[PATCH] iommu/arm-smmu-v3: Fix size calculation in arm_smmu_mm_invalidate_range()

[Nicolin Chen]

The arm_smmu_mm_invalidate_range function is designed to be called
by mm core for Shared Virtual Addressing purpose between IOMMU and
CPU MMU. However, the ways of two subsystems defining their "end"
addresses are slightly different. IOMMU defines its "end" address
using the last address of an address range, while mm core defines
that using the following address of an address range:

	include/linux/mm_types.h:
		unsigned long vm_end;
		/* The first byte after our end address ...

This mismatch resulted in an incorrect calculation for size so it
failed to be page-size aligned. Further, it caused a dead loop at
"while (iova < end)" check in __arm_smmu_tlb_inv_range function.

This patch fixes the issue by doing the calculation correctly.

Fixes: 2f7e8c553e98d ("iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops")
Cc: stable at vger.kernel.org
Signed-off-by: Nicolin Chen <nicolinc at nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
index 22ddd05bbdcd..c623dae1e115 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
@@ -183,7 +183,14 @@ static void arm_smmu_mm_invalidate_range(struct mmu_notifier *mn,
 {
 	struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn);
 	struct arm_smmu_domain *smmu_domain = smmu_mn->domain;
-	size_t size = end - start + 1;
+	size_t size;
+
+	/*
+	 * The mm_types defines vm_end as the first byte after the end address,
+	 * different from IOMMU subsystem using the last address of an address
+	 * range. So do a simple translation here by calculating size correctly.
+	 */
+	size = end - start;
 
 	if (!(smmu_domain->smmu->features & ARM_SMMU_FEAT_BTM))
 		arm_smmu_tlb_inv_range_asid(start, size, smmu_mn->cd->asid,
-- 
2.17.1