linux-kernel - [PATCH 4/5] swiotlb: Add API to register new pool

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Date:   Tue, 28 Apr 2020 17:09:17 +0530
From:   Srivatsa Vaddagiri <vatsa@...eaurora.org>
To:     konrad.wilk@...cle.com, mst@...hat.com, jasowang@...hat.com,
        jan.kiszka@...mens.com, will@...nel.org,
        stefano.stabellini@...inx.com
Cc:     iommu@...ts.linux-foundation.org,
        virtualization@...ts.linux-foundation.org,
        virtio-dev@...ts.oasis-open.org, tsoni@...eaurora.org,
        pratikp@...eaurora.org, vatsa@...eaurora.org,
        christoffer.dall@....com, alex.bennee@...aro.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 4/5] swiotlb: Add API to register new pool

This patch adds an interface for the swiotlb driver to recognize
a new memory pool. Upon successful initialization of the pool,
swiotlb returns a handle, which needs to be passed as an argument
for any future operations on the pool (map/unmap/alloc/free).

Signed-off-by: Srivatsa Vaddagiri <vatsa@...eaurora.org>
---
 include/linux/swiotlb.h |  9 ++++++++
 kernel/dma/swiotlb.c    | 60 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 957697e..97ac82a 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -182,6 +182,9 @@ static inline bool is_swiotlb_buffer(phys_addr_t paddr)
 	return paddr >= swiotlb_start() && paddr < swiotlb_end();
 }
 
+extern struct swiotlb_pool *swiotlb_register_pool(char *name,
+		phys_addr_t start, void *vstart, size_t size);
+
 void __init swiotlb_exit(void);
 unsigned int swiotlb_max_segment(void);
 size_t swiotlb_max_mapping_size(struct device *dev);
@@ -236,6 +239,12 @@ static inline void swiotlb_free(struct swiotlb_pool *pool,
 {
 }
 
+static struct swiotlb_pool *swiotlb_register_pool(char *name,
+		phys_addr_t start, void *vstart, size_t size)
+{
+	return NULL;
+}
+
 #endif /* CONFIG_SWIOTLB */
 
 extern void swiotlb_print_info(void);
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 7411ce5..9883744 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -36,6 +36,7 @@
 #include <linux/scatterlist.h>
 #include <linux/mem_encrypt.h>
 #include <linux/set_memory.h>
+#include <linux/slab.h>
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 #endif
@@ -736,6 +737,65 @@ size_t swiotlb_max_mapping_size(struct device *dev)
 	return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
 }
 
+struct swiotlb_pool *swiotlb_register_pool(char *name, phys_addr_t start,
+			void *vstart, size_t size)
+{
+	struct swiotlb_pool *pool;
+	unsigned long i, bytes;
+	unsigned long nslabs;
+
+	nslabs = size >> IO_TLB_SHIFT;
+	if (!nslabs)
+		return ERR_PTR(-EINVAL);
+
+	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+	if (!pool)
+		return ERR_PTR(-ENOMEM);
+
+	bytes = nslabs << IO_TLB_SHIFT;
+
+	strncpy(pool->name, name, sizeof(pool->name));
+	spin_lock_init(&pool->io_tlb_lock);
+	pool->late_alloc = 1;
+	pool->io_tlb_start = start;
+	pool->io_tlb_end = start + bytes;
+	pool->io_tlb_vstart = vstart;
+	pool->io_tlb_nslabs = nslabs;
+	pool->max_segment = rounddown(bytes, PAGE_SIZE);
+
+	/*
+	 * Allocate and initialize the free list array.  This array is used
+	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
+	 * between io_tlb_start and io_tlb_end.
+	 */
+	pool->io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL,
+			get_order(pool->io_tlb_nslabs * sizeof(int)));
+	if (!pool->io_tlb_list)
+		goto cleanup;
+
+	pool->io_tlb_orig_addr = (phys_addr_t *)
+		__get_free_pages(GFP_KERNEL,
+				 get_order(pool->io_tlb_nslabs *
+					   sizeof(phys_addr_t)));
+	if (!pool->io_tlb_orig_addr)
+		goto cleanup;
+
+	for (i = 0; i < pool->io_tlb_nslabs; i++) {
+		pool->io_tlb_list[i] = IO_TLB_SEGSIZE -
+						OFFSET(i, IO_TLB_SEGSIZE);
+		pool->io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
+	}
+
+	return pool;
+
+cleanup:
+	kfree(pool->io_tlb_list);
+	kfree(pool->io_tlb_orig_addr);
+	kfree(pool);
+
+	return ERR_PTR(-ENOMEM);
+}
+
 bool is_swiotlb_active(void)
 {
 	/*
-- 
2.7.4

-- 
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