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Subject[PATCH net-next RFC 1/5] xen-netback: Introduce TX grant map definitions
Date
This patch contains the new definitions necessary for grant mapping.

Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>

---
drivers/net/xen-netback/common.h | 22 ++++++
drivers/net/xen-netback/interface.c | 1 +
drivers/net/xen-netback/netback.c | 134 +++++++++++++++++++++++++++++++++++
3 files changed, 157 insertions(+)

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 55b8dec..36a3fda 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -79,6 +79,11 @@ struct pending_tx_info {
* if it is head of one or more tx
* reqs
*/
+ /* callback data for released SKBs. The callback is always
+ * xenvif_zerocopy_callback, ctx points to the next fragment, desc
+ * contains the pending_idx
+ */
+ struct ubuf_info callback_struct;
};

#define XEN_NETIF_TX_RING_SIZE __CONST_RING_SIZE(xen_netif_tx, PAGE_SIZE)
@@ -101,6 +106,8 @@ struct xenvif_rx_meta {

#define MAX_PENDING_REQS 256

+#define NETBACK_INVALID_HANDLE -1
+
struct xenvif {
/* Unique identifier for this interface. */
domid_t domid;
@@ -119,13 +126,22 @@ struct xenvif {
pending_ring_idx_t pending_cons;
u16 pending_ring[MAX_PENDING_REQS];
struct pending_tx_info pending_tx_info[MAX_PENDING_REQS];
+ grant_handle_t grant_tx_handle[MAX_PENDING_REQS];

/* Coalescing tx requests before copying makes number of grant
* copy ops greater or equal to number of slots required. In
* worst case a tx request consumes 2 gnttab_copy.
*/
struct gnttab_copy tx_copy_ops[2*MAX_PENDING_REQS];
+ struct gnttab_unmap_grant_ref tx_unmap_ops[MAX_PENDING_REQS];
+ struct gnttab_map_grant_ref tx_map_ops[MAX_PENDING_REQS];
+ /* passed to gnttab_[un]map_refs with pages under (un)mapping */
+ struct page *pages_to_gnt[MAX_PENDING_REQS];

+ spinlock_t dealloc_lock;
+ pending_ring_idx_t dealloc_prod;
+ pending_ring_idx_t dealloc_cons;
+ u16 dealloc_ring[MAX_PENDING_REQS];

/* Use kthread for guest RX */
struct task_struct *task;
@@ -226,6 +242,12 @@ void xenvif_rx_action(struct xenvif *vif);

int xenvif_kthread(void *data);

+/* Callback from stack when TX packet can be released */
+void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success);
+
+/* Unmap a pending page, usually has to be called before xenvif_idx_release */
+void xenvif_idx_unmap(struct xenvif *vif, u16 pending_idx);
+
extern bool separate_tx_rx_irq;

#endif /* __XEN_NETBACK__COMMON_H__ */
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index e4aa267..f5c3c57 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -37,6 +37,7 @@

#include <xen/events.h>
#include <asm/xen/hypercall.h>
+#include <xen/balloon.h>

#define XENVIF_QUEUE_LENGTH 32
#define XENVIF_NAPI_WEIGHT 64
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 828fdab..10470dc 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -869,6 +869,20 @@ static struct page *xenvif_alloc_page(struct xenvif *vif,
return page;
}

+static inline void xenvif_tx_create_gop(struct xenvif *vif, u16 pending_idx,
+ struct xen_netif_tx_request *txp,
+ struct gnttab_map_grant_ref *gop)
+{
+ vif->pages_to_gnt[gop-vif->tx_map_ops] = vif->mmap_pages[pending_idx];
+ gnttab_set_map_op(gop, idx_to_kaddr(vif, pending_idx),
+ GNTMAP_host_map | GNTMAP_readonly,
+ txp->gref, vif->domid);
+
+ memcpy(&vif->pending_tx_info[pending_idx].req, txp,
+ sizeof(*txp));
+
+}
+
static struct gnttab_copy *xenvif_get_requests(struct xenvif *vif,
struct sk_buff *skb,
struct xen_netif_tx_request *txp,
@@ -1652,6 +1666,106 @@ static int xenvif_tx_submit(struct xenvif *vif, int budget)
return work_done;
}

+void xenvif_zerocopy_callback(struct ubuf_info *ubuf, bool zerocopy_success)
+{
+ unsigned long flags;
+ pending_ring_idx_t index;
+ u16 pending_idx = ubuf->desc;
+ struct pending_tx_info *temp =
+ container_of(ubuf, struct pending_tx_info, callback_struct);
+ struct xenvif *vif =
+ container_of(temp - pending_idx, struct xenvif,
+ pending_tx_info[0]);
+
+ spin_lock_irqsave(&vif->dealloc_lock, flags);
+ do {
+ pending_idx = ubuf->desc;
+ ubuf = (struct ubuf_info *) ubuf->ctx;
+ index = pending_index(vif->dealloc_prod);
+ vif->dealloc_ring[index] = pending_idx;
+ /* Sync with xenvif_tx_action_dealloc:
+ * insert idx then incr producer.
+ */
+ smp_wmb();
+ vif->dealloc_prod++;
+ napi_schedule(&vif->napi);
+ } while (ubuf);
+ spin_unlock_irqrestore(&vif->dealloc_lock, flags);
+}
+
+static inline void xenvif_tx_action_dealloc(struct xenvif *vif)
+{
+ struct gnttab_unmap_grant_ref *gop;
+ pending_ring_idx_t dc, dp;
+ u16 pending_idx, pending_idx_release[MAX_PENDING_REQS];
+ unsigned int i = 0;
+
+ dc = vif->dealloc_cons;
+ gop = vif->tx_unmap_ops;
+
+ /* Free up any grants we have finished using */
+ do {
+ dp = vif->dealloc_prod;
+
+ /* Ensure we see all indices enqueued by netif_idx_release(). */
+ smp_rmb();
+
+ while (dc != dp) {
+
+ pending_idx_release[gop-vif->tx_unmap_ops] =
+ pending_idx =
+ vif->dealloc_ring[pending_index(dc++)];
+
+ /* Already unmapped? */
+ if (vif->grant_tx_handle[pending_idx] ==
+ NETBACK_INVALID_HANDLE) {
+ netdev_err(vif->dev,
+ "Trying to unmap invalid handle! "
+ "pending_idx: %x\n", pending_idx);
+ continue;
+ }
+
+ vif->pages_to_gnt[gop-vif->tx_unmap_ops] =
+ vif->mmap_pages[pending_idx];
+ gnttab_set_unmap_op(gop,
+ idx_to_kaddr(vif, pending_idx),
+ GNTMAP_host_map,
+ vif->grant_tx_handle[pending_idx]);
+ vif->grant_tx_handle[pending_idx] =
+ NETBACK_INVALID_HANDLE;
+ ++gop;
+ }
+
+ } while (dp != vif->dealloc_prod);
+
+ vif->dealloc_cons = dc;
+
+ if (gop - vif->tx_unmap_ops > 0) {
+ int ret;
+ ret = gnttab_unmap_refs(vif->tx_unmap_ops,
+ NULL,
+ vif->pages_to_gnt,
+ gop - vif->tx_unmap_ops);
+ if (ret) {
+ netdev_err(vif->dev, "Unmap fail: nr_ops %x ret %d\n",
+ gop - vif->tx_unmap_ops, ret);
+ for (i = 0; i < gop - vif->tx_unmap_ops; ++i) {
+ netdev_err(vif->dev,
+ " host_addr: %llx handle: %x status: %d\n",
+ gop[i].host_addr,
+ gop[i].handle,
+ gop[i].status);
+ }
+ BUG();
+ }
+ }
+
+ for (i = 0; i < gop - vif->tx_unmap_ops; ++i)
+ xenvif_idx_release(vif, pending_idx_release[i],
+ XEN_NETIF_RSP_OKAY);
+}
+
+
/* Called after netfront has transmitted */
int xenvif_tx_action(struct xenvif *vif, int budget)
{
@@ -1718,6 +1832,26 @@ static void xenvif_idx_release(struct xenvif *vif, u16 pending_idx,
vif->mmap_pages[pending_idx] = NULL;
}

+void xenvif_idx_unmap(struct xenvif *vif, u16 pending_idx)
+{
+ int ret;
+ if (vif->grant_tx_handle[pending_idx] == NETBACK_INVALID_HANDLE) {
+ netdev_err(vif->dev,
+ "Trying to unmap invalid handle! pending_idx: %x\n",
+ pending_idx);
+ return;
+ }
+ gnttab_set_unmap_op(&vif->tx_unmap_ops[0],
+ idx_to_kaddr(vif, pending_idx),
+ GNTMAP_host_map,
+ vif->grant_tx_handle[pending_idx]);
+ ret = gnttab_unmap_refs(vif->tx_unmap_ops,
+ NULL,
+ &vif->mmap_pages[pending_idx],
+ 1);
+ BUG_ON(ret);
+ vif->grant_tx_handle[pending_idx] = NETBACK_INVALID_HANDLE;
+}

static void make_tx_response(struct xenvif *vif,
struct xen_netif_tx_request *txp,

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