xsk: Introduce AF_XDP buffer allocation API

In order to simplify AF_XDP zero-copy enablement for NIC driver
developers, a new AF_XDP buffer allocation API is added. The
implementation is based on a single core (single producer/consumer)
buffer pool for the AF_XDP UMEM.

A buffer is allocated using the xsk_buff_alloc() function, and
returned using xsk_buff_free(). If a buffer is disassociated with the
pool, e.g. when a buffer is passed to an AF_XDP socket, a buffer is
said to be released. Currently, the release function is only used by
the AF_XDP internals and not visible to the driver.

Drivers using this API should register the XDP memory model with the
new MEM_TYPE_XSK_BUFF_POOL type.

The API is defined in net/xdp_sock_drv.h.

The buffer type is struct xdp_buff, and follows the lifetime of
regular xdp_buffs, i.e.  the lifetime of an xdp_buff is restricted to
a NAPI context. In other words, the API is not replacing xdp_frames.

In addition to introducing the API and implementations, the AF_XDP
core is migrated to use the new APIs.

rfc->v1: Fixed build errors/warnings for m68k and riscv. (kbuild test
         robot)
         Added headroom/chunk size getter. (Maxim/Björn)

v1->v2: Swapped SoBs. (Maxim)

v2->v3: Initialize struct xdp_buff member frame_sz. (Björn)
        Add API to query the DMA address of a frame. (Maxim)
        Do DMA sync for CPU till the end of the frame to handle
        possible growth (frame_sz). (Maxim)
Signed-off-by: NBjörn Töpel <bjorn.topel@intel.com>
Signed-off-by: NMaxim Mikityanskiy <maximmi@mellanox.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200520192103.355233-6-bjorn.topel@gmail.com

include/net/xdp.h

@@ -40,6 +40,7 @@ enum xdp_mem_type {
 	MEM_TYPE_PAGE_ORDER0,     /* Orig XDP full page model */
 	MEM_TYPE_PAGE_POOL,
 	MEM_TYPE_ZERO_COPY,
+	MEM_TYPE_XSK_BUFF_POOL,
 	MEM_TYPE_MAX,
 };
 
@@ -119,7 +120,8 @@ struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp)
 	int metasize;
 	int headroom;
 
-	if (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY)
+	if (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY ||
+	    xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL)
 		return xdp_convert_zc_to_xdp_frame(xdp);
 
 	/* Assure headroom is available for storing info */

include/net/xdp_sock.h

@@ -31,11 +31,13 @@ struct xdp_umem_fq_reuse {
 struct xdp_umem {
 	struct xsk_queue *fq;
 	struct xsk_queue *cq;
+	struct xsk_buff_pool *pool;
 	struct xdp_umem_page *pages;
 	u64 chunk_mask;
 	u64 size;
 	u32 headroom;
 	u32 chunk_size_nohr;
+	u32 chunk_size;
 	struct user_struct *user;
 	refcount_t users;
 	struct work_struct work;

include/net/xdp_sock_drv.h

@@ -7,6 +7,7 @@
 #define _LINUX_XDP_SOCK_DRV_H
 
 #include <net/xdp_sock.h>
+#include <net/xsk_buff_pool.h>
 
 #ifdef CONFIG_XDP_SOCKETS
 
@@ -101,6 +102,94 @@ static inline u32 xsk_umem_xdp_frame_sz(struct xdp_umem *umem)
 	return umem->chunk_size_nohr;
 }
 
+static inline u32 xsk_umem_get_headroom(struct xdp_umem *umem)
+{
+	return XDP_PACKET_HEADROOM + umem->headroom;
+}
+
+static inline u32 xsk_umem_get_chunk_size(struct xdp_umem *umem)
+{
+	return umem->chunk_size;
+}
+
+static inline u32 xsk_umem_get_rx_frame_size(struct xdp_umem *umem)
+{
+	return xsk_umem_get_chunk_size(umem) - xsk_umem_get_headroom(umem);
+}
+
+static inline void xsk_buff_set_rxq_info(struct xdp_umem *umem,
+					 struct xdp_rxq_info *rxq)
+{
+	xp_set_rxq_info(umem->pool, rxq);
+}
+
+static inline void xsk_buff_dma_unmap(struct xdp_umem *umem,
+				      unsigned long attrs)
+{
+	xp_dma_unmap(umem->pool, attrs);
+}
+
+static inline int xsk_buff_dma_map(struct xdp_umem *umem, struct device *dev,
+				   unsigned long attrs)
+{
+	return xp_dma_map(umem->pool, dev, attrs, umem->pgs, umem->npgs);
+}
+
+static inline dma_addr_t xsk_buff_xdp_get_dma(struct xdp_buff *xdp)
+{
+	struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);
+
+	return xp_get_dma(xskb);
+}
+
+static inline dma_addr_t xsk_buff_xdp_get_frame_dma(struct xdp_buff *xdp)
+{
+	struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);
+
+	return xp_get_frame_dma(xskb);
+}
+
+static inline struct xdp_buff *xsk_buff_alloc(struct xdp_umem *umem)
+{
+	return xp_alloc(umem->pool);
+}
+
+static inline bool xsk_buff_can_alloc(struct xdp_umem *umem, u32 count)
+{
+	return xp_can_alloc(umem->pool, count);
+}
+
+static inline void xsk_buff_free(struct xdp_buff *xdp)
+{
+	struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);
+
+	xp_free(xskb);
+}
+
+static inline dma_addr_t xsk_buff_raw_get_dma(struct xdp_umem *umem, u64 addr)
+{
+	return xp_raw_get_dma(umem->pool, addr);
+}
+
+static inline void *xsk_buff_raw_get_data(struct xdp_umem *umem, u64 addr)
+{
+	return xp_raw_get_data(umem->pool, addr);
+}
+
+static inline void xsk_buff_dma_sync_for_cpu(struct xdp_buff *xdp)
+{
+	struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);
+
+	xp_dma_sync_for_cpu(xskb);
+}
+
+static inline void xsk_buff_raw_dma_sync_for_device(struct xdp_umem *umem,
+						    dma_addr_t dma,
+						    size_t size)
+{
+	xp_dma_sync_for_device(umem->pool, dma, size);
+}
+
 #else
 
 static inline bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt)
@@ -212,6 +301,81 @@ static inline u32 xsk_umem_xdp_frame_sz(struct xdp_umem *umem)
 	return 0;
 }
 
+static inline u32 xsk_umem_get_headroom(struct xdp_umem *umem)
+{
+	return 0;
+}
+
+static inline u32 xsk_umem_get_chunk_size(struct xdp_umem *umem)
+{
+	return 0;
+}
+
+static inline u32 xsk_umem_get_rx_frame_size(struct xdp_umem *umem)
+{
+	return 0;
+}
+
+static inline void xsk_buff_set_rxq_info(struct xdp_umem *umem,
+					 struct xdp_rxq_info *rxq)
+{
+}
+
+static inline void xsk_buff_dma_unmap(struct xdp_umem *umem,
+				      unsigned long attrs)
+{
+}
+
+static inline int xsk_buff_dma_map(struct xdp_umem *umem, struct device *dev,
+				   unsigned long attrs)
+{
+	return 0;
+}
+
+static inline dma_addr_t xsk_buff_xdp_get_dma(struct xdp_buff *xdp)
+{
+	return 0;
+}
+
+static inline dma_addr_t xsk_buff_xdp_get_frame_dma(struct xdp_buff *xdp)
+{
+	return 0;
+}
+
+static inline struct xdp_buff *xsk_buff_alloc(struct xdp_umem *umem)
+{
+	return NULL;
+}
+
+static inline bool xsk_buff_can_alloc(struct xdp_umem *umem, u32 count)
+{
+	return false;
+}
+
+static inline void xsk_buff_free(struct xdp_buff *xdp)
+{
+}
+
+static inline dma_addr_t xsk_buff_raw_get_dma(struct xdp_umem *umem, u64 addr)
+{
+	return 0;
+}
+
+static inline void *xsk_buff_raw_get_data(struct xdp_umem *umem, u64 addr)
+{
+	return NULL;
+}
+
+static inline void xsk_buff_dma_sync_for_cpu(struct xdp_buff *xdp)
+{
+}
+
+static inline void xsk_buff_raw_dma_sync_for_device(struct xdp_umem *umem,
+						    dma_addr_t dma,
+						    size_t size)
+{
+}
+
 #endif /* CONFIG_XDP_SOCKETS */
 
 #endif /* _LINUX_XDP_SOCK_DRV_H */

include/net/xsk_buff_pool.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright(c) 2020 Intel Corporation. */
+
+#ifndef XSK_BUFF_POOL_H_
+#define XSK_BUFF_POOL_H_
+
+#include <linux/types.h>
+#include <linux/dma-mapping.h>
+#include <net/xdp.h>
+
+struct xsk_buff_pool;
+struct xdp_rxq_info;
+struct xsk_queue;
+struct xdp_desc;
+struct device;
+struct page;
+
+struct xdp_buff_xsk {
+	struct xdp_buff xdp;
+	dma_addr_t dma;
+	dma_addr_t frame_dma;
+	struct xsk_buff_pool *pool;
+	bool unaligned;
+	u64 orig_addr;
+	struct list_head free_list_node;
+};
+
+/* AF_XDP core. */
+struct xsk_buff_pool *xp_create(struct page **pages, u32 nr_pages, u32 chunks,
+				u32 chunk_size, u32 headroom, u64 size,
+				bool unaligned);
+void xp_set_fq(struct xsk_buff_pool *pool, struct xsk_queue *fq);
+void xp_destroy(struct xsk_buff_pool *pool);
+void xp_release(struct xdp_buff_xsk *xskb);
+u64 xp_get_handle(struct xdp_buff_xsk *xskb);
+bool xp_validate_desc(struct xsk_buff_pool *pool, struct xdp_desc *desc);
+
+/* AF_XDP, and XDP core. */
+void xp_free(struct xdp_buff_xsk *xskb);
+
+/* AF_XDP ZC drivers, via xdp_sock_buff.h */
+void xp_set_rxq_info(struct xsk_buff_pool *pool, struct xdp_rxq_info *rxq);
+int xp_dma_map(struct xsk_buff_pool *pool, struct device *dev,
+	       unsigned long attrs, struct page **pages, u32 nr_pages);
+void xp_dma_unmap(struct xsk_buff_pool *pool, unsigned long attrs);
+struct xdp_buff *xp_alloc(struct xsk_buff_pool *pool);
+bool xp_can_alloc(struct xsk_buff_pool *pool, u32 count);
+void *xp_raw_get_data(struct xsk_buff_pool *pool, u64 addr);
+dma_addr_t xp_raw_get_dma(struct xsk_buff_pool *pool, u64 addr);
+dma_addr_t xp_get_dma(struct xdp_buff_xsk *xskb);
+dma_addr_t xp_get_frame_dma(struct xdp_buff_xsk *xskb);
+void xp_dma_sync_for_cpu(struct xdp_buff_xsk *xskb);
+void xp_dma_sync_for_device(struct xsk_buff_pool *pool, dma_addr_t dma,
+			    size_t size);
+
+#endif /* XSK_BUFF_POOL_H_ */

include/trace/events/xdp.h

@@ -287,7 +287,8 @@ TRACE_EVENT(xdp_devmap_xmit,
 	FN(PAGE_SHARED)		\
 	FN(PAGE_ORDER0)		\
 	FN(PAGE_POOL)		\
-	FN(ZERO_COPY)
+	FN(ZERO_COPY)		\
+	FN(XSK_BUFF_POOL)
 
 #define __MEM_TYPE_TP_FN(x)	\
 	TRACE_DEFINE_ENUM(MEM_TYPE_##x);

net/core/xdp.c

@@ -17,6 +17,7 @@
 #include <net/xdp.h>
 #include <net/xdp_priv.h> /* struct xdp_mem_allocator */
 #include <trace/events/xdp.h>
+#include <net/xdp_sock_drv.h>
 
 #define REG_STATE_NEW		0x0
 #define REG_STATE_REGISTERED	0x1
@@ -361,7 +362,7 @@ EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);
  * of xdp_frames/pages in those cases.
  */
 static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
-			 unsigned long handle)
+			 unsigned long handle, struct xdp_buff *xdp)
 {
 	struct xdp_mem_allocator *xa;
 	struct page *page;
@@ -390,6 +391,11 @@ static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
 		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
 		xa->zc_alloc->free(xa->zc_alloc, handle);
 		rcu_read_unlock();
+		break;
+	case MEM_TYPE_XSK_BUFF_POOL:
+		/* NB! Only valid from an xdp_buff! */
+		xsk_buff_free(xdp);
+		break;
 	default:
 		/* Not possible, checked in xdp_rxq_info_reg_mem_model() */
 		break;
@@ -398,19 +404,19 @@ static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
 
 void xdp_return_frame(struct xdp_frame *xdpf)
 {
-	__xdp_return(xdpf->data, &xdpf->mem, false, 0);
+	__xdp_return(xdpf->data, &xdpf->mem, false, 0, NULL);
 }
 EXPORT_SYMBOL_GPL(xdp_return_frame);
 
 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
 {
-	__xdp_return(xdpf->data, &xdpf->mem, true, 0);
+	__xdp_return(xdpf->data, &xdpf->mem, true, 0, NULL);
 }
 EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
 
 void xdp_return_buff(struct xdp_buff *xdp)
 {
-	__xdp_return(xdp->data, &xdp->rxq->mem, true, xdp->handle);
+	__xdp_return(xdp->data, &xdp->rxq->mem, true, xdp->handle, xdp);
 }
 EXPORT_SYMBOL_GPL(xdp_return_buff);
 

net/xdp/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_XDP_SOCKETS) += xsk.o xdp_umem.o xsk_queue.o xskmap.o
+obj-$(CONFIG_XDP_SOCKETS) += xsk_buff_pool.o
 obj-$(CONFIG_XDP_SOCKETS_DIAG) += xsk_diag.o

net/xdp/xdp_umem.c

@@ -245,7 +245,7 @@ static void xdp_umem_release(struct xdp_umem *umem)
 	}
 
 	xsk_reuseq_destroy(umem);
-
+	xp_destroy(umem->pool);
 	xdp_umem_unmap_pages(umem);
 	xdp_umem_unpin_pages(umem);
 
@@ -390,6 +390,7 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
 	umem->size = size;
 	umem->headroom = headroom;
 	umem->chunk_size_nohr = chunk_size - headroom;
+	umem->chunk_size = chunk_size;
 	umem->npgs = size / PAGE_SIZE;
 	umem->pgs = NULL;
 	umem->user = NULL;
@@ -415,11 +416,21 @@ static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
 	}
 
 	err = xdp_umem_map_pages(umem);
-	if (!err)
-		return 0;
+	if (err)
+		goto out_pages;
 
-	kvfree(umem->pages);
+	umem->pool = xp_create(umem->pgs, umem->npgs, chunks, chunk_size,
+			       headroom, size, unaligned_chunks);
+	if (!umem->pool) {
+		err = -ENOMEM;
+		goto out_unmap;
+	}
+	return 0;
 
+out_unmap:
+	xdp_umem_unmap_pages(umem);
+out_pages:
+	kvfree(umem->pages);
 out_pin:
 	xdp_umem_unpin_pages(umem);
 out_account:

net/xdp/xsk.c

@@ -117,76 +117,67 @@ bool xsk_umem_uses_need_wakeup(struct xdp_umem *umem)
 }
 EXPORT_SYMBOL(xsk_umem_uses_need_wakeup);
 
-/* If a buffer crosses a page boundary, we need to do 2 memcpy's, one for
- * each page. This is only required in copy mode.
- */
-static void __xsk_rcv_memcpy(struct xdp_umem *umem, u64 addr, void *from_buf,
-			     u32 len, u32 metalen)
+static int __xsk_rcv_zc(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
 {
-	void *to_buf = xdp_umem_get_data(umem, addr);
-
-	addr = xsk_umem_add_offset_to_addr(addr);
-	if (xskq_cons_crosses_non_contig_pg(umem, addr, len + metalen)) {
-		void *next_pg_addr = umem->pages[(addr >> PAGE_SHIFT) + 1].addr;
-		u64 page_start = addr & ~(PAGE_SIZE - 1);
-		u64 first_len = PAGE_SIZE - (addr - page_start);
-
-		memcpy(to_buf, from_buf, first_len);
-		memcpy(next_pg_addr, from_buf + first_len,
-		       len + metalen - first_len);
+	struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);
+	u64 addr;
+	int err;
 
-		return;
+	addr = xp_get_handle(xskb);
+	err = xskq_prod_reserve_desc(xs->rx, addr, len);
+	if (err) {
+		xs->rx_dropped++;
+		return err;
 	}
 
-	memcpy(to_buf, from_buf, len + metalen);
+	xp_release(xskb);
+	return 0;
 }
 
-static int __xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
+static void xsk_copy_xdp(struct xdp_buff *to, struct xdp_buff *from, u32 len)
 {
-	u64 offset = xs->umem->headroom;
-	u64 addr, memcpy_addr;
-	void *from_buf;
+	void *from_buf, *to_buf;
 	u32 metalen;
-	int err;
-
-	if (!xskq_cons_peek_addr(xs->umem->fq, &addr, xs->umem) ||
-	    len > xs->umem->chunk_size_nohr - XDP_PACKET_HEADROOM) {
-		xs->rx_dropped++;
-		return -ENOSPC;
-	}
 
-	if (unlikely(xdp_data_meta_unsupported(xdp))) {
-		from_buf = xdp->data;
+	if (unlikely(xdp_data_meta_unsupported(from))) {
+		from_buf = from->data;
+		to_buf = to->data;
 		metalen = 0;
 	} else {
-		from_buf = xdp->data_meta;
-		metalen = xdp->data - xdp->data_meta;
+		from_buf = from->data_meta;
+		metalen = from->data - from->data_meta;
+		to_buf = to->data - metalen;
 	}
 
-	memcpy_addr = xsk_umem_adjust_offset(xs->umem, addr, offset);
-	__xsk_rcv_memcpy(xs->umem, memcpy_addr, from_buf, len, metalen);
-
-	offset += metalen;
-	addr = xsk_umem_adjust_offset(xs->umem, addr, offset);
-	err = xskq_prod_reserve_desc(xs->rx, addr, len);
-	if (!err) {
-		xskq_cons_release(xs->umem->fq);
-		xdp_return_buff(xdp);
-		return 0;
-	}
-
-	xs->rx_dropped++;
-	return err;
+	memcpy(to_buf, from_buf, len + metalen);
 }
 
-static int __xsk_rcv_zc(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
+static int __xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len,
+		     bool explicit_free)
 {
-	int err = xskq_prod_reserve_desc(xs->rx, xdp->handle, len);
+	struct xdp_buff *xsk_xdp;
+	int err;
 
-	if (err)
+	if (len > xsk_umem_get_rx_frame_size(xs->umem)) {
+		xs->rx_dropped++;
+		return -ENOSPC;
+	}
+
+	xsk_xdp = xsk_buff_alloc(xs->umem);
+	if (!xsk_xdp) {
 		xs->rx_dropped++;
+		return -ENOSPC;
+	}
 
-	return err;
+	xsk_copy_xdp(xsk_xdp, xdp, len);
+	err = __xsk_rcv_zc(xs, xsk_xdp, len);
+	if (err) {
+		xsk_buff_free(xsk_xdp);
+		return err;
+	}
+	if (explicit_free)
+		xdp_return_buff(xdp);
+	return 0;
 }
 
 static bool xsk_is_bound(struct xdp_sock *xs)
@@ -199,7 +190,8 @@ static bool xsk_is_bound(struct xdp_sock *xs)
 	return false;
 }
 
-static int xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
+static int xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp,
+		   bool explicit_free)
 {
 	u32 len;
 
@@ -211,8 +203,10 @@ static int xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
 
 	len = xdp->data_end - xdp->data;
 
-	return (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY) ?
-		__xsk_rcv_zc(xs, xdp, len) : __xsk_rcv(xs, xdp, len);
+	return xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY ||
+		xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL ?
+		__xsk_rcv_zc(xs, xdp, len) :
+		__xsk_rcv(xs, xdp, len, explicit_free);
 }
 
 static void xsk_flush(struct xdp_sock *xs)
@@ -224,46 +218,11 @@ static void xsk_flush(struct xdp_sock *xs)
 
 int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
 {
-	u32 metalen = xdp->data - xdp->data_meta;
-	u32 len = xdp->data_end - xdp->data;
-	u64 offset = xs->umem->headroom;
-	void *buffer;
-	u64 addr;
 	int err;
 
 	spin_lock_bh(&xs->rx_lock);
-
-	if (xs->dev != xdp->rxq->dev || xs->queue_id != xdp->rxq->queue_index) {
-		err = -EINVAL;
-		goto out_unlock;
-	}
-
-	if (!xskq_cons_peek_addr(xs->umem->fq, &addr, xs->umem) ||
-	    len > xs->umem->chunk_size_nohr - XDP_PACKET_HEADROOM) {
-		err = -ENOSPC;
-		goto out_drop;
-	}
-
-	addr = xsk_umem_adjust_offset(xs->umem, addr, offset);
-	buffer = xdp_umem_get_data(xs->umem, addr);
-	memcpy(buffer, xdp->data_meta, len + metalen);
-
-	addr = xsk_umem_adjust_offset(xs->umem, addr, metalen);
-	err = xskq_prod_reserve_desc(xs->rx, addr, len);
-	if (err)
-		goto out_drop;
-
-	xskq_cons_release(xs->umem->fq);
-	xskq_prod_submit(xs->rx);
-
-	spin_unlock_bh(&xs->rx_lock);
-
-	xs->sk.sk_data_ready(&xs->sk);
-	return 0;
-
-out_drop:
-	xs->rx_dropped++;
-out_unlock:
+	err = xsk_rcv(xs, xdp, false);
+	xsk_flush(xs);
 	spin_unlock_bh(&xs->rx_lock);
 	return err;
 }
@@ -273,7 +232,7 @@ int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp)
 	struct list_head *flush_list = this_cpu_ptr(&xskmap_flush_list);
 	int err;
 
-	err = xsk_rcv(xs, xdp);
+	err = xsk_rcv(xs, xdp, true);
 	if (err)
 		return err;
 
@@ -404,7 +363,7 @@ static int xsk_generic_xmit(struct sock *sk)
 
 		skb_put(skb, len);
 		addr = desc.addr;
-		buffer = xdp_umem_get_data(xs->umem, addr);
+		buffer = xsk_buff_raw_get_data(xs->umem, addr);
 		err = skb_store_bits(skb, 0, buffer, len);
 		/* This is the backpressure mechanism for the Tx path.
 		 * Reserve space in the completion queue and only proceed
@@ -860,6 +819,8 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
 		q = (optname == XDP_UMEM_FILL_RING) ? &xs->umem->fq :
 			&xs->umem->cq;
 		err = xsk_init_queue(entries, q, true);
+		if (optname == XDP_UMEM_FILL_RING)
+			xp_set_fq(xs->umem->pool, *q);
 		mutex_unlock(&xs->mutex);
 		return err;
 	}

net/xdp/xsk_buff_pool.c

+// SPDX-License-Identifier: GPL-2.0
+
+#include <net/xsk_buff_pool.h>
+#include <net/xdp_sock.h>
+#include <linux/dma-direct.h>
+#include <linux/dma-noncoherent.h>
+#include <linux/swiotlb.h>
+
+#include "xsk_queue.h"
+
+struct xsk_buff_pool {
+	struct xsk_queue *fq;
+	struct list_head free_list;
+	dma_addr_t *dma_pages;
+	struct xdp_buff_xsk *heads;
+	u64 chunk_mask;
+	u64 addrs_cnt;
+	u32 free_list_cnt;
+	u32 dma_pages_cnt;
+	u32 heads_cnt;
+	u32 free_heads_cnt;
+	u32 headroom;
+	u32 chunk_size;
+	u32 frame_len;
+	bool cheap_dma;
+	bool unaligned;
+	void *addrs;
+	struct device *dev;
+	struct xdp_buff_xsk *free_heads[];
+};
+
+static void xp_addr_unmap(struct xsk_buff_pool *pool)
+{
+	vunmap(pool->addrs);
+}
+
+static int xp_addr_map(struct xsk_buff_pool *pool,
+		       struct page **pages, u32 nr_pages)
+{
+	pool->addrs = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
+	if (!pool->addrs)
+		return -ENOMEM;
+	return 0;
+}
+
+void xp_destroy(struct xsk_buff_pool *pool)
+{
+	if (!pool)
+		return;
+
+	xp_addr_unmap(pool);
+	kvfree(pool->heads);
+	kvfree(pool);
+}
+
+struct xsk_buff_pool *xp_create(struct page **pages, u32 nr_pages, u32 chunks,
+				u32 chunk_size, u32 headroom, u64 size,
+				bool unaligned)
+{
+	struct xsk_buff_pool *pool;
+	struct xdp_buff_xsk *xskb;
+	int err;
+	u32 i;
+
+	pool = kvzalloc(struct_size(pool, free_heads, chunks), GFP_KERNEL);
+	if (!pool)
+		goto out;
+
+	pool->heads = kvcalloc(chunks, sizeof(*pool->heads), GFP_KERNEL);
+	if (!pool->heads)
+		goto out;
+
+	pool->chunk_mask = ~((u64)chunk_size - 1);
+	pool->addrs_cnt = size;
+	pool->heads_cnt = chunks;
+	pool->free_heads_cnt = chunks;
+	pool->headroom = headroom;
+	pool->chunk_size = chunk_size;
+	pool->cheap_dma = true;
+	pool->unaligned = unaligned;
+	pool->frame_len = chunk_size - headroom - XDP_PACKET_HEADROOM;
+	INIT_LIST_HEAD(&pool->free_list);
+
+	for (i = 0; i < pool->free_heads_cnt; i++) {
+		xskb = &pool->heads[i];
+		xskb->pool = pool;
+		xskb->xdp.frame_sz = chunk_size - headroom;
+		pool->free_heads[i] = xskb;
+	}
+
+	err = xp_addr_map(pool, pages, nr_pages);
+	if (!err)
+		return pool;
+
+out:
+	xp_destroy(pool);
+	return NULL;
+}
+
+void xp_set_fq(struct xsk_buff_pool *pool, struct xsk_queue *fq)
+{
+	pool->fq = fq;
+}
+
+void xp_set_rxq_info(struct xsk_buff_pool *pool, struct xdp_rxq_info *rxq)
+{
+	u32 i;
+
+	for (i = 0; i < pool->heads_cnt; i++)
+		pool->heads[i].xdp.rxq = rxq;
+}
+EXPORT_SYMBOL(xp_set_rxq_info);
+
+void xp_dma_unmap(struct xsk_buff_pool *pool, unsigned long attrs)
+{
+	dma_addr_t *dma;
+	u32 i;
+
+	if (pool->dma_pages_cnt == 0)
+		return;
+
+	for (i = 0; i < pool->dma_pages_cnt; i++) {
+		dma = &pool->dma_pages[i];
+		if (*dma) {
+			dma_unmap_page_attrs(pool->dev, *dma, PAGE_SIZE,
+					     DMA_BIDIRECTIONAL, attrs);
+			*dma = 0;
+		}
+	}
+
+	kvfree(pool->dma_pages);
+	pool->dma_pages_cnt = 0;
+	pool->dev = NULL;
+}
+EXPORT_SYMBOL(xp_dma_unmap);
+
+static void xp_check_dma_contiguity(struct xsk_buff_pool *pool)
+{
+	u32 i;
+
+	for (i = 0; i < pool->dma_pages_cnt - 1; i++) {
+		if (pool->dma_pages[i] + PAGE_SIZE == pool->dma_pages[i + 1])
+			pool->dma_pages[i] |= XSK_NEXT_PG_CONTIG_MASK;
+		else
+			pool->dma_pages[i] &= ~XSK_NEXT_PG_CONTIG_MASK;
+	}
+}
+
+static bool __maybe_unused xp_check_swiotlb_dma(struct xsk_buff_pool *pool)
+{
+#if defined(CONFIG_SWIOTLB)
+	phys_addr_t paddr;
+	u32 i;
+
+	for (i = 0; i < pool->dma_pages_cnt; i++) {
+		paddr = dma_to_phys(pool->dev, pool->dma_pages[i]);
+		if (is_swiotlb_buffer(paddr))
+			return false;
+	}
+#endif
+	return true;
+}
+
+static bool xp_check_cheap_dma(struct xsk_buff_pool *pool)
+{
+#if defined(CONFIG_HAS_DMA)
+	const struct dma_map_ops *ops = get_dma_ops(pool->dev);
+
+	if (ops) {
+		return !ops->sync_single_for_cpu &&
+			!ops->sync_single_for_device;
+	}
+
+	if (!dma_is_direct(ops))
+		return false;
+
+	if (!xp_check_swiotlb_dma(pool))
+		return false;
+
+	if (!dev_is_dma_coherent(pool->dev)) {
+#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) ||		\
+	defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL) ||	\
+	defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE)
+		return false;
+#endif
+	}
+#endif
+	return true;
+}
+
+int xp_dma_map(struct xsk_buff_pool *pool, struct device *dev,
+	       unsigned long attrs, struct page **pages, u32 nr_pages)
+{
+	dma_addr_t dma;
+	u32 i;
+
+	pool->dma_pages = kvcalloc(nr_pages, sizeof(*pool->dma_pages),
+				   GFP_KERNEL);
+	if (!pool->dma_pages)
+		return -ENOMEM;
+
+	pool->dev = dev;
+	pool->dma_pages_cnt = nr_pages;
+
+	for (i = 0; i < pool->dma_pages_cnt; i++) {
+		dma = dma_map_page_attrs(dev, pages[i], 0, PAGE_SIZE,
+					 DMA_BIDIRECTIONAL, attrs);
+		if (dma_mapping_error(dev, dma)) {
+			xp_dma_unmap(pool, attrs);
+			return -ENOMEM;
+		}
+		pool->dma_pages[i] = dma;
+	}
+
+	if (pool->unaligned)
+		xp_check_dma_contiguity(pool);
+
+	pool->dev = dev;
+	pool->cheap_dma = xp_check_cheap_dma(pool);
+	return 0;
+}
+EXPORT_SYMBOL(xp_dma_map);
+
+static bool xp_desc_crosses_non_contig_pg(struct xsk_buff_pool *pool,
+					  u64 addr, u32 len)
+{
+	bool cross_pg = (addr & (PAGE_SIZE - 1)) + len > PAGE_SIZE;
+
+	if (pool->dma_pages_cnt && cross_pg) {
+		return !(pool->dma_pages[addr >> PAGE_SHIFT] &
+			 XSK_NEXT_PG_CONTIG_MASK);
+	}
+	return false;
+}
+
+static bool xp_addr_crosses_non_contig_pg(struct xsk_buff_pool *pool,
+					  u64 addr)
+{
+	return xp_desc_crosses_non_contig_pg(pool, addr, pool->chunk_size);
+}
+
+void xp_release(struct xdp_buff_xsk *xskb)
+{
+	xskb->pool->free_heads[xskb->pool->free_heads_cnt++] = xskb;
+}
+
+static u64 xp_aligned_extract_addr(struct xsk_buff_pool *pool, u64 addr)
+{
+	return addr & pool->chunk_mask;
+}
+
+static u64 xp_unaligned_extract_addr(u64 addr)
+{
+	return addr & XSK_UNALIGNED_BUF_ADDR_MASK;
+}
+
+static u64 xp_unaligned_extract_offset(u64 addr)
+{
+	return addr >> XSK_UNALIGNED_BUF_OFFSET_SHIFT;
+}
+
+static u64 xp_unaligned_add_offset_to_addr(u64 addr)
+{
+	return xp_unaligned_extract_addr(addr) +
+		xp_unaligned_extract_offset(addr);
+}
+
+static bool xp_check_unaligned(struct xsk_buff_pool *pool, u64 *addr)
+{
+	*addr = xp_unaligned_extract_addr(*addr);
+	if (*addr >= pool->addrs_cnt ||
+	    *addr + pool->chunk_size > pool->addrs_cnt ||
+	    xp_addr_crosses_non_contig_pg(pool, *addr))
+		return false;
+	return true;
+}
+
+static bool xp_check_aligned(struct xsk_buff_pool *pool, u64 *addr)
+{
+	*addr = xp_aligned_extract_addr(pool, *addr);
+	return *addr < pool->addrs_cnt;
+}
+
+static struct xdp_buff_xsk *__xp_alloc(struct xsk_buff_pool *pool)
+{
+	struct xdp_buff_xsk *xskb;
+	u64 addr;
+	bool ok;
+
+	if (pool->free_heads_cnt == 0)
+		return NULL;
+
+	xskb = pool->free_heads[--pool->free_heads_cnt];
+
+	for (;;) {
+		if (!xskq_cons_peek_addr_unchecked(pool->fq, &addr)) {
+			xp_release(xskb);
+			return NULL;
+		}
+
+		ok = pool->unaligned ? xp_check_unaligned(pool, &addr) :
+		     xp_check_aligned(pool, &addr);
+		if (!ok) {
+			pool->fq->invalid_descs++;
+			xskq_cons_release(pool->fq);
+			continue;
+		}
+		break;
+	}
+	xskq_cons_release(pool->fq);
+
+	xskb->orig_addr = addr;
+	xskb->xdp.data_hard_start = pool->addrs + addr + pool->headroom;
+	if (pool->dma_pages_cnt) {
+		xskb->frame_dma = (pool->dma_pages[addr >> PAGE_SHIFT] &
+				   ~XSK_NEXT_PG_CONTIG_MASK) +
+				  (addr & ~PAGE_MASK);
+		xskb->dma = xskb->frame_dma + pool->headroom +
+			    XDP_PACKET_HEADROOM;
+	}
+	return xskb;
+}
+
+struct xdp_buff *xp_alloc(struct xsk_buff_pool *pool)
+{
+	struct xdp_buff_xsk *xskb;
+
+	if (!pool->free_list_cnt) {
+		xskb = __xp_alloc(pool);
+		if (!xskb)
+			return NULL;
+	} else {
+		pool->free_list_cnt--;
+		xskb = list_first_entry(&pool->free_list, struct xdp_buff_xsk,
+					free_list_node);
+		list_del(&xskb->free_list_node);
+	}
+
+	xskb->xdp.data = xskb->xdp.data_hard_start + XDP_PACKET_HEADROOM;
+	xskb->xdp.data_meta = xskb->xdp.data;
+
+	if (!pool->cheap_dma) {
+		dma_sync_single_range_for_device(pool->dev, xskb->dma, 0,
+						 pool->frame_len,
+						 DMA_BIDIRECTIONAL);
+	}
+	return &xskb->xdp;
+}
+EXPORT_SYMBOL(xp_alloc);
+
+bool xp_can_alloc(struct xsk_buff_pool *pool, u32 count)
+{
+	if (pool->free_list_cnt >= count)
+		return true;
+	return xskq_cons_has_entries(pool->fq, count - pool->free_list_cnt);
+}
+EXPORT_SYMBOL(xp_can_alloc);
+
+void xp_free(struct xdp_buff_xsk *xskb)
+{
+	xskb->pool->free_list_cnt++;
+	list_add(&xskb->free_list_node, &xskb->pool->free_list);
+}
+EXPORT_SYMBOL(xp_free);
+
+static bool xp_aligned_validate_desc(struct xsk_buff_pool *pool,
+				     struct xdp_desc *desc)
+{
+	u64 chunk, chunk_end;
+
+	chunk = xp_aligned_extract_addr(pool, desc->addr);
+	chunk_end = xp_aligned_extract_addr(pool, desc->addr + desc->len);
+	if (chunk != chunk_end)
+		return false;
+
+	if (chunk >= pool->addrs_cnt)
+		return false;
+
+	if (desc->options)
+		return false;
+	return true;
+}
+
+static bool xp_unaligned_validate_desc(struct xsk_buff_pool *pool,
+				       struct xdp_desc *desc)
+{
+	u64 addr, base_addr;
+
+	base_addr = xp_unaligned_extract_addr(desc->addr);
+	addr = xp_unaligned_add_offset_to_addr(desc->addr);
+
+	if (desc->len > pool->chunk_size)
+		return false;
+
+	if (base_addr >= pool->addrs_cnt || addr >= pool->addrs_cnt ||
+	    xp_desc_crosses_non_contig_pg(pool, addr, desc->len))
+		return false;
+
+	if (desc->options)
+		return false;
+	return true;
+}
+
+bool xp_validate_desc(struct xsk_buff_pool *pool, struct xdp_desc *desc)
+{
+	return pool->unaligned ? xp_unaligned_validate_desc(pool, desc) :
+		xp_aligned_validate_desc(pool, desc);
+}
+
+u64 xp_get_handle(struct xdp_buff_xsk *xskb)
+{
+	u64 offset = xskb->xdp.data - xskb->xdp.data_hard_start;
+
+	offset += xskb->pool->headroom;
+	if (!xskb->pool->unaligned)
+		return xskb->orig_addr + offset;
+	return xskb->orig_addr + (offset << XSK_UNALIGNED_BUF_OFFSET_SHIFT);
+}
+
+void *xp_raw_get_data(struct xsk_buff_pool *pool, u64 addr)
+{
+	addr = pool->unaligned ? xp_unaligned_add_offset_to_addr(addr) : addr;
+	return pool->addrs + addr;
+}
+EXPORT_SYMBOL(xp_raw_get_data);
+
+dma_addr_t xp_raw_get_dma(struct xsk_buff_pool *pool, u64 addr)
+{
+	addr = pool->unaligned ? xp_unaligned_add_offset_to_addr(addr) : addr;
+	return (pool->dma_pages[addr >> PAGE_SHIFT] &
+		~XSK_NEXT_PG_CONTIG_MASK) +
+		(addr & ~PAGE_MASK);
+}
+EXPORT_SYMBOL(xp_raw_get_dma);
+
+dma_addr_t xp_get_dma(struct xdp_buff_xsk *xskb)
+{
+	return xskb->dma;
+}
+EXPORT_SYMBOL(xp_get_dma);
+
+dma_addr_t xp_get_frame_dma(struct xdp_buff_xsk *xskb)
+{
+	return xskb->frame_dma;
+}
+EXPORT_SYMBOL(xp_get_frame_dma);
+
+void xp_dma_sync_for_cpu(struct xdp_buff_xsk *xskb)
+{
+	if (xskb->pool->cheap_dma)
+		return;
+
+	dma_sync_single_range_for_cpu(xskb->pool->dev, xskb->dma, 0,
+				      xskb->pool->frame_len, DMA_BIDIRECTIONAL);
+}
+EXPORT_SYMBOL(xp_dma_sync_for_cpu);
+
+void xp_dma_sync_for_device(struct xsk_buff_pool *pool, dma_addr_t dma,
+			    size_t size)
+{
+	if (pool->cheap_dma)
+		return;
+
+	dma_sync_single_range_for_device(pool->dev, dma, 0,
+					 size, DMA_BIDIRECTIONAL);
+}
+EXPORT_SYMBOL(xp_dma_sync_for_device);

net/xdp/xsk_diag.c

@@ -56,7 +56,7 @@ static int xsk_diag_put_umem(const struct xdp_sock *xs, struct sk_buff *nlskb)
 	du.id = umem->id;
 	du.size = umem->size;
 	du.num_pages = umem->npgs;
-	du.chunk_size = umem->chunk_size_nohr + umem->headroom;
+	du.chunk_size = umem->chunk_size;
 	du.headroom = umem->headroom;
 	du.ifindex = umem->dev ? umem->dev->ifindex : 0;
 	du.queue_id = umem->queue_id;

net/xdp/xsk_queue.h

@@ -9,6 +9,7 @@
 #include <linux/types.h>
 #include <linux/if_xdp.h>
 #include <net/xdp_sock.h>
+#include <net/xsk_buff_pool.h>
 
 #include "xsk.h"
 
@@ -172,31 +173,45 @@ static inline bool xskq_cons_read_addr(struct xsk_queue *q, u64 *addr,
 	return false;
 }
 
-static inline bool xskq_cons_is_valid_desc(struct xsk_queue *q,
-					   struct xdp_desc *d,
-					   struct xdp_umem *umem)
+static inline bool xskq_cons_read_addr_aligned(struct xsk_queue *q, u64 *addr)
 {
-	if (umem->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG) {
-		if (!xskq_cons_is_valid_unaligned(q, d->addr, d->len, umem))
-			return false;
+	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
 
-		if (d->len > umem->chunk_size_nohr || d->options) {
-			q->invalid_descs++;
-			return false;
-		}
+	while (q->cached_cons != q->cached_prod) {
+		u32 idx = q->cached_cons & q->ring_mask;
+
+		*addr = ring->desc[idx];
+		if (xskq_cons_is_valid_addr(q, *addr))
+			return true;
 
+		q->cached_cons++;
+	}
+
+	return false;
+}
+
+static inline bool xskq_cons_read_addr_unchecked(struct xsk_queue *q, u64 *addr)
+{
+	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
+
+	if (q->cached_cons != q->cached_prod) {
+		u32 idx = q->cached_cons & q->ring_mask;
+
+		*addr = ring->desc[idx];
 		return true;
 	}
 
-	if (!xskq_cons_is_valid_addr(q, d->addr))
-		return false;
+	return false;
+}
 
-	if (((d->addr + d->len) & q->chunk_mask) != (d->addr & q->chunk_mask) ||
-	    d->options) {
+static inline bool xskq_cons_is_valid_desc(struct xsk_queue *q,
+					   struct xdp_desc *d,
+					   struct xdp_umem *umem)
+{
+	if (!xp_validate_desc(umem->pool, d)) {
 		q->invalid_descs++;
 		return false;
 	}
-
 	return true;
 }
 
@@ -260,6 +275,20 @@ static inline bool xskq_cons_peek_addr(struct xsk_queue *q, u64 *addr,
 	return xskq_cons_read_addr(q, addr, umem);
 }
 
+static inline bool xskq_cons_peek_addr_aligned(struct xsk_queue *q, u64 *addr)
+{
+	if (q->cached_prod == q->cached_cons)
+		xskq_cons_get_entries(q);
+	return xskq_cons_read_addr_aligned(q, addr);
+}
+
+static inline bool xskq_cons_peek_addr_unchecked(struct xsk_queue *q, u64 *addr)
+{
+	if (q->cached_prod == q->cached_cons)
+		xskq_cons_get_entries(q);
+	return xskq_cons_read_addr_unchecked(q, addr);
+}
+
 static inline bool xskq_cons_peek_desc(struct xsk_queue *q,
 				       struct xdp_desc *desc,
 				       struct xdp_umem *umem)