linux-kernel - [PATCH] iommu/vt-d: improve ITE fault handling if device was released

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Date: Wed, 28 Feb 2024 23:07:24 -0500
From: Ethan Zhao <haifeng.zhao@...ux.intel.com>
To: baolu.lu@...ux.intel.com,
	bhelgaas@...gle.com,
	robin.murphy@....com,
	jgg@...pe.ca
Cc: kevin.tian@...el.com,
	dwmw2@...radead.org,
	will@...nel.org,
	lukas@...ner.de,
	yi.l.liu@...el.com,
	dan.carpenter@...aro.org,
	iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Ethan Zhao <haifeng.zhao@...ux.intel.com>
Subject: [PATCH] iommu/vt-d: improve ITE fault handling if device was released

Break the loop to blindly retry the timeout ATS invalidation request
after ITE fault hit if device was released or isn't present anymore.

This is part of the followup of prior proposed patchset

https://do-db2.lkml.org/lkml/2024/2/22/350

Fixes: 6ba6c3a4cacf ("VT-d: add device IOTLB invalidation support")
Signed-off-by: Ethan Zhao <haifeng.zhao@...ux.intel.com>
---
 drivers/iommu/intel/dmar.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
index d14797aabb7a..d01d68205557 100644
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -1273,6 +1273,9 @@ static int qi_check_fault(struct intel_iommu *iommu, int index, int wait_index)
 {
 	u32 fault;
 	int head, tail;
+	u64 iqe_err, ite_sid;
+	struct device *dev = NULL;
+	struct pci_dev *pdev = NULL;
 	struct q_inval *qi = iommu->qi;
 	int shift = qi_shift(iommu);
 
@@ -1317,6 +1320,13 @@ static int qi_check_fault(struct intel_iommu *iommu, int index, int wait_index)
 		tail = readl(iommu->reg + DMAR_IQT_REG);
 		tail = ((tail >> shift) - 1 + QI_LENGTH) % QI_LENGTH;
 
+		/*
+		 * SID field is valid only when the ITE field is Set in FSTS_REG
+		 * see Intel VT-d spec r4.1, section 11.4.9.9
+		 */
+		iqe_err = dmar_readq(iommu->reg + DMAR_IQER_REG);
+		ite_sid = DMAR_IQER_REG_ITESID(iqe_err);
+
 		writel(DMA_FSTS_ITE, iommu->reg + DMAR_FSTS_REG);
 		pr_info("Invalidation Time-out Error (ITE) cleared\n");
 
@@ -1326,6 +1336,21 @@ static int qi_check_fault(struct intel_iommu *iommu, int index, int wait_index)
 			head = (head - 2 + QI_LENGTH) % QI_LENGTH;
 		} while (head != tail);
 
+		/*
+		 * If got ITE, we need to check if the sid of ITE is one of the
+		 * current valid ATS invalidation target devices, if no, or the
+		 * target device isn't presnet, don't try this request anymore.
+		 * 0 value of ite_sid means old VT-d device, no ite_sid value.
+		 */
+		if (ite_sid) {
+			dev = device_rbtree_find(iommu, ite_sid);
+			if (!dev || !dev_is_pci(dev))
+				return -ETIMEDOUT;
+			pdev = to_pci_dev(dev);
+			if (!pci_device_is_present(pdev) &&
+				ite_sid == pci_dev_id(pci_physfn(pdev)))
+				return -ETIMEDOUT;
+		}
 		if (qi->desc_status[wait_index] == QI_ABORT)
 			return -EAGAIN;
 	}
-- 
2.31.1