linux-stable.git/drivers/hv/ring_buffer.c, branch linux-5.10.y

Drivers: hv: vmbus: Drop error message when 'No request id available'

2024-03-15T14:48:22+00:00

[ Upstream commit 0c85c54bf7faeb80c6b76901ed77d93acef0207d ]

Running out of request IDs on a channel essentially produces the same
effect as running out of space in the ring buffer, in that -EAGAIN is
returned.  The error message in hv_ringbuffer_write() should either be
dropped (since we don't output a message when the ring buffer is full)
or be made conditional/debug-only.

Suggested-by: Michael Kelley 
Signed-off-by: Andrea Parri (Microsoft) 
Fixes: e8b7db38449ac ("Drivers: hv: vmbus: Add vmbus_requestor data structure for VMBus hardening")
Link: https://lore.kernel.org/r/20210301191348.196485-1-parri.andrea@gmail.com
Signed-off-by: Wei Liu 
Signed-off-by: Sasha Levin

Drivers: hv: vmbus: Add vmbus_requestor data structure for VMBus hardening

2024-03-15T14:48:21+00:00

[ Upstream commit e8b7db38449ac5b950a3f00519171c4be3e226ff ]

Currently, VMbus drivers use pointers into guest memory as request IDs
for interactions with Hyper-V. To be more robust in the face of errors
or malicious behavior from a compromised Hyper-V, avoid exposing
guest memory addresses to Hyper-V. Also avoid Hyper-V giving back a
bad request ID that is then treated as the address of a guest data
structure with no validation. Instead, encapsulate these memory
addresses and provide small integers as request IDs.

Signed-off-by: Andres Beltran 
Co-developed-by: Andrea Parri (Microsoft) 
Signed-off-by: Andrea Parri (Microsoft) 
Reviewed-by: Michael Kelley 
Reviewed-by: Wei Liu 
Link: https://lore.kernel.org/r/20201109100402.8946-2-parri.andrea@gmail.com
Signed-off-by: Wei Liu 
Stable-dep-of: 9cae43da9867 ("hv_netvsc: Register VF in netvsc_probe if NET_DEVICE_REGISTER missed")
Signed-off-by: Sasha Levin

video: hyperv_fb: Avoid taking busy spinlock on panic path

2023-01-14T09:16:13+00:00

[ Upstream commit 1d044ca035dc22df0d3b39e56f2881071d9118bd ]

The Hyper-V framebuffer code registers a panic notifier in order
to try updating its fbdev if the kernel crashed. The notifier
callback is straightforward, but it calls the vmbus_sendpacket()
routine eventually, and such function takes a spinlock for the
ring buffer operations.

Panic path runs in atomic context, with local interrupts and
preemption disabled, and all secondary CPUs shutdown. That said,
taking a spinlock might cause a lockup if a secondary CPU was
disabled with such lock taken. Fix it here by checking if the
ring buffer spinlock is busy on Hyper-V framebuffer panic notifier;
if so, bail-out avoiding the potential lockup scenario.

Cc: Andrea Parri (Microsoft) 
Cc: Dexuan Cui 
Cc: Haiyang Zhang 
Cc: "K. Y. Srinivasan" 
Cc: Michael Kelley 
Cc: Stephen Hemminger 
Cc: Tianyu Lan 
Cc: Wei Liu 
Tested-by: Fabio A M Martins 
Signed-off-by: Guilherme G. Piccoli 
Reviewed-by: Michael Kelley 
Link: https://lore.kernel.org/r/20220819221731.480795-10-gpiccoli@igalia.com
Signed-off-by: Wei Liu 
Signed-off-by: Sasha Levin

Drivers: hv: vmbus: Prevent load re-ordering when reading ring buffer

2022-04-20T07:23:20+00:00

[ Upstream commit b6cae15b5710c8097aad26a2e5e752c323ee5348 ]

When reading a packet from a host-to-guest ring buffer, there is no
memory barrier between reading the write index (to see if there is
a packet to read) and reading the contents of the packet. The Hyper-V
host uses store-release when updating the write index to ensure that
writes of the packet data are completed first. On the guest side,
the processor can reorder and read the packet data before the write
index, and sometimes get stale packet data. Getting such stale packet
data has been observed in a reproducible case in a VM on ARM64.

Fix this by using virt_load_acquire() to read the write index,
ensuring that reads of the packet data cannot be reordered
before it. Preventing such reordering is logically correct, and
with this change, getting stale data can no longer be reproduced.

Signed-off-by: Michael Kelley 
Reviewed-by: Andrea Parri (Microsoft) 
Link: https://lore.kernel.org/r/1648394710-33480-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu 
Signed-off-by: Sasha Levin

drivers: hv: vmbus: Introduce latency testing

2019-11-22T01:10:44+00:00

Introduce user specified latency in the packet reception path
By exposing the test parameters as part of the debugfs channel
attributes. We will control the testing state via these attributes.

Signed-off-by: Branden Bonaby 
Reviewed-by: Michael Kelley 
Signed-off-by: Sasha Levin

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 320

2019-06-05T15:37:05+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms and conditions of the gnu general public license
  version 2 as published by the free software foundation this program
  is distributed in the hope it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details you should have received a copy of the gnu general
  public license along with this program if not write to the free
  software foundation inc 59 temple place suite 330 boston ma 02111
  1307 usa

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 33 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Reviewed-by: Kate Stewart 
Reviewed-by: Alexios Zavras 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190530000435.254582722@linutronix.de
Signed-off-by: Greg Kroah-Hartman

Drivers: hv: vmbus: Fix race condition with new ring_buffer_info mutex

2019-04-10T22:58:56+00:00

Fix a race condition that can result in a ring buffer pointer being set
to null while a "_show" function is reading the ring buffer's data. This
problem was discussed here: https://lkml.org/lkml/2018/10/18/779

To fix the race condition, add a new mutex lock to the
"hv_ring_buffer_info" struct. Add a new function,
"hv_ringbuffer_pre_init()", where a channel's inbound and outbound
ring_buffer_info mutex locks are initialized.

Acquire/release the locks in the "hv_ringbuffer_cleanup()" function,
which is where the ring buffer pointers are set to null.

Acquire/release the locks in the four channel-level "_show" functions
that access ring buffer data. Remove the "const" qualifier from the
"vmbus_channel" parameter and the "rbi" variable of the channel-level
"_show" functions so that the locks can be acquired/released in these
functions.

Acquire/release the locks in hv_ringbuffer_get_debuginfo(). Remove the
"const" qualifier from the "hv_ring_buffer_info" parameter so that the
locks can be acquired/released in this function.

Signed-off-by: Kimberly Brown 
Reviewed-by: Michael Kelley 
Signed-off-by: Sasha Levin

Drivers: hv: vmbus: Set ring_info field to 0 and remove memset

2019-04-10T22:58:56+00:00

Set "ring_info->priv_read_index" to 0. Now, all of ring_info's fields
are explicitly set in this function. The memset() call is no longer
necessary, so remove it.

Signed-off-by: Kimberly Brown 
Reviewed-by: Michael Kelley 
Signed-off-by: Sasha Levin

Drivers: hv: vmbus: Expose counters for interrupts and full conditions

2019-02-15T01:56:10+00:00

Counter values for per-channel interrupts and ring buffer full
conditions are useful for investigating performance.

Expose counters in sysfs for 2 types of guest to host interrupts:
1) Interrupts caused by the channel's outbound ring buffer transitioning
from empty to not empty
2) Interrupts caused by the channel's inbound ring buffer transitioning
from full to not full while a packet is waiting for enough buffer space to
become available

Expose 2 counters in sysfs for the number of times that write operations
encountered a full outbound ring buffer:
1) The total number of write operations that encountered a full
condition
2) The number of write operations that were the first to encounter a
full condition

Increment the outbound full condition counters in the
hv_ringbuffer_write() function because, for most drivers, a full
outbound ring buffer is detected in that function. Also increment the
outbound full condition counters in the set_channel_pending_send_size()
function. In the hv_sock driver, a full outbound ring buffer is detected
and set_channel_pending_send_size() is called before
hv_ringbuffer_write() is called.

I tested this patch by confirming that the sysfs files were created and
observing the counter values. The values seemed to increase by a
reasonable amount when the Hyper-v related drivers were in use.

Signed-off-by: Kimberly Brown 
Reviewed-by:  Michael Kelley 
Signed-off-by: Sasha Levin

Drivers: hv: vmbus: Check for ring when getting debug info

2019-01-09T19:20:47+00:00

fc96df16a1ce is good and can already fix the "return stack garbage" issue,
but let's also improve hv_ringbuffer_get_debuginfo(), which would silently
return stack garbage, if people forget to check channel->state or
ring_info->ring_buffer, when using the function in the future.

Having an error check in the function would eliminate the potential risk.

Add a Fixes tag to indicate the patch depdendency.

Fixes: fc96df16a1ce ("Drivers: hv: vmbus: Return -EINVAL for the sys files for unopened channels")
Cc: stable@vger.kernel.org
Cc: K. Y. Srinivasan 
Cc: Haiyang Zhang 
Signed-off-by: Stephen Hemminger 
Signed-off-by: Dexuan Cui 
Signed-off-by: Sasha Levin