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synced 2024-08-21 16:29:59 +00:00
![Vitaly Kuznetsov](/assets/img/avatar_default.png)
The following crash happens when a never-used device is unbound from
uio_hv_generic driver:
kernel BUG at mm/slub.c:321!
invalid opcode: 0000 [#1] SMP PTI
CPU: 0 PID: 4001 Comm: bash Kdump: loaded Tainted: G X --------- --- 5.14.0-0.rc2.23.el9.x86_64 #1
Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS 090008 12/07/2018
RIP: 0010:__slab_free+0x1d5/0x3d0
...
Call Trace:
? pick_next_task_fair+0x18e/0x3b0
? __cond_resched+0x16/0x40
? vunmap_pmd_range.isra.0+0x154/0x1c0
? __vunmap+0x22d/0x290
? hv_ringbuffer_cleanup+0x36/0x40 [hv_vmbus]
kfree+0x331/0x380
? hv_uio_remove+0x43/0x60 [uio_hv_generic]
hv_ringbuffer_cleanup+0x36/0x40 [hv_vmbus]
vmbus_free_ring+0x21/0x60 [hv_vmbus]
hv_uio_remove+0x4f/0x60 [uio_hv_generic]
vmbus_remove+0x23/0x30 [hv_vmbus]
__device_release_driver+0x17a/0x230
device_driver_detach+0x3c/0xa0
unbind_store+0x113/0x130
...
The problem appears to be that we free 'ring_info->pkt_buffer' twice:
first, when the device is unbound from in-kernel driver (netvsc in this
case) and second from hv_uio_remove(). Normally, ring buffer is supposed
to be re-initialized from hv_uio_open() but this happens when UIO device
is being opened and this is not guaranteed to happen.
Generally, it is OK to call hv_ringbuffer_cleanup() twice for the same
channel (which is being handed over between in-kernel drivers and UIO) even
if we didn't call hv_ringbuffer_init() in between. We, however, need to
avoid kfree() call for an already freed pointer.
Fixes: adae1e931a
("Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20210831143916.144983-1-vkuznets@redhat.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
629 lines
18 KiB
C
629 lines
18 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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*
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* Copyright (c) 2009, Microsoft Corporation.
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*
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* Authors:
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* Haiyang Zhang <haiyangz@microsoft.com>
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* Hank Janssen <hjanssen@microsoft.com>
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* K. Y. Srinivasan <kys@microsoft.com>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/hyperv.h>
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#include <linux/uio.h>
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#include <linux/vmalloc.h>
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#include <linux/slab.h>
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#include <linux/prefetch.h>
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#include "hyperv_vmbus.h"
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#define VMBUS_PKT_TRAILER 8
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/*
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* When we write to the ring buffer, check if the host needs to
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* be signaled. Here is the details of this protocol:
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*
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* 1. The host guarantees that while it is draining the
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* ring buffer, it will set the interrupt_mask to
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* indicate it does not need to be interrupted when
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* new data is placed.
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*
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* 2. The host guarantees that it will completely drain
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* the ring buffer before exiting the read loop. Further,
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* once the ring buffer is empty, it will clear the
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* interrupt_mask and re-check to see if new data has
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* arrived.
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*
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* KYS: Oct. 30, 2016:
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* It looks like Windows hosts have logic to deal with DOS attacks that
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* can be triggered if it receives interrupts when it is not expecting
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* the interrupt. The host expects interrupts only when the ring
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* transitions from empty to non-empty (or full to non full on the guest
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* to host ring).
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* So, base the signaling decision solely on the ring state until the
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* host logic is fixed.
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*/
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static void hv_signal_on_write(u32 old_write, struct vmbus_channel *channel)
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{
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struct hv_ring_buffer_info *rbi = &channel->outbound;
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virt_mb();
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if (READ_ONCE(rbi->ring_buffer->interrupt_mask))
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return;
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/* check interrupt_mask before read_index */
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virt_rmb();
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/*
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* This is the only case we need to signal when the
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* ring transitions from being empty to non-empty.
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*/
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if (old_write == READ_ONCE(rbi->ring_buffer->read_index)) {
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++channel->intr_out_empty;
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vmbus_setevent(channel);
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}
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}
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/* Get the next write location for the specified ring buffer. */
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static inline u32
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hv_get_next_write_location(struct hv_ring_buffer_info *ring_info)
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{
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u32 next = ring_info->ring_buffer->write_index;
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return next;
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}
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/* Set the next write location for the specified ring buffer. */
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static inline void
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hv_set_next_write_location(struct hv_ring_buffer_info *ring_info,
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u32 next_write_location)
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{
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ring_info->ring_buffer->write_index = next_write_location;
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}
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/* Get the size of the ring buffer. */
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static inline u32
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hv_get_ring_buffersize(const struct hv_ring_buffer_info *ring_info)
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{
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return ring_info->ring_datasize;
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}
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/* Get the read and write indices as u64 of the specified ring buffer. */
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static inline u64
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hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
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{
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return (u64)ring_info->ring_buffer->write_index << 32;
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}
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/*
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* Helper routine to copy from source to ring buffer.
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* Assume there is enough room. Handles wrap-around in dest case only!!
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*/
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static u32 hv_copyto_ringbuffer(
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struct hv_ring_buffer_info *ring_info,
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u32 start_write_offset,
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const void *src,
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u32 srclen)
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{
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void *ring_buffer = hv_get_ring_buffer(ring_info);
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u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
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memcpy(ring_buffer + start_write_offset, src, srclen);
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start_write_offset += srclen;
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if (start_write_offset >= ring_buffer_size)
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start_write_offset -= ring_buffer_size;
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return start_write_offset;
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}
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/*
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*
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* hv_get_ringbuffer_availbytes()
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*
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* Get number of bytes available to read and to write to
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* for the specified ring buffer
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*/
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static void
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hv_get_ringbuffer_availbytes(const struct hv_ring_buffer_info *rbi,
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u32 *read, u32 *write)
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{
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u32 read_loc, write_loc, dsize;
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/* Capture the read/write indices before they changed */
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read_loc = READ_ONCE(rbi->ring_buffer->read_index);
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write_loc = READ_ONCE(rbi->ring_buffer->write_index);
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dsize = rbi->ring_datasize;
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*write = write_loc >= read_loc ? dsize - (write_loc - read_loc) :
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read_loc - write_loc;
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*read = dsize - *write;
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}
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/* Get various debug metrics for the specified ring buffer. */
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int hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
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struct hv_ring_buffer_debug_info *debug_info)
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{
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u32 bytes_avail_towrite;
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u32 bytes_avail_toread;
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mutex_lock(&ring_info->ring_buffer_mutex);
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if (!ring_info->ring_buffer) {
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mutex_unlock(&ring_info->ring_buffer_mutex);
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return -EINVAL;
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}
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hv_get_ringbuffer_availbytes(ring_info,
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&bytes_avail_toread,
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&bytes_avail_towrite);
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debug_info->bytes_avail_toread = bytes_avail_toread;
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debug_info->bytes_avail_towrite = bytes_avail_towrite;
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debug_info->current_read_index = ring_info->ring_buffer->read_index;
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debug_info->current_write_index = ring_info->ring_buffer->write_index;
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debug_info->current_interrupt_mask
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= ring_info->ring_buffer->interrupt_mask;
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mutex_unlock(&ring_info->ring_buffer_mutex);
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return 0;
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}
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EXPORT_SYMBOL_GPL(hv_ringbuffer_get_debuginfo);
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/* Initialize a channel's ring buffer info mutex locks */
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void hv_ringbuffer_pre_init(struct vmbus_channel *channel)
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{
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mutex_init(&channel->inbound.ring_buffer_mutex);
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mutex_init(&channel->outbound.ring_buffer_mutex);
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}
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/* Initialize the ring buffer. */
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int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
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struct page *pages, u32 page_cnt, u32 max_pkt_size)
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{
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int i;
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struct page **pages_wraparound;
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BUILD_BUG_ON((sizeof(struct hv_ring_buffer) != PAGE_SIZE));
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/*
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* First page holds struct hv_ring_buffer, do wraparound mapping for
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* the rest.
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*/
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pages_wraparound = kcalloc(page_cnt * 2 - 1, sizeof(struct page *),
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GFP_KERNEL);
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if (!pages_wraparound)
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return -ENOMEM;
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pages_wraparound[0] = pages;
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for (i = 0; i < 2 * (page_cnt - 1); i++)
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pages_wraparound[i + 1] = &pages[i % (page_cnt - 1) + 1];
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ring_info->ring_buffer = (struct hv_ring_buffer *)
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vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP, PAGE_KERNEL);
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kfree(pages_wraparound);
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if (!ring_info->ring_buffer)
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return -ENOMEM;
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ring_info->ring_buffer->read_index =
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ring_info->ring_buffer->write_index = 0;
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/* Set the feature bit for enabling flow control. */
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ring_info->ring_buffer->feature_bits.value = 1;
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ring_info->ring_size = page_cnt << PAGE_SHIFT;
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ring_info->ring_size_div10_reciprocal =
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reciprocal_value(ring_info->ring_size / 10);
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ring_info->ring_datasize = ring_info->ring_size -
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sizeof(struct hv_ring_buffer);
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ring_info->priv_read_index = 0;
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/* Initialize buffer that holds copies of incoming packets */
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if (max_pkt_size) {
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ring_info->pkt_buffer = kzalloc(max_pkt_size, GFP_KERNEL);
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if (!ring_info->pkt_buffer)
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return -ENOMEM;
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ring_info->pkt_buffer_size = max_pkt_size;
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}
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spin_lock_init(&ring_info->ring_lock);
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return 0;
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}
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/* Cleanup the ring buffer. */
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void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
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{
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mutex_lock(&ring_info->ring_buffer_mutex);
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vunmap(ring_info->ring_buffer);
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ring_info->ring_buffer = NULL;
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mutex_unlock(&ring_info->ring_buffer_mutex);
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kfree(ring_info->pkt_buffer);
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ring_info->pkt_buffer = NULL;
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ring_info->pkt_buffer_size = 0;
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}
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/* Write to the ring buffer. */
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int hv_ringbuffer_write(struct vmbus_channel *channel,
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const struct kvec *kv_list, u32 kv_count,
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u64 requestid)
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{
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int i;
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u32 bytes_avail_towrite;
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u32 totalbytes_towrite = sizeof(u64);
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u32 next_write_location;
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u32 old_write;
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u64 prev_indices;
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unsigned long flags;
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struct hv_ring_buffer_info *outring_info = &channel->outbound;
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struct vmpacket_descriptor *desc = kv_list[0].iov_base;
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u64 rqst_id = VMBUS_NO_RQSTOR;
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if (channel->rescind)
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return -ENODEV;
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for (i = 0; i < kv_count; i++)
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totalbytes_towrite += kv_list[i].iov_len;
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spin_lock_irqsave(&outring_info->ring_lock, flags);
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bytes_avail_towrite = hv_get_bytes_to_write(outring_info);
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/*
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* If there is only room for the packet, assume it is full.
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* Otherwise, the next time around, we think the ring buffer
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* is empty since the read index == write index.
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*/
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if (bytes_avail_towrite <= totalbytes_towrite) {
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++channel->out_full_total;
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if (!channel->out_full_flag) {
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++channel->out_full_first;
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channel->out_full_flag = true;
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}
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spin_unlock_irqrestore(&outring_info->ring_lock, flags);
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return -EAGAIN;
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}
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channel->out_full_flag = false;
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/* Write to the ring buffer */
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next_write_location = hv_get_next_write_location(outring_info);
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old_write = next_write_location;
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for (i = 0; i < kv_count; i++) {
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next_write_location = hv_copyto_ringbuffer(outring_info,
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next_write_location,
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kv_list[i].iov_base,
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kv_list[i].iov_len);
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}
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/*
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* Allocate the request ID after the data has been copied into the
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* ring buffer. Once this request ID is allocated, the completion
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* path could find the data and free it.
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*/
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if (desc->flags == VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED) {
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if (channel->next_request_id_callback != NULL) {
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rqst_id = channel->next_request_id_callback(channel, requestid);
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if (rqst_id == VMBUS_RQST_ERROR) {
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spin_unlock_irqrestore(&outring_info->ring_lock, flags);
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return -EAGAIN;
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}
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}
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}
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desc = hv_get_ring_buffer(outring_info) + old_write;
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desc->trans_id = (rqst_id == VMBUS_NO_RQSTOR) ? requestid : rqst_id;
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/* Set previous packet start */
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prev_indices = hv_get_ring_bufferindices(outring_info);
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next_write_location = hv_copyto_ringbuffer(outring_info,
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next_write_location,
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&prev_indices,
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sizeof(u64));
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/* Issue a full memory barrier before updating the write index */
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virt_mb();
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/* Now, update the write location */
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hv_set_next_write_location(outring_info, next_write_location);
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spin_unlock_irqrestore(&outring_info->ring_lock, flags);
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hv_signal_on_write(old_write, channel);
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if (channel->rescind) {
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if (rqst_id != VMBUS_NO_RQSTOR) {
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/* Reclaim request ID to avoid leak of IDs */
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if (channel->request_addr_callback != NULL)
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channel->request_addr_callback(channel, rqst_id);
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}
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return -ENODEV;
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}
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return 0;
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}
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int hv_ringbuffer_read(struct vmbus_channel *channel,
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void *buffer, u32 buflen, u32 *buffer_actual_len,
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u64 *requestid, bool raw)
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{
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struct vmpacket_descriptor *desc;
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u32 packetlen, offset;
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if (unlikely(buflen == 0))
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return -EINVAL;
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*buffer_actual_len = 0;
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*requestid = 0;
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/* Make sure there is something to read */
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desc = hv_pkt_iter_first(channel);
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if (desc == NULL) {
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/*
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* No error is set when there is even no header, drivers are
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* supposed to analyze buffer_actual_len.
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*/
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return 0;
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}
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offset = raw ? 0 : (desc->offset8 << 3);
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packetlen = (desc->len8 << 3) - offset;
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*buffer_actual_len = packetlen;
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*requestid = desc->trans_id;
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if (unlikely(packetlen > buflen))
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return -ENOBUFS;
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/* since ring is double mapped, only one copy is necessary */
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memcpy(buffer, (const char *)desc + offset, packetlen);
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/* Advance ring index to next packet descriptor */
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__hv_pkt_iter_next(channel, desc, true);
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/* Notify host of update */
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hv_pkt_iter_close(channel);
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return 0;
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}
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/*
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* Determine number of bytes available in ring buffer after
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* the current iterator (priv_read_index) location.
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*
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* This is similar to hv_get_bytes_to_read but with private
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* read index instead.
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*/
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static u32 hv_pkt_iter_avail(const struct hv_ring_buffer_info *rbi)
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{
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u32 priv_read_loc = rbi->priv_read_index;
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u32 write_loc = READ_ONCE(rbi->ring_buffer->write_index);
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if (write_loc >= priv_read_loc)
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return write_loc - priv_read_loc;
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else
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return (rbi->ring_datasize - priv_read_loc) + write_loc;
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}
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/*
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* Get first vmbus packet without copying it out of the ring buffer
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*/
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struct vmpacket_descriptor *hv_pkt_iter_first_raw(struct vmbus_channel *channel)
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{
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struct hv_ring_buffer_info *rbi = &channel->inbound;
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hv_debug_delay_test(channel, MESSAGE_DELAY);
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if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
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return NULL;
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return (struct vmpacket_descriptor *)(hv_get_ring_buffer(rbi) + rbi->priv_read_index);
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}
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EXPORT_SYMBOL_GPL(hv_pkt_iter_first_raw);
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/*
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* Get first vmbus packet from ring buffer after read_index
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*
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* If ring buffer is empty, returns NULL and no other action needed.
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*/
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struct vmpacket_descriptor *hv_pkt_iter_first(struct vmbus_channel *channel)
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{
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struct hv_ring_buffer_info *rbi = &channel->inbound;
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struct vmpacket_descriptor *desc, *desc_copy;
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u32 bytes_avail, pkt_len, pkt_offset;
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desc = hv_pkt_iter_first_raw(channel);
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if (!desc)
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return NULL;
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bytes_avail = min(rbi->pkt_buffer_size, hv_pkt_iter_avail(rbi));
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/*
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* Ensure the compiler does not use references to incoming Hyper-V values (which
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* 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;
|
|
|
|
return desc_copy;
|
|
}
|
|
EXPORT_SYMBOL_GPL(hv_pkt_iter_first);
|
|
|
|
/*
|
|
* Get next vmbus packet from ring buffer.
|
|
*
|
|
* Advances the current location (priv_read_index) and checks for more
|
|
* data. If the end of the ring buffer is reached, then return NULL.
|
|
*/
|
|
struct vmpacket_descriptor *
|
|
__hv_pkt_iter_next(struct vmbus_channel *channel,
|
|
const struct vmpacket_descriptor *desc,
|
|
bool copy)
|
|
{
|
|
struct hv_ring_buffer_info *rbi = &channel->inbound;
|
|
u32 packetlen = desc->len8 << 3;
|
|
u32 dsize = rbi->ring_datasize;
|
|
|
|
hv_debug_delay_test(channel, MESSAGE_DELAY);
|
|
/* bump offset to next potential packet */
|
|
rbi->priv_read_index += packetlen + VMBUS_PKT_TRAILER;
|
|
if (rbi->priv_read_index >= dsize)
|
|
rbi->priv_read_index -= dsize;
|
|
|
|
/* more data? */
|
|
return copy ? hv_pkt_iter_first(channel) : hv_pkt_iter_first_raw(channel);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__hv_pkt_iter_next);
|
|
|
|
/* How many bytes were read in this iterator cycle */
|
|
static u32 hv_pkt_iter_bytes_read(const struct hv_ring_buffer_info *rbi,
|
|
u32 start_read_index)
|
|
{
|
|
if (rbi->priv_read_index >= start_read_index)
|
|
return rbi->priv_read_index - start_read_index;
|
|
else
|
|
return rbi->ring_datasize - start_read_index +
|
|
rbi->priv_read_index;
|
|
}
|
|
|
|
/*
|
|
* Update host ring buffer after iterating over packets. If the host has
|
|
* stopped queuing new entries because it found the ring buffer full, and
|
|
* sufficient space is being freed up, signal the host. But be careful to
|
|
* only signal the host when necessary, both for performance reasons and
|
|
* because Hyper-V protects itself by throttling guests that signal
|
|
* inappropriately.
|
|
*
|
|
* Determining when to signal is tricky. There are three key data inputs
|
|
* that must be handled in this order to avoid race conditions:
|
|
*
|
|
* 1. Update the read_index
|
|
* 2. Read the pending_send_sz
|
|
* 3. Read the current write_index
|
|
*
|
|
* The interrupt_mask is not used to determine when to signal. The
|
|
* interrupt_mask is used only on the guest->host ring buffer when
|
|
* sending requests to the host. The host does not use it on the host->
|
|
* guest ring buffer to indicate whether it should be signaled.
|
|
*/
|
|
void hv_pkt_iter_close(struct vmbus_channel *channel)
|
|
{
|
|
struct hv_ring_buffer_info *rbi = &channel->inbound;
|
|
u32 curr_write_sz, pending_sz, bytes_read, start_read_index;
|
|
|
|
/*
|
|
* Make sure all reads are done before we update the read index since
|
|
* the writer may start writing to the read area once the read index
|
|
* is updated.
|
|
*/
|
|
virt_rmb();
|
|
start_read_index = rbi->ring_buffer->read_index;
|
|
rbi->ring_buffer->read_index = rbi->priv_read_index;
|
|
|
|
/*
|
|
* Older versions of Hyper-V (before WS2102 and Win8) do not
|
|
* implement pending_send_sz and simply poll if the host->guest
|
|
* ring buffer is full. No signaling is needed or expected.
|
|
*/
|
|
if (!rbi->ring_buffer->feature_bits.feat_pending_send_sz)
|
|
return;
|
|
|
|
/*
|
|
* Issue a full memory barrier before making the signaling decision.
|
|
* If reading pending_send_sz were to be reordered and happen
|
|
* before we commit the new read_index, a race could occur. If the
|
|
* host were to set the pending_send_sz after we have sampled
|
|
* pending_send_sz, and the ring buffer blocks before we commit the
|
|
* read index, we could miss sending the interrupt. Issue a full
|
|
* memory barrier to address this.
|
|
*/
|
|
virt_mb();
|
|
|
|
/*
|
|
* If the pending_send_sz is zero, then the ring buffer is not
|
|
* blocked and there is no need to signal. This is far by the
|
|
* most common case, so exit quickly for best performance.
|
|
*/
|
|
pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz);
|
|
if (!pending_sz)
|
|
return;
|
|
|
|
/*
|
|
* Ensure the read of write_index in hv_get_bytes_to_write()
|
|
* happens after the read of pending_send_sz.
|
|
*/
|
|
virt_rmb();
|
|
curr_write_sz = hv_get_bytes_to_write(rbi);
|
|
bytes_read = hv_pkt_iter_bytes_read(rbi, start_read_index);
|
|
|
|
/*
|
|
* We want to signal the host only if we're transitioning
|
|
* from a "not enough free space" state to a "enough free
|
|
* space" state. For example, it's possible that this function
|
|
* could run and free up enough space to signal the host, and then
|
|
* run again and free up additional space before the host has a
|
|
* chance to clear the pending_send_sz. The 2nd invocation would
|
|
* be a null transition from "enough free space" to "enough free
|
|
* space", which doesn't warrant a signal.
|
|
*
|
|
* Exactly filling the ring buffer is treated as "not enough
|
|
* space". The ring buffer always must have at least one byte
|
|
* empty so the empty and full conditions are distinguishable.
|
|
* hv_get_bytes_to_write() doesn't fully tell the truth in
|
|
* this regard.
|
|
*
|
|
* So first check if we were in the "enough free space" state
|
|
* before we began the iteration. If so, the host was not
|
|
* blocked, and there's no need to signal.
|
|
*/
|
|
if (curr_write_sz - bytes_read > pending_sz)
|
|
return;
|
|
|
|
/*
|
|
* Similarly, if the new state is "not enough space", then
|
|
* there's no need to signal.
|
|
*/
|
|
if (curr_write_sz <= pending_sz)
|
|
return;
|
|
|
|
++channel->intr_in_full;
|
|
vmbus_setevent(channel);
|
|
}
|
|
EXPORT_SYMBOL_GPL(hv_pkt_iter_close);
|