfn(pdev)->pri_cap);
+}
+EXPORT_SYMBOL_GPL(pci_pri_supported);
+
 #define PASID_NUMBER_SHIFT	8
 #define PASID_NUMBER_MASK	(0x1f << PASID_NUMBER_SHIFT)
 /**
diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h
index f75c307f346d..fc989295daf3 100644
--- a/include/linux/pci-ats.h
+++ b/include/linux/pci-ats.h
@@ -28,6 +28,10 @@ int pci_enable_pri(struct pci_dev *pdev, u32 reqs);
 void pci_disable_pri(struct pci_dev *pdev);
 int pci_reset_pri(struct pci_dev *pdev);
 int pci_prg_resp_pasid_required(struct pci_dev *pdev);
+bool pci_pri_supported(struct pci_dev *pdev);
+#else
+bool pci_pri_supported(struct pci_dev *pdev)
+{ return false; }
 #endif /* CONFIG_PCI_PRI */
 
 #ifdef CONFIG_PCI_PASID
-- 
2.7.4