diff options
Diffstat (limited to 'drivers/hv/ring_buffer.c')
| -rw-r--r-- | drivers/hv/ring_buffer.c | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index 5d11d93..4af7130 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -66,14 +66,25 @@ u32 hv_end_read(struct hv_ring_buffer_info *rbi) * once the ring buffer is empty, it will clear the * interrupt_mask and re-check to see if new data has * arrived. + * + * KYS: Oct. 30, 2016: + * It looks like Windows hosts have logic to deal with DOS attacks that + * can be triggered if it receives interrupts when it is not expecting + * the interrupt. The host expects interrupts only when the ring + * transitions from empty to non-empty (or full to non full on the guest + * to host ring). + * So, base the signaling decision solely on the ring state until the + * host logic is fixed. */ -static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi, - enum hv_signal_policy policy) +static void hv_signal_on_write(u32 old_write, struct vmbus_channel *channel, + bool kick_q) { + struct hv_ring_buffer_info *rbi = &channel->outbound; + virt_mb(); if (READ_ONCE(rbi->ring_buffer->interrupt_mask)) - return false; + return; /* check interrupt_mask before read_index */ virt_rmb(); @@ -82,9 +93,9 @@ static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi, * ring transitions from being empty to non-empty. */ if (old_write == READ_ONCE(rbi->ring_buffer->read_index)) - return true; + vmbus_setevent(channel); - return false; + return; } /* Get the next write location for the specified ring buffer. */ @@ -273,9 +284,9 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) } /* Write to the ring buffer. */ -int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, - struct kvec *kv_list, u32 kv_count, bool *signal, bool lock, - enum hv_signal_policy policy) +int hv_ringbuffer_write(struct vmbus_channel *channel, + struct kvec *kv_list, u32 kv_count, bool lock, + bool kick_q) { int i = 0; u32 bytes_avail_towrite; @@ -285,6 +296,7 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, u32 old_write; u64 prev_indices = 0; unsigned long flags = 0; + struct hv_ring_buffer_info *outring_info = &channel->outbound; for (i = 0; i < kv_count; i++) totalbytes_towrite += kv_list[i].iov_len; @@ -337,7 +349,7 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info, if (lock) spin_unlock_irqrestore(&outring_info->ring_lock, flags); - *signal = hv_need_to_signal(old_write, outring_info, policy); + hv_signal_on_write(old_write, channel, kick_q); return 0; } |