iommu/amd: Use IVHD EFR for early initialization of IOMMU features

IOMMU Extended Feature Register (EFR) is used to communicate
the supported features for each IOMMU to the IOMMU driver.
This is normally read from the PCI MMIO register offset 0x30,
and used by the iommu_feature() helper function.

However, there are certain scenarios where the information is needed
prior to PCI initialization, and the iommu_feature() function is used
prematurely w/o warning. This has caused incorrect initialization of IOMMU.
This is the case for the commit 6d39bdee238f ("iommu/amd: Enforce 4k
mapping for certain IOMMU data structures")

Since, the EFR is also available in the IVHD header, and is available to
the driver prior to PCI initialization. Therefore, default to using
the IVHD EFR instead.

Fixes: 6d39bdee238f ("iommu/amd: Enforce 4k mapping for certain IOMMU data structures")
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Tested-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Robert Richter <rrichter@amd.com>
Link: https://lore.kernel.org/r/20210120135002.2682-1-suravee.suthikulpanit@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 54 insertions, 2 deletions

diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
index 6a1f7048dacc..83d8ab2aed9f 100644
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -257,6 +257,8 @@ static void init_device_table_dma(void);
 
 static bool amd_iommu_pre_enabled = true;
 
+static u32 amd_iommu_ivinfo __initdata;
+
 bool translation_pre_enabled(struct amd_iommu *iommu)
 {
 	return (iommu->flags & AMD_IOMMU_FLAG_TRANS_PRE_ENABLED);
@@ -296,6 +298,18 @@ int amd_iommu_get_num_iommus(void)
 	return amd_iommus_present;
 }
 
+/*
+ * For IVHD type 0x11/0x40, EFR is also available via IVHD.
+ * Default to IVHD EFR since it is available sooner
+ * (i.e. before PCI init).
+ */
+static void __init early_iommu_features_init(struct amd_iommu *iommu,
+					     struct ivhd_header *h)
+{
+	if (amd_iommu_ivinfo & IOMMU_IVINFO_EFRSUP)
+		iommu->features = h->efr_reg;
+}
+
 /* Access to l1 and l2 indexed register spaces */
 
 static u32 iommu_read_l1(struct amd_iommu *iommu, u16 l1, u8 address)
@@ -1577,6 +1591,9 @@ static int __init init_iommu_one(struct amd_iommu *iommu, struct ivhd_header *h)
 
 		if (h->efr_reg & BIT(IOMMU_EFR_XTSUP_SHIFT))
 			amd_iommu_xt_mode = IRQ_REMAP_X2APIC_MODE;
+
+		early_iommu_features_init(iommu, h);
+
 		break;
 	default:
 		return -EINVAL;
@@ -1770,6 +1787,35 @@ static const struct attribute_group *amd_iommu_groups[] = {
 	NULL,
 };
 
+/*
+ * Note: IVHD 0x11 and 0x40 also contains exact copy
+ * of the IOMMU Extended Feature Register [MMIO Offset 0030h].
+ * Default to EFR in IVHD since it is available sooner (i.e. before PCI init).
+ */
+static void __init late_iommu_features_init(struct amd_iommu *iommu)
+{
+	u64 features;
+
+	if (!(iommu->cap & (1 << IOMMU_CAP_EFR)))
+		return;
+
+	/* read extended feature bits */
+	features = readq(iommu->mmio_base + MMIO_EXT_FEATURES);
+
+	if (!iommu->features) {
+		iommu->features = features;
+		return;
+	}
+
+	/*
+	 * Sanity check and warn if EFR values from
+	 * IVHD and MMIO conflict.
+	 */
+	if (features != iommu->features)
+		pr_warn(FW_WARN "EFR mismatch. Use IVHD EFR (%#llx : %#llx\n).",
+			features, iommu->features);
+}
+
 static int __init iommu_init_pci(struct amd_iommu *iommu)
 {
 	int cap_ptr = iommu->cap_ptr;
@@ -1789,8 +1835,7 @@ static int __init iommu_init_pci(struct amd_iommu *iommu)
 	if (!(iommu->cap & (1 << IOMMU_CAP_IOTLB)))
 		amd_iommu_iotlb_sup = false;
 
-	/* read extended feature bits */
-	iommu->features = readq(iommu->mmio_base + MMIO_EXT_FEATURES);
+	late_iommu_features_init(iommu);
 
 	if (iommu_feature(iommu, FEATURE_GT)) {
 		int glxval;
@@ -2607,6 +2652,11 @@ static void __init free_dma_resources(void)
 	free_unity_maps();
 }
 
+static void __init ivinfo_init(void *ivrs)
+{
+	amd_iommu_ivinfo = *((u32 *)(ivrs + IOMMU_IVINFO_OFFSET));
+}
+
 /*
  * This is the hardware init function for AMD IOMMU in the system.
  * This function is called either from amd_iommu_init or from the interrupt
@@ -2661,6 +2711,8 @@ static int __init early_amd_iommu_init(void)
 	if (ret)
 		goto out;
 
+	ivinfo_init(ivrs_base);
+
 	amd_iommu_target_ivhd_type = get_highest_supported_ivhd_type(ivrs_base);
 	DUMP_printk("Using IVHD type %#x\n", amd_iommu_target_ivhd_type);