On Tue, Jan 14, 2020 at 12:52:30PM +0100, Jean-Philippe Brucker wrote:

On Tue, Jan 14, 2020 at 11:06:52AM +0000, Will Deacon wrote:

quoted

quoted

 /* Context descriptor manipulation functions */
+static int arm_smmu_alloc_cd_leaf_table(struct arm_smmu_device *smmu,
+					struct arm_smmu_cd_table *table,
+					size_t num_entries)
+{
+	size_t size = num_entries * (CTXDESC_CD_DWORDS << 3);
+
+	table->ptr = dmam_alloc_coherent(smmu->dev, size, &table->ptr_dma,
+					 GFP_KERNEL);
+	if (!table->ptr) {
+		dev_warn(smmu->dev,
+			 "failed to allocate context descriptor table\n");
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void arm_smmu_free_cd_leaf_table(struct arm_smmu_device *smmu,
+					struct arm_smmu_cd_table *table,
+					size_t num_entries)
+{
+	size_t size = num_entries * (CTXDESC_CD_DWORDS << 3);
+
+	dmam_free_coherent(smmu->dev, size, table->ptr, table->ptr_dma);
+}

I think we'd be better off taking the 'arm_smmu_s1_cfg' as a parameter here
instead of the table pointer and a num_entries value, since the code above
implies that we support partial freeing of the context descriptors.

I can do that as a follow-up patch if you agree. Thoughts?

Do you mean only changing the arguments of arm_smmu_free_cd_leaf_table(),
or arm_smmu_alloc_cd_leaf_table() as well? For free() I agree, for alloc()
I'm not sure it would look better.

Yeah, just for free(). I'll spin something on top after I've finished
reviewing the series.

For my tests I have a debug patch that allocates PASIDs randomly which
quickly consumes DMA for leaf tables. So I do have to free the leaves
individually when they aren't used, but it will be easy for me to update.

Cool.

Will