[RFC PATCH v2 4/9] iommu/arm-smmu-v3-sva: Allocate new ASID from installed_smmus

[Michael Shavit]

Pick an ASID that is within the supported range of all SMMUs that the
domain is installed to.

Signed-off-by: Michael Shavit <mshavit at google.com>
---

(no changes since v1)

 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   | 23 +++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

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 fe88a7880ad57..92d2f8c4e90a8 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
@@ -66,6 +66,20 @@ static int arm_smmu_write_ctx_desc_devices(struct arm_smmu_domain *smmu_domain,
 	return ret;
 }
 
+static u32 arm_smmu_domain_max_asid_bits(struct arm_smmu_domain *smmu_domain)
+{
+	struct arm_smmu_master *master;
+	unsigned long flags;
+	u32 asid_bits = 16;
+
+	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
+	list_for_each_entry(master, &smmu_domain->devices,
+			    domain_head)
+		asid_bits = min(asid_bits, master->smmu->asid_bits);
+	spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
+	return asid_bits;
+}
+
 /*
  * Check if the CPU ASID is available on the SMMU side. If a private context
  * descriptor is using it, try to replace it.
@@ -76,7 +90,6 @@ arm_smmu_share_asid(struct mm_struct *mm, u16 asid)
 	int ret;
 	u32 new_asid;
 	struct arm_smmu_ctx_desc *cd;
-	struct arm_smmu_device *smmu;
 	struct arm_smmu_domain *smmu_domain;
 
 	cd = xa_load(&arm_smmu_asid_xa, asid);
@@ -92,10 +105,12 @@ arm_smmu_share_asid(struct mm_struct *mm, u16 asid)
 	}
 
 	smmu_domain = container_of(cd, struct arm_smmu_domain, cd);
-	smmu = smmu_domain->smmu;
 
-	ret = xa_alloc(&arm_smmu_asid_xa, &new_asid, cd,
-		       XA_LIMIT(1, (1 << smmu->asid_bits) - 1), GFP_KERNEL);
+	ret = xa_alloc(
+		&arm_smmu_asid_xa, &new_asid, cd,
+		XA_LIMIT(1,
+			 (1 << arm_smmu_domain_max_asid_bits(smmu_domain)) - 1),
+		GFP_KERNEL);
 	if (ret)
 		return ERR_PTR(-ENOSPC);
 	/*
-- 
2.42.0.rc1.204.g551eb34607-goog