[PATCH 1/3] iommu/amd: Introduce helper function to check feature bit on all IOMMUs

[Suravee Suthikulpanit]

IOMMU advertises feature via Extended Features Register (EFR).
The helper function checks if the specified feature bit is set
across all IOMMUs.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
 drivers/iommu/amd/init.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 46280e6e1535..c97961451ac5 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -298,6 +298,19 @@ int amd_iommu_get_num_iommus(void)
 	return amd_iommus_present;
 }
 
+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)
+			return false;
+	}
+
+	return true;
+}
 /*
  * For IVHD type 0x11/0x40, EFR is also available via IVHD.
  * Default to IVHD EFR since it is available sooner
-- 
2.17.1