[RFC PATCH 04/45] iommu/io-pgtable: Add configure() operation

[Jean-Philippe Brucker]

Allow IOMMU drivers to create the io-pgtable configuration without
allocating any tables. This will be used by the SMMUv3-KVM driver to
initialize a config and pass it to KVM.

Signed-off-by: Jean-Philippe Brucker <jean-philippe at linaro.org>
---
 include/linux/io-pgtable.h     | 14 +++++++++++
 drivers/iommu/io-pgtable-arm.c | 46 ++++++++++++++++++++++++++--------
 drivers/iommu/io-pgtable.c     | 15 +++++++++++
 3 files changed, 65 insertions(+), 10 deletions(-)

diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index 1b0c26241a78..ee6484d7a5e0 100644
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h
@@ -191,6 +191,18 @@ struct io_pgtable_ops *alloc_io_pgtable_ops(struct io_pgtable_cfg *cfg,
  */
 void free_io_pgtable_ops(struct io_pgtable_ops *ops);
 
+/**
+ * io_pgtable_configure - Create page table config
+ *
+ * @cfg:	The page table configuration.
+ * @pgd_size:	On success, size of the top-level table in bytes.
+ *
+ * Initialize @cfg in the same way as alloc_io_pgtable_ops(), without allocating
+ * anything.
+ *
+ * Not all io_pgtable drivers implement this operation.
+ */
+int io_pgtable_configure(struct io_pgtable_cfg *cfg, size_t *pgd_size);
 
 /*
  * Internal structures for page table allocator implementations.
@@ -241,10 +253,12 @@ io_pgtable_tlb_add_page(struct io_pgtable *iop,
  *
  * @alloc: Allocate a set of page tables described by cfg.
  * @free:  Free the page tables associated with iop.
+ * @configure: Create the configuration without allocating anything. Optional.
  */
 struct io_pgtable_init_fns {
 	struct io_pgtable *(*alloc)(struct io_pgtable_cfg *cfg, void *cookie);
 	void (*free)(struct io_pgtable *iop);
+	int (*configure)(struct io_pgtable_cfg *cfg, size_t *pgd_size);
 };
 
 extern struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s1_init_fns;
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index b76b903400de..c412500efadf 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -118,6 +118,18 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
 	return NULL;
 }
 
+static int arm_64_lpae_configure_s1(struct io_pgtable_cfg *cfg, size_t *pgd_size)
+{
+	int ret;
+	struct arm_lpae_io_pgtable data = {};
+
+	ret = arm_lpae_init_pgtable_s1(cfg, &data);
+	if (ret)
+		return ret;
+	*pgd_size = sizeof(arm_lpae_iopte) << data.pgd_bits;
+	return 0;
+}
+
 static struct io_pgtable *
 arm_64_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie)
 {
@@ -148,6 +160,18 @@ arm_64_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie)
 	return NULL;
 }
 
+static int arm_64_lpae_configure_s2(struct io_pgtable_cfg *cfg, size_t *pgd_size)
+{
+	int ret;
+	struct arm_lpae_io_pgtable data = {};
+
+	ret = arm_lpae_init_pgtable_s2(cfg, &data);
+	if (ret)
+		return ret;
+	*pgd_size = sizeof(arm_lpae_iopte) << data.pgd_bits;
+	return 0;
+}
+
 static struct io_pgtable *
 arm_32_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
 {
@@ -231,28 +255,30 @@ arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
 }
 
 struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s1_init_fns = {
-	.alloc	= arm_64_lpae_alloc_pgtable_s1,
-	.free	= arm_lpae_free_pgtable,
+	.alloc		= arm_64_lpae_alloc_pgtable_s1,
+	.free		= arm_lpae_free_pgtable,
+	.configure	= arm_64_lpae_configure_s1,
 };
 
 struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s2_init_fns = {
-	.alloc	= arm_64_lpae_alloc_pgtable_s2,
-	.free	= arm_lpae_free_pgtable,
+	.alloc		= arm_64_lpae_alloc_pgtable_s2,
+	.free		= arm_lpae_free_pgtable,
+	.configure	= arm_64_lpae_configure_s2,
 };
 
 struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s1_init_fns = {
-	.alloc	= arm_32_lpae_alloc_pgtable_s1,
-	.free	= arm_lpae_free_pgtable,
+	.alloc		= arm_32_lpae_alloc_pgtable_s1,
+	.free		= arm_lpae_free_pgtable,
 };
 
 struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s2_init_fns = {
-	.alloc	= arm_32_lpae_alloc_pgtable_s2,
-	.free	= arm_lpae_free_pgtable,
+	.alloc		= arm_32_lpae_alloc_pgtable_s2,
+	.free		= arm_lpae_free_pgtable,
 };
 
 struct io_pgtable_init_fns io_pgtable_arm_mali_lpae_init_fns = {
-	.alloc	= arm_mali_lpae_alloc_pgtable,
-	.free	= arm_lpae_free_pgtable,
+	.alloc		= arm_mali_lpae_alloc_pgtable,
+	.free		= arm_lpae_free_pgtable,
 };
 
 #ifdef CONFIG_IOMMU_IO_PGTABLE_LPAE_SELFTEST
diff --git a/drivers/iommu/io-pgtable.c b/drivers/iommu/io-pgtable.c
index 79e459f95012..2aba691db1da 100644
--- a/drivers/iommu/io-pgtable.c
+++ b/drivers/iommu/io-pgtable.c
@@ -74,3 +74,18 @@ void free_io_pgtable_ops(struct io_pgtable_ops *ops)
 	io_pgtable_init_table[iop->cfg.fmt]->free(iop);
 }
 EXPORT_SYMBOL_GPL(free_io_pgtable_ops);
+
+int io_pgtable_configure(struct io_pgtable_cfg *cfg, size_t *pgd_size)
+{
+	const struct io_pgtable_init_fns *fns;
+
+	if (cfg->fmt >= IO_PGTABLE_NUM_FMTS)
+		return -EINVAL;
+
+	fns = io_pgtable_init_table[cfg->fmt];
+	if (!fns || !fns->configure)
+		return -EOPNOTSUPP;
+
+	return fns->configure(cfg, pgd_size);
+}
+EXPORT_SYMBOL_GPL(io_pgtable_configure);
-- 
2.39.0