[RFC PATCH] IOMMU: SMMUv2: Support for Extended Stream ID (16 bit)

[Aleksey Makarov]

Enable the Extended Stream ID feature when available.

This patch on top of series "[PATCH v7 00/19] KVM PCIe/MSI passthrough
on ARM/ARM64 and IOVA reserved regions" by Eric Auger allows
to passthrough an external PCIe network card on a ThunderX server
successfully.

Without this patch that card caused a warning like

	pci 0006:90:00.0: stream ID 0x9000 out of range for SMMU (0x7fff)

during boot.

Signed-off-by: Aleksey Makarov <aleksey.makarov@xxxxxxxxxx>
---
 drivers/iommu/arm-smmu.c | 53 +++++++++++++++++++++++++++++++++---------------
 1 file changed, 37 insertions(+), 16 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 13d26009b8e0..d160c12828f4 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -24,6 +24,7 @@
  *	- v7/v8 long-descriptor format
  *	- Non-secure access to the SMMU
  *	- Context fault reporting
+ *	- Extended Stream ID (16 bit)
  */
 
 #define pr_fmt(fmt) "arm-smmu: " fmt
@@ -87,6 +88,7 @@
 #define sCR0_CLIENTPD			(1 << 0)
 #define sCR0_GFRE			(1 << 1)
 #define sCR0_GFIE			(1 << 2)
+#define sCR0_EXIDENABLE			(1 << 3)
 #define sCR0_GCFGFRE			(1 << 4)
 #define sCR0_GCFGFIE			(1 << 5)
 #define sCR0_USFCFG			(1 << 10)
@@ -126,6 +128,7 @@
 #define ID0_NUMIRPT_MASK		0xff
 #define ID0_NUMSIDB_SHIFT		9
 #define ID0_NUMSIDB_MASK		0xf
+#define ID0_EXIDS			(1 << 8)
 #define ID0_NUMSMRG_SHIFT		0
 #define ID0_NUMSMRG_MASK		0xff
 
@@ -169,6 +172,7 @@
 #define ARM_SMMU_GR0_S2CR(n)		(0xc00 + ((n) << 2))
 #define S2CR_CBNDX_SHIFT		0
 #define S2CR_CBNDX_MASK			0xff
+#define S2CR_EXIDVALID			(1 << 10)
 #define S2CR_TYPE_SHIFT			16
 #define S2CR_TYPE_MASK			0x3
 enum arm_smmu_s2cr_type {
@@ -354,6 +358,7 @@ struct arm_smmu_device {
 #define ARM_SMMU_FEAT_FMT_AARCH64_64K	(1 << 9)
 #define ARM_SMMU_FEAT_FMT_AARCH32_L	(1 << 10)
 #define ARM_SMMU_FEAT_FMT_AARCH32_S	(1 << 11)
+#define ARM_SMMU_FEAT_EXIDS		(1 << 12)
 	u32				features;
 
 #define ARM_SMMU_OPT_SECURE_CFG_ACCESS (1 << 0)
@@ -1051,7 +1056,7 @@ static void arm_smmu_write_smr(struct arm_smmu_device *smmu, int idx)
 	struct arm_smmu_smr *smr = smmu->smrs + idx;
 	u32 reg = smr->id << SMR_ID_SHIFT | smr->mask << SMR_MASK_SHIFT;
 
-	if (smr->valid)
+	if (!(smmu->features & ARM_SMMU_FEAT_EXIDS) && smr->valid)
 		reg |= SMR_VALID;
 	writel_relaxed(reg, ARM_SMMU_GR0(smmu) + ARM_SMMU_GR0_SMR(idx));
 }
@@ -1063,6 +1068,9 @@ static void arm_smmu_write_s2cr(struct arm_smmu_device *smmu, int idx)
 		  (s2cr->cbndx & S2CR_CBNDX_MASK) << S2CR_CBNDX_SHIFT |
 		  (s2cr->privcfg & S2CR_PRIVCFG_MASK) << S2CR_PRIVCFG_SHIFT;
 
+	if (smmu->features & ARM_SMMU_FEAT_EXIDS && smmu->smrs &&
+	    smmu->smrs[idx].valid)
+		reg |= S2CR_EXIDVALID;
 	writel_relaxed(reg, ARM_SMMU_GR0(smmu) + ARM_SMMU_GR0_S2CR(idx));
 }
 
@@ -1674,6 +1682,9 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu)
 	if (smmu->features & ARM_SMMU_FEAT_VMID16)
 		reg |= sCR0_VMID16EN;
 
+	if (smmu->features & ARM_SMMU_FEAT_EXIDS)
+		reg |= sCR0_EXIDENABLE;
+
 	/* Push the button */
 	__arm_smmu_tlb_sync(smmu);
 	writel(reg, ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sCR0);
@@ -1761,7 +1772,12 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
 			   "\t(IDR0.CTTW overridden by FW configuration)\n");
 
 	/* Max. number of entries we have for stream matching/indexing */
-	size = 1 << ((id >> ID0_NUMSIDB_SHIFT) & ID0_NUMSIDB_MASK);
+	if (smmu->version == ARM_SMMU_V2 && id & ID0_EXIDS) {
+		smmu->features |= ARM_SMMU_FEAT_EXIDS;
+		size = (1 << 16);
+	} else {
+		size = 1 << ((id >> ID0_NUMSIDB_SHIFT) & ID0_NUMSIDB_MASK);
+	}
 	smmu->streamid_mask = size - 1;
 	if (id & ID0_SMS) {
 		u32 smr;
@@ -1774,20 +1790,25 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
 			return -ENODEV;
 		}
 
-		/*
-		 * SMR.ID bits may not be preserved if the corresponding MASK
-		 * bits are set, so check each one separately. We can reject
-		 * masters later if they try to claim IDs outside these masks.
-		 */
-		smr = smmu->streamid_mask << SMR_ID_SHIFT;
-		writel_relaxed(smr, gr0_base + ARM_SMMU_GR0_SMR(0));
-		smr = readl_relaxed(gr0_base + ARM_SMMU_GR0_SMR(0));
-		smmu->streamid_mask = smr >> SMR_ID_SHIFT;
-
-		smr = smmu->streamid_mask << SMR_MASK_SHIFT;
-		writel_relaxed(smr, gr0_base + ARM_SMMU_GR0_SMR(0));
-		smr = readl_relaxed(gr0_base + ARM_SMMU_GR0_SMR(0));
-		smmu->smr_mask_mask = smr >> SMR_MASK_SHIFT;
+		if (smmu->features & ARM_SMMU_FEAT_EXIDS) {
+			smmu->smr_mask_mask = smmu->streamid_mask;
+		} else {
+			/*
+			 * SMR.ID bits may not be preserved if the corresponding
+			 * MASK bits are set, so check each one separately.
+			 * We can reject masters later if they try to claim IDs
+			 * outside these masks.
+			 */
+			smr = smmu->streamid_mask << SMR_ID_SHIFT;
+			writel_relaxed(smr, gr0_base + ARM_SMMU_GR0_SMR(0));
+			smr = readl_relaxed(gr0_base + ARM_SMMU_GR0_SMR(0));
+			smmu->streamid_mask = smr >> SMR_ID_SHIFT;
+
+			smr = smmu->streamid_mask << SMR_MASK_SHIFT;
+			writel_relaxed(smr, gr0_base + ARM_SMMU_GR0_SMR(0));
+			smr = readl_relaxed(gr0_base + ARM_SMMU_GR0_SMR(0));
+			smmu->smr_mask_mask = smr >> SMR_MASK_SHIFT;
+		}
 
 		/* Zero-initialised to mark as invalid */
 		smmu->smrs = devm_kcalloc(smmu->dev, size, sizeof(*smmu->smrs),
-- 
2.11.0