Merge commit '5bc66170dc486556a1e36fd384463536573f4b82' into x86/urgent

From Borislav Petkov <bp@amd64.org>:

Below is a RAS fix which reverts the addition of a sysfs attribute
which we agreed is not needed, post-factum. And this should go in now
because that sysfs attribute is going to end up in 3.7 otherwise and
thus exposed to userspace; removing it then would be a lot harder.

This is done as a merge rather than a simple patch/cherry-pick since
the baseline for this patch was not in the previous x86/urgent.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 39 insertions, 13 deletions

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 682633bfe00..f2d6b78d901 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -40,6 +40,7 @@
 
 #include <net/tcp.h>
 
+#include <xen/xen.h>
 #include <xen/events.h>
 #include <xen/interface/memory.h>
 
@@ -334,21 +335,35 @@ unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)
 
 	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 		unsigned long size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
+		unsigned long offset = skb_shinfo(skb)->frags[i].page_offset;
 		unsigned long bytes;
+
+		offset &= ~PAGE_MASK;
+
 		while (size > 0) {
+			BUG_ON(offset >= PAGE_SIZE);
 			BUG_ON(copy_off > MAX_BUFFER_OFFSET);
 
-			if (start_new_rx_buffer(copy_off, size, 0)) {
+			bytes = PAGE_SIZE - offset;
+
+			if (bytes > size)
+				bytes = size;
+
+			if (start_new_rx_buffer(copy_off, bytes, 0)) {
 				count++;
 				copy_off = 0;
 			}
 
-			bytes = size;
 			if (copy_off + bytes > MAX_BUFFER_OFFSET)
 				bytes = MAX_BUFFER_OFFSET - copy_off;
 
 			copy_off += bytes;
+
+			offset += bytes;
 			size -= bytes;
+
+			if (offset == PAGE_SIZE)
+				offset = 0;
 		}
 	}
 	return count;
@@ -402,14 +417,24 @@ static void netbk_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
 	unsigned long bytes;
 
 	/* Data must not cross a page boundary. */
-	BUG_ON(size + offset > PAGE_SIZE);
+	BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
 
 	meta = npo->meta + npo->meta_prod - 1;
 
+	/* Skip unused frames from start of page */
+	page += offset >> PAGE_SHIFT;
+	offset &= ~PAGE_MASK;
+
 	while (size > 0) {
+		BUG_ON(offset >= PAGE_SIZE);
 		BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);
 
-		if (start_new_rx_buffer(npo->copy_off, size, *head)) {
+		bytes = PAGE_SIZE - offset;
+
+		if (bytes > size)
+			bytes = size;
+
+		if (start_new_rx_buffer(npo->copy_off, bytes, *head)) {
 			/*
 			 * Netfront requires there to be some data in the head
 			 * buffer.
@@ -419,7 +444,6 @@ static void netbk_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
 			meta = get_next_rx_buffer(vif, npo);
 		}
 
-		bytes = size;
 		if (npo->copy_off + bytes > MAX_BUFFER_OFFSET)
 			bytes = MAX_BUFFER_OFFSET - npo->copy_off;
 
@@ -452,6 +476,13 @@ static void netbk_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
 		offset += bytes;
 		size -= bytes;
 
+		/* Next frame */
+		if (offset == PAGE_SIZE && size) {
+			BUG_ON(!PageCompound(page));
+			page++;
+			offset = 0;
+		}
+
 		/* Leave a gap for the GSO descriptor. */
 		if (*head && skb_shinfo(skb)->gso_size && !vif->gso_prefix)
 			vif->rx.req_cons++;
@@ -635,9 +666,7 @@ static void xen_netbk_rx_action(struct xen_netbk *netbk)
 		return;
 
 	BUG_ON(npo.copy_prod > ARRAY_SIZE(netbk->grant_copy_op));
-	ret = HYPERVISOR_grant_table_op(GNTTABOP_copy, &netbk->grant_copy_op,
-					npo.copy_prod);
-	BUG_ON(ret != 0);
+	gnttab_batch_copy(netbk->grant_copy_op, npo.copy_prod);
 
 	while ((skb = __skb_dequeue(&rxq)) != NULL) {
 		sco = (struct skb_cb_overlay *)skb->cb;
@@ -1460,18 +1489,15 @@ static void xen_netbk_tx_submit(struct xen_netbk *netbk)
 static void xen_netbk_tx_action(struct xen_netbk *netbk)
 {
 	unsigned nr_gops;
-	int ret;
 
 	nr_gops = xen_netbk_tx_build_gops(netbk);
 
 	if (nr_gops == 0)
 		return;
-	ret = HYPERVISOR_grant_table_op(GNTTABOP_copy,
-					netbk->tx_copy_ops, nr_gops);
-	BUG_ON(ret);
 
-	xen_netbk_tx_submit(netbk);
+	gnttab_batch_copy(netbk->tx_copy_ops, nr_gops);
 
+	xen_netbk_tx_submit(netbk);
 }
 
 static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx)