From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Hyperv's synic (that we emulate) is a feature that allows the guest
to place some magic (4k) pages of RAM anywhere it likes in GPA.
This confuses vhost's RAM section merging when these pages
land over the top of hugepages.

This v3 takes a different approach to v2 and v1.
It avoids doing the hugepage alignment except for vhost-user:

  a) Vhost kernel : doesn't need alignment, it's turned off
     synic won't cause a problem.

  b) vhost user : Already filters out anything without an fd
     synic won't cause a problem.

(Not tried vhost-user yet, it currently seems broken even without this).

This might also cause some other reported problems with vga
pages causing similar issues.

bz: https://bugzilla.redhat.com/show_bug.cgi?id=1779041

Dr. David Alan Gilbert (2):
  vhost: Add names to section rounded warning
  vhost: Only align sections for vhost-user

 hw/virtio/vhost.c | 39 +++++++++++++++++++++------------------
 1 file changed, 21 insertions(+), 18 deletions(-)

-- 
2.24.1

Patchew URL: https://patchew.org/QEMU/20200116202414.157959-1-dgilbert@redhat.com/



Hi,

This series seems to have some coding style problems. See output below for
more information:

Message-id: 20200116202414.157959-1-dgilbert@redhat.com
Type: series
Subject: [PATCH v3 0/2] Fix hyperv synic on vhost

=== TEST SCRIPT BEGIN ===
#!/bin/bash
git rev-parse base > /dev/null || exit 0
git config --local diff.renamelimit 0
git config --local diff.renames True
git config --local diff.algorithm histogram
./scripts/checkpatch.pl --mailback base..
=== TEST SCRIPT END ===

From https://github.com/patchew-project/qemu
 * [new tag]         patchew/20200116202414.157959-1-dgilbert@redhat.com -> patchew/20200116202414.157959-1-dgilbert@redhat.com
Switched to a new branch 'test'
f7aeff2 vhost: Only align sections for vhost-user
5bb467f vhost: Add names to section rounded warning

=== OUTPUT BEGIN ===
1/2 Checking commit 5bb467f4ac3b (vhost: Add names to section rounded warning)
2/2 Checking commit f7aeff24a99a (vhost: Only align sections for vhost-user)
ERROR: trailing whitespace
#45: FILE: hw/virtio/vhost.c:554:
+    if (dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER) {   $

WARNING: line over 80 characters
#60: FILE: hw/virtio/vhost.c:569:
+        trace_vhost_region_add_section_aligned(section->mr->name, mrs_gpa, mrs_size,

total: 1 errors, 1 warnings, 43 lines checked

Patch 2/2 has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

=== OUTPUT END ===

Test command exited with code: 1


The full log is available at
http://patchew.org/logs/20200116202414.157959-1-dgilbert@redhat.com/testing.checkpatch/?type=message.
---
Email generated automatically by Patchew [https://patchew.org/].
Please send your feedback to patchew-devel@redhat.com

* no-reply@patchew.org (no-reply@patchew.org) wrote:
> Patchew URL: https://patchew.org/QEMU/20200116202414.157959-1-dgilbert@redhat.com/
> 
> 
> 
> Hi,
> 
> This series seems to have some coding style problems. See output below for
> more information:
> 
> Message-id: 20200116202414.157959-1-dgilbert@redhat.com
> Type: series
> Subject: [PATCH v3 0/2] Fix hyperv synic on vhost
> 
> === TEST SCRIPT BEGIN ===
> #!/bin/bash
> git rev-parse base > /dev/null || exit 0
> git config --local diff.renamelimit 0
> git config --local diff.renames True
> git config --local diff.algorithm histogram
> ./scripts/checkpatch.pl --mailback base..
> === TEST SCRIPT END ===
> 
> From https://github.com/patchew-project/qemu
>  * [new tag]         patchew/20200116202414.157959-1-dgilbert@redhat.com -> patchew/20200116202414.157959-1-dgilbert@redhat.com
> Switched to a new branch 'test'
> f7aeff2 vhost: Only align sections for vhost-user
> 5bb467f vhost: Add names to section rounded warning
> 
> === OUTPUT BEGIN ===
> 1/2 Checking commit 5bb467f4ac3b (vhost: Add names to section rounded warning)
> 2/2 Checking commit f7aeff24a99a (vhost: Only align sections for vhost-user)
> ERROR: trailing whitespace
> #45: FILE: hw/virtio/vhost.c:554:
> +    if (dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER) {   $
> 
> WARNING: line over 80 characters
> #60: FILE: hw/virtio/vhost.c:569:
> +        trace_vhost_region_add_section_aligned(section->mr->name, mrs_gpa, mrs_size,
> 
> total: 1 errors, 1 warnings, 43 lines checked

Oops, minor whitespace; easy to fix if people actually like this fix.

Dave

> Patch 2/2 has style problems, please review.  If any of these errors
> are false positives report them to the maintainer, see
> CHECKPATCH in MAINTAINERS.
> 
> === OUTPUT END ===
> 
> Test command exited with code: 1
> 
> 
> The full log is available at
> http://patchew.org/logs/20200116202414.157959-1-dgilbert@redhat.com/testing.checkpatch/?type=message.
> ---
> Email generated automatically by Patchew [https://patchew.org/].
> Please send your feedback to patchew-devel@redhat.com
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK