@@ -6,7 +6,7 @@
/* Rx buffer management */
/**
- * libeth_rx_hw_len - get the actual buffer size to be passed to HW
+ * libeth_rx_hw_len_mtu - get the actual buffer size to be passed to HW
* @pp: &page_pool_params of the netdev to calculate the size for
* @max_len: maximum buffer size for a single descriptor
*
@@ -14,7 +14,7 @@
* MTU the @dev has, HW required alignment, minimum and maximum allowed values,
* and system's page size.
*/
-static u32 libeth_rx_hw_len(const struct page_pool_params *pp, u32 max_len)
+static u32 libeth_rx_hw_len_mtu(const struct page_pool_params *pp, u32 max_len)
{
u32 len;
@@ -26,6 +26,118 @@ static u32 libeth_rx_hw_len(const struct page_pool_params *pp, u32 max_len)
return len;
}
+/**
+ * libeth_rx_hw_len_truesize - get the short buffer size to be passed to HW
+ * @pp: &page_pool_params of the netdev to calculate the size for
+ * @max_len: maximum buffer size for a single descriptor
+ * @truesize: desired truesize for the buffers
+ *
+ * Return: HW-writeable length per one buffer to pass it to the HW ignoring the
+ * MTU and closest to the passed truesize. Can be used for "short" buffer
+ * queues to fragment pages more efficiently.
+ */
+static u32 libeth_rx_hw_len_truesize(const struct page_pool_params *pp,
+ u32 max_len, u32 truesize)
+{
+ u32 min, len;
+
+ min = SKB_HEAD_ALIGN(pp->offset + LIBETH_RX_BUF_STRIDE);
+ truesize = clamp(roundup_pow_of_two(truesize), roundup_pow_of_two(min),
+ PAGE_SIZE << LIBETH_RX_PAGE_ORDER);
+
+ len = SKB_WITH_OVERHEAD(truesize - pp->offset);
+ len = ALIGN_DOWN(len, LIBETH_RX_BUF_STRIDE) ? : LIBETH_RX_BUF_STRIDE;
+ len = min3(len, ALIGN_DOWN(max_len ? : U32_MAX, LIBETH_RX_BUF_STRIDE),
+ pp->max_len);
+
+ return len;
+}
+
+/**
+ * libeth_rx_page_pool_params - calculate params with the stack overhead
+ * @fq: buffer queue to calculate the size for
+ * @pp: &page_pool_params of the netdev
+ *
+ * Set the PP params to will all needed stack overhead (headroom, tailroom) and
+ * both the HW buffer length and the truesize for all types of buffers. For
+ * "short" buffers, truesize never exceeds the "wanted" one; for the rest,
+ * it can be up to the page size.
+ *
+ * Return: true on success, false on invalid input params.
+ */
+static bool libeth_rx_page_pool_params(struct libeth_fq *fq,
+ struct page_pool_params *pp)
+{
+ pp->offset = LIBETH_SKB_HEADROOM;
+ /* HW-writeable / syncable length per one page */
+ pp->max_len = LIBETH_RX_PAGE_LEN(pp->offset);
+
+ /* HW-writeable length per buffer */
+ switch (fq->type) {
+ case LIBETH_FQE_MTU:
+ fq->buf_len = libeth_rx_hw_len_mtu(pp, fq->buf_len);
+ break;
+ case LIBETH_FQE_SHORT:
+ fq->buf_len = libeth_rx_hw_len_truesize(pp, fq->buf_len,
+ fq->truesize);
+ break;
+ case LIBETH_FQE_HDR:
+ fq->buf_len = ALIGN(LIBETH_MAX_HEAD, LIBETH_RX_BUF_STRIDE);
+ break;
+ default:
+ return false;
+ }
+
+ /* Buffer size to allocate */
+ fq->truesize = roundup_pow_of_two(SKB_HEAD_ALIGN(pp->offset +
+ fq->buf_len));
+
+ return true;
+}
+
+/**
+ * libeth_rx_page_pool_params_zc - calculate params without the stack overhead
+ * @fq: buffer queue to calculate the size for
+ * @pp: &page_pool_params of the netdev
+ *
+ * Set the PP params to exclude the stack overhead and both the buffer length
+ * and the truesize, which are equal for the data buffers. Note that this
+ * requires separate header buffers to be always active and account the
+ * overhead.
+ * With the MTU == ``PAGE_SIZE``, this allows the kernel to enable the zerocopy
+ * mode.
+ *
+ * Return: true on success, false on invalid input params.
+ */
+static bool libeth_rx_page_pool_params_zc(struct libeth_fq *fq,
+ struct page_pool_params *pp)
+{
+ u32 mtu, max;
+
+ pp->offset = 0;
+ pp->max_len = PAGE_SIZE << LIBETH_RX_PAGE_ORDER;
+
+ switch (fq->type) {
+ case LIBETH_FQE_MTU:
+ mtu = READ_ONCE(pp->netdev->mtu);
+ break;
+ case LIBETH_FQE_SHORT:
+ mtu = fq->truesize;
+ break;
+ default:
+ return false;
+ }
+
+ mtu = roundup_pow_of_two(mtu);
+ max = min(rounddown_pow_of_two(fq->buf_len ? : U32_MAX),
+ pp->max_len);
+
+ fq->buf_len = clamp(mtu, LIBETH_RX_BUF_STRIDE, max);
+ fq->truesize = fq->buf_len;
+
+ return true;
+}
+
/**
* libeth_rx_fq_create - create a PP with the default libeth settings
* @fq: buffer queue struct to fill
@@ -44,19 +156,17 @@ int libeth_rx_fq_create(struct libeth_fq *fq, struct napi_struct *napi)
.netdev = napi->dev,
.napi = napi,
.dma_dir = DMA_FROM_DEVICE,
- .offset = LIBETH_SKB_HEADROOM,
};
struct libeth_fqe *fqes;
struct page_pool *pool;
+ bool ret;
- /* HW-writeable / syncable length per one page */
- pp.max_len = LIBETH_RX_PAGE_LEN(pp.offset);
-
- /* HW-writeable length per buffer */
- fq->buf_len = libeth_rx_hw_len(&pp, fq->buf_len);
- /* Buffer size to allocate */
- fq->truesize = roundup_pow_of_two(SKB_HEAD_ALIGN(pp.offset +
- fq->buf_len));
+ if (!fq->hsplit)
+ ret = libeth_rx_page_pool_params(fq, &pp);
+ else
+ ret = libeth_rx_page_pool_params_zc(fq, &pp);
+ if (!ret)
+ return -EINVAL;
pool = page_pool_create(&pp);
if (IS_ERR(pool))
@@ -17,6 +17,8 @@
#define LIBETH_MAX_HEADROOM LIBETH_SKB_HEADROOM
/* Link layer / L2 overhead: Ethernet, 2 VLAN tags (C + S), FCS */
#define LIBETH_RX_LL_LEN (ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN)
+/* Maximum supported L2-L4 header length */
+#define LIBETH_MAX_HEAD roundup_pow_of_two(max(MAX_HEADER, 256))
/* Always use order-0 pages */
#define LIBETH_RX_PAGE_ORDER 0
@@ -43,6 +45,18 @@ struct libeth_fqe {
u32 truesize;
} __aligned_largest;
+/**
+ * enum libeth_fqe_type - enum representing types of Rx buffers
+ * @LIBETH_FQE_MTU: buffer size is determined by MTU
+ * @LIBETH_FQE_SHORT: buffer size is smaller than MTU, for short frames
+ * @LIBETH_FQE_HDR: buffer size is ```LIBETH_MAX_HEAD```-sized, for headers
+ */
+enum libeth_fqe_type {
+ LIBETH_FQE_MTU = 0U,
+ LIBETH_FQE_SHORT,
+ LIBETH_FQE_HDR,
+};
+
/**
* struct libeth_fq - structure representing a buffer (fill) queue
* @fp: hotpath part of the structure
@@ -50,6 +64,8 @@ struct libeth_fqe {
* @fqes: array of Rx buffers
* @truesize: size to allocate per buffer, w/overhead
* @count: number of descriptors/buffers the queue has
+ * @type: type of the buffers this queue has
+ * @hsplit: flag whether header split is enabled
* @buf_len: HW-writeable length per each buffer
* @nid: ID of the closest NUMA node with memory
*/
@@ -63,6 +79,9 @@ struct libeth_fq {
);
/* Cold fields */
+ enum libeth_fqe_type type:2;
+ bool hsplit:1;
+
u32 buf_len;
int nid;
};