[PATCH 08/11] RISC-V: drivers/iommu/riscv: Add page table support

[Tomasz Jeznach <tjeznach@rivosinc.com>]

Introduces I/O page level translation services, with 4K, 2M, 1G page
size support and enables page level iommu_map/unmap domain interfaces.

Co-developed-by: Sebastien Boeuf <seb@rivosinc.com>
Signed-off-by: Sebastien Boeuf <seb@rivosinc.com>
Signed-off-by: Tomasz Jeznach <tjeznach@rivosinc.com>
---
 drivers/iommu/io-pgtable.c       |   3 +
 drivers/iommu/riscv/Makefile     |   2 +-
 drivers/iommu/riscv/io_pgtable.c | 266 +++++++++++++++++++++++++++++++
 drivers/iommu/riscv/iommu.c      |  40 +++--
 drivers/iommu/riscv/iommu.h      |   1 +
 include/linux/io-pgtable.h       |   2 +
 6 files changed, 297 insertions(+), 17 deletions(-)
 create mode 100644 drivers/iommu/riscv/io_pgtable.c

diff --git a/drivers/iommu/io-pgtable.c b/drivers/iommu/io-pgtable.c
index b843fcd365d2..c4807175934f 100644
--- a/drivers/iommu/io-pgtable.c
+++ b/drivers/iommu/io-pgtable.c
@@ -32,6 +32,9 @@ io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = {
 	[AMD_IOMMU_V1] = &io_pgtable_amd_iommu_v1_init_fns,
 	[AMD_IOMMU_V2] = &io_pgtable_amd_iommu_v2_init_fns,
 #endif
+#ifdef CONFIG_RISCV_IOMMU
+	[RISCV_IOMMU] = &io_pgtable_riscv_init_fns,
+#endif
 };
 
 struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt,
diff --git a/drivers/iommu/riscv/Makefile b/drivers/iommu/riscv/Makefile
index 9523eb053cfc..13af452c3052 100644
--- a/drivers/iommu/riscv/Makefile
+++ b/drivers/iommu/riscv/Makefile
@@ -1 +1 @@
-obj-$(CONFIG_RISCV_IOMMU) += iommu.o iommu-pci.o iommu-platform.o iommu-sysfs.o
\ No newline at end of file
+obj-$(CONFIG_RISCV_IOMMU) += iommu.o iommu-pci.o iommu-platform.o iommu-sysfs.o io_pgtable.o
diff --git a/drivers/iommu/riscv/io_pgtable.c b/drivers/iommu/riscv/io_pgtable.c
new file mode 100644
index 000000000000..b6e603e6726e
--- /dev/null
+++ b/drivers/iommu/riscv/io_pgtable.c
@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright © 2022-2023 Rivos Inc.
+ *
+ * RISC-V IOMMU page table allocator.
+ *
+ * Authors:
+ *	Tomasz Jeznach <tjeznach@rivosinc.com>
+ *	Sebastien Boeuf <seb@rivosinc.com>
+ */
+
+#include <linux/atomic.h>
+#include <linux/bitops.h>
+#include <linux/io-pgtable.h>
+#include <linux/kernel.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/dma-mapping.h>
+
+#include "iommu.h"
+
+#define io_pgtable_to_domain(x) \
+	container_of((x), struct riscv_iommu_domain, pgtbl)
+
+#define io_pgtable_ops_to_domain(x) \
+	io_pgtable_to_domain(container_of((x), struct io_pgtable, ops))
+
+static inline size_t get_page_size(size_t size)
+{
+	if (size >= IOMMU_PAGE_SIZE_512G)
+		return IOMMU_PAGE_SIZE_512G;
+
+	if (size >= IOMMU_PAGE_SIZE_1G)
+		return IOMMU_PAGE_SIZE_1G;
+
+	if (size >= IOMMU_PAGE_SIZE_2M)
+		return IOMMU_PAGE_SIZE_2M;
+
+	return IOMMU_PAGE_SIZE_4K;
+}
+
+static void riscv_iommu_pt_walk_free(pmd_t * ptp, unsigned shift, bool root)
+{
+	pmd_t *pte, *pt_base;
+	int i;
+
+	if (shift == PAGE_SHIFT)
+		return;
+
+	if (root)
+		pt_base = ptp;
+	else
+		pt_base =
+		    (pmd_t *) pfn_to_virt(__page_val_to_pfn(pmd_val(*ptp)));
+
+	/* Recursively free all sub page table pages */
+	for (i = 0; i < PTRS_PER_PMD; i++) {
+		pte = pt_base + i;
+		if (pmd_present(*pte) && !pmd_leaf(*pte))
+			riscv_iommu_pt_walk_free(pte, shift - 9, false);
+	}
+
+	/* Now free the current page table page */
+	if (!root && pmd_present(*pt_base))
+		free_page((unsigned long)pt_base);
+}
+
+static void riscv_iommu_free_pgtable(struct io_pgtable *iop)
+{
+	struct riscv_iommu_domain *domain = io_pgtable_to_domain(iop);
+	riscv_iommu_pt_walk_free((pmd_t *) domain->pgd_root, PGDIR_SHIFT, true);
+}
+
+static pte_t *riscv_iommu_pt_walk_alloc(pmd_t * ptp, unsigned long iova,
+					unsigned shift, bool root,
+					size_t pgsize,
+					unsigned long (*pd_alloc)(gfp_t),
+					gfp_t gfp)
+{
+	pmd_t *pte;
+	unsigned long pfn;
+
+	if (root)
+		pte = ptp + ((iova >> shift) & (PTRS_PER_PMD - 1));
+	else
+		pte = (pmd_t *) pfn_to_virt(__page_val_to_pfn(pmd_val(*ptp))) +
+		    ((iova >> shift) & (PTRS_PER_PMD - 1));
+
+	if ((1ULL << shift) <= pgsize) {
+		if (pmd_present(*pte) && !pmd_leaf(*pte))
+			riscv_iommu_pt_walk_free(pte, shift - 9, false);
+		return (pte_t *) pte;
+	}
+
+	if (pmd_none(*pte)) {
+		pfn = pd_alloc ? virt_to_pfn(pd_alloc(gfp)) : 0;
+		if (!pfn)
+			return NULL;
+		set_pmd(pte, __pmd((pfn << _PAGE_PFN_SHIFT) | _PAGE_TABLE));
+	}
+
+	return riscv_iommu_pt_walk_alloc(pte, iova, shift - 9, false,
+					 pgsize, pd_alloc, gfp);
+}
+
+static pte_t *riscv_iommu_pt_walk_fetch(pmd_t * ptp,
+					unsigned long iova, unsigned shift,
+					bool root)
+{
+	pmd_t *pte;
+
+	if (root)
+		pte = ptp + ((iova >> shift) & (PTRS_PER_PMD - 1));
+	else
+		pte = (pmd_t *) pfn_to_virt(__page_val_to_pfn(pmd_val(*ptp))) +
+		    ((iova >> shift) & (PTRS_PER_PMD - 1));
+
+	if (pmd_leaf(*pte))
+		return (pte_t *) pte;
+	else if (pmd_none(*pte))
+		return NULL;
+	else if (shift == PAGE_SHIFT)
+		return NULL;
+
+	return riscv_iommu_pt_walk_fetch(pte, iova, shift - 9, false);
+}
+
+static int riscv_iommu_map_pages(struct io_pgtable_ops *ops,
+				 unsigned long iova, phys_addr_t phys,
+				 size_t pgsize, size_t pgcount, int prot,
+				 gfp_t gfp, size_t *mapped)
+{
+	struct riscv_iommu_domain *domain = io_pgtable_ops_to_domain(ops);
+	size_t size = 0;
+	size_t page_size = get_page_size(pgsize);
+	pte_t *pte;
+	pte_t pte_val;
+	pgprot_t pte_prot;
+
+	if (domain->domain.type == IOMMU_DOMAIN_BLOCKED)
+		return -ENODEV;
+
+	if (domain->domain.type == IOMMU_DOMAIN_IDENTITY) {
+		*mapped = pgsize * pgcount;
+		return 0;
+	}
+
+	pte_prot = (prot & IOMMU_WRITE) ?
+	    __pgprot(_PAGE_BASE | _PAGE_READ | _PAGE_WRITE | _PAGE_DIRTY) :
+	    __pgprot(_PAGE_BASE | _PAGE_READ);
+
+	while (pgcount--) {
+		pte =
+		    riscv_iommu_pt_walk_alloc((pmd_t *) domain->pgd_root, iova,
+					      PGDIR_SHIFT, true, page_size,
+					      get_zeroed_page, gfp);
+		if (!pte) {
+			*mapped = size;
+			return -ENOMEM;
+		}
+
+		pte_val = pfn_pte(phys_to_pfn(phys), pte_prot);
+
+		set_pte(pte, pte_val);
+
+		size += page_size;
+		iova += page_size;
+		phys += page_size;
+	}
+
+	*mapped = size;
+	return 0;
+}
+
+static size_t riscv_iommu_unmap_pages(struct io_pgtable_ops *ops,
+				      unsigned long iova, size_t pgsize,
+				      size_t pgcount,
+				      struct iommu_iotlb_gather *gather)
+{
+	struct riscv_iommu_domain *domain = io_pgtable_ops_to_domain(ops);
+	size_t size = 0;
+	size_t page_size = get_page_size(pgsize);
+	pte_t *pte;
+
+	if (domain->domain.type == IOMMU_DOMAIN_IDENTITY)
+		return pgsize * pgcount;
+
+	while (pgcount--) {
+		pte = riscv_iommu_pt_walk_fetch((pmd_t *) domain->pgd_root,
+						iova, PGDIR_SHIFT, true);
+		if (!pte)
+			return size;
+
+		set_pte(pte, __pte(0));
+
+		iommu_iotlb_gather_add_page(&domain->domain, gather, iova,
+					    pgsize);
+
+		size += page_size;
+		iova += page_size;
+	}
+
+	return size;
+}
+
+static phys_addr_t riscv_iommu_iova_to_phys(struct io_pgtable_ops *ops,
+					    unsigned long iova)
+{
+	struct riscv_iommu_domain *domain = io_pgtable_ops_to_domain(ops);
+	pte_t *pte;
+
+	if (domain->domain.type == IOMMU_DOMAIN_IDENTITY)
+		return (phys_addr_t) iova;
+
+	pte = riscv_iommu_pt_walk_fetch((pmd_t *) domain->pgd_root,
+					iova, PGDIR_SHIFT, true);
+	if (!pte || !pte_present(*pte))
+		return 0;
+
+	return (pfn_to_phys(pte_pfn(*pte)) | (iova & PAGE_MASK));
+}
+
+static void riscv_iommu_tlb_inv_all(void *cookie)
+{
+}
+
+static void riscv_iommu_tlb_inv_walk(unsigned long iova, size_t size,
+				     size_t granule, void *cookie)
+{
+}
+
+static void riscv_iommu_tlb_add_page(struct iommu_iotlb_gather *gather,
+				     unsigned long iova, size_t granule,
+				     void *cookie)
+{
+}
+
+static const struct iommu_flush_ops riscv_iommu_flush_ops = {
+	.tlb_flush_all = riscv_iommu_tlb_inv_all,
+	.tlb_flush_walk = riscv_iommu_tlb_inv_walk,
+	.tlb_add_page = riscv_iommu_tlb_add_page,
+};
+
+/* NOTE: cfg should point to riscv_iommu_domain structure member pgtbl.cfg */
+static struct io_pgtable *riscv_iommu_alloc_pgtable(struct io_pgtable_cfg *cfg,
+						    void *cookie)
+{
+	struct io_pgtable *iop = container_of(cfg, struct io_pgtable, cfg);
+
+	cfg->pgsize_bitmap = SZ_4K | SZ_2M | SZ_1G;
+	cfg->ias = 57;		// va mode, SvXX -> ias
+	cfg->oas = 57;		// pa mode, or SvXX+4 -> oas
+	cfg->tlb = &riscv_iommu_flush_ops;
+
+	iop->ops.map_pages = riscv_iommu_map_pages;
+	iop->ops.unmap_pages = riscv_iommu_unmap_pages;
+	iop->ops.iova_to_phys = riscv_iommu_iova_to_phys;
+
+	return iop;
+}
+
+struct io_pgtable_init_fns io_pgtable_riscv_init_fns = {
+	.alloc = riscv_iommu_alloc_pgtable,
+	.free = riscv_iommu_free_pgtable,
+};
diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
index 9ee7d2b222b5..2ef6952a2109 100644
--- a/drivers/iommu/riscv/iommu.c
+++ b/drivers/iommu/riscv/iommu.c
@@ -807,7 +807,7 @@ static struct iommu_device *riscv_iommu_probe_device(struct device *dev)
 	/* Initial DC pointer can be NULL if IOMMU is configured in OFF or BARE mode */
 	ep->dc = riscv_iommu_get_dc(iommu, ep->devid);
 
-	dev_info(iommu->dev, "adding device to iommu with devid %i in domain %i\n",
+	dev_dbg(iommu->dev, "adding device to iommu with devid %i in domain %i\n",
 		ep->devid, ep->domid);
 
 	dev_iommu_priv_set(dev, ep);
@@ -874,7 +874,10 @@ static struct iommu_domain *riscv_iommu_domain_alloc(unsigned type)
 {
 	struct riscv_iommu_domain *domain;
 
-	if (type != IOMMU_DOMAIN_IDENTITY &&
+	if (type != IOMMU_DOMAIN_DMA &&
+	    type != IOMMU_DOMAIN_DMA_FQ &&
+	    type != IOMMU_DOMAIN_UNMANAGED &&
+	    type != IOMMU_DOMAIN_IDENTITY &&
 	    type != IOMMU_DOMAIN_BLOCKED)
 		return NULL;
 
@@ -890,7 +893,7 @@ static struct iommu_domain *riscv_iommu_domain_alloc(unsigned type)
 	domain->pscid = ida_alloc_range(&riscv_iommu_pscids, 1,
 					RISCV_IOMMU_MAX_PSCID, GFP_KERNEL);
 
-	printk("domain type %x alloc %u\n", type, domain->pscid);
+	printk("domain alloc %u\n", domain->pscid);
 
 	return &domain->domain;
 }
@@ -903,6 +906,9 @@ static void riscv_iommu_domain_free(struct iommu_domain *iommu_domain)
 		pr_warn("IOMMU domain is not empty!\n");
 	}
 
+	if (domain->pgtbl.cookie)
+		free_io_pgtable_ops(&domain->pgtbl.ops);
+
 	if (domain->pgd_root)
 		free_pages((unsigned long)domain->pgd_root, 0);
 
@@ -959,6 +965,9 @@ static int riscv_iommu_domain_finalize(struct riscv_iommu_domain *domain,
 	if (!domain->pgd_root)
 		return -ENOMEM;
 
+	if (!alloc_io_pgtable_ops(RISCV_IOMMU, &domain->pgtbl.cfg, domain))
+		return -ENOMEM;
+
 	return 0;
 }
 
@@ -1006,9 +1015,8 @@ static int riscv_iommu_attach_dev(struct iommu_domain *iommu_domain, struct devi
 		return 0;
 	}
 
-	if (!dc) {
+	if (!dc)
 		return -ENODEV;
-	}
 
 	/*
 	 * S-Stage translation table. G-Stage remains unmodified (BARE).
@@ -1104,12 +1112,11 @@ static int riscv_iommu_map_pages(struct iommu_domain *iommu_domain,
 {
 	struct riscv_iommu_domain *domain = iommu_domain_to_riscv(iommu_domain);
 
-	if (domain->domain.type == IOMMU_DOMAIN_IDENTITY) {
-		*mapped = pgsize * pgcount;
-		return 0;
-	}
+	if (!domain->pgtbl.ops.map_pages)
+		return -ENODEV;
 
-	return -ENODEV;
+	return domain->pgtbl.ops.map_pages(&domain->pgtbl.ops, iova, phys,
+					   pgsize, pgcount, prot, gfp, mapped);
 }
 
 static size_t riscv_iommu_unmap_pages(struct iommu_domain *iommu_domain,
@@ -1118,10 +1125,11 @@ static size_t riscv_iommu_unmap_pages(struct iommu_domain *iommu_domain,
 {
 	struct riscv_iommu_domain *domain = iommu_domain_to_riscv(iommu_domain);
 
-	if (domain->domain.type == IOMMU_DOMAIN_IDENTITY)
-		return pgsize * pgcount;
+	if (!domain->pgtbl.ops.unmap_pages)
+		return 0;
 
-	return 0;
+	return domain->pgtbl.ops.unmap_pages(&domain->pgtbl.ops, iova, pgsize,
+					     pgcount, gather);
 }
 
 static phys_addr_t riscv_iommu_iova_to_phys(struct iommu_domain *iommu_domain,
@@ -1129,10 +1137,10 @@ static phys_addr_t riscv_iommu_iova_to_phys(struct iommu_domain *iommu_domain,
 {
 	struct riscv_iommu_domain *domain = iommu_domain_to_riscv(iommu_domain);
 
-	if (domain->domain.type == IOMMU_DOMAIN_IDENTITY)
-		return (phys_addr_t) iova;
+	if (!domain->pgtbl.ops.iova_to_phys)
+		return 0;
 
-	return 0;
+	return domain->pgtbl.ops.iova_to_phys(&domain->pgtbl.ops, iova);
 }
 
 /*
diff --git a/drivers/iommu/riscv/iommu.h b/drivers/iommu/riscv/iommu.h
index 9140df71e17b..fe32a4eff14e 100644
--- a/drivers/iommu/riscv/iommu.h
+++ b/drivers/iommu/riscv/iommu.h
@@ -88,6 +88,7 @@ struct riscv_iommu_device {
 
 struct riscv_iommu_domain {
 	struct iommu_domain domain;
+	struct io_pgtable pgtbl;
 
 	struct list_head endpoints;
 	struct mutex lock;
diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index 1b7a44b35616..8dd9d3a28e3a 100644
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h
@@ -19,6 +19,7 @@ enum io_pgtable_fmt {
 	AMD_IOMMU_V2,
 	APPLE_DART,
 	APPLE_DART2,
+	RISCV_IOMMU,
 	IO_PGTABLE_NUM_FMTS,
 };
 
@@ -258,5 +259,6 @@ extern struct io_pgtable_init_fns io_pgtable_arm_mali_lpae_init_fns;
 extern struct io_pgtable_init_fns io_pgtable_amd_iommu_v1_init_fns;
 extern struct io_pgtable_init_fns io_pgtable_amd_iommu_v2_init_fns;
 extern struct io_pgtable_init_fns io_pgtable_apple_dart_init_fns;
+extern struct io_pgtable_init_fns io_pgtable_riscv_init_fns;
 
 #endif /* __IO_PGTABLE_H */
-- 
2.34.1


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