iommu/amd: Enable GT mode when supported by IOMMU

This feature needs to be enabled before IOMMUv2 DTEs can be
set up.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

drivers/iommu/amd_iommu_init.c

@@ -623,6 +623,14 @@ static void __init free_ppr_log(struct amd_iommu *iommu)
 	free_pages((unsigned long)iommu->ppr_log, get_order(PPR_LOG_SIZE));
 }
 
+static void iommu_enable_gt(struct amd_iommu *iommu)
+{
+	if (!iommu_feature(iommu, FEATURE_GT))
+		return;
+
+	iommu_feature_enable(iommu, CONTROL_GT_EN);
+}
+
 /* sets a specific bit in the device table entry. */
 static void set_dev_entry_bit(u16 devid, u8 bit)
 {
@@ -1338,6 +1346,7 @@ static void enable_iommus(void)
 		iommu_enable_command_buffer(iommu);
 		iommu_enable_event_buffer(iommu);
 		iommu_enable_ppr_log(iommu);
+		iommu_enable_gt(iommu);
 		iommu_set_exclusion_range(iommu);
 		iommu_init_msi(iommu);
 		iommu_enable(iommu);

drivers/iommu/amd_iommu_types.h

@@ -129,6 +129,7 @@
 #define CONTROL_PPFLOG_EN       0x0dULL
 #define CONTROL_PPFINT_EN       0x0eULL
 #define CONTROL_PPR_EN          0x0fULL
+#define CONTROL_GT_EN           0x10ULL
 
 /* command specific defines */
 #define CMD_COMPL_WAIT          0x01