| 2023-07-03 05:34:30 |
Chengen Du |
bug |
|
|
added bug |
| 2023-07-03 05:34:51 |
Chengen Du |
nominated for series |
|
Ubuntu Jammy |
|
| 2023-07-03 05:34:51 |
Chengen Du |
bug task added |
|
qemu (Ubuntu Jammy) |
|
| 2023-07-03 05:37:00 |
Chengen Du |
qemu (Ubuntu): assignee |
|
ChengEn, Du (chengendu) |
|
| 2023-07-03 05:37:03 |
Chengen Du |
qemu (Ubuntu Jammy): assignee |
|
ChengEn, Du (chengendu) |
|
| 2023-07-03 05:43:29 |
Chengen Du |
attachment added |
|
jammy_use_the_request_length_for_iov_alignment.debdiff https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/2025591/+attachment/5683484/+files/jammy_use_the_request_length_for_iov_alignment.debdiff |
|
| 2023-07-03 05:43:53 |
Chengen Du |
qemu (Ubuntu Jammy): status |
New |
In Progress |
|
| 2023-07-03 05:43:57 |
Chengen Du |
qemu (Ubuntu): status |
New |
In Progress |
|
| 2023-07-03 06:50:03 |
Chengen Du |
tags |
|
sts-sponsor sts-sru-needed |
|
| 2023-07-03 08:16:39 |
Ubuntu Foundations Team Bug Bot |
tags |
sts-sponsor sts-sru-needed |
patch sts-sponsor sts-sru-needed |
|
| 2023-07-03 08:16:42 |
Ubuntu Foundations Team Bug Bot |
bug |
|
|
added subscriber Ubuntu Sponsors |
| 2023-07-03 19:16:11 |
Mauricio Faria de Oliveira |
removed subscriber Ubuntu Sponsors |
|
|
|
| 2023-07-03 19:18:32 |
Mauricio Faria de Oliveira |
tags |
patch sts-sponsor sts-sru-needed |
patch se-sponsor-mfo |
|
| 2023-07-03 19:19:49 |
Mauricio Faria de Oliveira |
bug |
|
|
added subscriber Support Engineering Sponsors |
| 2023-07-03 22:11:45 |
Mauricio Faria de Oliveira |
description |
[Impact]
When the logical block size of the virtual block device is smaller than the block device it is backed by on the host,
qemu encounters a situation where it needs to bounce unaligned buffers during the use of direct IO.
In the past, the logical block size happened to align with the memory page offset, leading qemu to mistakenly use the memory offset as the block size.
However, a kernel commit b1a000d3b8ec resolved this issue by separating memory alignment from the logical block size.
As a result, qemu now has an incorrect understanding of the minimum vector size.
[Fix]
Upstream commit 25474d90aa50 fixed this issue.
==========
Author: Keith Busch <kbusch@kernel.org>
CommitDate: Fri Sep 30 18:43:44 2022 +0200
block: use the request length for iov alignment
An iov length needs to be aligned to the logical block size, which may
be larger than the memory alignment.
Tested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Message-Id: <20220929200523.3218710-3-kbusch@meta.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
==========
[Test Plan]
1. Get a ubuntu image and convert it to RAW format
wget https://cloud-images.ubuntu.com/jammy/current/jammy-server-cloudimg-amd64-disk-kvm.img
qemu-img convert jammy-server-cloudimg-amd64-disk-kvm.img jammy-server-cloudimg-amd64-disk-kvm.raw
2. Set up a loop device with RAW image
losetup -b 4096 -f jammy-server-cloudimg-amd64-disk-kvm.raw
3. Get loop device number by `losetup -a` command
4. Start the virtual machine
qemu-system-x86_64 -enable-kvm -drive file=/dev/loopX,format=raw,cache=none --nographic
[Where problems could occur]
The patch addressed the issue of misusing the memory offset as the block size.
This problem only occurred when the cache option was set to "none" and the Linux kernel being used had the commit b1a000d3b8ec.
However, it is worth noting that the patch also worked effectively with older kernels.
[Other Info] |
[Impact]
* Failure to boot VMs on Jammy with the HWE 6.2 kernel
(from Lunar) when using direct IO (e.g., cache=none)
if the virtual block device's block size is smaller
than the host device/file's block size.
* The issue might become increasingly more common with
storage with 4k sector size, and as Jammy/22.04 ages
and users go to newer/HWE kernels for newer hardware.
[Fix]
* When the logical block size of the virtual block device
is smaller than the block device's it is backed by on
the host, qemu encounters a situation where it needs to
bounce unaligned buffers during the use of direct IO.
In the past, the logical block size happened to align
with the memory page offset, leading qemu to mistakenly
use the memory offset as the block size.
However, a kernel commit b1a000d3b8ec (in Linux v6.0)
resolved this issue by separating memory alignment
from the logical block size.
As a result, qemu now has an incorrect understanding
of the minimum vector size.
The qemu commit 25474d90aa50 ("block: use the request
length for iov alignment") fixes this (in QEMU v7.2).
[Test Plan]
* Run qemu with a block device (default block size: 512)
backed by a loop device with block size of 4096 bytes,
without cache (ie, direct IO) on Jammy with HWE kernel:
LOOPDEV=$(losetup --find --show --sector-size 4096 jammy.raw)
qemu-system-x86_64 -drive file=$LOOPDEV,format=raw,cache=none \
-boot order=c -nodefaults -no-user-config \
-nographic -serial stdio -enable-kvm
Expected:
# qemu-system-x86_64 ...
SeaBIOS (version 1.15.0-1)
Booting from Hard Disk...
GRUB_FORCE_PARTUUID set, initrdless boot failed. Attempting with initrd.
Linux version <...>
...
Actual:
# qemu-system-x86_64 ...
SeaBIOS (version 1.15.0-1)
Booting from Hard Disk...
Boot failed: could not read the boot disk
Booting from Floppy...
Boot failed: could not read the boot disk
No bootable device.
<ctrl-c>
qemu-system-x86_64: terminating on signal 2
[Where problems could occur]
* Potential regressions would likely manifest in QEMU
file I/O path, possibly with errors or performance
differences due to the change in alignment detection.
These should be easy to test on early testing with
a relatively small test matrix:
- (host) kernel: GA (5.15) and HWE (6.2)
- (host) block size 512 and 4096 bytes
An incremental patch for tracing the old/new value
used by QEMU (changed by the fix) will be used for
verification/debugging purposes.
[Other Info]
* Kinetic is affected (QEMU 7.0 < 7.2) but will not
be fixed due to EOL in ~2 weeks and Lunar (upgrade)
is fixed. |
|
| 2023-07-03 22:12:19 |
Mauricio Faria de Oliveira |
nominated for series |
|
Ubuntu Kinetic |
|
| 2023-07-03 22:12:19 |
Mauricio Faria de Oliveira |
bug task added |
|
qemu (Ubuntu Kinetic) |
|
| 2023-07-03 22:12:19 |
Mauricio Faria de Oliveira |
nominated for series |
|
Ubuntu Lunar |
|
| 2023-07-03 22:12:19 |
Mauricio Faria de Oliveira |
bug task added |
|
qemu (Ubuntu Lunar) |
|
| 2023-07-03 22:12:36 |
Mauricio Faria de Oliveira |
qemu (Ubuntu Jammy): importance |
Undecided |
High |
|
| 2023-07-03 22:12:40 |
Mauricio Faria de Oliveira |
qemu (Ubuntu Kinetic): status |
New |
Won't Fix |
|
| 2023-07-03 22:12:45 |
Mauricio Faria de Oliveira |
qemu (Ubuntu Lunar): status |
New |
Invalid |
|
| 2023-07-03 22:12:52 |
Mauricio Faria de Oliveira |
qemu (Ubuntu): status |
In Progress |
Invalid |
|
| 2023-07-03 22:12:55 |
Mauricio Faria de Oliveira |
qemu (Ubuntu): assignee |
ChengEn, Du (chengendu) |
|
|
| 2023-07-03 22:15:09 |
Mauricio Faria de Oliveira |
summary |
Align the iov length to the logical block size |
Boot error on Jammy on the 6.2 HWE kernel (Lunar) with direct IO if virtual block size < host block size |
|
| 2023-07-03 22:15:38 |
Mauricio Faria de Oliveira |
description |
[Impact]
* Failure to boot VMs on Jammy with the HWE 6.2 kernel
(from Lunar) when using direct IO (e.g., cache=none)
if the virtual block device's block size is smaller
than the host device/file's block size.
* The issue might become increasingly more common with
storage with 4k sector size, and as Jammy/22.04 ages
and users go to newer/HWE kernels for newer hardware.
[Fix]
* When the logical block size of the virtual block device
is smaller than the block device's it is backed by on
the host, qemu encounters a situation where it needs to
bounce unaligned buffers during the use of direct IO.
In the past, the logical block size happened to align
with the memory page offset, leading qemu to mistakenly
use the memory offset as the block size.
However, a kernel commit b1a000d3b8ec (in Linux v6.0)
resolved this issue by separating memory alignment
from the logical block size.
As a result, qemu now has an incorrect understanding
of the minimum vector size.
The qemu commit 25474d90aa50 ("block: use the request
length for iov alignment") fixes this (in QEMU v7.2).
[Test Plan]
* Run qemu with a block device (default block size: 512)
backed by a loop device with block size of 4096 bytes,
without cache (ie, direct IO) on Jammy with HWE kernel:
LOOPDEV=$(losetup --find --show --sector-size 4096 jammy.raw)
qemu-system-x86_64 -drive file=$LOOPDEV,format=raw,cache=none \
-boot order=c -nodefaults -no-user-config \
-nographic -serial stdio -enable-kvm
Expected:
# qemu-system-x86_64 ...
SeaBIOS (version 1.15.0-1)
Booting from Hard Disk...
GRUB_FORCE_PARTUUID set, initrdless boot failed. Attempting with initrd.
Linux version <...>
...
Actual:
# qemu-system-x86_64 ...
SeaBIOS (version 1.15.0-1)
Booting from Hard Disk...
Boot failed: could not read the boot disk
Booting from Floppy...
Boot failed: could not read the boot disk
No bootable device.
<ctrl-c>
qemu-system-x86_64: terminating on signal 2
[Where problems could occur]
* Potential regressions would likely manifest in QEMU
file I/O path, possibly with errors or performance
differences due to the change in alignment detection.
These should be easy to test on early testing with
a relatively small test matrix:
- (host) kernel: GA (5.15) and HWE (6.2)
- (host) block size 512 and 4096 bytes
An incremental patch for tracing the old/new value
used by QEMU (changed by the fix) will be used for
verification/debugging purposes.
[Other Info]
* Kinetic is affected (QEMU 7.0 < 7.2) but will not
be fixed due to EOL in ~2 weeks and Lunar (upgrade)
is fixed. |
[Impact]
* Failure to boot VMs on Jammy with the HWE 6.2 kernel
(from Lunar) when using direct IO (e.g., cache=none)
if the virtual block device's block size is smaller
than the host device/file's block size.
* The issue might become increasingly more common with
storage with 4k sector size, and as Jammy/22.04 ages
and users go to newer/HWE kernels for newer hardware.
[Fix]
* When the logical block size of the virtual block device
is smaller than the block device's it is backed by on
the host, qemu encounters a situation where it needs to
bounce unaligned buffers during the use of direct IO.
In the past, the logical block size happened to align
with the memory page offset, leading qemu to mistakenly
use the memory offset as the block size.
However, a kernel commit b1a000d3b8ec (in Linux v6.0)
resolved this issue by separating memory alignment
from the logical block size.
As a result, qemu now has an incorrect understanding
of the minimum vector size.
The qemu commit 25474d90aa50 ("block: use the request
length for iov alignment") fixes this (in QEMU v7.2).
[Test Plan]
* Run qemu with a block device (default block size: 512)
backed by a loop device with block size of 4096 bytes,
without cache (ie, direct IO) on Jammy with HWE kernel:
LOOPDEV=$(losetup --find --show --sector-size 4096 jammy.raw)
qemu-system-x86_64 -drive file=$LOOPDEV,format=raw,cache=none \
-boot order=c -nodefaults -no-user-config \
-nographic -serial stdio -enable-kvm
Expected:
# qemu-system-x86_64 ...
SeaBIOS (version 1.15.0-1)
Booting from Hard Disk...
GRUB_FORCE_PARTUUID set, initrdless boot failed. Attempting with initrd.
Linux version <...>
...
Actual:
# qemu-system-x86_64 ...
SeaBIOS (version 1.15.0-1)
Booting from Hard Disk...
Boot failed: could not read the boot disk
Booting from Floppy...
Boot failed: could not read the boot disk
No bootable device.
[Where problems could occur]
* Potential regressions would likely manifest in QEMU
file I/O path, possibly with errors or performance
differences due to the change in alignment detection.
These should be easy to test on early testing with
a relatively small test matrix:
- (host) kernel: GA (5.15) and HWE (6.2)
- (host) block size 512 and 4096 bytes
An incremental patch for tracing the old/new value
used by QEMU (changed by the fix) will be used for
verification/debugging purposes.
[Other Info]
* Kinetic is affected (QEMU 7.0 < 7.2) but will not
be fixed due to EOL in ~2 weeks and Lunar (upgrade)
is fixed. |
|
| 2023-07-04 03:44:17 |
Ubuntu Archive Robot |
bug |
|
|
added subscriber Mauricio Faria de Oliveira |
| 2023-07-04 13:42:28 |
Mauricio Faria de Oliveira |
attachment added |
|
lp2025591-qemu-jammy-v2.debdiff https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/2025591/+attachment/5683853/+files/lp2025591-qemu-jammy-v2.debdiff |
|
| 2023-07-04 15:25:34 |
Tyler Stachecki |
bug |
|
|
added subscriber Tyler Stachecki |
| 2023-07-05 13:49:30 |
Robie Basak |
qemu (Ubuntu Jammy): status |
In Progress |
Fix Committed |
|
| 2023-07-05 13:49:31 |
Robie Basak |
bug |
|
|
added subscriber Ubuntu Stable Release Updates Team |
| 2023-07-05 13:49:33 |
Robie Basak |
bug |
|
|
added subscriber SRU Verification |
| 2023-07-05 13:49:43 |
Robie Basak |
tags |
patch se-sponsor-mfo |
patch se-sponsor-mfo verification-needed verification-needed-jammy |
|
| 2023-07-05 17:31:27 |
Mauricio Faria de Oliveira |
tags |
patch se-sponsor-mfo verification-needed verification-needed-jammy |
patch verification-done verification-done-jammy |
|
| 2023-07-13 14:52:59 |
Launchpad Janitor |
qemu (Ubuntu Jammy): status |
Fix Committed |
Fix Released |
|
| 2023-07-13 14:53:05 |
Andreas Hasenack |
removed subscriber Ubuntu Stable Release Updates Team |
|
|
|
