Revert "Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer"

This reverts commit a8c3209998afb5c4941b49e35b513cea9050cb4a.

It is reported that the said commit caused regression in netvsc.

Reported-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>

11 files changed, 25 insertions, 139 deletions

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 9aa789e5f22b..0bd202de7960 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -597,15 +597,12 @@ static int __vmbus_open(struct vmbus_channel *newchannel,
 	newchannel->onchannel_callback = onchannelcallback;
 	newchannel->channel_callback_context = context;
 
-	if (!newchannel->max_pkt_size)
-		newchannel->max_pkt_size = VMBUS_DEFAULT_MAX_PKT_SIZE;
-
-	err = hv_ringbuffer_init(&newchannel->outbound, page, send_pages, 0);
+	err = hv_ringbuffer_init(&newchannel->outbound, page, send_pages);
 	if (err)
 		goto error_clean_ring;
 
-	err = hv_ringbuffer_init(&newchannel->inbound, &page[send_pages],
-				 recv_pages, newchannel->max_pkt_size);
+	err = hv_ringbuffer_init(&newchannel->inbound,
+				 &page[send_pages], recv_pages);
 	if (err)
 		goto error_clean_ring;
 
diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c
index 660036da7449..59ce85e00a02 100644
--- a/drivers/hv/hv_fcopy.c
+++ b/drivers/hv/hv_fcopy.c
@@ -349,7 +349,6 @@ int hv_fcopy_init(struct hv_util_service *srv)
 {
 	recv_buffer = srv->recv_buffer;
 	fcopy_transaction.recv_channel = srv->channel;
-	fcopy_transaction.recv_channel->max_pkt_size = HV_HYP_PAGE_SIZE * 2;
 
 	/*
 	 * When this driver loads, the user level daemon that
diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
index c698592b83e4..b49962d312ce 100644
--- a/drivers/hv/hv_kvp.c
+++ b/drivers/hv/hv_kvp.c
@@ -757,7 +757,6 @@ hv_kvp_init(struct hv_util_service *srv)
 {
 	recv_buffer = srv->recv_buffer;
 	kvp_transaction.recv_channel = srv->channel;
-	kvp_transaction.recv_channel->max_pkt_size = HV_HYP_PAGE_SIZE * 4;
 
 	/*
 	 * When this driver loads, the user level daemon that
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 42f3d9d123a1..9416e09ebd58 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -174,7 +174,7 @@ extern int hv_synic_cleanup(unsigned int cpu);
 void hv_ringbuffer_pre_init(struct vmbus_channel *channel);
 
 int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
-		       struct page *pages, u32 pagecnt, u32 max_pkt_size);
+		       struct page *pages, u32 pagecnt);
 
 void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info);
 
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 29e90477363a..35833d4d1a1d 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -190,7 +190,7 @@ void hv_ringbuffer_pre_init(struct vmbus_channel *channel)
 
 /* Initialize the ring buffer. */
 int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
-		       struct page *pages, u32 page_cnt, u32 max_pkt_size)
+		       struct page *pages, u32 page_cnt)
 {
 	int i;
 	struct page **pages_wraparound;
@@ -232,14 +232,6 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
 		sizeof(struct hv_ring_buffer);
 	ring_info->priv_read_index = 0;
 
-	/* Initialize buffer that holds copies of incoming packets */
-	if (max_pkt_size) {
-		ring_info->pkt_buffer = kzalloc(max_pkt_size, GFP_KERNEL);
-		if (!ring_info->pkt_buffer)
-			return -ENOMEM;
-		ring_info->pkt_buffer_size = max_pkt_size;
-	}
-
 	spin_lock_init(&ring_info->ring_lock);
 
 	return 0;
@@ -252,9 +244,6 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
 	vunmap(ring_info->ring_buffer);
 	ring_info->ring_buffer = NULL;
 	mutex_unlock(&ring_info->ring_buffer_mutex);
-
-	kfree(ring_info->pkt_buffer);
-	ring_info->pkt_buffer_size = 0;
 }
 
 /* Write to the ring buffer. */
@@ -396,7 +385,7 @@ int hv_ringbuffer_read(struct vmbus_channel *channel,
 	memcpy(buffer, (const char *)desc + offset, packetlen);
 
 	/* Advance ring index to next packet descriptor */
-	__hv_pkt_iter_next(channel, desc, true);
+	__hv_pkt_iter_next(channel, desc);
 
 	/* Notify host of update */
 	hv_pkt_iter_close(channel);
@@ -423,22 +412,6 @@ static u32 hv_pkt_iter_avail(const struct hv_ring_buffer_info *rbi)
 }
 
 /*
- * Get first vmbus packet without copying it out of the ring buffer
- */
-struct vmpacket_descriptor *hv_pkt_iter_first_raw(struct vmbus_channel *channel)
-{
-	struct hv_ring_buffer_info *rbi = &channel->inbound;
-
-	hv_debug_delay_test(channel, MESSAGE_DELAY);
-
-	if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
-		return NULL;
-
-	return (struct vmpacket_descriptor *)(hv_get_ring_buffer(rbi) + rbi->priv_read_index);
-}
-EXPORT_SYMBOL_GPL(hv_pkt_iter_first_raw);
-
-/*
  * Get first vmbus packet from ring buffer after read_index
  *
  * If ring buffer is empty, returns NULL and no other action needed.
@@ -446,49 +419,17 @@ EXPORT_SYMBOL_GPL(hv_pkt_iter_first_raw);
 struct vmpacket_descriptor *hv_pkt_iter_first(struct vmbus_channel *channel)
 {
 	struct hv_ring_buffer_info *rbi = &channel->inbound;
-	struct vmpacket_descriptor *desc, *desc_copy;
-	u32 bytes_avail, pkt_len, pkt_offset;
+	struct vmpacket_descriptor *desc;
 
-	desc = hv_pkt_iter_first_raw(channel);
-	if (!desc)
+	hv_debug_delay_test(channel, MESSAGE_DELAY);
+	if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
 		return NULL;
 
-	bytes_avail = min(rbi->pkt_buffer_size, hv_pkt_iter_avail(rbi));
-
-	/*
-	 * Ensure the compiler does not use references to incoming Hyper-V values (which
-	 * could change at any moment) when reading local variables later in the code
-	 */
-	pkt_len = READ_ONCE(desc->len8) << 3;
-	pkt_offset = READ_ONCE(desc->offset8) << 3;
-
-	/*
-	 * If pkt_len is invalid, set it to the smaller of hv_pkt_iter_avail() and
-	 * rbi->pkt_buffer_size
-	 */
-	if (pkt_len < sizeof(struct vmpacket_descriptor) || pkt_len > bytes_avail)
-		pkt_len = bytes_avail;
-
-	/*
-	 * If pkt_offset is invalid, arbitrarily set it to
-	 * the size of vmpacket_descriptor
-	 */
-	if (pkt_offset < sizeof(struct vmpacket_descriptor) || pkt_offset > pkt_len)
-		pkt_offset = sizeof(struct vmpacket_descriptor);
-
-	/* Copy the Hyper-V packet out of the ring buffer */
-	desc_copy = (struct vmpacket_descriptor *)rbi->pkt_buffer;
-	memcpy(desc_copy, desc, pkt_len);
-
-	/*
-	 * Hyper-V could still change len8 and offset8 after the earlier read.
-	 * Ensure that desc_copy has legal values for len8 and offset8 that
-	 * are consistent with the copy we just made
-	 */
-	desc_copy->len8 = pkt_len >> 3;
-	desc_copy->offset8 = pkt_offset >> 3;
+	desc = hv_get_ring_buffer(rbi) + rbi->priv_read_index;
+	if (desc)
+		prefetch((char *)desc + (desc->len8 << 3));
 
-	return desc_copy;
+	return desc;
 }
 EXPORT_SYMBOL_GPL(hv_pkt_iter_first);
 
@@ -500,8 +441,7 @@ EXPORT_SYMBOL_GPL(hv_pkt_iter_first);
  */
 struct vmpacket_descriptor *
 __hv_pkt_iter_next(struct vmbus_channel *channel,
-		   const struct vmpacket_descriptor *desc,
-		   bool copy)
+		   const struct vmpacket_descriptor *desc)
 {
 	struct hv_ring_buffer_info *rbi = &channel->inbound;
 	u32 packetlen = desc->len8 << 3;
@@ -514,7 +454,7 @@ __hv_pkt_iter_next(struct vmbus_channel *channel,
 		rbi->priv_read_index -= dsize;
 
 	/* more data? */
-	return copy ? hv_pkt_iter_first(channel) : hv_pkt_iter_first_raw(channel);
+	return hv_pkt_iter_first(channel);
 }
 EXPORT_SYMBOL_GPL(__hv_pkt_iter_next);
 
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 7ea6936f86ef..2a87cfa27ac0 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -860,12 +860,9 @@ static inline u32 netvsc_rqstor_size(unsigned long ringbytes)
 		ringbytes / NETVSC_MIN_IN_MSG_SIZE;
 }
 
-#define NETVSC_MAX_XFER_PAGE_RANGES 375
 #define NETVSC_XFER_HEADER_SIZE(rng_cnt) \
 		(offsetof(struct vmtransfer_page_packet_header, ranges) + \
 		(rng_cnt) * sizeof(struct vmtransfer_page_range))
-#define NETVSC_MAX_PKT_SIZE (NETVSC_XFER_HEADER_SIZE(NETVSC_MAX_XFER_PAGE_RANGES) + \
-		sizeof(struct nvsp_message) + (sizeof(u32) * VRSS_SEND_TAB_SIZE))
 
 struct multi_send_data {
 	struct sk_buff *skb; /* skb containing the pkt */
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 51005f2d4a82..2353623259f3 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -1544,8 +1544,6 @@ struct netvsc_device *netvsc_device_add(struct hv_device *device,
 
 	/* Open the channel */
 	device->channel->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes);
-	device->channel->max_pkt_size = NETVSC_MAX_PKT_SIZE;
-
 	ret = vmbus_open(device->channel, netvsc_ring_bytes,
 			 netvsc_ring_bytes,  NULL, 0,
 			 netvsc_channel_cb, net_device->chan_table);
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 7e6dee2f02a4..598713c0d5a8 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -1174,8 +1174,6 @@ static void netvsc_sc_open(struct vmbus_channel *new_sc)
 	nvchan->channel = new_sc;
 
 	new_sc->rqstor_size = netvsc_rqstor_size(netvsc_ring_bytes);
-	new_sc->max_pkt_size = NETVSC_MAX_PKT_SIZE;
-
 	ret = vmbus_open(new_sc, netvsc_ring_bytes,
 			 netvsc_ring_bytes, NULL, 0,
 			 netvsc_channel_cb, nvchan);
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 7e59284dbf5b..2e4fa77445fd 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -414,14 +414,6 @@ static void storvsc_on_channel_callback(void *context);
 #define STORVSC_IDE_MAX_TARGETS				1
 #define STORVSC_IDE_MAX_CHANNELS			1
 
-/*
- * Upper bound on the size of a storvsc packet. vmscsi_size_delta is not
- * included in the calculation because it is set after STORVSC_MAX_PKT_SIZE
- * is used in storvsc_connect_to_vsp
- */
-#define STORVSC_MAX_PKT_SIZE (sizeof(struct vmpacket_descriptor) +\
-			      sizeof(struct vstor_packet))
-
 struct storvsc_cmd_request {
 	struct scsi_cmnd *cmd;
 
@@ -706,7 +698,6 @@ static void handle_sc_creation(struct vmbus_channel *new_sc)
 		return;
 
 	memset(&props, 0, sizeof(struct vmstorage_channel_properties));
-	new_sc->max_pkt_size = STORVSC_MAX_PKT_SIZE;
 
 	/*
 	 * The size of vmbus_requestor is an upper bound on the number of requests
@@ -1289,7 +1280,6 @@ static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size,
 
 	memset(&props, 0, sizeof(struct vmstorage_channel_properties));
 
-	device->channel->max_pkt_size = STORVSC_MAX_PKT_SIZE;
 	/*
 	 * The size of vmbus_requestor is an upper bound on the number of requests
 	 * that can be in-progress at any one time across all channels.
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 9dd22af1b7f6..f1d74dcf0353 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -181,10 +181,6 @@ struct hv_ring_buffer_info {
 	 * being freed while the ring buffer is being accessed.
 	 */
 	struct mutex ring_buffer_mutex;
-
-	/* Buffer that holds a copy of an incoming host packet */
-	void *pkt_buffer;
-	u32 pkt_buffer_size;
 };
 
 
@@ -792,8 +788,6 @@ struct vmbus_device {
 	bool allowed_in_isolated;
 };
 
-#define VMBUS_DEFAULT_MAX_PKT_SIZE 4096
-
 struct vmbus_channel {
 	struct list_head listentry;
 
@@ -1016,9 +1010,6 @@ struct vmbus_channel {
 	/* request/transaction ids for VMBus */
 	struct vmbus_requestor requestor;
 	u32 rqstor_size;
-
-	/* The max size of a packet on this channel */
-	u32 max_pkt_size;
 };
 
 u64 vmbus_next_request_id(struct vmbus_requestor *rqstor, u64 rqst_addr);
@@ -1661,43 +1652,14 @@ static inline u32 hv_pkt_datalen(const struct vmpacket_descriptor *desc)
 
 
 struct vmpacket_descriptor *
-hv_pkt_iter_first_raw(struct vmbus_channel *channel);
-
-struct vmpacket_descriptor *
 hv_pkt_iter_first(struct vmbus_channel *channel);
 
 struct vmpacket_descriptor *
 __hv_pkt_iter_next(struct vmbus_channel *channel,
-		   const struct vmpacket_descriptor *pkt,
-		   bool copy);
+		   const struct vmpacket_descriptor *pkt);
 
 void hv_pkt_iter_close(struct vmbus_channel *channel);
 
-static inline struct vmpacket_descriptor *
-hv_pkt_iter_next_pkt(struct vmbus_channel *channel,
-		     const struct vmpacket_descriptor *pkt,
-		     bool copy)
-{
-	struct vmpacket_descriptor *nxt;
-
-	nxt = __hv_pkt_iter_next(channel, pkt, copy);
-	if (!nxt)
-		hv_pkt_iter_close(channel);
-
-	return nxt;
-}
-
-/*
- * Get next packet descriptor without copying it out of the ring buffer
- * If at end of list, return NULL and update host.
- */
-static inline struct vmpacket_descriptor *
-hv_pkt_iter_next_raw(struct vmbus_channel *channel,
-		     const struct vmpacket_descriptor *pkt)
-{
-	return hv_pkt_iter_next_pkt(channel, pkt, false);
-}
-
 /*
  * Get next packet descriptor from iterator
  * If at end of list, return NULL and update host.
@@ -1706,7 +1668,13 @@ static inline struct vmpacket_descriptor *
 hv_pkt_iter_next(struct vmbus_channel *channel,
 		 const struct vmpacket_descriptor *pkt)
 {
-	return hv_pkt_iter_next_pkt(channel, pkt, true);
+	struct vmpacket_descriptor *nxt;
+
+	nxt = __hv_pkt_iter_next(channel, pkt);
+	if (!nxt)
+		hv_pkt_iter_close(channel);
+
+	return nxt;
 }
 
 #define foreach_vmbus_pkt(pkt, channel) \
diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
index cd8b7c1ca9f1..630b851f8150 100644
--- a/net/vmw_vsock/hyperv_transport.c
+++ b/net/vmw_vsock/hyperv_transport.c
@@ -600,7 +600,7 @@ static ssize_t hvs_stream_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
 		return -EOPNOTSUPP;
 
 	if (need_refill) {
-		hvs->recv_desc = hv_pkt_iter_first_raw(hvs->chan);
+		hvs->recv_desc = hv_pkt_iter_first(hvs->chan);
 		ret = hvs_update_recv_data(hvs);
 		if (ret)
 			return ret;
@@ -614,7 +614,7 @@ static ssize_t hvs_stream_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
 
 	hvs->recv_data_len -= to_read;
 	if (hvs->recv_data_len == 0) {
-		hvs->recv_desc = hv_pkt_iter_next_raw(hvs->chan, hvs->recv_desc);
+		hvs->recv_desc = hv_pkt_iter_next(hvs->chan, hvs->recv_desc);
 		if (hvs->recv_desc) {
 			ret = hvs_update_recv_data(hvs);
 			if (ret)