[PATCH v2 1/7] iommu/amd: Warn when found inconsistency EFR mask

[Suravee Suthikulpanit via iommu <iommu@lists.linux-foundation.org>]

The function check_feature_on_all_iommus() checks to ensure if an IOMMU
feature support bit is set on the Extended Feature Register (EFR).
Current logic iterates through all IOMMU, and returns false when it
found the first unset bit.

To provide more thorough checking, modify the logic to iterate through all
IOMMUs even when found that the bit is not set, and also throws a FW_BUG
warning if inconsistency is found.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 drivers/iommu/amd/init.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 3dd0f26039c7..b3e4551ce9dd 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -261,18 +261,29 @@ int amd_iommu_get_num_iommus(void)
 }
 
 #ifdef CONFIG_IRQ_REMAP
+/*
+ * Iterate through all the IOMMUs to verify if the specified
+ * EFR bitmask of IOMMU feature are set.
+ * Warn and return false if found inconsistency.
+ */
 static bool check_feature_on_all_iommus(u64 mask)
 {
 	bool ret = false;
 	struct amd_iommu *iommu;
 
 	for_each_iommu(iommu) {
-		ret = iommu_feature(iommu, mask);
-		if (!ret)
+		bool tmp = iommu_feature(iommu, mask);
+
+		if ((ret != tmp) &&
+		    !list_is_first(&iommu->list, &amd_iommu_list)) {
+			pr_err(FW_BUG "Found inconsistent EFR mask (%#llx) on iommu%d (%04x:%02x:%02x.%01x).\n",
+			       mask, iommu->index, iommu->pci_seg->id, PCI_BUS_NUM(iommu->devid),
+			       PCI_SLOT(iommu->devid), PCI_FUNC(iommu->devid));
 			return false;
+		}
+		ret = tmp;
 	}
-
-	return true;
+	return ret;
 }
 #endif
 
-- 
2.32.0

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