[net-next,v8,10/17] io_uring/zcrx: add io_zcrx_area

Commit Message

David Wei Dec. 4, 2024, 5:21 p.m. UTC

From: David Wei <[e-mail]>

Add io_zcrx_area that represents a region of userspace memory that is
used for zero copy. During ifq registration, userspace passes in the
uaddr and len of userspace memory, which is then pinned by the kernel.
Each net_iov is mapped to one of these pages.

The freelist is a spinlock protected list that keeps track of all the
net_iovs/pages that aren't used.

For now, there is only one area per ifq and area registration happens
implicitly as part of ifq registration. There is no API for
adding/removing areas yet. The struct for area registration is there for
future extensibility once we support multiple areas and TCP devmem.

Reviewed-by: Jens Axboe <[e-mail]>
Signed-off-by: Pavel Begunkov <[e-mail]>
Signed-off-by: David Wei <[e-mail]>
---
 include/uapi/linux/io_uring.h |  9 ++++
 io_uring/rsrc.c               |  2 +-
 io_uring/rsrc.h               |  1 +
 io_uring/zcrx.c               | 93 ++++++++++++++++++++++++++++++++++-
 io_uring/zcrx.h               | 16 ++++++
 5 files changed, 118 insertions(+), 3 deletions(-)

Patch

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 552377a1e496..7d72de92378d 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -978,6 +978,15 @@  struct io_uring_zcrx_offsets {
 	__u64	__resv[2];
 };
 
+struct io_uring_zcrx_area_reg {
+	__u64	addr;
+	__u64	len;
+	__u64	rq_area_token;
+	__u32	flags;
+	__u32	__resv1;
+	__u64	__resv2[2];
+};
+
 /*
  * Argument for IORING_REGISTER_ZCRX_IFQ
  */
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index adaae8630932..0d05e9944b0e 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -77,7 +77,7 @@  static int io_account_mem(struct io_ring_ctx *ctx, unsigned long nr_pages)
 	return 0;
 }
 
-static int io_buffer_validate(struct iovec *iov)
+int io_buffer_validate(struct iovec *iov)
 {
 	unsigned long tmp, acct_len = iov->iov_len + (PAGE_SIZE - 1);
 
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 7a4668deaa1a..bd23387c1549 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -65,6 +65,7 @@  int io_register_rsrc_update(struct io_ring_ctx *ctx, void __user *arg,
 			    unsigned size, unsigned type);
 int io_register_rsrc(struct io_ring_ctx *ctx, void __user *arg,
 			unsigned int size, unsigned int type);
+int io_buffer_validate(struct iovec *iov);
 
 static inline struct io_rsrc_node *io_rsrc_node_lookup(struct io_rsrc_data *data,
 						       int index)
diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index 3e5644718f54..8f838add94a4 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -10,6 +10,7 @@ 
 #include "kbuf.h"
 #include "memmap.h"
 #include "zcrx.h"
+#include "rsrc.h"
 
 #define IO_RQ_MAX_ENTRIES		32768
 
@@ -43,6 +44,83 @@  static void io_free_rbuf_ring(struct io_zcrx_ifq *ifq)
 	ifq->rqes = NULL;
 }
 
+static void io_zcrx_free_area(struct io_zcrx_area *area)
+{
+	if (area->freelist)
+		kvfree(area->freelist);
+	if (area->nia.niovs)
+		kvfree(area->nia.niovs);
+	if (area->pages) {
+		unpin_user_pages(area->pages, area->nia.num_niovs);
+		kvfree(area->pages);
+	}
+	kfree(area);
+}
+
+static int io_zcrx_create_area(struct io_ring_ctx *ctx,
+			       struct io_zcrx_ifq *ifq,
+			       struct io_zcrx_area **res,
+			       struct io_uring_zcrx_area_reg *area_reg)
+{
+	struct io_zcrx_area *area;
+	int i, ret, nr_pages;
+	struct iovec iov;
+
+	if (area_reg->flags || area_reg->rq_area_token)
+		return -EINVAL;
+	if (area_reg->__resv1 || area_reg->__resv2[0] || area_reg->__resv2[1])
+		return -EINVAL;
+	if (area_reg->addr & ~PAGE_MASK || area_reg->len & ~PAGE_MASK)
+		return -EINVAL;
+
+	iov.iov_base = u64_to_user_ptr(area_reg->addr);
+	iov.iov_len = area_reg->len;
+	ret = io_buffer_validate(&iov);
+	if (ret)
+		return ret;
+
+	ret = -ENOMEM;
+	area = kzalloc(sizeof(*area), GFP_KERNEL);
+	if (!area)
+		goto err;
+
+	area->pages = io_pin_pages((unsigned long)area_reg->addr, area_reg->len,
+				   &nr_pages);
+	if (IS_ERR(area->pages)) {
+		ret = PTR_ERR(area->pages);
+		area->pages = NULL;
+		goto err;
+	}
+	area->nia.num_niovs = nr_pages;
+
+	area->nia.niovs = kvmalloc_array(nr_pages, sizeof(area->nia.niovs[0]),
+					 GFP_KERNEL | __GFP_ZERO);
+	if (!area->nia.niovs)
+		goto err;
+
+	area->freelist = kvmalloc_array(nr_pages, sizeof(area->freelist[0]),
+					GFP_KERNEL | __GFP_ZERO);
+	if (!area->freelist)
+		goto err;
+
+	for (i = 0; i < nr_pages; i++) {
+		area->freelist[i] = i;
+	}
+
+	area->free_count = nr_pages;
+	area->ifq = ifq;
+	/* we're only supporting one area per ifq for now */
+	area->area_id = 0;
+	area_reg->rq_area_token = (u64)area->area_id << IORING_ZCRX_AREA_SHIFT;
+	spin_lock_init(&area->freelist_lock);
+	*res = area;
+	return 0;
+err:
+	if (area)
+		io_zcrx_free_area(area);
+	return ret;
+}
+
 static struct io_zcrx_ifq *io_zcrx_ifq_alloc(struct io_ring_ctx *ctx)
 {
 	struct io_zcrx_ifq *ifq;
@@ -58,6 +136,9 @@  static struct io_zcrx_ifq *io_zcrx_ifq_alloc(struct io_ring_ctx *ctx)
 
 static void io_zcrx_ifq_free(struct io_zcrx_ifq *ifq)
 {
+	if (ifq->area)
+		io_zcrx_free_area(ifq->area);
+
 	io_free_rbuf_ring(ifq);
 	kfree(ifq);
 }
@@ -65,6 +146,7 @@  static void io_zcrx_ifq_free(struct io_zcrx_ifq *ifq)
 int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
 			  struct io_uring_zcrx_ifq_reg __user *arg)
 {
+	struct io_uring_zcrx_area_reg area;
 	struct io_uring_zcrx_ifq_reg reg;
 	struct io_uring_region_desc rd;
 	struct io_zcrx_ifq *ifq;
@@ -99,7 +181,7 @@  int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
 	}
 	reg.rq_entries = roundup_pow_of_two(reg.rq_entries);
 
-	if (!reg.area_ptr)
+	if (copy_from_user(&area, u64_to_user_ptr(reg.area_ptr), sizeof(area)))
 		return -EFAULT;
 
 	ifq = io_zcrx_ifq_alloc(ctx);
@@ -110,6 +192,10 @@  int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
 	if (ret)
 		goto err;
 
+	ret = io_zcrx_create_area(ctx, ifq, &ifq->area, &area);
+	if (ret)
+		goto err;
+
 	ifq->rq_entries = reg.rq_entries;
 	ifq->if_rxq = reg.if_rxq;
 
@@ -124,7 +210,10 @@  int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
 		ret = -EFAULT;
 		goto err;
 	}
-
+	if (copy_to_user(u64_to_user_ptr(reg.area_ptr), &area, sizeof(area))) {
+		ret = -EFAULT;
+		goto err;
+	}
 	ctx->ifq = ifq;
 	return 0;
 err:
diff --git a/io_uring/zcrx.h b/io_uring/zcrx.h
index 178c515fea04..07742c0cfcf3 100644
--- a/io_uring/zcrx.h
+++ b/io_uring/zcrx.h
@@ -3,10 +3,26 @@ 
 #define IOU_ZC_RX_H
 
 #include <linux/io_uring_types.h>
+#include <net/page_pool/types.h>
+
+struct io_zcrx_area {
+	struct net_iov_area	nia;
+	struct io_zcrx_ifq	*ifq;
+
+	u16			area_id;
+	struct page		**pages;
+
+	/* freelist */
+	spinlock_t		freelist_lock ____cacheline_aligned_in_smp;
+	u32			free_count;
+	u32			*freelist;
+};
 
 struct io_zcrx_ifq {
 	struct io_ring_ctx		*ctx;
 	struct net_device		*dev;
+	struct io_zcrx_area		*area;
+
 	struct io_uring			*rq_ring;
 	struct io_uring_zcrx_rqe 	*rqes;
 	u32				rq_entries;