[PATCH v2 26/40] iommu/arm-smmu-v3: Enable broadcast TLB maintenance

[Jean-Philippe Brucker]

The SMMUv3 can handle invalidation targeted at TLB entries with shared
ASIDs. If the implementation supports broadcast TLB maintenance, enable it
and keep track of it in a feature bit. The SMMU will then be affected by
inner-shareable TLB invalidations from other agents.

A major side-effect of this change is that stage-2 translation contexts
are now affected by all invalidations by VMID. VMIDs are all shared and
the only ways to prevent over-invalidation, since the stage-2 page tables
are not shared between CPU and SMMU, are to either disable BTM or allocate
different VMIDs. This patch does not address the problem.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker at arm.com>
---
 drivers/iommu/arm-smmu-v3.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 280a5d9be839..073cba33ae6c 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -64,6 +64,7 @@
 #define IDR0_ASID16			(1 << 12)
 #define IDR0_ATS			(1 << 10)
 #define IDR0_HYP			(1 << 9)
+#define IDR0_BTM			(1 << 5)
 #define IDR0_COHACC			(1 << 4)
 #define IDR0_TTF			GENMASK(3, 2)
 #define IDR0_TTF_AARCH64		2
@@ -523,6 +524,7 @@ struct arm_smmu_device {
 #define ARM_SMMU_FEAT_STALL_FORCE	(1 << 13)
 #define ARM_SMMU_FEAT_VAX		(1 << 14)
 #define ARM_SMMU_FEAT_E2H		(1 << 15)
+#define ARM_SMMU_FEAT_BTM		(1 << 16)
 	u32				features;
 
 #define ARM_SMMU_OPT_SKIP_PREFETCH	(1 << 0)
@@ -2459,11 +2461,14 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
 	writel_relaxed(reg, smmu->base + ARM_SMMU_CR1);
 
 	/* CR2 (random crap) */
-	reg = CR2_PTM | CR2_RECINVSID;
+	reg = CR2_RECINVSID;
 
 	if (smmu->features & ARM_SMMU_FEAT_E2H)
 		reg |= CR2_E2H;
 
+	if (!(smmu->features & ARM_SMMU_FEAT_BTM))
+		reg |= CR2_PTM;
+
 	writel_relaxed(reg, smmu->base + ARM_SMMU_CR2);
 
 	/* Stream table */
@@ -2564,6 +2569,7 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
 {
 	u32 reg;
 	bool coherent = smmu->features & ARM_SMMU_FEAT_COHERENCY;
+	bool vhe = cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN);
 
 	/* IDR0 */
 	reg = readl_relaxed(smmu->base + ARM_SMMU_IDR0);
@@ -2613,10 +2619,19 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
 
 	if (reg & IDR0_HYP) {
 		smmu->features |= ARM_SMMU_FEAT_HYP;
-		if (cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN))
+		if (vhe)
 			smmu->features |= ARM_SMMU_FEAT_E2H;
 	}
 
+	/*
+	 * If the CPU is using VHE, but the SMMU doesn't support it, the SMMU
+	 * will create TLB entries for NH-EL1 world and will miss the
+	 * broadcasted TLB invalidations that target EL2-E2H world. Don't enable
+	 * BTM in that case.
+	 */
+	if (reg & IDR0_BTM && (!vhe || reg & IDR0_HYP))
+		smmu->features |= ARM_SMMU_FEAT_BTM;
+
 	/*
 	 * The coherency feature as set by FW is used in preference to the ID
 	 * register, but warn on mismatch.
-- 
2.17.0